Diseases and Husbandry of Cattle 2024-25 Notes PDF

University of Edinburgh Royal (Dick) School of Veterinary Studies ICC FARM ANIMAL DISEASES AND HUSBANDRY OF CATTLE Course Organiser: Jeanne Dennehy Codes: L4FACA01-54 Fourth Year Lecture Course, Semester 1: 2024: Session 2024-25 DISEASES AND HUSBANDRY OF CATTLE CONTENTS Lecture Code Lecture Title Page CA01 Introduction, preventative medicine and health planning 1 CA02 Production disease in dairy cattle and costs 6 CA03-5 Helping your clients maximise health, welfare, and productivity in 12 a beef suckler herd CA06-7 Farm animal pharmacology and therapeutics 27 CA08 Dairy calf health, management, and welfare 34 CA09-10 Diarrhoea 43 CA11 Housing requirements and assessment 53 CA12-13 Bovine respiratory diseases (young stock) 56 CA14-15 Medical conditions of the bovine gastro-intestinal tract 68 CA16 Respiratory Disease of Adult Cattle 76 CA17-18 Surgical conditions of the bovine abdomen 80 CA19 Common surgical procedures in farm animals 92 CA20 Endemic infectious diseases 1 99 CA21 Endemic infectious diseases 2 108 CA22 Endemic infectious diseases 3 116 CA23-24 Farm animal ophthalmology and bovine skin diseases 122 CA25 Urinary tract disease in farm animals 130 CA26-27 Practical nutrition 134 CA28 Farm animal toxicology 1 (plant poisons) 147 CA29 Farm animal toxicology 2 (mycotoxins and metals) 152 CA30-31 Trace elements 158 CA32 Diet assessment in Dairy Cattle 170 CA33-36 Mastitis 176 CA37 Routine foot care and prevention of lameness in cattle 204 CA38 Claw horn disease in cattle 208 CA39 Infectious causes of lameness in cattle 212 CA40 Herd lameness 217 CA41 Energy balance disorders in ruminants 221 CA42 Hypocalcaemia (milk fever) 226 CA43 Hypomagnesaemia (grass staggers) 231 CA44 Downer cow 236 CA45 Reproduction - The pregnant cow 241 CA46 Reproduction - The postpartum cow 1 247 CA47 Reproduction - The postpartum cow 2 251 CA48-49 Reproductive surgery – Ruminant 1&2 255 CA50-51 Reproduction - Management of dairy cattle for maximum 264 reproductive efficiency 1&2 CA52 Reproduction - The Postpartum Cow 3 276 CA53 Reproduction – Infertility and abortion in cattle 281 CA54 Practical aspects of artificial breeding techniques in the cattle and 286 sheep breeding industry R(D)SVS Husbandry and Diseases of Cattle Introduction and Health Planning Alastair Macrae Sept 2024 Brief overview of UK livestock farming as of August 2024 The price paid to UK dairy farmers for their milk was very high in 2022 (see left graph below). Unfortunately this resulted in an increase in milk production from the UK dairy herd, which has subsequently led to a drop in milk price as demand was not able to keep up with the excess supply. In contrast, beef prices (see right graph below) have remained consistently high in 2024 as a result of increased demand for beef from consumers, reduced supply and high export levels to the EU. Unfortunately whilst these prices for milk and beef are good, farmers have been faced with significant increases in input costs – especially the three “F”s (feed, fertilizer and fuel). Therefore many livestock farms are continuing to struggle to make a profit, and so significant numbers of dairy farmers have stopped milk production. Having left the EU, the UK is now free to design its own agricultural subsidy policy to replace the EU’s Common Agricultural Policy (CAP). In 2018, UK farmers received around £3.5 billion per year in CAP payments. England has published plans to adopt the principle of “public money for public goods”, meaning that farmers will be paid for mainly environmental benefits, as opposed to farming, and direct subsidy payments to farmers will end by 2024. However Scotland is planning to keep direct subsidy payments until 2026, after which 70% of the subsidy system will be direct payments to farmers to support production, and 30% will be for environmental schemes. With the rising cost of living, food security has been prominent, and there has been public hostility to proposed UK government trade deals involving the importation of “chlorinated chicken” and “hormone treated beef” from countries such as Australia. This illustrates the UK public concerns over the import of cheaper foodstuffs produced under lower standards compared to those in place in the UK. There are also significant environmental concerns facing farming, relating to issues such as greenhouse gas emissions (resulting from methane emissions from ruminant livestock as well as slurry), as well as nitrate and phosphate contamination of watercourses. In the Netherlands, it has been estimated that over 10,000 livestock farms will need to close if the country is to meet its nitrogen reduction targets. Another significant pressure on the agricultural industry is the use of antimicrobial drugs, mainly due to concerns over Antimicrobial Resistance (AMR). RUMA’s Targets Task Force set targets in 2017 for UK livestock sectors to reduce their use of antimicrobial drugs, resulting in a 50% reduction in two years. Part of this has been driven by changes in the Red Tractor Farm Assurance standards, which now only allow the use of Highest Priority - Critically Important antibiotics (HP-CIAs) after sensitivity testing showing that they are the only antibiotics that can be used. In terms of animal disease control, this is either decided by A) the government, which controls Notifiable Diseases such as Bovine Tuberculosis, Foot & Mouth Disease and Bluetongue or B) the agricultural industry, which has voluntary schemes involved in the control of diseases such as Johne’s Disease in dairy cattle (National Johne's Management Plan) or BVD in England (BVDFree England). 1 R(D)SVS Husbandry and Diseases of Cattle Introduction and Health Planning Alastair Macrae Sept 2024 Preventative Medicine Programmes and Herd/Flock Health Planning Preventative medicine programmes involve a combination of regular veterinary visits and good herd management to achieve and maintain optimum animal health and production. Emphasis is placed on the prevention of disease rather than treatment, as by the time disease becomes apparent, production will have already been lost. The focus therefore moves away from individual sick animal treatment, to whole herd/flock management. Traditionally, this has predominantly involved fertility work on cattle farms by the veterinary surgeon (PDing cows, fortnightly fertility visits etc.) as well as other advisory work on mastitis control, programme for anthelmintic treatments etc. Principles of preventative medicine In order for a preventative medicine programme to work successfully, the farmer/manager must be skilled and motivated to improve the performance of the farm. There must also be a system of records in place for production performance and disease rates. The veterinary surgeon must also be trained and enthusiastic, with knowledge not only of disease conditions but also farm management, performance and economics. Communication skills and client education are one of the key skills needed in implanting preventative medicine programmes. It involves a team approach, including the veterinary surgeon, the farmer/manager, farm staff, nutritional advisors, laboratory and diagnostic services, financial advisors etc. In return, the veterinary surgeon must be able to charge realistic fees for these services. Aims and objectives Optimising health status, by prevention of disease and losses due to subclinical disease Increased efficiency and productivity Increased longevity – by reducing “forced” culling and death rates Ensuring good animal welfare and husbandry Production of good quality produce, and ensuring food safety Maximising profitability Objectives set in health plans must be SMART targets:  Specific. Aims should be clearly known to the farmer, stockmen and vet, and targeted for each individual farm.  Measurable. The results of the objectives should be recorded, in order to see if progress is being made, or the situation needs to be re-examined.  Achievable. There is no point in setting unrealistic targets (eg. eliminating mastitis). It will only lead to disillusionment (for both the farmer and vet!!)  Relevant. The targets must be relevant in terms of the overall production aims of the farm. If the BMSCC is already in the premium band, is there any point in trying to reduce it even further?  Time-based. The targets should be met within a reasonable period. If not, the reasons for failure should be examined and the target reassessed. Targets can be set using data from standard texts (your lecture notes will contain most of the relevant targets for dairy, beef and sheep farms; or use of SAC/AHDB/QMS Beef and Sheep Yearbooks). They must be up-to-date and specific for each individual farm. The costs for some of the most important disease conditions have been worked out (see lecture on production diseases), and thus the value of these targets can be demonstrated to the farmer. 2 R(D)SVS Husbandry and Diseases of Cattle Introduction and Health Planning Alastair Macrae Sept 2024 Overview of a preventative medicine (Herd Health and Production) protocol Objectives Execution Farm Data Clinical inspection evaluation examination Decision making Farm inspection Herd and Clinical data external data examination data Monitoring Evaluation Interpretation Have targets been met? Yes No Follow-up Continue monitoring Reset targets Analysis Diagnosis Intervention Follow-up Evaluation of interventions 3 R(D)SVS Husbandry and Diseases of Cattle Introduction and Health Planning Alastair Macrae Sept 2024 Overview of components of a preventative medicine programme 1. Objectives. Defining objectives is a basic components of any preventative medicine programme, and the key point is that these vary from farm to farm – each farm must be treated as an individual. The targets must be agreed between the farmer and the vet. 2. Implementation of programme (execution). a) Data evaluation. There needs to be data to evaluate!! – so there must be some method of recording farm health data, to assess current performance. Some of this will be done automatically to comply with legislation (eg. movements via BCMS, medicines book). Is this data accurate? b) Clinical examination. Clinical examination of individual animals is also a part of the programme, but does not necessarily focus on individual sick animals. c) Farm inspection. This will concentrate on management of the farm, and includes ration evaluation, feeding and pasture management, milking routine etc. 3. Decision making. This is based on monitoring, evaluation and interpretation of all the factors discussed in implementation of your advice. 4. Follow up. Just because the targets may have been met, there should be no let-up in control measures/protocols. Sections of a preventative medicine or health plan This list takes into to account all the factors previously discussed but is not exhaustive, and is given to show the rough areas that a health plan should address. It is vital that a health plan is tailored for the individual farm – all of these headings will vary according to the multitude of different production systems found. It should be reviewed annually (at least). 1. Details of farm. 2. Current production data. This needs to be taken from accurate farm records, and will include calving/lambing percentages, disease and disposal rates, milk production etc. 3. Production targets Monitoring and recording of past and current performance Setting of targets in context of farm and husbandry performance 4. Reproductive performance. 5. Nutritional management. Although detailed nutritional management and ration formulation is usually left to nutritional advisors, health plans should incorporate regular body condition scoring, use of metabolic profiles, advice on changes in ration etc. 6. Replacement policy. This will vary depending on whether of not the farm is closed or not. If animals are brought in, isolation and inspection facilities should be available. 7. Disease control. 8. Control of infectious disease. This should be targeted to the major infectious disease conditions on the farm, but may include: current status of infectious diseases on the farm, identification of diseases and ongoing monitoring, vaccination programmes etc. 9. Parasite control. Protocols may be necessary for:  Endoparasites – gastrointestinal, lungworm, fasciolosis.  Ectoparasites – lice, sheep scab, mange mites, blowfly, tick-borne diseases. 10. Neonatal care. 11. Biosecurity. This is discussed on the next page. 12. Medicines usage. This is a statutory requirement (medicines book, records, storage). 13. Stockmanship and management. 14. Calendar of health plan. This can be an excellent method of showing an overview of the health plan, highlighting routine procedures/treatments and review of plan. 4 R(D)SVS Husbandry and Diseases of Cattle Introduction and Health Planning Alastair Macrae Sept 2024 Biosecurity helps in the control and even eradication of diseases, resulting in reduced drug usage and increased profitability. In its broadest sense, biosecurity means: Preventing the introduction of new diseases onto the farm. Minimising the spread of disease within the herd/flock. 1. Maintain a closed herd/flock. The most common source of new diseases is the introduction of infected animals including purchases, hire, away wintering of hoggs etc. 2. Operate an isolation policy for purchased stock. Ideally, animals should be bought from a herd/flock of known health status that matches that of the recipient herd. Purchased stock (or stock returning from shows) should be isolated away from all other stock for a minimum period of 4 weeks, and regularly inspected for signs of disease. 3. Provide clean feed and water. Food and water (eg. streams, rivers and flooded pastures) may all represent a risk of the introduction of disease (eg. Salmonella, liver fluke). 4. Control visitors and vehicles. High-risk visitors include lambing help, contractors (eg. CLA with shearing), veterinary surgeons, feed companies and knacker services. All must clean and disinfect themselves and equipment between farms (and be seen to do so). 5. Control rodents and birds. 6. Define and monitor health status. In addition to the prevention of new infections, the herd/flock needs to be monitored regularly to assess the health status. 7. Operate a disease control programme. This can involve vaccination programmes, strategic medication, culling, husbandry and nutritional advice. It will also involve the control of zoonotic pathogens. Further reading: Duncan, A.L. (1990) Health security in cattle herds. In Practice 12 pp 29-32 Application of preventative medicine programmes / health plans on farm Show interest and enthusiasm for setting up preventative medicine plan. Select suitable clients, who will be receptive and enthusiastic for health plan. Easiest to start as a consequence of disease investigation/control plan (“foot in the door” – eg. mastitis or BMSCC control plan). Use drug company help with diagnostic tests to help assess presence of disease (eg. Intervet DairyCheck bulk milk tank sampling for BVD and Leptospirosis). Use all available records to help build up knowledge of the farm and production targets. Set realistic targets. The plan must be designed for the individual farm. Give the correct advice. This not only depends on an accurate knowledge of the disease and its prognosis; but also epidemiology, controls, economics and disease costings. Get the advice implemented. This is not only dependant on giving the correct advice, but working as a team with the dairyman/shepherd and farm manager. Receive payment for the advice given. Review the plan. The health plan needs to reviewed annually (at least), with further visits if/when problems arise. Further reading: Radostots, O.M. (2001) Herd Health: Food Animal Production Medicine. Third Edition. Brand, A., Noordhuizen, J.P.T.M. and Schukken, Y.H. (1996) Herd Health and Production Management in Dairy Practice. Farm Assurance Schemes https://assurance.redtractor.org.uk/ 5 R(D)SVS Husbandry and Diseases of Cattle Production diseases Alastair Macrae September 2024 Disease conditions commonly encountered in UK dairy herds Over the past 30 years, the Dairy Herd Health and Productivity Service (DHHPS) has collected data on the occurrence of disease in dairy cattle in the UK, via a system of collection and analysis of farm data. This is then used to produce a system of quarterly reports for the farmer and his veterinary surgeon, in order to identify trends in disease and target interventions. Disposal rates in UK dairy herds (2007-2012) Median Suggested Average (25% - 75% range) target 140 cows Average herd size 155 cows (96 – 192 cows) 4.5% Infertility or FTC 4.9% Below 6% (2.4 – 6.8) Percent of herd sold due 2.8% Mastitis 3.5% Below 6% (1.2 – 4.9) 1.7% Lameness 2.2% Below 6% (0 – 3.1) 2.6% Age 3.6% - (0.8 – 5.1) 0% Yield 0.9% - (0 – 1.3) Other (including 5.1% 6.3% - to: death) (2.4 – 8.4) 21.2% Below Total 21.4% (16.1 – 25.9) 20% The overall culling rate has remained relatively constant at around 20 – 24%, which means that a fifth of the dairy herd is replaced annually. The current average lifespan of dairy cows in the UK is only 3.04 lactations (NMR records) – in the USA, it is nearly two lactations. It is clearly desirable to keep cows in the herd for longer - they remain profitable for as long as possible, save on replacement costs and produce more milk over their lifetime. Cows are culled for two main reasons:  “Forced” or involuntary culls. These are animals that must be culled due to death, disease or poor reproductive performance, and represent over half of all cows culled. The three most common reasons are infertility, mastitis and lameness.  “Selected” or voluntary culls. These are animals that the farmer chooses to cull for reasons such as poor milk yield, old age, poor conformation, temperament etc. The ideal situation for the dairy farmer is to minimise culling through “forced” reasons, and thus have control over which cows are culled. By choosing which cows to cull, the farmer can improve the genetics of his herd by bringing in replacements that are of higher quality than the cows being culled. 6 R(D)SVS Husbandry and Diseases of Cattle Production diseases Alastair Macrae September 2024 Disease rates in UK dairy herds (2007-2012) These figures are given as the number of cases per 100 cows per year. Median Average (25% - 75% range) 11.1 Fertility 26.1 (0 – 35) 5.9 Assisted calving 7.2 (2.1 – 9.9) 32.5 Mastitis 37.5 (20.6 – 48.7) Digestive disease 0 1.1 (including LDAs) (0 – 1.4) 0 Hypomagnesaemia 0.2 (0 – 0) 4.1 Hypocalcaemia 4.9 (0.8 – 7.5) 0 Ketosis 0.6 (0 – 0.6) 17 Lameness 22.3 (9.3 – 29.9) 0.8 Injury 0.8 (0 – 1.2) 0.6 Other 2.6 (0 – 2.6) These figures serve to emphasise that the major disease problems in UK dairy herds are infertility, mastitis and lameness. As well as obvious problems with cow welfare, these diseases all have major influences on productivity as well as cow health. One of the major problems with investigating disease rates is a lack of suitable records, and collecting / analysing data is vital for disease investigation and diagnosis. All of these disease conditions in dairy cows are called production diseases, and they all have several factors in common: They are all associated with the peri-parturient cow, and in particular the metabolic stress of early lactation. They all have a multifactorial aetiology. They may not be seen as spectacular individual cases, and the farmer may be unaware of the extent of the problem. Observed clinical cases are usually only the “tip of the iceberg”, with a far greater number of subclinical cases that will be inhibiting milk production. They are inter-related, and can increase susceptibility to each other. (eg. a cow with milk fever will be more susceptible to mastitis). They all cost money. The cost o 7 R(D)SVS Husbandry and Diseases of Cattle Production diseases Alastair Macrae September 2024 There are two main types of costs associated with disease:  Direct costs.  Indirect costs.  Treatment cost (drugs).  Increased culling rate.  Veterinary costs (vet’s time).  Possible risk of fatality.  Labour costs (herdsman’s time).  Susceptibility to other disease.  Discarded milk (antibiotic withdrawal).  Extended calving interval.  Reduction in milk yield.  Extra services per conception.  Mortality. Cost of culling a dairy cow A farmer will currently receive approximately £600 from the sale of a cull cow. However, the cost of a replacement heifer is £2,000 on average in the UK. Other costs that must be taken into account include the lower milk yield from a heifer (1400 litres for the subsequent lactation, equating to £322) and the smaller calf from a heifer (£8). Figures in 2012 for the cost of a cull cow range from £1,328 for a live cull at the end of lactation, to £3,307 for a fatality in early lactation. The cost of a fatality is even greater, and has been calculated to cost over £3,000. This is because the farmer will not receive any income from the dead cow, and will pay to get her removed. Infertility A large number of studies have implicated poor reproductive performance as one of the major sources of economic loss in dairy herds. The term “infertility” is a misnomer – it is actually a failure to get the cow back in calf when the farmer wants (most cows will probably get back in calf if given enough time). A 365 day calving interval is still accepted as being the target for the average dairy herd in the UK. The cost of an extra day on the calving interval is often quoted to be £4 per day. This is predominantly made up of reduced milk per cow per year, as well as reduced calf sales and extra AI costs. An Australian website is available (containing a cost calculator) to help identify the costs of poor fertility in dairy herds. It is called the InCalf project, available at: https://www.dairyaustralia.com.au/animal-management-and-milk-quality/fertility 8 R(D)SVS Husbandry and Diseases of Cattle Production diseases Alastair Macrae September 2024 Management Infertility Stillbirth 6.8 4.3 2.9 Prolapsed uterus Mastitis 11.5 Milk fever 1.8 2.3 Metritis RFM 4.7 5.8 3.4 6.8 2.0 Ketosis 2.4 50.4 Ruminal LDA 2.5 acidosis Nutrition Lameness Relationships between some of the peri-parturient diseases of dairy cattle. Numbers next to the dotted arrows indicate odds ratios, taken from Israeli dairy herds (eg. a cow with milk fever is 11.5 times more likely to develop a prolapsed uterus than a cow without milk fever). Adapted from Markusfeld, O. (1987) Journal of Dairy Science 70, p158-166 9 R(D)SVS Husbandry and Diseases of Cattle Production diseases Alastair Macrae September 2024 Mastitis Although mastitis rates have fallen in the last 40 years, rates have steadied at around 40 cases/100 cows/year and may even be slightly increasing. There has also been pressure on farmers to control mastitis via bonuses and/or penalties on the hygienic quality of milk (SCC and Bactoscan). The major economic costs of clinical mastitis are due to: Treatment costs. These are relatively minor, especially in mild cases that are treated by the herdsman and respond to intramammary tubes alone. Cost of discarded milk. Milk contaminated with antibiotics has to be discarded, and the farmer will receive no payment for it. Lower milk yields. A mild case of mastitis will reduce lactation yields by approximately 5%, whereas an average loss of 15% is seen in severe cases of mastitis. Higher culling rate. Given that typical prevalence rates of mastitis will be 90% mild (Grade I and II), 9.8% severe (Grade III) and 0.2% fatal, an average case of mastitis has been calculated to cost £201.20 (Direct costs £103.71 and indirect costs £73.46, plus repeat treatments). Total costs range from £168.77 for a mild case to £1709.35 for a fatal case. Note that the costs due to treatment and vets time are relatively minor, with the majority of the costs coming from the cost of discarded milk, reduction in yields and indirect costs. It should be noted that these figures only calculate the cost of clinical mastitis, and that subclinical infections can also cause important economic losses due to raised SCC, Bactoscan and reduction in milk yield. There are a number of mastitis cost calculators available on the internet which can be very useful to help farmers realise the true cost of mastitis in their herd, and are an essential part of any mastitis control plan. eg. mastitis cost calculator at https://www.mastitiscontrolplan.co.uk/qpro-tools/135-simple-cost-calculator Lameness Lameness is a major concern in dairy herds, not only because of economic losses but also compromised welfare. Lameness is estimated to cost the UK dairy industry over £80 million annually (2003 figures). The main economic losses caused by lameness are due to: Poorer fertility. Lame cows have a delayed return to oestrus after calving, as well as poor demonstration of signs of oestrus. As they have reduced intakes of food, they undergo prolonged NEB in early lactation. This leads to:  Increased calving interval.  Increased number of services per conception. Higher culling rate. Lower milk yields. Mild and subclinical cases of lameness have been estimated to reduce milk yields by 2½ - 5%, whereas severe lameness will reduce yields by 10-15%. Predisposition to other diseases (eg. mastitis). 10 R(D)SVS Husbandry and Diseases of Cattle Production diseases Alastair Macrae September 2024 Summary of costs of lameness in UK dairy cattle These costs have been calculated based on the prevalence of the various types of lameness in the UK. Note that the indirect costs are always much higher than the direct costs, and thus most farmers are unaware of the true costs of lameness to the herd (as well as probably being unaware of the true rate of lameness within the herd). Treatment costs tend to be minor. An average case of lameness (based on 41% digital lameness, 38% interdigital and 21% solar ulcers) will cost £178.22 (Direct costs £71.70 and indirect costs £99.86, plus recurrence rates). These total costs range from £81.48 for a case of interdigital lameness, to £324.17 for a solar ulcer. Milk fever Costs involved in the majority of cases of milk fever that respond to farmer’s treatment alone are relatively low (£40.42), but can escalate markedly if the case becomes complicated. An average case has been calculated to cost £209.62. Overall costs of disease Using some of these recent figures, we can get an overall figure of the costs of disease in an average UK dairy herd. Even if we only look at the three most important diseases of dairy cattle, total costs can be obtained per 100 cows per year. Direct costs only Direct and indirect Costs  38 cases of mastitis £3230 £7638  21 cases of lameness £1512 £3738  Calving to conception interval of 115 days £9000 £9000 (115-85 days x £3 x 100 cows) Total £13,742 £20,376 By reducing the disease problems in an average UK dairy herd by half (performed by the top 25% of herds), this leads to savings of £7,000 (direct costs) or £10,000 (direct and indirect costs) per 100 cows per year. Further reading Esslemont, R.J. and Kossaibati, M.A. (2002). The costs of poor fertility and disease in UK dairy herds (Trends in DAISY herds over 10 seasons). DAISY Research Report No. 5. Intervet. University of Minnesota Extension Service website (excellent costings sheets): https://extension.umn.edu/animals-and-livestock#dairy Macrae AI and Esslemont RJ (2015) Chapter 33. The prevalence and cost of important endemic diseases and fertility in dairy herds in the UK. In: Bovine Medicine. 3rd Edition. Ed. Cockcroft P.D. pp 325-337. Wiley Blackwell, Oxford. 11 CA03-05 Helping your clients maximise health, welfare, & productivity in a beef suckler herd, Tom Woods; Year 4 ICC Farm Animal; 2024-25 Helping your clients maximise health, welfare, and productivity in a beef suckler herd You need to review lectures on: cattle fertility and breeding suckler cattle and the UK system nutrition in cattle, specifically measurement of protein and energy balance feeds for cattle and how we measure their quality You’ll know better where all this material is, but definitely re-visit: Animal Life and Food Safety 1: CA1 – Cattle Husbandry Animal Life and Food Safety 2: CA5-8 – about beef production, including beef from dairy. You will find these resources really helpful: The AHDB have published an excellent set of guides designed for farmers (the Better Returns program). These can be found at and http://beefandlamb.ahdb.org.uk/returns/... And specifically at http://beefandlamb.ahdb.org.uk/returns/breeding/ These guides cover a lot of the material in these lectures, are really nicely illustrated, and are incredibly accessible. I particularly recommend….. http://beefandlamb.ahdb.org.uk/wp/wp-content/uploads/2014/09/BRP-Manual-8-Optimising- suckler-herd-fertility-090914.pdf http://beefandlamb.ahdb.org.uk/wp/wp-content/uploads/2016/08/BRP-Feeding-suckler-cows-and- calves-manual-5-170816.pdf https://www.qmscotland.co.uk/sites/default/files/qm2879_suckler_herd_a5_brochure_aw_0817_s ingle_0.pdf These resources describe UK systems. If you have time, look into how beef is produced in, for example Argentina, New Zealand, Kenya, or Spain. Remember that a lot of prime beef in the UK is produced from dairy (breeding dairy cows to beef breed semen). That will be discussed during the dairy calf learning sessions. There are a few exercises to work on. Doing these exercises will provide you with the learning you require to start you on your journey to becoming an advocate for sustainable and welfare friendly global beef production. You will need the material flagged here and will also find that your solutions improve as you have more lectures on specific syndromes. Please feel free to contact me to discuss any of these questions or any other areas ([email protected]). 12 CA03-05 Helping your clients maximise health, welfare, & productivity in a beef suckler herd, Tom Woods; Year 4 ICC Farm Animal; 2024-25 Efficiency in beef suckler herds For suckler herds to run at maximum efficiency, cows should rear a calf every 12 months. To do this, herds should run a restricted breeding period, maximise fertility in both cows and bulls, and maximise calf survival. The diagram below gives an overview. Exercise: To know where a farm is doing well and not so well you need to support farms to monitor their performance at different points / stages in their production cycle. This is so you can know where to concentrate your investment for change. For this you need to count things and measure things. How would you count or record success at each of the stages in this chart? Create an excel sheet that you could give to farms to help them with their recording. When on EMS ask if you can see herd health plans and look at data the vets use with their clients. Do some investigation into industry KPIs (UK and other areas? How are they established? Do you need to do any extra testing or procedures to compliment farm data? How much will this cost farmers? And what will they gain? 13 CA03-05 Helping your clients maximise health, welfare, & productivity in a beef suckler herd, Tom Woods; Year 4 ICC Farm Animal; 2024-25 Measuring success A few key numbers will help to monitor the efficiency of beer suckler herds. Refer to the flow diagram above for another summary. Measure Target Cow : Bull ratio (make sure to account for 1:50 (1:20 for young bull) any AI) Date bulls in and bulls out of cow pens / Ideally a 9 week mating period (3 cycles) fields Percentage of cows / heifers in calf at PD At least 95% Date of first calving to date of last calving 9-12 week calving period Rate of calving (calves born week 1:3, 1:9) ≥65% in first 3 weeks, ~94% by week 9 Calves alive at one week old ≥98% Calves alive at weaning ≥98% Age at sale 12 months (bull beef) to 18 months (steers and heifer) Exercise: Why are these KPIs as they are? How are they set up? What would an improvement in these KPIs mean for a farmer? How much did a spring born ‘store’ calf sell for last year in Scotland? What makes up the costs of rearing a calf from birth to store sale? Is it possible to calculate an amount each extra calf is worth to the farmer? (Doing this allows you to predict whether interventions are worthwhile – say the farmer lost 5 calves last year to scour and has 700 cows, what is the maximum logical amount of money the farm should invest in vaccine from a purely economic standpoint? Think about all the hidden costs of these deaths) 14 CA03-05 Helping your clients maximise health, welfare, & productivity in a beef suckler herd, Tom Woods; Year 4 ICC Farm Animal; 2024-25 Bull selection and management Economics A bull is an important investment for both dairy and beef herds. A fully fertile, experienced bull, will be able to achieve a 90% pregnancy rate when running with 50 normal cycling cows for nine weeks. Whilst infertility is relatively uncommon, it is estimated that 20-30% of bulls are unable to achieve this pregnancy rate and are hence classified as sub-fertile. The consequences of an infertile or sub-fertile bull are particularly serious for block calving herds. To maintain the block, cows that are not in calf by the end of the breeding season should be culled and will need to be replaced, or become expensive ‘carry overs’. These cows continue to eat the farms resources and create emissions while not being productive. Due to the extensive use of artificial insemination in the dairy industry, these notes will concentrate on beef suckler herds. However, many of the principals are just as applicable to bulls in a dairy herd. Many farm managers do not calculate the cost of keeping and maintaining a bull. AHDB Beef & Lamb estimate that more than 35% of breeding bulls are culled or die within five years of purchase, with poor mobility being the main reason for culling. The lifespan of a bull, depreciation, costs of maintenance (feed, housing and healthcare) and expected prolificacy can be used to calculate the cost of a bull per calf sired. AHDB Beef & Lamb have used typical market values to illustrate this calculation (Table 1 and a purchase cost of £3300). The aim of a forage-fed bull should be to produce at least 30 calves per year and to last seven breeding years, equating to a cost of £30/calf. The risk of barren cows increases with an increasing cow:bull ratio. This target of 7 seasons and 30 calves is a compromise. Remember this is just the cost of bull purchase and does not included maintenance. Remember that bulls can not be used on their daughters and this can be tricky for farms that use their own replacements. 15 CA03-05 Helping your clients maximise health, welfare, & productivity in a beef suckler herd, Tom Woods; Year 4 ICC Farm Animal; 2024-25 Table 1: Number of calves sired by a bull and cost of bull per calf produced over its lifetime (Source: AHDB Beef & Lamb) No. Calves per bull per year No. years Calves per bull per year years used used 10 20 30 40 50 10 20 30 40 50 1 10 20 30 40 50 1 £330 £165 £110 £8 £6 3 6 3 30 60 90 12 150 3 £143 £72 £48 £3 £2 0 6 9 5 50 100 15 20 250 5 £106 £53 £35 £2 £2 0 0 7 1 7 70 140 21 28 350 7 £90 £45 £30 £2 £1 0 0 3 8 9 90 180 27 36 450 9 £81 £41 £27 £2 £1 0 0 0 6 Selection of bulls Many purchasers in the UK still select bulls according to appearance alone. This is an unreliable way of predicting a bull’s potential. Whilst a bull should certainly be safe to handle and in good health, its genetic merit can only be assessed through the use of estimated breeding values (EBVs). Furthermore, the continued reliance on the visual appearance of bulls at purchase has encouraged pedigree breeders to feed stock bulls excessive amounts of concentrates in the run up to sale. This results in bulls that: Are over conditioned and hence will lose body condition when put to work. This will have a deleterious effect on semen quality. Are prone to lameness due to poor foot conformation resulting from a syndrome similar to laminitis (refer to lameness lectures) Have more fat in their scrotum which leads to reduced fertility. The detailed calculation and interpretation of EBVs are beyond the scope of these notes. However, the following are some broad guidelines. EBVs are: Breed specific, therefore bulls of different breeds cannot be compared Usually presented relative to the ‘average’ for the breed Reliant on phenotypic data collected from recorded pedigree (not commercial) herds Calculated using BLUP (Best Linear Unbiased Prediction), an algorithm that uses phenotypic data from the animal itself (where available), its relatives and progeny to calculate the 16 CA03-05 Helping your clients maximise health, welfare, & productivity in a beef suckler herd, Tom Woods; Year 4 ICC Farm Animal; 2024-25 genetic value of the bull while controlling for the influence of the environment on the phenotype Of variable accuracy – the more information available on the performance of the bull’s progeny and relatives, the more accurate the EBV A description of a bull’s genetic potential, but remember that the bull makes up half the genetics of a calf, hence a bull with a 200 day weight EBV of +40 kg will produce calves that are 20 kg heavier at 200 days than the breed average Often combined to generate indices to facilitate more balanced breeding programmes Being revolutionised by SNP (single nucleotide polymorphism) CHIP technology where genomic EBVs (gEBVs) for a bull can be calculated using a DNA sample taken at birth, hence accelerating the rate of genetic progress Most importantly, for biosecurity reasons, bulls are usually bought before they are bred and so they are unproven. Therefore, values are set according to the potential set by a bull’s relatives or by gEBVs. Before a bull can be chosen, the herd must decide what traits they wish to select for. If the bull’s progeny will be used as replacement breeding females, then maternal traits such as milk production and maternal calving ease will take prominence. If the bull is to be used as a terminal sire, then traits such as direct calving ease, 200 day weight and eye muscle area will take prominence. Whilst maternal and terminal traits are not necessarily mutually exclusive, some traits may conflict with one another. For example, a bull with a good direct calving ease EBV will produce smaller calves that are born more easily, however these calves will grow into adults with a smaller frame and hence be less likely to calve easily themselves. Conversely, a bull with a good maternal calving ease EBV will produce larger calves that will grow into adults with a larger frame and hence be more likely to calve easily themselves. This makes it challenging to breed replacement females from heifers (hence slowing the rate of genetic progress in the herd) as bulls with a good direct calving ease EBV should be used to serve heifers. Once it has been decided whether one is selecting for maternal or terminal traits, then the herd’s performance records, market requirements and margin should be carefully scrutinised to decide which of these traits should be prioritised i.e. it is of little use to select for calves that are 50 kg heavier at weaning if 10% of them must be born by caesarean section. The ideal terminal sire should produce calves that are born easily, grow rapidly and have good conformation. As EBVs cannot be compared between breeds, the choice of breed is difficult. Breeds such as Aberdeen Angus and to some extent Hereford are chosen based on market requirements (a significant premium being paid by consumers for these branded products). Some breeds are well known for producing heavier carcases (e.g. Charolais) or carcases of good conformation (e.g. Limousin and British Blue). That said, breed choice can often seem arbitrary and dependent on the personal preference of the herd manager or marketing of breed societies and pedigree breeders. In some countries, additional considerations are important. For example at high altitude, bulls are selected on the basis of low pulmonary arterial pressure (PAP) measurements taken using a catheter passed through the jugular and right side of the heart to reduce the risk of brisket disease (altitude sickness) in their progeny. 17 CA03-05 Helping your clients maximise health, welfare, & productivity in a beef suckler herd, Tom Woods; Year 4 ICC Farm Animal; 2024-25 Infectious disease The following should occur around the purchase of a new bull: Isolate for 28 days and observed carefully for signs of infectious disease Screen for BVD virus (unless from CHECS accredited free herds) Source from a risk level 1 Johne’s accredited herd and if more than 2 years old, blood test for Johne’s disease antibodies Screen for IBR and Leptospirosis antibodies where required. Bear in mind that many herds are either endemically infected or do not know their status for these diseases, and so should vaccinate bulls on arrival. Only buy ‘virgin’ bulls. Non-virgin and hired bulls are a major disease risk, especially with respect to Campylobacter fetus venerealis. Treat for liver fluke if from high risk farms (check for antibody or examine a faecal sample) Consider the risk of introduction of resistant Strongyle type worms and lungworm. A quarantine treatment may be required. Consider collection and analysis of faecal samples. Bull breeding soundness examination (BBSE) Pregnancy diagnosis often is carried out in herds, but later on and for management reasons. The only way to conclusively determine whether a bull is fertile is to pregnancy diagnose 50 cows after they have run with that bull only for nine weeks. This is usually not possible under commercial circumstances, and in block calving herds is too late to correct the problem. A BBSE, conducted by a veterinary surgeon, can be used to provide a correlate of a bull’s fertility in advance of the breeding season. BBSEs are commonly undertaken: Prior/after sale 6-8 weeks before the breeding season – bulls that fail a BBSE are unlikely to recover prior to the breeding season (spermatogenesis takes two months), however there must be sufficient time to source a replacement bull When a problem is suspected e.g. after illness or at the request of an insurance company 18 CA03-05 Helping your clients maximise health, welfare, & productivity in a beef suckler herd, Tom Woods; Year 4 ICC Farm Animal; 2024-25 Level 1 – Physical exam History Body condition score – bulls should be 3.0-3.5 General clinical examination Eyes – bull must be able to see females Jaws – mandible and maxilla should show no signs of pathology and teeth should meet dental pad Musculoskeletal system – bull should have a normal gait with good conformation (beware post/sickle hocked bulls, bulls with poor foot conformation or limb rotation, valgus or varus) Visual appraisal of scrotum shape Scrotal circumference – should be over 32 cm by 18 months and over 34 cm by 24 months, but there are separate breed standards. Scrotal circumference has been shown to be directly related to sperm output and the fertility of the bull’s daughters Palpation of testes and epididymis (orchitis, epididymitis, degeneration) – testes should have consistency of a ripe tomato Rectal palpation of accessory sex glands (vesiculitis) Palpation of sheath and inspection of the tip of the penis (haematoma, trauma, (para)phymosis, persistent frenulum, corkscrew deformity, fibropapilloma) Assess sheath conformation – if the sheath is too close to the body or too pendulous, then the bull may have difficulties with intromission Level 2 – Physical exam + semen evaluation Semen can be collected by electro-ejaculation, artificial vagina or rectal massage An artificial vagina provides the most ‘physiological’ sample, however unless the bull is specifically trained (e.g. stud bulls) it requires a bulling cow, bull of correct temperament and represents a significant health and safety risk to the collector Electro-ejaculation is an act of veterinary medicine. A sample can be obtained from most bulls, however the density and volume of the sample are highly variable and not related to the bull’s fertility. Some bulls resent collection and the procedure should be abandoned in these animals Handling of the semen sample is critical (temperature) – all equipment should be warmed to 37oC to avoid cold shocking sperm Assess volume and density (watery, milky, creamy) Using a microscope with the 4x objective, assess gross motility (scale 1-5). This is a function of the density of the sample and not directly related to fertility Dilute the semen in warm saline and examine under a warm cover slip using the 10x objective. A minimum of 60% sperm should be progressively motile Make a smear using eosin and nigrosin stain. Using the 100x oil immersion objective, count 100 spermatozoa and calculate the percentage of sperm that are morphologically normal. A minimum of 70% of the sperm should be morphologically normal If a bull has not ejaculated for some time, then he may produce a sample of poor quality, known as a ‘rusty load’. In these instances, a second or third sample should be collected after a period of 10 minutes 19 CA03-05 Helping your clients maximise health, welfare, & productivity in a beef suckler herd, Tom Woods; Year 4 ICC Farm Animal; 2024-25 Morphological abnormalities can be classified as primary (occurring during early spermatogenesis) and secondary (occurring during epididymal transit) with primary abnormalities usually being considered more serious Primary abnormalities include misshaped heads, abnormal mid-pieces and tails Secondary abnormalities include detached heads, bent tails and protoplasmic droplets Compensable defects are ones that can be compensated for with more sperm cells. These defects include those that don’t allow the sperm to reach the oocyte – bent tails, detached heads, coiled tails. Non-compensable defects are those which allow the defective sperm to reach and fertilise the oocyst. They cannot be compensated for by increasing the number of sperm cells in an ejaculate – pyriform heads, nuclear vacuoles, knobbed acrosome. These defects generally have a more serious impact on a bull’s fertility. Level 3 – Physical exam + semen evaluation + libido/serving capacity NOTE: Level 3 exams are not commonly performed Need to observe the bull mating females to ensure good libido and normal intromission. Five non pregnant cows can be injected with prostaglandin 3-4 days prior to the BBSE to ensure a cow is bulling on the day of the visit If a level 3 exam is not performed, the client should be advised to observe the bull mounting and achieving intromission when put out with a group of cows Your findings should be carefully recorded and a copy of the results given to the client and another retained in the practice. The BCVA provide carbon copy certificate books that can be completed following a BBSE. An unsatisfactory result in any aspect of the examination will result in the bull failing the examination. A bull should not be culled on the basis of a single evaluation and a re-test 60 days later should always be offered. General management Bulls are often ‘forgotten about’ for most of the year and only given attention immediately prior to the breeding season. Bulls that are kept in a small bull-pen and fed a poor quality ration or excessive concentrates in the run up to the breeding season are unlikely to be physically fit and fully fertile. Whilst bulls can be challenging to manage, they should be: Monitored all year and maintained at body condition 3.0-3.5 Put out to grass (if they are to be used at grass) at least two months prior to use as dietary changes just prior to use should be avoided Housed in a bull pen with an exercise area when indoors Given regular foot care – feet should be lifted and trimmed at least annually as lameness is the single biggest problem in bulls Included in the herd’s vaccination and parasite control programmes Young inexperienced bulls should only be expected to serve a maximum of 20-30 cows over a 9 week mating period, compared to a mature bull that can serve 40-50 cows. Most herds will run a single bull with a group of cows to reduce the risk of bulls fighting and, in some cases, so that the parentage of the calves can be determined. To reduce the impact of a bull failure on the herd’s 20 CA03-05 Helping your clients maximise health, welfare, & productivity in a beef suckler herd, Tom Woods; Year 4 ICC Farm Animal; 2024-25 overall performance, bulls are sometimes rotated between groups every 2-3 weeks. Some herds will run multiple bulls with a group of cows. However, this requires careful management to avoid fighting as in some instances, separating two bulls for just a few days can result in them fighting when reintroduced to one another. Managing Suckler Cows and Heifers Whether calving in the autumn or spring, compact calving periods have a number of advantages: 21 CA03-05 Helping your clients maximise health, welfare, & productivity in a beef suckler herd, Tom Woods; Year 4 ICC Farm Animal; 2024-25 Maximising cow fertility Careful Figure 2: AHDB ‘better returns’ scheme (http://beefandlamb.ahdb.org.uk/returns/breeding/) management of nutrition throughout a cow’s productive cycle is essential to maximise fertility and productivity. Plane of nutrition and body condition score are related to return of normal ovarian cyclicity. Both over- and under-conditioned cows are more likely to experience dystocia and decreased neonatal calf survival. A diet providing sufficient energy and protein is essential for adequate colostrum and milk production, and therefore nutritional planning is central to calf survival and growth. Body condition score should be carefully monitored throughout the year. BCS loss and gain is worked around when cheap food is available balanced with the requirements of pregnancy and lactation (cheap grass is available only in the summer!). BCS is a simple way to monitor response to the ration. Cows should be grouped and managed by BCS. However, beware the fat cow that may be receiving inadequate nutrition (e.g. inadequate protein to support milk production). The timing of weaning can be utilised to help manage body condition score. It is possible, especially for autumn calving cows, to leave calves to suckle for longer to help reduce body condition. Unless properly trained, it is not the job of a vet to formulate rations. However, it is within your remit to check that the provided diet is accessible and adequate. Ensure that feed space is adequate, enquire about grazing management, and recommend nutritional profiling 4-6 weeks before calving. This will monitor whether the cows are receiving: adequate energy (essential for calf growth and good recovery following calving) protein (essential for high quality and quantity of colostrum and milk production) minerals (calcium, magnesium, selenium, copper, iodine would be the most common deficiencies) (http://www.ed.ac.uk/vet/services/farm-animal-services/dairy/blood-testing/beef-suckler-tests). Cows take approximately two weeks to equilibrate following a dietary change. Therefore, blood sampling must occur at least two weeks following any change in ration. Feeding is the major variable cost in suckler herds and planning and monitoring can help manage conserved forage supplies and reduce the need for buying feed in. 22 CA03-05 Helping your clients maximise health, welfare, & productivity in a beef suckler herd, Tom Woods; Year 4 ICC Farm Animal; 2024-25 With good management and nutrition, 95% pregnancy rate should be possible following a 90 day breeding period. As mentioned above, it is not as practical to carry out early pregnancy detection in beef cows as it is in dairy herds. Handling is more challenging (cows are often at grass and have calves at foot). However, the farmer should monitor bulling and should report if cows are seen to return to service. Saying that, pregnancy diagnosis in beef cows is a very useful management tool. For ease, it is often carried out around the time of housing. However, 6-8 post the end of the breeding period is best practice. It allows cows to be selected and then conditioned for culling Barren heifers can still be sold as prime beef (18 months old) Only those pregnant cows that need it receive higher cost feeds. Diseases that lead to abortion reduce the calf crop. Therefore, quarantine and biosecurity are essential. Vaccinations should be used against causes of abortion such as BVD and leptospirosis. Farmers should be encouraged to keep good records in beef suckler herds. Health records and calving records can help identify cows to cull, and good records of calving allow analysis of fertility performance. A calving pattern histogram is a useful way of investigating overall beef herd reproductive efficiency. A theoretical calving pattern histogram for 100 cow herd with average pregnancy rate of 60% to each cycle is shown below. % cows calving Day of calving period Therefore, with a 60% pregnancy rate per cycle and all cows cycling at start of breeding season, one should expect 84% of cows to be in calf by week 6 of the breeding period and 94% by week 9. Deviations from this can suggest problems with bull fertility or extended anoestrus. Maximising heifer fertility Advantages of homebred replacements are: reduced the risk of buying in disease. replacements can be selected that best suit the farm (from cows that perform well). However, the breeding for heifer replacements is often different to the breeding required for the best finished cattle and this can make bull choice difficult. Synchronisation and AI offers an option for some farms. Suitable cows can be bred with high maternal trait bulls (remember only 50% of 23 CA03-05 Helping your clients maximise health, welfare, & productivity in a beef suckler herd, Tom Woods; Year 4 ICC Farm Animal; 2024-25 the cows AI’d will produce heifers unless sexed semen is used – this is less available for beef breeds and sometimes has reduced fertility). Heifers need to be at the correct size for breeding (60-65% of adult body weight) to maximise the chance that they are reproductively active (see calf rearing lectures). Calving heifers at around 2 years old is thought to maximise their productivity, reduces heifer rearing costs, and allows heifers to fit into a herd’s block calving pattern. Heifers should calve early in the calving period to give them the maximum amount of time to recover before re-breeding. Mate heifers with an easy calving bull for 6-7 weeks only. PD and remove non-pregnant heifers for sale. Feed during pregnancy for BCS 3 at calving, too fat - dystocia, too thin - extended post-partum anoestrus. If possible, run first calvers as a separate group until pregnant again Think about including gestation length in breeding choices (a shorter gestation length gives a longer period in which a cow can get pregnant and remain in a 365 day calving interval). Gestation length is genetically controlled. Autumn verses spring calving block The decision should be made according to farm resources (housing and labour) including how the cattle fit within other enterprises such as a sheep flock. When is feed cheapest on this farm? Can it produce adequate high quality conserved forage to sustain lactation autumn calving cows through the winter housing period? Is adequate high quality grazing around at the time of calving? Is there adequate feed space for the groups on the farm? When is the best time for this farm to be finishing cattle? Are the pens big enough to allow bulling for autumn calving cows? Is the housing needed for other things in spring (for example, lambing). Having both a spring and autumn calving group can allow a spread of sales across the year, but can also lead to lots of cows having extended calving intervals. It will also result in lots of different age groups which can make management complicated. Management of Suckler Beef Calves – from Birth to Slaughter Suckler herd income can often be dramatically improved by increasing the number of calves per cow. Most losses occur through a high barren rate or through high neonatal mortality. The most common causes of perinatal / neonatal mortality include: 24 CA03-05 Helping your clients maximise health, welfare, & productivity in a beef suckler herd, Tom Woods; Year 4 ICC Farm Animal; 2024-25 Dystocia (perinatal hypoxia, trauma) Failure of passive transfer from inadequate colostrum intake Early infection due to a dirty calving environment. Congenital anomalies (limb deformities, heart defects) Most of these problems can be prevented or reduced by good management. Dystocia The common causes of dystocia are: Poor choice of bull badly matched to cow breed and confirmation Under grown heifers, and cases of misalliance High twinning rate (possibly associated with nutrition or genetics – poorly understood) Over-conditioned cows Under-conditioned cows (energy problems) Metabolic problems (hypocalcaemia or low selenium) Failure of passive transfer and a dirty environment In the author’s opinion, these two factors are responsible for most of the problems that calves experience in their first 2 months of life. In addition, any problems experienced in these first two months have knock-on effects all the way to finishing. A lot of the work on colostrum requirement has been carried out in dairy calves, mainly because of the practice of removing calves from their dam shortly after birth. Therefore, colostrum management is fully described during the dairy calf lecture. Some has been carried out in beef calves. In practice the same principles, monitoring, and targets seem to work for beef calves. The most common consequences of failure of passive transfer are an increase in the number of cases of meningitis, diarrhoea, respiratory disease, umbilical infection, and joint ill. If farms are reporting this always consider and investigate colostrum management. This will involve investigation of cow nutrition, dystocia rates, and how neonates are observed and managed following birth. Direct measurement of colostrum quality is harder in beef cows and only really works when the cow is milked out and the colostrum is tested just prior to feeding to the calf. Small amounts of colostrum expressed onto a Brix refractometer is not representative of the colostrum available to the suckling calf. You can measure failure of passive transfer in calves using GGT, serum total protein or the zinc sulphate turbidity test. We believe that the best age to test is the same as for dairy calves (2-7 days old) and therefore, as for dairy calves, this should be considered a herd level rather than an individual animal test. Feeding the suckled calf At 4 months old (~ 120 days), half its requirement should be met by grass, silage or creep feed, rather than milk. At this stage, a calf will convert feed to bodyweight more efficiently than at any other time in its life. Regardless of production system, maximising 200-day weight will be cost- 25 CA03-05 Helping your clients maximise health, welfare, & productivity in a beef suckler herd, Tom Woods; Year 4 ICC Farm Animal; 2024-25 effective. Creep feeding can be introduced at any time after calving, but should be fed for at least three weeks before weaning to reduce stress and to minimise a drop in performance at weaning. Creep feeds can support the rumen development in calves to get them ready for weaning (high in digestible fibre, relatively low in starch, between 14-16% protein). Weaning the suckled calf Once calves are 6-7 months old (200 days), 75% of its nutrient requirement should be from feeds other than milk. Feeding the cow on expensive silage and concentrates to produce milk is wasteful once the calf can eat silage and concentrates itself. Therefore, it is usual to wean spring born calves from 6 months of age. This helps to protect the body condition of the cow ready for the winter period when feed is less available and more expensive. Weaning in autumn calving cows on low-cost grazing can be delayed up until calves are 10 months of age. This can be used to help manage the condition of the cow in mid to late pregnancy. BEWARE of growth checks in the calves as they have to compete with the cows for grass. Alternatively, calves can be weaned earlier and feed supply to the cow controlled (they could follow the calves through grazing). In situations where calves are causing excess loss of body condition from the cow, weaning should occur immediately. Otherwise, expensive conserved feeds will be needed to allow for an increase in BCS of the cows. Finishing rations Finishing rations contain less forage and more supplement than growing rations. This leads to increased rumen acidity and can be challenging to animal health (bloat, CCN, abomasal ulceration, nutritional diarrhoea). The rumen microbial population has to change from supporting a large population of fibre digesting bacteria to supporting a large population of starch digesting bacteria. Finishing rations should therefore be introduced gradually and forage amounts slowly reduced over a period of a week. There are other options for finishing cattle, including off grass using strip or paddock grazing for example. Condition and weight should continue to be carefully monitored to allow efficient finishing. 26 L4FACA06-7 – Farm animal pharmacology and therapeutics; Alex Corbishley; 4th Yr ICC Farm Animal; 2024-2025 Farm and production animal pharmacology and therapeutics Introduction Third year may seem like some time ago, however lectures in pharmacology from the CFC course are very relevant to the farm and production animal course. Lectures which I think are particularly relevant and which should be reviewed include: o Antimicrobials o Anthelmintics o Antiprotozoals/anticoccidials o Ectoparasiticides These lecture topics covered agents by class and referred to all species. Now is a good time to begin putting these agents into context. Go through these and identify those that are licensed in food and production animal species. We will be drawing on this information during the lectures. The NOAH compendium available on-line (www.noah.co.uk) and the Veterinary Medicines Directorate (www.vmd.defra.gov.uk) are useful resources for ascertaining which products are licensed for these species in the United Kingdom. These lectures as well as being an opportunity to remind you of the relevance of last year’s pharmacology course are an opportunity to cover a number of specific topics of particular importance in Farm and Production Animal Medicine. These include: Legislation surrounding the use of drugs in farm and production animals including – the cascade, record keeping (both farmer and vet), prescriptions, in-feed medication, withdrawal periods and MRLs. Principles of farm and production animal therapeutics including – ruminant versus non-ruminant pharmacology; drug administration and herd or group treatment versus the individual. Economic and ethical influences on drug use - cost is crucial in treatment of food producing species. Specific examples will be used to exemplify these factors which will influence decisions to treat and choices of drug used. Legislation Legislation governs all aspects of veterinary drug use but there are a number of areas where specific rules or restrictions apply to the use of medicines in food producing species. Useful sources for up to date information on legislation include: www.vmd.defra.gov.uk this is the Veterinary Medicines directorate web site www.noah.co.uk this is the National Office of Animal Health website The legislation governing all aspects pertaining to veterinary medicines is covered by the Veterinary Medicines Regulations 2005. These regulations are reassessed on an annual basis. The regulations themselves comprise quite a weighty document but separate guidance is available on the veterinary medicines directorate website. Each guidance section addresses a different aspect of the legislation and this is provided in a more user friendly format. Make sure that you are familiar with the legislation. It is not possible to cover all aspects in these two lectures. 27 L4FACA06-7 – Farm animal pharmacology and therapeutics; Alex Corbishley; 4th Yr ICC Farm Animal; 2024-2025 The cascade for food producing species The legislation states that in all species if there is a product that is licensed for the particular condition being treated and the particular species then this product should be used. If such a product above does not exist or is not available in Great Britain, then “The Cascade” provides a series of options which may be used in order to prevent the suffering of the animal. In general the conditions and steps are: Option 1: A product licensed for another condition in the same species or a product licensed for another animal species with the same condition Option 2: A) A UK human licensed product or B) In accordance with a special import certificate, a veterinary medicine authorised for veterinary use outside the UK Option 3: A product prepared extemporaneously by a veterinary surgeon, a pharmacist or a person holding a manufacturer’s authorisation as prescribed by the VS; or in exceptional circumtsances, a human licensed product from outwith the UK Following Brexit, the rules for Northern Ireland differ slightly - please check these yourself if planning to work in Northern Ireland or importing medicines. In addition for Food producing species the prescribing veterinary surgeon must: o Ensure that the treatment is only used for animals on a single holding. o If the medicine is imported from another state, it must be licensed for food producing animals in that state. o Ensure that the drug is listed in the GB MRL Register of permitted substances which can be found on the following website (again, different rules apply to Northern Ireland, so please check these yourself): https://assets.publishing.service.gov.uk/government/uploads/system/uploads/ attachment_data/file/1100404/MB_2__2097921-v1- MRLs_in_GB_editable_version.pdf o Examples of drugs NOT permitted in food producing animals include the two antimicrobials metronidazole and chloramphenicol o Specify a withdrawal period. i. If the medicine prescribed does not state a withdrawal period for that species then the V.S. must stipulate a withdrawal period which should not be less than 7 days for milk and eggs, 28 days for meat and 500 degree days for meat from fish. o Keep appropriate records for a period of 5 years. These will include the following information i. Name and address of owner ii. Identification of animal(s) treated iii. Date iv. Diagnosis v. Details of drug and dose used including batch numbers vi. Duration of treatment vii. Withdrawal period applied 28 L4FACA06-7 – Farm animal pharmacology and therapeutics; Alex Corbishley; 4th Yr ICC Farm Animal; 2024-2025 What are MRLs and ADIs? The differences in the cascade for food producing species are primarily in place to protect the consumer. In other words when an individual eats meat, milk, eggs, honey and so on there needs to be an assurance that levels of drugs in these products are within “safe limits”. To this end maximum residue limits (MRLs) are set for certain drugs based on the calculated ADI (or acceptable daily intake) for that particular drug. Withdrawal periods are then established which take into account the MRL for the drug and its pharmacokinetics in the animal; allowing a determination of the amount of time it takes for levels of the drug to fall below the MRL and hence identifying a suitable withdrawal period for that product. ADI: as we have already said stands for acceptable daily intake of a particular drug. The calculation of the ADI includes an extremely large safety factor. In addition, the MRL calculation assumes an average daily intake per person of 500g of meat, 1.5 litres of milk, 2 eggs and 20g of honey !!!! Record Keeping For food and production animal species there is a legal requirement for records to be kept both by the animal owner (for example the farmer) and by the veterinary surgeon. In the case of the owner:  At time of purchase o Proof of purchase o Name and address of supplier o Name and batch number of drug o Date of purchase o Quantity o Withdrawal period  At time of administration o Name of product o Amount of product o Date of administration o Withdrawal period o Identification of animal(s) treated o If product administered by the veterinary surgeon then the vet can enter the information directly into your records or give you the information which should also include the name and address of the administering veterinary surgeon  At time of disposal (unless administered to an animal) o Name of product o Amount disposed of o How disposed of All records must be kept for five years In the case of the veterinary surgeon: For POMs: As a veterinary surgeon you are permitted to supply POMs (both POM-V and POM-VPS). If you do this you must keep the following records of all in and out going transactions:  Date and nature of transaction 29 L4FACA06-7 – Farm animal pharmacology and therapeutics; Alex Corbishley; 4th Yr ICC Farm Animal; 2024-2025  Identification of the product  Quantity  Name and address of either the supplier or the recipient  A copy of any prescriptions and the name and address of the person who wrote the prescription  Batch number and date once product is in use Remember the legal categories of veterinary medicines. Think of the list and see which ones are relevant to drugs used in farm and production animal species. For drugs prescribed under the cascade: Records must be kept detailing the following information:  Date of examination of animal  Name and address of owner  Identification of animals treated  Diagnosis  Trade name of the product if there is one  Batch number  Name and quantity of active ingredient  Dose administered  Duration of treatment  Withdrawal period Again all records must be kept for a period of five years In-feed medication Medicines that are incorporated into feed are now either classified as POM-V or POM- VPS (the latter relates specifically to anthelmintics for use in-feed) under the “new” legislation. Since they are POM drugs then a prescription is required. In the case of written prescriptions these require a specific MFSp (medicated feed stuff prescription) which will contain additional details to a standard prescription. Information which must be present on a MFSp includes:  the name and address of the person prescribing the product;  the qualifications enabling the person to prescribe the product;  the name and address of the owner or keeper of the animal;  the species of animal, identification and number of the animals;  the premises at which the animals are kept if this is different from the address of the owner or keeper;  the date of the prescription;  the signature or other authentication of the person prescribing the product;  the name and amount of the product prescribed;  the dosage and administration instructions;  any necessary warnings;  the withdrawal period if relevant;  the manufacturer or the distributor of the feedingstuffs (who must be approved for the purpose);  a statement that, if the validity exceeds one month, not more than 31 days supply may be provided at any time; 30 L4FACA06-7 – Farm animal pharmacology and therapeutics; Alex Corbishley; 4th Yr ICC Farm Animal; 2024-2025  the name, type and quantity of feedingstuffs to be used;  the inclusion rate of the veterinary medicinal product and the resulting inclusion rate of the active substance;  any special instructions for the stock farmer and  the percentage of the prescribed feedingstuffs to be added to the daily ration. Some principles of farm and production animal therapeutics Differences in drug pharmacology We have already come across many examples of interspecies variability in drug pharmacokinetics and pharmacodynamics. Briefly some drugs exhibit tremendous interspecies variation while others are handled very similarly and values may readily be extrapolated from one species to another. In general it is fair to say that interspecies variation is usually due to pharmacokinetic differences rather than pharmacodynamic differences. As always there are exceptions to the rule. When considering farm and production animal species a number of factors come into play. This is not an exhaustive list but highlights some of the main differences. Absorption of drugs:  The ruminal microflora is capable of catalysing hydrolytic and reductive reactions and so may readily inactivate orally administered drugs before they ever reach the systemic circulation.  Conversely orally administered drugs may adversely affect gastrointestinal microflora and interfere with normal digestive processes. This may occur particularly with orally administered drugs but may also be associated with systemic administration. The main category of drug associated with these types of effects would of course be the antimicrobial agents. Which antimicrobials do you think would be most problematic?  Oral modified drug release delivery systems otherwise known as boluses take advantage of the unique anatomy of the ruminant stomach. Since the bolus is retained in the rumen this allows time for the sustained or pulsatile release of drug to occur. Metabolism of drugs:  In ruminant species highly significant changes are observed in metabolic capability in preruminant versus the ruminant animal. This is thought to be associated with changes in the diet resulting in a change in the nature and complexity of nutrients to which the liver is exposed. o For example both the NADPH-dependent reductase and Cytochrome-P450 families of enzymes increase by about 50% in the transition from preruminant to ruminant animal.  Differences in hepatic metabolism of certain anthelmintic drugs, (benzimidazoles, clorsulon) probably explains the higher dose requirement seen in cattle and goats versus sheep for these anthelmintics.  In general for drugs that undergo hepatic metabolism, half-lives seem to be shorter in cattle and horses compared to dogs and cats. o Of course there are exceptions for example theophylline in the horse and phenylbutazone in cattle to name two. 31 L4FACA06-7 – Farm animal pharmacology and therapeutics; Alex Corbishley; 4th Yr ICC Farm Animal; 2024-2025 This will be a good time to quickly review last year’s notes and remind yourself of hepatic metabolism and some specific examples of drugs that can affect the functioning of metabolic enzymes in the liver. Excretion:  Urinary pH. The urinary pH in herbivorous animals such as sheep, cattle and horses is generally alkaline (pH 7-9) in contrast to carnivorous animals where urinary pH is acidic (pH 5.5-7). This may affect the elimination of certain drugs through the urinary tract. In general acidic drugs will be predominantly ionised in an alkaline pH and elimination should be enhanced since the drug will remain in the urine. By contrast alkaline drugs will be primarily unionised and therefore are more readily reabsorbed from the urine reducing the rate of their elimination. o Note that milk fed animals generally excrete an acidic urine. Pharmacodynamics:  Differences may occur at the receptor level. (Here’s one of those exceptions!) Take for example the 2-adrenoceptor agonist xylazine. The dose required on a mg/kg basis in cattle is very significantly less than in some other species. This is thought to be due to an increased sensitivity of the receptor site in this species. Practical aspects of therapeutics in farm and production animals. Companion animals are most commonly treated on an individual basis whereas it is common in F & P species for treatment to be applied on a group basis. Therefore the method of drug administration needs to be cost effective, time and labour effective, efficient (the majority of animals need to receive the correct dose) and safeguard animal welfare and carcass quality. Options include: Bulk administration in feed or water. o Dose needs to be based on the expected feed or water consumption and obviously there will be individual animal variation The use of a rumen bolus. o Primarily employed for the delivery of anthelmintics to cattle. The use of multi-dose injectors. o Used to deliver IM or SC injections. It is very important to change the needle at regular intervals. Pour-ons o Primarily used for certain anthelmintics Long acting injections. o Especially relevant in relation to antimicrobials. Certain drugs by nature of the drug itself or the formulation have long half-lives reducing the need for repeated treatments. A word on injection site lesions: More published information available on this in the U.S versus the U.K. Be aware that lesions caused in young calves often will not resolve and may often enlarge as the animal matures. In an ideal world injections should be given s/c but need to have a carcass friendly injection site and still adhere to the label requirements for the drug. 32 L4FACA06-7 – Farm animal pharmacology and therapeutics; Alex Corbishley; 4th Yr ICC Farm Animal; 2024-2025 Ideally i/m injections should be given in the neck away from the more expensive cuts of meat. Maximum volume for injection should be 10mLs. Needle selection can be important. 16 or 18 gauge needle depending on size of the animal. 5/8 or ½ inch ideal for s/c and 1 or 1 ½ inch ideal for i.m. Keep injection sites 4 inches apart if possible. Ethical and cost considerations There is a need to balance animal welfare concerns with cost and practicality of treatment. Sometimes this is a difficult balancing act. The table below lists the comparative prices of certain antimicrobials. Even though the precise price will vary from the time of putting these notes together, the relative price should remain broadly similar. Selected antimicrobials used in farm animal practice. Prices compared based on a single dose for both a 250 kg bovine and a 50 kg pig. Drug name Trade name Cost per Cost for Cost for unit 250 kg 50 kg pig bovine Oxytetracycline Alamycin LA 20p/mL £5.00 £1.00 Amoxicillin Amoxypen inj 21p/mL £2.45 £0.49 Enrofloxacin Baytril 58p/mL £7.25 £1.45 Sulphadoxine/trimethoprim Diatrim 16p/mL £2.40 £0.48 Cefquinome Cobactan 40p/mL £4.00 £0.80 Ceporex Cephalexin 35p/mL £3.40 - Tulathromycin Draxxin £2.50/mL £15.62 £3.12 Ceftiofur Excenel 60p/mL £3.00 £1.87 Florfenicol Nuflor 57p/mL £9.50 - *Prices above were accurate at the time that this table was created. **Remember that some of the above preparations may need to be administered repeatedly on a daily basis whereas others provide antimicrobial cover for several days and only one treatment may be required. 33 L4FACA08 – Dairy Calf Management, Health, and Welfare 4th Year ICC Farm Animal 2024 Rearing successful dairy calves: No longer a by-product of milk production Dairy calves have sometimes been seen as by-products of milk production. However, in recent years as the profit margins on milk have been more and more squeezed, and as public (and therefore governmental) awareness and interest in how milk is produced has increased. There has been increased interest and research effort into what determines future success in calves raised to produce milk. Preparation of heifers in a sustainable, profitable, and welfare friendly way is as essential to the future of dairy farming in the UK as routine fertility visits. There is high quality research demonstrating how early life experience (health and nutrition) has a life-long impact on health, not only of the next, but also subsequent generations of humans, and it is no different for calves. Their experience as neonates shape’s their future. Longitudinal studies of dairy heifers from birth through their productive life are providing excellent quality and practical evidence for effective farm level interventions. It is our role as vets to work with our clients to pick which interventions will be the most useful for different enterprises. We can do this through identification of where problems are or where KPIs are not being met, and then coming up with sensible farm specific solutions, followed by continued monitoring to check changes have been effective. Although this material concentrates on rearing dairy calves, a lot of it is also relevant for successful rearing of beef calves. Targets for heifer rearing Dairy heifers that calve at 2 years old (22 – 24 months) and continue to produce a calf every year (approx. 365 days from previous calving) are the most profitable. Allows seasonal calving patterns if required. If heifers do not calve by 24 months they can get fat and this reduces fertility and longevity. They also are longer in the herd before they are productive / start paying their way. To achieve calving by 24 months, heifers have to reach target weights at key times, not least because puberty is influenced by body weight, but also so that the animal is an adequate size to calve. The accepted targets are 60% of adult weight at service and 85% of adult weight at calving. It is suggest

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