0. FEEDLOT NUTRITION AND HEALTH MANAGEMENT

Induction of Cattle into Feedlots

• Newly arrived cattle frequently experience bruising, inflammation, tissue protein mobilisation, dehydration, and insufficient rumen substrate
• Cattle are subjected to mixing, novel feed and water systems, additional handling, novel stimuli, dust, and differing climatic conditions
• Psychological disorientation, immunosuppression, and reduced gut function may result
• Induction and handling for the first 40 days are critical for health and performance

Initial Feedlot Procedures

• Upon arrival, cattle need highly palatable, high-protein hay and clean water
• Legume hays are ideal, provided in feed troughs and hay racks
• Limit hay provision to a maximum of 3 days to avoid diluting nutrient intake
• Smooth transition to starter ration involves including the same legume hay familiar to the cattle

Induction Timing and Practices

• Exhausted and debilitated cattle benefit from delayed induction involving rest, rehydration, and feeding
• Induction should not be delayed beyond 3 days due to adverse effects on close-out performance
• Pens for induction should be accumulated over a maximum of 3 days
• Agents routinely administered during induction include visual ear-tags, hormonal growth promotants, anthelmintics, and clostridial vaccines
• Other possible vaccines are against IBR (BHV1), Mannheimia haemolytica, and BVDV
• Visual tags are still used for identification in pens despite the use of NLIS tags and automatic scanners

Australian Feedlot Cattle Practices

• Accepted is that cattle have been treated with a hormonal growth promotant
• Benefit:cost ratio from HGP use is often approximately 10:1
• No human safety concerns exist with registered HGPs
• A knockdown anthelmintic is adequate due to the absence of gastrointestinal parasite reinfestation
• Flukicide use is debated, with liver condemnations from fluke scarring costing $6/head+
• Drenching with a flukicide at induction won't help if liver scarring occurred before arrival
• Some feedlots use flukicides on domestic cattle from known fluke areas like the tablelands of NSW

Infectious Bovine Rhinotracheitis (IBR) and Bovine Respiratory Disease (BRD)

• IBR is caused by BHV1 and is best addressed as a separate entity
• Now a vaccine is effective against IBR in Australia
• Prevention of IBR is cost-effective, but bronchopneumonia of BRD still happens
• Rhinogard is a modified live intranasal vaccine, which requires proper storage and handling
• A 2-shot combined vaccine against Mannheimia haemolytica and BHV1 (Bovilis MH+IBR) can be used
• BRD is a stress-induced disease complex with viral initiators and bacterial pathogens
• Mannheimia haemolytica fills the microbial ecological niche in BRD
• Vaccination against M. haemolytica alone has a limited effect on the incidence of BRD
• The response to vaccination against M. haemolytica varies with the proportion of BRD cases succumbing to it

Vitamin Use at Feedlots

• Injectable vitamin ADE at feedlot entry has no effect on health/performance, even at low inclusion rates
• Responses to B-vitamins are variable; only vitamin B12 for cobalt-deficient cattle shows potential
• Drenching cattle with microbial inoculants at induction is unsupported by data
• Supplying water, energy, and nitrogen/protein to rumen microbes is effective for stimulating their proliferation

Lactic Acidosis

• Excessive consumption of readily fermentable carbohydrates leads to VFA production
• Over time, VFA production depresses rumen pH, causing lactic acid producing bacteria overgrowth
• Associated diseases are feedlot bloat, laminitis, PEM, and liver abscessation
• Etiology and pathogenesis includes high CHO intake, excess VFA production, and S. bovis and Lactobacillus spp. overgrowth
• Rumen pH decreases (5 or less), cellulolytic bacteria and protozoa die, and chemical rumenitis may precipitate

Rumen Damage and Clinical Signs

• Liver abscessation (F. necrophorum and A. pyogenes) and chronic damage to the rumen epithelium occurs, reducing absorptive capacity
• Mycotic rumenitis (Mucor, Rhyzopus, Absidia) rarely occurs 4-5 days later
• Rumen stasis occurs as pH nears 5, decreased salivation limits bicarbonate production
• Clinical signs include stilted gait, grey/dark green watery scours, anorexia, ruminal stasis, dehydration, recumbency, and death in less than 24 hours

Post Mortem and Treatment

• Low rumen pH, note time since death (roughage pH 6-7, grain pH 5.5-6.5, lactic acidosis <5)
• Rumenitis with papillae necrosis, note time since death
• For mild cases, observe for worsening and put onto hay; for anorexia, diarrhea, depression, and mild dehydration, remove concentrates
• Drench with 500g NaHCO3, 500g MgO, and 500ml paraffin oil in 8L of water
• Acute, severely affected animals often respond poorly to IV fluids with bicarbonate, corticosteroids, and rumenotomy

Prognosis and Prevention

• Prognosis is fair if HR < 100, guarded if HR 100 to 120, and grave if HR > 120
• Consider pen treatment when bubbly scours incidence exceeds 3%
• Check feed processing and delivery, reduce by one diet until fecal scores improve
• For severe pen problems (10%+ bubbly scours), also put hay in racks
• Allow cattle to access hay upon arrival at the feedlot before induction
• Starter rations should be 50% or less grain
• Bring cattle onto full feed slowly (10-14 to 21 days)

More About Bloat

• NaHCO3 can be added to high grain diets at about 0.75% and virginiamycin at 20 ppm, justifying its use
• Adjustments to feed must be gradual, with increases in grain no more than 10%
• Avoid varying feed intake and ensure the feed trough is full during peak times plus trough space is sufficient
• Also, avoid overcrowding pens, feed more during cold/wet/windy conditions as well as when barometric pressure drops
• Grain milling targets with bulk density variance of ± 1 kg/hL and moisture variance of ± 1% must be maintained
• Roughage should be of sufficient chop length

Gaseous vs Frothy Bloat

• Gaseous bloat involves lactic acidosis to rumenitis to inflammation of the eructation stimulating area to decreased eructation to build up of fermentative gas
• Frothy bloat is from lactic acidosis to gram-positive bacteria to thick slime, gas is trapped in the slime to air bubbles that cannot be eructated
• Caused by the ingestion of legumes

Clinical signs of mild bloat

• Only decreased average daily gain (ADG) and decreased feed efficiency occur
• Mildly affected animals show distension on one side without evidence of discomfort

Treatment for Bloat

• Moderate include animal must be removed from feed
• Animal must have a stomach tube to relieve pressure
• Give Defoaming Agent & / or Paraffin
• Severe, recumbent animals die in respiratory distress
• To treat, a trocar into rumen on the left side and perform a rumenotomy, if required

Laminitis

• Commonly linked to Lactic Acidosis
• Clinical sign is "cats on hot bricks”, stilted gait
• Salvage is only available through slaughter if feeding ability is impaired

Polioencephalomalacia (PEM)

• Sulphites impair thiamine, at an increased rate under acidic conditions
• Rumen bacteria like Bacillus thiaminolyticus, Bacillus aneurolyticus, and Clostridium sporogenes produce thiaminases
• High dietary intakes of sulfate (e.g. from molasses, wet distillers grains, or high S bore water) have thiamine-antagonistic activities
• Acidic rumen conditions increases likelihood of PEM

Mechanism of acidic rumen in PEM

• PEM increases thiaminase exoenzyme release via acid shock, as well as its destruction by related sulfite production.

Thiamine deficiency

• Lowers transketolase activity, which is an important nervous tissue enzyme and ATP supplier
• When ATPase Na-K pump fails and sodium overloads, brain cells swell, causing necrosis and clinical signs like blindness or tremors etc
• The worst affected brain regions are the frontal, parietal, and occipital areas of the cerebral cortex and the thalamus

Agents linked with PEM

• High Grain Rations
• Increased rates of molasses inclusion
• Increased levels of sulphide intake (eg. in some water)
• Lactic Acidosis, releasing the 'acid shocking' bacteria

Salmonellosis

• A stress-induced illness more commonly found in inanition situations
• Salmonella typhimurium, S. bovis-morbificans, and S. dublin are all examples
• Common infection sources include water contamination and carrier animals
• The faeco-oral route of transmission is possible.

Liver Fluke Burdens

• Feedlot cattle acutely suffer intestinal invasion and major inflammatory response Frequently, spread to mesenteric lymph nodes and bacteremia causes lung, spleen, and liver issues (this occurs if high BRD case fatalities increase with underlying salmonella factor).

Post Mortem & Diagnosis

• Post Mortem findings include edematous, inflammation and swelling in small and large intestines
• Diagnosis available from clinical signs of Salmonellae
• Grossly, the Salmonella cultures and analyses include nodes in the mesenteric area, possibly liver, spleen or lung

Salmonellosis Treatment & Prevention

• Treatment includes the drug Trimethoprim/Sulfadiazine, using methods such as Trivetrin and Trisoprim
• Feed is added as medication in an outbreak (sulfadimidine is mixed for consistent concentration)
• Move infected clinical cases to get individual clean treatment, and keep contacts away from the clean pen
• Reduce time off feed, by minimizing/managing stress when delivering new feedlot cattle to the area

Preventative Management for Bacteria

• Take preventative measures to safeguard against water contamination and transmission via grooming
• Also manage water foul near drinking areas and any source where microbes could migrate easily

Urea Poisoning & Ammonia Toxicosis

• Rare events include the intake of available NPN, plus free ammonia crossing the portal of circulation
• The rumen’s pH impacts the availability of free-moving ammonia as indicated where at 6.4 then 1/1000 is freed versus pH’s 8.4 creating 1/10
• Abdominal/muscle/teeth and other pain happens fast after ingestion
• Breath problems and violent death shortly follows those symptoms

Diagnosis & Treatment of Urea Problems

• Use Rumen samples with high pH values and Blood NH3 concentrations in tests
• Treatment includes efficient rumen emptying and inhibiting future loose Ammonia from rumen pH changes
• Lower rumen temperature will reduce death rate after an intoxication

Steps towards Prevention of Inclusion Errors in Feed

• Assure that 30% or less of the protein is from NPN sources to avoid the adverse reactions of palatability
• Avoid overfilling the feeding troughs with pooled Nitrogen, especially if rain is coming

Bovine Respiratory Disease (BRD)

• BRD starts with a viral infection in cattle, caused via Parainfluenza 3 (PI3) and Pestivirus in many cases
• High risk increases occur in Australian cattle, as well as naïve cattle that interact with rising rates of viral infection

Infection, Bacteria and BRD

• BRD factors include Mannheimia haemolytica with Pasteurella multocida as potential causes
• Other bacteria could include Salmonella spp & Trueperella pyogenes in other occurrences
• Mycoplasma is an area is being analyzed, with findings point to BRD pathogen classifications

Diagnosis & Signs

• To find if BRD is the case in certain situations, study the clinical signs via rectal and temp readings
• Note and compare sounds (especially when disturbed) and levels of nasal discharge

Treatment & Prevention for BRD

• OTC in 100mg (3/10 for different weights) and Tulathromycin are common regimens used for care
• Antibiotic application includes meloxicam and OTC Vitamin supplements
• Move Saleyard cattle from the general area to contain risk, while mass medicating “high risk” cattle

Infectious IBR Rhinotracheitis

• It’s agent as Bovine Herpesvirus triggers clinical stress that hurts mechanisms of the lung
• The clinical signs are similar to BRD, plus profuse salivation and a stretching neck
• Diagnosis checks Pyrexia stages with Auscultation for trachea related indication

Treatment & Prevention of IBR

• For treatment, do what has worked well earlier for BRD, but include + vaccination with Rhinogard as key

iii Atypical Pneumonia

• Irritant with manure components, but also with molds, act as the biggest factors of pneumonia (ammonia and methane exposure)
• These results involve allergic reactions, linked back to MGA ingredients and lower infection rates

Symptoms, & Diagnosis

• Hypoxia and Dyspnoea as well as bronchial noise can all provide evidence of infection
• Edema within the lining alveoli, must be contrasted with auscultation and past analyses for conclusion

Management for mouldy areas & prevention

• Management factors are necessary during infections, notably appropriate surface levels and non-mouldy hay

Necrotic Laryngitis (Honkers)

• Fusobacterium necrophorum is considered the causal factor in the Honkers
• It Impairs the airway, causing intense swelling and symptoms.

Further Characterizations

• Dyspnoea (even with inspiratory stridor) is associated and has been shown to be difficult during tests

Muscoskeletal Conditions

• Lameness can come from concrete, injuries, and footrot
• Infection generally stems from bacteria from F. necrophorum, as infection requires damaged skin
• Wet yards, stones, deficiencies of nutrition could trigger and create infectious environments

Clinical Signs of Lameness

• Look for inflammation and swelling to see infection states
• Also, feet may have a strong necrotic smell, for better info

Diagnosis & Action Steps

• Injection to isolate is key
• Keep environments safe and dry by implementing proper pen and treatment strategies

Bruising from Handling

• May start gangrene in muscles that will inhibit movement and cause death

Lameness-Tetanus

• Walking problems occur with tetanus
• Tetanus is caused by recent wounds

Disease type & Occurrence

• Feeding high carbohydrate and sugars cause entertoxamia
• Look to liver fluke infections and abscessations for black diseases

Oedema type vs Blackleg localizing

• Look for similarities and penetrating wounds, to gauge the problem better

Clostridial Contaminants

• Clostridium produces paralysis that causes respiratory attacks from organism
• Monitor feed and rodents if contaminated

Urinary Tracts

• Urolithiasis forms crystals that trigger conditions that constrict urethra

Development of Urolithiasis

• Grain diets and Vitamin A play roles in calculi developments
• High inclusions add to problems that are already elevated

Sequences of Struvite growth

• Organic building blocks trigger aggregate, Matrix binding causes growth and alkalinity concerns

Events of Urine

• May include Crystals on hairs and abdominal discomfort
• Also related is rupture from bladder problems stemming from urine in belly

Surgery for treatment

• Key for Slaughter and Urethrostomy for the long fed
• Additions to treatment, might suggest using Calcium, NH4, and monitoring pH if complications arise

Heat Stress, Symptoms & Pathogenesis

• Limited airflow and prolonged temperature is a cause
• Signs of open mouth range from high rectal temps that result in death
• Injection to scleral results in haemorrhages of the heart

Remedy and Further Monitoring

• To treat wet cattle and monitor windflow
• Develop a plan in case problems occur, monitor sprinklers throughout to restrict handling
• Monitor water and other aspects that may be compromised

Parasites

• Most likely affects lighter cattle with weaker weight in terms of fluke More study is warranted for feedlot study in cattle, given that some products are only used in specified conditions, against E bacteria
• Preventing contamination can prevent the need for feedlot diets overall