2024 Stage 2 Reproductive Technologies Test Revision Booklet Updated.docx

Revision guide Test: Wednesday Week 9 Lesson 1&2 ____________________________________________________ THE WHY… Towards Improving the Outcomes of Assisted Reproductive Technologies of Cattle and Sheep, with Particular Focus on Recipient Management Abstract: The Australian agricultural industry co...

Revision guide Test: Wednesday Week 9 Lesson 1&2 ____________________________________________________ THE WHY… Towards Improving the Outcomes of Assisted Reproductive Technologies of Cattle and Sheep, with Particular Focus on Recipient Management Abstract: The Australian agricultural industry contributes AUD 47 billion to the Australian economy, and Australia is the world’s largest exporter of sheep meat and the third largest for beef. Within Australia, sheep meat consumption continues to rise, with beef consumption being amongst the highest in the world; therefore, efficient strategies to increase herd/flock size are integral to the success of these industries. Reproductive management is crucial to increasing the efficiency of Australian breeding programs. The use of assisted reproductive technologies (ARTs) has the potential to increase efficiency significantly. The implementation of multiple ovulation and embryo transfer (MOET) and juvenile in vitro fertilization and embryo transfer (JIVET) in combination with genomic selection and natural mating and AI is the most efficient way to increase genetic gain, and thus increase reproductive efficiency within the Australian livestock industries. However, ARTs are costly, and high variation, particularly between embryo transfer recipients in their ability to maintain pregnancy, is a significant constraint to the widespread commercial adoption of ARTs. The use of a phenotypic marker for the selection of recipients, as well as the better management of recipient animals, may be an efficient and cost-effective means to increase the productivity of the Australian livestock industry. Full article: animals-10-00293.pdf (nih.gov) To feed the world's growing population, global agriculture will have to double its food production by 2050. Increasing our knowledge and understanding of genetics and reproduction and the application of this through the utilisation of reproductive technologies is essential for us to reach this goal from a global perspective. Checklist I can: Describe in detail the three reproductive technologies (ET, Invitro fertilisation, AI) Describe a sheep’s reproductive tract and oestrous cycle (anatomy and hormones) Make decisions on the when to use AI, ET or IVF and justify why. Link these decisions to profitability and explain why this technology would make more money in my opinion Read a bull sale catalogue and identify the better bull and justify why Describe what EBVS/ASBV's are Explain how EBV's and ASBV’s can be used to increase profitability Explain why taking the accuracy of data into account is important Explain why people invest such high amounts into a single animal Identify traits which are particularly important for a range of enterprises and justify why Explain the benefit of investing more financially into genetics upfront and be able to explain how I will make more in the long run Explain the oestrus cycle and can justify the importance of knowing this when using reproductive technologies Compare the benefits of different reproduction methods/technologies Justify the use of reproductive technologies economically Explain why efficiency is important in agricultural production and how reproductive technologies can assist with this Explain the link between genetic superiority and income Explain why commercial producers tend not to use reproductive technologies Discuss the ethical considerations that need to be taken into account when using reproductive technologies Explain how reproductive technologies can assist the use of genetics even if an animal is unable to be joined Notes Reproduction Reproductive efficiency in beef and dairy cattle is measured by a cow’s ability to have a calf every 12 months, whilst continuing to achieve her production for beef and/or milk. The higher percentage of females that can achieve this in a herd, the better the reproductive efficiency. If you plot the reproductive activities of a cow over 12 months (Figure 1), it becomes clear that on average the time frame for conception to achieve this goal is relatively short (55 days). If gestation periods are longer, such as in Bos indicus genotypes, or cows fail to cycle for a long duration after calving, this window becomes even shorter. Breeders must ensure that their cows are managed so that they can conceive within this tight window.   Figure 1: The 12 month reproductive cycle of a productive cow.   A basic understanding of the oestrous cycle and the hormonal interactions can assist in understanding how to manage cattle during this conception period. Alternatively, it can also give reason to using artificial intervention to improve the chances of conception to ensure a cow has a calf on a yearly basis. Natural Mating: Overview The vast majority of the Australian beef herd is naturally mated. The extensive nature of many Australian beef operations has traditionally been responsible for this statistic. In contrast, the use of natural mating in the Australian dairy herd is rather low, with only 16% of herds using natural mating as their only reproduction management strategy . The intensive nature of the Australian dairy herd and the rapid progression of genomic technologies has certainly contributed to the adoption of AI technologies. This industry has proven the benefits of AI over natural mating, as herds that use AI, generally produce over 1000 L more milk per cow per year than herds that do not .  Advantages vs Disadvantages The major advantage of choosing to use natural mating in a cattle herd is the reduction of labour and ease of just placing a bull in with the nominated group of cows or heifers. Some farms/stations do not have adequate resources, such as facilities or staff, to be able to effectively implement artificial reproduction programs and so natural mating becomes a logical choice. If a breeder is interested in increasing the genetics of their herd, it is often not cost-effective to use only naturally mated sires. There is a variety of reasons for this: A sire can only physically mate with a small number of cows per year, generating a small number of calves per year. If a breeder would like high-quality genetics, these sires are usually expensive to purchase, making the cost per calf born usually high. In larger herds, some breeders will purchase this sire, and collect semen from him to use in AI, ET or IVF programs to maximise his potential. When only using natural mating, most breeders will retain the sires in their herd for multiple years. This limits genetic progress, as new sires with increasing genetic potential are not used. If you only have a small herd, and you have invested in a new high genetic merit sire, he will soon become superseded as his progeny will be at joining age creating inbreeding issues. In most herds, dairy or beef, natural sires are required even if some level of assisted reproduction programs are being used. Natural sires can be eliminated, but this usually requires a high level of management with assisted reproductive protocols. Many herds are choosing to breed their own sires for their natural mating requirements. Breeders may choose to select a nucleus of females and use intensive AI, ET or IVF programs and breed a sire. These sires are then able to be used in the other portion of their herd. Best practice natural mating Failure to get your females in calf has significant ramifications on revenue in any livestock enterprises. There are a couple of key tips that can ensure you can maximise optimal results: Always ensure your sire/s have passed a veterinary bull breeding soundness examination (VBBSE) by an ACV accredited veterinarian. Including a sperm morphology as part of the exam is highly recommended. Many producers see this as only providing value at the point of sale. However, pre-mating testing of herd sires can significantly reduce the incidence of bull failure, ensuring that your profits are protected. See BULLCHECKTM for more information. Consider any diseases that can cause reproductive loss. Consult your veterinarian about the risks in your herd and region. Implement a vaccination and control program for those that are identified as being a risk. Pregnancy diagnose after your nominated breeding period. Request foetal aging and keep records on your cows. You will be able to track the fertility of your herd and problem solve when issues may arise. Avoid all year round mating. Join females over a defined, short as possible period. Keeping your herd in a tight calving pattern will ensure that your fertile cows remain in your herd and sub-fertile cows can be culled. If you are limited to all year round mating due to your management system, ensure you implement a rigorous pregnancy diagnosis scheme and/or consider segregating cows into calving groups to ensure that cows are calving each year. When calving patterns are not ideal for the breeding season, or cows are not cycling soon after they have calved, synchronisation can be used as a solution. The use of a Cue-Mate® device can stimulate cows to commence cycling and synchronise them to cycle over a defined short period. Breeders will use this as a strategy to improving their calving in their natural mating system. Consultation with a veterinarian or an expert, can advise how this may work in your system. Artificial Insemination The process of artificial insemination (AI) is where the semen that has been previously collected from the male of choice is deposited into the uterus of the female near the time of ovulation. The practice of AI has been used in livestock for decades, forming routine practice of many livestock breeding enterprises. Traditionally AI has been used in operations where the aim is for producing breeding stock such as studs. With advances in synchronisation protocols and genetic technologies, the practice of AI is becoming more common in commercial livestock enterprises. The most common reason a breeder uses AI, is to cost effectively access elite or unique genetics from sires that are not available on farm. With the use of synchronisation protocols females can have their ovulation synchronised to occur at a pre-determined time. Not only does this improve the feasibility of implementing AI on farm, but can also provide sundry management benefits ensuring your calving will occur over a shortened pre-determined time. Overview Artificial insemination is used in approximately 84% of commercial and stud stock dairy herds  forming part of the routine management. The dairy industry has used AI to maximise the genetic improvement tools that are available. The use of AI is very common in stud beef herds where breeders are seeking to produce elite bulls for sale or on farm use. In recent times commercial beef breeders are utilising AI to improve the quality of their female herd and also their steer progeny to ensure they are consistently meeting their market specifications. Developments in the field of fixed-time AI (FTAI) also offer managerial benefits in addition to the genetic improvement gained from AI. These advances are seeing AI rapidly adopted in the Australian beef industry. How do producers use AI? There are two methods of implementing an AI program into either your dairy or beef herd, through heat detection, or FTAI. Heat detection and AI: Heat detection and AI requires the accurate detection of when the cow is in ‘standing heat’ or is in oestrus. Ovulation on average occurs 26 to 30 hours after the onset of standing heat. To get the best result, the aim is to have the female inseminated 0 to 16 hours prior to the time of ovulation. As frozen-thawed sperm does not remain viable for as long as a natural ejaculate, it is necessary to AI close as possible to the time of ovulation. It is recommended that the female is inseminated 12 to 24 hours after the onset of standing heat (Figure 1). Usually at this point in time, the female is no longer in standing heat. A common mistake is to inseminate the females too early, failing to acknowledge the long duration from the onset of heat to the time of ovulation. For optimal results, it is critical that heat detection is accurate. It is recommended that heat detection is carried out twice daily for at least 45 min intervals by trained personnel. Use of heat detection aids can be used to indicate whether or not a female has been in standing heat, but this should not substitute physical observation of the females. If heat detection is inaccurate then females may not be submitted to AI OR be inseminated at the wrong time, both contributing to low number of calves born to AI and delayed conception in the cow herd.   Figure 1: Timing of ovulation relative to the time of standing heat or oestrus. Producers will use heat detection and AI when… They personally have the skills to AI or have on farm staff that can AI and are readily available to inseminate cows/heifers as they present on heat. There is sufficient and available trained labour on farm to observe for heat. Cows can be individually identified, drafted and separated for AI. Semen is expensive or rare, ensuring that each cow that receives a dose of semen has had a true heat. Small mobs are being submitted to AI – usually < 50 head. Fixed-time AI (FTAI): FTAI enables 100% of the mob to be submitted to AI without the need for any heat detection. It is necessary to synchronise the time of ovulation of each female in the herd using a synchronisation protocol so that the AI activity can occur at the one time for the whole herd. The aim is for the majority of the herd to ovulate within a 12 hour window after the time of AI. Administering synchronisation treatments for FTAI can be performed by farm staff with basic training. The synchronisation products are supplied by your veterinarian and/or your AI provider.  Producers will use FTAI when… There are no skilled AI technicians on farm, or the on farm technician is inexperienced in larger groups of animals. There is no provision of labour to accurately detect standing heat. Drafting and separating cows in standing heat is difficult or stressful to cattle/personnel, or they would like to spend less time on these activities. Semen is abundant or affordable. Mob sizes are large. There is a desire to reap the benefits of tighter calving and fertility improvements through synchronisation. Collect semen from sires that are on farm, and use chilled in an FTAI program. Combination of heat detection and FTAI: Why not make the most of what each technology can offer? In some programs, females are synchronised for FTAI. The operator will then heat detect the females up to 48 to 72 hours after the time the Cue-Mate® is removed. When the heat detection period has ceased, the balance of the females that have not been observed in heat, are FTAI. In these programs, the operator may choose to use more expensive or rare semen in these females that have been observed in heat, and a lower value or surplus semen in the females that are FTAI. This is an example of the many options that are available in protocol design and it is worth discussing your options with your veterinarian or expert. Heat detection vs. FTAI Pros 100% of the mob is submitted to AI. Activities are pre-planned at a particular time and day. Easier to plan off-farm labour. The whole mob is synchronised to one day. Calving occurs over a shortened period, early in the season. Earlier calves are heavier. Stimulates cows to cycle after calving. Generally results in more calves being born to AI. Don’t miss any cycles due to silent heats. Synchronisation treatments may treat some reproductive disorders. An excellent protocol if you collect and chill semen to be used within a specific timeframe. Cons A semen straw is required for every female in the program. Synchronisation treatments can be more expensive than heat detection, but is often offset by labour and managerial benefits. Unless intensive re-synchronisation programs are run, physical sires are still required. Heat Detection AI Pros Great for when semen is expensive or rare as only females that have been observed in heat are AI. If an AI technician is on farm, and there are small numbers in the mob, this may be a more affordable option. Some producers are more comfortable when they have observed the female on heat. Cons Accurate heat detection is required – costly in terms of labour. Risk of missing cows in heat, delaying the time to conception e.g. cows that have silent or discrete signs of heat such as lactating dairy cows. Requires drafting facilities to separate animals on heat. Labour tends to be costly. Generally results in fewer calves born by AI sires than when using FTAI. Expected Results Expected results from AI programs are highly dependent on a variety of factors. Key factors affecting the outcome of AI programs are as follows: Breed Body condition Lactation status Genetics Semen quality Disease Pasture type and quality Climate Experience of AI technician Overall management and husbandry quality   Embryo Transfer Cattle may be superovulated so that they will have multiple ovulations allowing numerous embryos to be collected on each flushing occasion. ET is also commonly referred to as MOET (Multiple Ovulation and Embryo Transfer), that refers to the whole process from superovulation of the donor female, flushing of the embryos, to the transfer of the embryos to the recipient female. Embryo transfer is a tool used by livestock breeders worldwide to assist in the transfer of genetics. Embryos may be frozen and shipped in liquid nitrogen that may be cheaper than physically transporting live animals. Overview The practice of ET is commonly used in stud cattle herds in Australia. Producers that have identified elite females in their herds often choose to use ET to maximise the genetic potential of these cows to a variety of elite sires. When producers actively utilise ET, a higher percentage of females will exist in the herd from their selected elite donor females. The majority of donor cows flushed each year globally are dairy breeds. However, in Australia, approximately 80% of the donor cows flushed each year are beef, which is possibly due to our proportionally larger beef herd. Advantages ET focuses on maximising the genetic potential of the high performing females in your herd. Although AI is a suitable choice for most herds, it only allows a breeder to maximise the genetic potential of elite sires. ET enables a cow to have many more calves in her lifetime than what is possible via natural mating. Embryo transfer is also a perfect way to introduce new or unique genetics into your herd. The freezing of cattle embryos that have been produced in vivo (fertilised and matured in the donor female) is well established. Therefore, frozen embryos can be purchased and transferred from farm to farm or around the globe and transferred into recipients yielding acceptable pregnancy rates that are sometimes comparable to fresh transferred embryos. Approximately half of the embryos transferred in Australia have been frozen .   How do producers use ET? Implementing ET programs on farm generally require two groups of females to be treated: Donor females Recipient females The general process of ET follows the following steps: Donor cows are selected and synchronised using Cue-Mate® and treated to superovulate with Folltropin-V®. Donor cows are inseminated with the sire of choice. At a similar time recipient cows are synchronised using Cue-Mate® and eCG. Approximately 7 days (time varies) after the donor cow ovulates, the veterinarian will flush the embryos from the donor cows and transfer them to recipient cows. If recipient cows are not available, embryos may be stored in liquid nitrogen until they are available.        Expected Results The expected outcome in any reproduction program is determined by a variety of factors. Factors that can contribute to the quantity and quality of embryos retrieved from donor cows and the likelihood that a recipient will become pregnant after embryo transfer could be, and are not limited to: Breed Age Body condition score Nutrition/Diet Disease Management Compliance when administering treatments.   The results obtained are highly reliant on the quality of the program management. At times pregnancy rates of up to 80% with fresh-transferred embryos can occur. However, on average, it is generally expected that when good quality embryos are transferred a pregnancy rate of approximately 65 to 70% with fresh and 60 to 65% with frozen embryos will result. The most variable aspect is the amount of transferable embryos that are retrieved from the donor female. When the embryos are flushed they are graded for quality, some may be suitable to transfer and others may not. Breed tends to be the largest factor contributing to this variation. In Vitro Fertilisation VF (In Vitro Fertilisation) technology has been used in livestock for many years, but in recent times, the use of IVF is growing. Livestock breeders can gain benefits in genetic improvement which are similar to ET systems. That is, breeders are able to maximise the genetic gain from the dam whilst using their sire of choice. The process of IVF relies on the extraction of the oocyte (unfertilised egg) from the ovary of the donor female, which is then matured, fertilised and cultured in vitro (in the lab). This differs to ET systems as the process occurs all within the donor female prior to flushing. In IVF, as oocytes are directly retrieved from the ovary of the donor female, more oocytes can be collected sometimes resulting in more embryos produced than in ET. Nevertheless, pregnancy rates are generally lower than ET programs and hence, don’t always result in more calves born. IVF can be the technology of choice for some livestock breeders. Generally IVF is selected over ET when the females are poor responders to superovulation treatments. This may be due to breed, a reproductive disorder, age of the female or for an undiagnosed reason. Overview The majority of IVF programs in cattle are conducted in South America, which accounts for about 85% of the IVF embryos produced globally. In Australia, the majority of embryos are produced through ET, in vivo (within the donor cow). The use of IVF is growing, particularly in the northern regions of Australia, as Bos indicus cattle breeds that dominate this region, tend to respond the best to the IVF procedures. Bos indicus cattle tend to yield more embryos than other breeds, yet tend to not respond as well to superovulatory treatments used in conventional ET. The use of IVF in Bos taurus breeds of cattle is possible, but are generally treated with some superovulation treatments to ensure a reasonable yield of oocytes. In Australia the majority of IVF derived embryos transferred to recipient females are fresh. Some frozen transfers do occur, however due to the high variability in pregnancy rates from these embryos, most practitioners and breeders prefer to use fresh where possible.   Advantages The reason breeders choose to use IVF is to maximise the genetic potential of elite donor females in their herd. The main advantage of using IVF in cattle is to get a higher yield of embryos in cattle where conventional ET programs are not working effectively. This generally includes cattle that do not respond well to superovulation treatments. This tends to be Bos indicus cattle, older females, or females that have reproductive disorders that won’t enable embryos to be flushed from the uterus. As Bos indicus females tend to have a large number of follicles present on their ovaries as compared to Bos taurus breeds, they tend to yield a higher number of oocytes. In addition, the proportion of oocytes that convert to embryos are much higher in Bos indicus breeds than others. For most IVF programs, the donor female doesn’t require any treatments to superovulate nor synchronise their ovulation. The oocytes are collected by an experienced veterinarian using a process called ‘ovum pick up’ commonly referred to as OPU. During OPU the veterinarian will use a vacuum pressured needle, passed transvaginally, to puncture any antral follicles that are present on the ovary. The needle will then extract the follicular fluid and the oocyte that is then transferred to a holding vial. After completion of OPU the oocytes are incubated and transferred to the laboratory. Up to 3 OPUs per female can be performed in a 30 to 40 day interval. Generally this means that numerous embryos may be collected from a female and also enable her to calve every 12 months.   Once the oocytes are at the laboratory, they will be matured using a process called ‘in vitro maturation’ or IVM. After the maturation process, the oocytes are fertilised with the semen preferred by the breeder. The oocytes are then cultured for a further 6 days, so that they can reach development to an appropriate embryo stage (usually morula) that will be suitable for transfer into recipients. The embryos are graded so that only suitable good quality embryos are transferred into recipients. The recipient cows are usually treated previously to synchronise their ovulation to ensure that they are at the correct stage in their cycle to receive the embryo. It is possible to preserve the embryos by freezing, however pregnancy rates to frozen IVF embryos are typically variable and can be low. In Australia, the average conception rate to transferred fresh IVF embryos is approximately 40 to 45%. As per any assisted reproduction program, there are a variety of variables that can affect the result. Semen quality, breed and technician can significantly contribute to the outcome. The table below outlines the average results that can be expected in ‘unselected’ donor females. If you ‘pre-select’ your donor cows by choosing the ones that are most likely to yield a higher number of embryos, it is possible that these statistics will increase.   EBV’s / ASBV’s Estimated breeding values (EBV) or Australian Sheep Breeding Values (ASBVs) estimate the performance of the offspring of an animal. They are the most accurate tools the sheep industry has to predict performance of the next generation and to establish why animals performed the way they did. ASBVs are the best prediction for an animal’s genetic merit for a particular trait. There are ASBVs for many traits that impact the performance and profitability of your flock. These include health and welfare, growth, fleece, carcase, reproduction and visual traits. ASBVs are predicted using an animal’s phenotype (or raw measurements) and pedigree information (who they are related to). These breeding values estimate which genes an animal has for a trait based on how much an animal expresses that trait. For most traits, lots of genes control performance. These are called polygenic traits. Therefore, ASBVs are predictions of genetics based on what is known about an animal at the time. ASBVs do change as more information becomes available and we get closer to knowing the true genetics of an animal. Higher heritability traits have higher accuracy because they are easier to predict. Genetics are playing a bigger role for these traits. Selection indexes help you to select sheep which match the breeding objective. To make selection more efficient, ASBVs for several traits are combined to give a single value. Indexes work well because they: Place emphasis on traits – weighting depending on economic value. Take into account correlations – get the ideal balance between traits. Enable gain across many traits. The index reflects the performance of the sheep relative to the breeding objective of the index. Accuracy Description >50% The EBVs are preliminary. EBVs in this range will have been calculated based on very little information. These EBVs could change substantially as more direct performance information becomes available on the animal. 50-74% The EBVs are of medium accuracy. EBVs in this range will usually have been calculated based on the animal’s own performance and some limited pedigree information. 75-90% The EBVs are of medium-high accuracy. EBVs in this range will usually have been calculated based on the animal’s own performance coupled with the performance for a small number of the animal’s progeny. 90-100% The EBVs are a high accuracy estimate of the animal’s true breeding value. It is unlikely that EBVs will change considerably with addition of more progeny data. Terminology to know With a partner, test yourself on the following terms: Accuracy Angus Artificial insemination ASBV’s Breeders Breeding program Bull Check Calves at foot Crossbred Crossbreeding EBV’s Elite Embryo transfer Ethical considerations Ewe Extension officer Fertilisation Genetic quality Genomic testing Heifer Heifer calf In vitro Justify Management technique Milk yield Natural breeding Natural joining Oestrus cycle Performance Poll Hereford Preg testing Profit Purebred Ram Reginal Reliability Replacement heifers Reproductive technologies Reproductive traits Season Semen sexing Social and welfare considerations Steer Stud Texel Trait Trait leader Weaned Yearling eye muscle depth Yearling fat depth Yearling weight Practice Questions Justify why a producer would economically invest into a breeding program. __________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ Fill in the blanks here: Using your knowledge of the oestrous cycle in sheep (and/or cattle), explain the complete cycle in as much detail as possible: __________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________________________________________________________________ __________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________________________________________________________________ __________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ Fill out the following tables of traits you would choose to improve through a breeding program: Trait Justification Explain why a producer would carry out a breeding program using reproductive technology over natural mating. __________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ______________________________________________________________________________________________________________________________________________________________________________________________ Describe the following methods that can be used in a breeding program. Natural mating __________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ Artificial Insemination _________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ Embryo Transfer _________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ In Vitro Fertilisation _________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ Discuss ethical considerations of reproductive technologies. _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________    Identify why semen would be collected from a bull. Discuss what the collected semen can be used to make money.  _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ Explain the benefits of using Artificial Insemination over natural mating   _________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ Explain why embryo transfer might be used more often than in vitro fertilisation _________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ Using the terms Phenotype and Genotype, write the formula out discussed in class. __________________________________________________________________________________ Looking at the formula you have just written, discuss the limitations that exist from a management perspective when trying to maximise economic output in livestock through breeding. _________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ What are EBV’s and how are they used? __________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ What are ASBV’s and how are they used? __________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ What is genomic testing and why is it used? ___________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ Sire selection is critical regardless of the type of reproduction. There are a range of ways that a producer can make this decision. Explain how visual assessment, EBV/ASBV’s, reproductive technologies and genomic testing can be used in conjunction with each other to assist a producer to select a ram or bull. Justify the use of each of these in combination to yield the best results. Ensure to include economical justification within this. ___________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ Explain why speeding up genetic gain of breeding stock is economically beneficial to the producer and contributes to doubling world food production by 2050. ___________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ ___________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ Give two clear reasons why a farmer may opt to use a bull/ram, rather than implement a reproductive technology. ___________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ Imagine you are a vet, what recommendations would you make to a farmer before they purchased a new bull or ram? __________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ Explain what oestrus synchronisation is. Why may this be easier and more time efficient for a farmer? __________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ Why must farmers ensure that an ewe/cow is in oestrus prior to AI? __________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ Artificial Insemination is not widely used on stations in the Northern Territory, provide an explanation for this fact. ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ Read the following article, http://www.abc.net.au/news/rural/2016-06-29/making-stud-calf-using-artificial-insemination/7554644 and explain how cattle producers can use A.I. to access genetics which best suit their herd. __________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ Traditionally, reproductive technologies have only been used in stud operations. However, increases in A.I. in commercial operations have been observed. Research this and then discuss if you think this will continue to increase. __________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ Explain how A.I. must be used in conjunction with E.T., for E.T. to be successful. __________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ Outline how ‘average’ quality cows, can be used to multiply superior cattle using E.T. __________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ Define ‘heritability’ and explain using the table below, which traits a farmer could make greater progress on in one generation. Explain your answer. __________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ Earlier this year, a three-month old dairy heifer sold at International Dairy Week for $251,000. Explain how the purchasers would intend to make a profit after outlaying such a significant amount for the heifer. _______________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ From a management perspective, consider the benefits of reproductive technologies. Consider factors such as injury, biosecurity, accessibility to genetics and labour. ________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ Over five years, a stud dairy farmer wants to increase the overall milk yield of his heifers. Traditionally he has only used natural mating. Suggest a reproductive technology which the farmer could adopt to improve his overall milk yield. Explain your answer. A beef farmer has implemented Artificial Insemination into his breeding program. Unfortunately, the success rate was only 40% of cows in calf. Suggest two ways in which the farmer can increase the success rate of the A.I. Draw a flow chart for each of the following methods used for reproduction. Include as much details as you can. Natural mating Artificial Insemination Embryo Transfer In vitro Fertilisation Westminster School (305) Stage II Agricultural and Horticultural Studies TASK DESCRIPTION: Genetics and Reproduction Practice Test ASSESSMENT TYPE AND NUMBER: Skills and Application Task 2 – Practice Run Task Objectives: To assess theory concepts from both the reproductive technologies and genetic units To assess students’ ability to apply concepts learnt in realistic scenarios or situations To assess students’ knowledge within a supervised environment Task Description: The following practice test is based around the theory components learnt within the genetics and reproductive technologies unit this term. The guidelines of this practice test are outline below – The practice test will be conducted under supervised conditions. All questions are to be answered. You will have 100 minutes to complete the test. Scribble paper for making notes will be provided. Please refer to the Performance Standards at the back of the test paper if required. Use of a calculator is permitted. Define ASBVs (Australian Sheep Breeding Values) and explain how they are used in sheep breeding programs. In 2021, a stud breeder sold a 6-month-old merino ram for $50,000. Explain, in accordance with the price they paid, why the purchasers could justify paying this much for the ram and what you think they planned to do with the ram to regain the money they have outlaid. List 6 traits that Sheep Genetics Australia records, explain why this trait is recorded, and what information it provides to a sheep producer. A sheep farmer has had his 100 ewes pregnancy tested. Look at the following data from this pregnancy test. Ram Name Number of Ewes Joined Number of Ewes in Lamb Charlie Chaplin 40 38 Simon 40 39 Tommy 40 10 Explain the method of reproduction that has been used in the above table. b. Explain, from looking at the data, one major problem you can identify. Explain what may have caused this. c. If you were the vet who pregnancy tested the ewes, suggest what your advice may have been regarding this result Within the Australian Sheep Industry, there has been a growing demand for merino wool with higher quality and quantity. Therefore, there is a need for breeding programs that focus on improving wool traits. a. Discuss the role of ASBVs in improving wool traits in merino sheep. b. In addition to ASBVs, what other breeding techniques or technologies can a merino sheep farmer use to improve wool traits? Explain your answer. c. Discuss the social and welfare implications (disadvantages/advantages) of selective breeding for wool traits. Over five years, a stud merino farmer wants to increase the overall wool yield of his flock. Traditionally he has only used natural mating (purchasing merino rams from around Australia). Suggest a change in procedure which this farmer could make to improve his overall wool yield. Explain your answer. A sheep farmer has implemented Artificial Insemination into his breeding program. Unfortunately, the success rate was only 50% of ewes in lamb. Suggest two ways in which the farmer can increase the success rate of the A.I. A sheep farmer has been breeding merino sheep for a number of years. The farmer's management program includes the following: Located in Western Australia 500 ewes Produces approximately 1,000 lambs each year for sale Retains 20% of ewe lambs as replacement breeding stock Sells the remainder of the lambs through the local livestock market The farmer is interested in using ASBVs to improve the performance of their flock. Recommend 5 traits the farmer could focus on to improve the performance of their sheep, and their overall profit. Explain why you have selected each of these traits. A ram farmer has a flock of Border Leicester ewes and wants to improve the genetic performance of his flock. The farmer is considering using artificial insemination (AI) to breed his ewes. Suggest two advantages and two disadvantages of using AI in a sheep breeding program. A stud sheep breeder is considering using embryo transfer (ET) to multiply the genetic potential of their elite ewes. Explain the procedure of embryo transfer in sheep and suggest two advantages and two disadvantages of using ET in a sheep breeding program. A sheep farmer is concerned about inbreeding in their flock. Explain the concept of inbreeding and its effects on sheep breeding. Suggest two methods that the farmer can use to reduce inbreeding in their flock. A farmer has a flock of merino sheep and wants to improve their resistance to parasites. Suggest two traits that the farmer could focus on to improve the parasite resistance of their sheep, and explain why these traits are important for resistance. A farmer is considering crossbreeding their merino ewes with another breed to improve meat quality. Explain the concept of crossbreeding and suggest two breeds that could be used in a crossbreeding program with merino sheep. Explain why you have chosen these breeds. A farmer is interested in using genomic testing to select superior breeding animals in their flock. Explain the concept of genomic testing and its advantages and disadvantages in sheep breeding programs. MODEL ANSWERS: ASBVs (Australian Sheep Breeding Values) are measurements that estimate the genetic potential of an individual sheep for certain traits, such as wool quality and quantity, growth rate, and disease resistance. These values are calculated by comparing the animal's performance to the average performance of its contemporaries, taking into account environmental factors such as age and sex. ASBVs are used in sheep breeding programs to inform breeding decisions, as animals with higher ASBVs are more likely to pass on desirable traits to their offspring. By selecting animals with higher ASBVs for breeding, breeders can improve the overall genetic quality of their flock and increase productivity and profitability. The purchasers of the $50,000 merino ram likely justified the high price based on the ram's exceptional genetics and potential to improve their breeding program. It is possible that the ram had high ASBVs for desirable traits such as wool quality and quantity, growth rate, and disease resistance. Additionally, the ram may have had a proven track record of producing high-quality offspring. By incorporating this ram into their breeding program, the purchasers could expect to see an improvement in the quality and productivity of their flock. To regain the money they have outlaid, the purchasers may plan to sell offspring of the ram at a premium price or use them to improve their own flock's genetics. Six traits that Sheep Genetics Australia records include: fleece weight, fibre diameter, staple length, staple strength, worm egg count, and eye muscle depth. These traits are recorded to provide information to sheep producers on the genetic potential of individual sheep for wool production, disease resistance, and meat quality. Fleece weight is an important trait as it is directly related to wool production and profitability. Fibre diameter affects wool quality and can impact the value of the fleece. Staple length is important for processing efficiency and product quality. Staple strength is important for durability and wear. Worm egg count is a measure of parasite resistance, which can impact sheep health and productivity. Eye muscle depth is an indicator of meat quality, with deeper eye muscles generally being associated with better meat quality. 4) a. The method of reproduction used in the above table is natural mating, as the ewes were joined with a ram to conceive. b. One major problem that can be identified from the data is the low pregnancy rate for Tommy, with only 10 out of 40 ewes in lamb. This may have been caused by poor fertility in Tommy or poor management practices, such as inadequate nutrition or poor breeding timing. c. If I were the vet who pregnancy tested the ewes, my advice would depend on the cause of the low pregnancy rate for Tommy. If poor fertility was the issue, I may recommend culling Tommy or seeking veterinary assistance to improve fertility. If poor management practices were the issue, I would advise the farmer to address these issues to improve reproductive performance in their flock. 5) a. ASBVs play a crucial role in improving wool traits in merino sheep by allowing breeders to select animals with desirable wool traits for breeding. By selecting animals with high ASBVs for wool quality and quantity, breeders can improve the overall genetic quality of their flock and increase wool production and profitability. Additionally, ASBVs can help breeders to improve other traits that are indirectly related to wool quality, such as disease resistance and growth rate. b. In addition to ASBVs, merino sheep farmers can use other breeding techniques and technologies to improve wool traits. These include artificial insemination, embryo transfer, and genomic selection. Artificial insemination and embryo transfer allow breeders to use genetics from elite animals to improve their flock without physically bringing the animals onto their property. Genomic selection uses DNA analysis to identify animals with desirable traits, allowing breed To improve overall wool yield, the stud merino farmer could implement a controlled mating program, also known as joining to specific rams. This method involves using selected rams that have demonstrated desirable wool traits and breeding them with a group of ewes that have been selected for their wool traits. This process ensures that the desired genetic traits are passed on to the next generation, resulting in improved wool yield. The farmer could use Artificial Insemination (AI) to ensure that the selected rams' genetics are passed onto a greater number of ewes, increasing the likelihood of genetic improvement. To increase the success rate of A.I, the sheep farmer could consider the following approaches: i. Improve the quality of the semen used in the A.I process. Poor semen quality is a common reason for the low success rate of A.I, and the farmer should ensure that they are using semen from a reputable source, that has been properly stored and handled. ii. Improve the timing of the A.I process. Timing is crucial in A.I, and the farmer should ensure that the ewes are in the right stage of their reproductive cycle for successful insemination. This may involve synchronizing the oestrous cycle of the ewes to ensure that the A.I is carried out during the optimum time. 8) To improve the performance of their flock and overall profit, the merino sheep farmer could focus on the following five traits using ASBVs: i. Wool Yield: Selecting rams with high ASBVs for wool yield will increase the fleece weight of the offspring, resulting in a higher profit. ii. Fibre diameter: Rams with low ASBVs for fibre diameter produce finer wool, which is in high demand and has a higher market value. iii. Worm resistance: Selecting rams with high ASBVs for worm resistance will produce offspring that require less drenching, resulting in reduced costs and labour. iv. Birth weight: Selecting rams with high ASBVs for birth weight will increase lamb survival rates, resulting in higher overall lamb production and therefore higher profit. v. Carcase weight: Selecting rams with high ASBVs for carcase weight will increase the weight of the lambs at slaughter, resulting in higher overall profit. Advantages of using AI in a sheep breeding program include the ability to introduce desirable genetics from rams that may not be locally available, which can result in faster genetic progress. Additionally, using AI allows the farmer to avoid the cost of purchasing and maintaining a ram. Disadvantages of using AI include the cost associated with the procedure and the need for specialized equipment and skills. Additionally, there is a risk of lower conception rates and higher rates of pregnancy loss compared to natural mating, which can result in lower overall reproductive success. Embryo transfer (ET) is a reproductive technology that allows the genetic material of an elite female to be transferred to multiple recipient females. In sheep breeding programs, the procedure involves the superovulation of the donor ewe to produce multiple eggs, which are then fertilized using artificial insemination. The fertilized eggs are then collected and transferred into the reproductive tract of recipient ewes. The recipient ewes carry the pregnancy to term and give birth to offspring that are genetically identical to the donor ewe. Advantages of using ET in a sheep breeding program include the ability to multiply the genetic potential of elite females, which can accelerate genetic gain in a flock. Another advantage is the ability to preserve rare or endangered breeds by using ET to produce offspring from a small number of genetically valuable individuals. Disadvantages of using ET include the high cost of the procedure, which may not be feasible for some breeders. Another disadvantage is the potential for reduced fertility and increased embryonic loss in recipient females, which can reduce the overall success of the procedure. Inbreeding is the mating of closely related individuals within a population or flock. The effects of inbreeding on sheep breeding include reduced genetic diversity, which can increase the risk of genetic disorders and decrease performance and productivity. Inbreeding can also lead to reduced fertility, lower growth rates, and reduced resistance to disease. Methods that a farmer can use to reduce inbreeding in their flock include outcrossing, which involves mating individuals from different flocks or breeds to increase genetic diversity. Another method is to implement a breeding program that uses selection to avoid mating closely related individuals. This can involve using pedigree records to track the genetic relationships between individuals in the flock and avoiding matings that would produce offspring with high levels of inbreeding. Two traits that a farmer could focus on to improve the parasite resistance of their merino sheep include fecal egg count (FEC) and resilience. FEC measures the number of parasite eggs present in a sheep's feces and is an indicator of the level of parasite burden in the animal. By selecting for low FEC, a farmer can breed sheep that are less susceptible to parasitic infections. Resilience is a trait that measures the ability of a sheep to maintain production levels in the face of a parasite challenge. By selecting for high resilience, a farmer can breed sheep that are better able to resist the negative effects of parasitic infections. Crossbreeding is the mating of individuals from different breeds to produce offspring with desirable traits from both parental breeds. In a crossbreeding program with merino sheep, two breeds that could be used include the Texel and the Suffolk. The Texel is known for its meat quality, and its use in a crossbreeding program can improve the meat yield and carcass quality of merino lambs. The Suffolk is a breed that is known for its growth rate and feed efficiency, which can improve the growth and productivity of crossbred lambs. Genomic testing is a technology that uses DNA markers to estimate the genetic value of individuals for various traits. In sheep breeding programs, genomic testing can be used to identify superior breeding animals and accelerate genetic gain. The advantages of using genomic testing include the ability to select breeding animals at a younger age, which can reduce generation intervals and increase the rate of genetic improvement. Another advantage is the ability to increase the accuracy of selection for traits that are difficult to measure directly, such as disease resistance. The disadvantages of using genomic testing include the high cost of the procedure, which may not be feasible for all breeders. Another disadvantage is the potential for incomplete or inaccurate information due to incomplete knowledge of the sheep genome. Finally, the use of genomic testing may also raise ethical concerns related to genetic privacy and ownership of genetic information. Please use the following section to answer questions from the textbook.

Show More Show Less