High Genetic Merit Research Articles

Generating Cloned Goats by Somatic Cell Nuclear Transfer—Molecular Determinants and Application to Transgenics and Biomedicine

The domestic goat (Capra aegagrus hircus), a mammalian species with high genetic merit for production of milk and meat, can be a tremendously valuable tool for transgenic research. This research is focused on the production and multiplication of genetically engineered or genome-edited cloned specimens by applying somatic cell nuclear transfer (SCNT), which is a dynamically developing assisted reproductive technology (ART). The efficiency of generating the SCNT-derived embryos, conceptuses, and progeny in goats was found to be determined by a variety of factors controlling the biological, molecular, and epigenetic events. On the one hand, the pivotal objective of our paper was to demonstrate the progress and the state-of-the-art achievements related to the innovative and highly efficient solutions used for the creation of transgenic cloned does and bucks. On the other hand, this review seeks to highlight not only current goals and obstacles but also future challenges to be faced by the approaches applied to propagate genetically modified SCNT-derived goats for the purposes of pharmacology, biomedicine, nutritional biotechnology, the agri-food industry, and modern livestock breeding.

287 Effects of Number of Sperm and Site of Uterine Semen Deposition on Conception Rate and Number of Embryos in Weaned Sows Receiving a Single Fixed Time Insemination

Abstract Induced ovulation with single fixed time artificial insemination (SFTAI), combined with uterine (IUI) or deep uterine insemination (DUI), could improve fertility with low numbers of sperm and allow greater use of high genetic merit boars. At weaning (0 h), sows (n = 534) were assigned by parity and estrus induction method (eCG or Control) to receive 1200 × 106 sperm by IUI, 600, 300, or 150 × 106 sperm by IUI or DUI, or 75 × 106 sperm by DUI. At 80 h post weaning, sows received OvuGel and 26 h later a pooled semen SFTAI. Ultrasound was performed to determine follicle size and time of ovulation (OV). Sows were slaughtered 27 d after AI to determine pregnancy and litter traits. There was no effect (P > 0.05) of eCG on estrus (93%) within 5 d of weaning or follicle size (6.1 mm) at OvuGel, but wean-to-estrus (3.8 vs. 4.0 d,P < 0.01) and AI-to-OV (15.9 vs. 17.0 h, P = 0.04) intervals and AI-to OV were slightly reduced. eCG did not affect pregnancy rate (78.6%), number of CL (21.7), or number of viable embryos (12.2). There was no effect of number of sperm or site of insemination (P > 0.05) on pregnancy rate (range: 80.9% to 70.5%), but AI occurring after ovulation reduced pregnancy rate (P < 0.02). Total number of embryos (range: 16.5 to 10.3) increased with CL number (P < 0.001) but was not affected by number of sperm or site of insemination (P > 0.05). Higher sperm treatments (1200 and 600 x 106) had more embryos compared to lower sperm treatments (P < 0.01), suggesting that lower sperm numbers effects litter size more than the pregnancy status. Acceptable fertility can be achieved with low sperm numbers when using SFTAI and uterine deposition, but AI-to-OV interval and ovulation rate influence final fertility.

A comparison of farm labour, profitability, and carbon footprint of different management strategies in Northern European grassland sheep systems

CONTEXTSheep production systems need to become more carbon efficient to meet growing public demands on climate change. Some of the ways postulated to achieve this is to implement new technologies and management strategies such as precision livestock farming (PLF), increased use of high genetic merit animals with estimated breeding values through artificial insemination (AI) where practical, and the use of prolific breeds. However, the carbon footprint impact of these strategies has not to-date been quantified. Additionally, international experience indicates that uptake of such strategies is low due, in part, to the perception of increased workload especially during busy periods of the sheep year. OBJECTIVESThis trans-European study investigates the impact of differing sheep management strategies on farm labour input, carbon footprint as well as the on-farm profitability, to address these concerns. METHODSFour management strategies were considered i) use of technology (PLF), ii) use of performance recording for higher genetic merit, iii) use of AI for higher genetic merit and iv) and use of prolific breeds, in 14 case study flocks located in areas typical of Northern European grassland sheep production systems across Scotland, France, Ireland and Norway. For each management strategy, paired case study flocks were identified. Labour was assessed at key handling events using video recording, farmers' diaries, and questionnaires, which were later quantified and classed into key tasks to create normalised labour profiles for each case study flock. The carbon footprint was quantified using a carbon calculator tool (www.agrecalc.com). Financial net margins were calculated. RESULTS AND CONCLUSIONSResults highlighted that introducing PLF technology on extensive farms reduced labour by 20% and increased economic margins by £9/ewe but with a concurrent increase in carbon emissions (kg CO2e/ kg of meat produced). Using performance recording on sheep farms for achieving higher genetic merit increased economic margins by £6/ewe, and reduced carbon emissions (kg CO2e) per kg of meat produced but resulted in 10% extra labour. AI on farms increased economic margins by £50/ewe, did not incur extra labour and increased carbon efficiency in terms of kg CO2e/kg meat produced. Finally, high prolific breeds did not significantly increase labour input at key handling events and resulted by higher economic margins (+£3/ewe), without a change in terms of kg CO2e/kg meat produced. SIGNIFICANCEThese novel case studies clearly illustrate it is possible to increase carbon and labour efficiency by adopting technology, changing breeding management or ewe breed on sheep farms.

The impact of maternal genetic merit and country of origin on ewe reproductive performance, lambing performance, and ewe survival.

The objective of this study was to investigate the impact of the ewe’s maternal genetic merit and country of origin [New Zealand (NZ) or Ireland] on ewe reproductive, lambing, and productivity traits. The study was performed over a 4-yr period (2016–2019) and consisted of three genetic groups: high maternal genetic merit (NZ), high maternal genetic merit Irish (High Irish), and low maternal genetic merit Irish (Low Irish) ewes. Each group contained 30 Suffolk and 30 Texel ewes, selected based on the respective national maternal genetic indexes; i.e., either the NZ Maternal Worth (NZ group) or the €uro-star Replacement index (Irish groups). The impact of maternal genetic merit on reproductive traits such as litter size; lambing traits such as gestation length, birth weight, lambing difficulty, mothering ability; and productivity traits such as the number of lambs born and weaned was analyzed using linear mixed models. For binary traits, the impact of maternal genetic merit on reproductive traits such as conception to first artificial insemination (AI) service; lambing traits such as dystocia and perinatal lamb mortality; and productivity traits such as ewe survival was analyzed using logistic regression. NZ ewes outperformed Low Irish ewes for conception to first AI (P < 0.05) and litter size (P = 0.05). Irish ewes were more likely to suffer from dystocia [6.84 (High Irish) and 8.25 (Low Irish) times] compared to NZ ewes (P < 0.001); birth weight and perinatal mortality did not differ between groups (P > 0.05). Lambs born from NZ ewes were 4.67 [95% confidence interval (CI): 1.89–11.55; P < 0.001] and 6.54 (95% CI: 2.56–16.71; P<0.001) times more likely to stand up and suckle unassisted relative to lambs born from High or Low Irish ewes, respectively. NZ and High Irish ewes had a greater number of lambs born and weaned throughout the duration of the study compared to their Low Irish counterparts (P<0.001). NZ ewes tended to be more likely to survive from one year to the next compared with Low Irish ewes (P=0.07). Irish ewes of high maternal genetic merit outperformed their low counterparts in total number of lambs born and weaned per ewe, but performance did not differ across other traits investigated. This highlights the importance of continuous development of the Irish maternal sheep index to ensure favorable improvements in reproductive, lambing, and productivity traits at the farm level. Overall, results demonstrate the suitability of NZ genetics in an Irish production system.

The Autumn Low Milk Yield Syndrome in High Genetic Merit Dairy Cattle: The Possible Role of a Dysregulated Innate Immune Response.

Simple SummaryMilk yield worldwide is dominated by few cosmopolitan dairy cattle breeds producing high production levels in the framework of hygiene standards that have dramatically improved over the years. Yet, there is evidence that such achievements have gone along with substantial animal health and welfare problems for many years, exemplified by reduced life expectancy and high herd replacement rates. Also, these animals are very susceptible to diverse environmental stressors, among which hot summer climate plays a central role in the occurrence of diverse disease cases underlying early cull from the herd. Milk production is also affected by heat stress, both directly and indirectly, as shown by low milk yield in the following autumn period. This article highlights the low milk yield syndrome and sets it into a conceptual framework, based on the crucial role of the innate immune system in the response to non-infectious stressors and in adaptation physiology at large.The analysis of milk yield data shows that high genetic merit dairy cows do not express their full production potential in autumn. Therefore, we focused on metabolic stress and inflammatory response in the dry and peripartum periods as possible causes thereof. It was our understanding that some cows could not cope with the stress imposed by their physiological and productive status by means of adequate adaptation strategies. Accordingly, this study highlights the noxious factors with a potential to affect cows in the above transition period: hot summer climate, adverse genetic traits, poor coping with unfavorable environmental conditions, outright production diseases and consequences thereof. In particular, the detrimental effects in the dry period of overcrowding, photoperiod change and heat stress on mammary gland development and milk production are highlighted in the context of the autumn low milk yield syndrome. The latter could be largely accounted for by a “memory” effect on the innate immune system induced in summer by diverse stressors after dry-off, according to strong circumstantial and indirect experimental evidence. The “memory” effect is based on distinct epigenetic changes of innate immunity genes, as already shown in cases of bovine mastitis. Following a primary stimulation, the innate immune system would be able to achieve a state known as “trained immunity”, a sort of “education” which modifies the response to the same or similar stressors upon a subsequent exposure. In our scenario, the “education” of the innate immune system would induce a major shift in the metabolism of inflammatory cells following their reprogramming. This would entail a higher basal consumption of glucose, in competition with the need for the synthesis of milk. Also, there is strong evidence that the inflammatory response generated in the dry period leads to a notable reduction of dry matter intake after calving, and to a reduced efficiency of oxidative phosphorylation in mitochondria. On the whole, an effective control of the stressors in the dry period is badly needed for better disease control and optimal production levels in dairy cattle.

Herd life, lifetime production, and profitability of Viking Red-sired and Montbéliarde-sired crossbred cows compared with their Holstein herdmates

The first 2 generations from a 3-breed rotation of the Viking Red (VR), Montbéliarde (MO), and Holstein (HO) breeds were compared with their HO herdmates in high-performance commercial herds in Minnesota. The designed study enrolled pure HO females in 2008 to initiate a comparison of 3-breed rotational crossbreds with their HO herdmates. Sires of cows were proven artificial insemination bulls selected for high genetic merit in each of the 3 breeds. The first-generation cows calved for a first time from 2010 to 2014 and had 376 VR × HO and 358 MO × HO crossbreds to compare with their 640 HO herdmates. The second-generation cows calved for a first time from 2012 to 2014 and had 109 VR × MO/HO and 117 MO × VR/HO crossbreds to compare with their 250 HO herdmates. Collection of data ceased on December 31, 2017, and all cows studied had the opportunity for 45 mo in the herd after first calving. Production of milk, fat, and protein (kg) during lifetimes of cows was estimated from test-day observations with best prediction. The lifetime profit function included revenue and cost. Revenue was from production, calves, and slaughter of cull cows. Costs included feed cost during lactation, lactating overhead cost, dry cow cost (including feed cost during dry periods), replacement cost, health treatment cost, insemination cost, fertility hormone cost, pregnancy diagnosis cost, hoof trimming cost, and carcass disposal cost. For individual cows with herd life longer than 45 mo after first calving, survival of cows was projected beyond 45 mo after first calving to estimate herd life, production, and profitability. The 2-breed crossbreds had +158 d longer herd life and the 3-breed crossbreds had +147 d longer herd life compared with their respective HO herdmates. Also, 12.4% of the 2-breed crossbreds died up to 45 mo after first calving compared with 16.3% of their HO herdmates. Furthermore, approximately 29% of both the 2-breed and 3-breed crossbreds lived beyond 45 mo after first calving compared with approximately 18% of their respective HO herdmates. On a lifetime basis, the 2-breed and 3-breed crossbreds provided +$122 and +$134, respectively, more cull cow revenue compared with their HO herdmates. For lifetime replacement cost, the 2-breed crossbreds did not differ from their HO herdmates; however, the 3-breed crossbreds had -$28 less lifetime replacement cost compared with their HO herdmates because of their younger age at first calving. The combined 2-breed crossbreds had +$0.473 (+13%) more daily profit (ignoring potential differences for feed efficiency) and the combined 3-breed crossbreds had +$0.342 (+9%) more daily profit compared with their respective HO herdmates. This resulted in +$173 more profit/cow annually for the combined 2-breed crossbreds and +$125 more profit/cow annually for the combined 3-breed crossbreds compared with their respective HO herdmates.

Conservation and improvement of Kankrej cattle (Bos indicus): Status vis-Ã -vis strategies

The present study was conducted at Livestock Research Station, to compare performance of Kankrej cattle at farm and field condition, and to suggest strategies for the overall improvement of this prestigious breed. The average lactation yield (lit.), standard lactation (lit.), fat percentage, age at first calving and calving interval in the farmers herd was 1669.96±12.24 (1523), 1751.23±12.94 (617), 4.13±0.03 (617), 1464.08±18.41 (260) and 549.93±8.61 (387), respectively during the initial phage of progeny testing program initiated by station and the performance of migratory herd was 2.64 litre (wet average). While, the average lactation yield (lit.), standard lactation (lit.), fat percentage, age at first calving and calving interval at station was 2682.27±126.71 (59), 2501.15±87.72 (59), 4.08±0.09 (49), 1218.42±35.27 (12) and 435.73±13.94 (36), respectively (Elite herd, Anonymous 2018). The lactation yield of daughters born under the progeny testing program was 2050.29±119.20 (104) litres. Looking to the performance gap between the herd maintained at station, field and pastoralist indicates wide scope for the genetic improvement in Kankrej breed by following strict breeding strategies which are discussed in this paper. Conclusively, intensive selective breeding with the use of artificial insemination technology at large scale and progeny testing with precise recording at small scale will solve the purpose in the non-migratory population while, supply of high genetic merit male calf or proven bull’s male calf to the Maldharis having migratory population.

145 Comparison of single to multiple injections of follicle-stimulating hormone before ovum pickup in Holstein heifers: Oocyte recovery and embryo production

The demand for invitro-produced embryos from heifers with high genetic merit has increased over time. Synchronization and stimulation of follicular growth before ovum pickup (OPU) has been used to improve oocyte quality and, consequently, embryo production. Multiple injections involve extra labour and stress for both personnel and cattle. The release of FSH can be prolonged by using 0.5% hyaluronan (HA) as a diluent, allowing a decrease in the number of injections. The objective of this study was to compare oocyte recovery and embryo production between single or multiple injections of FSH before OPU of Holstein heifers. During April and May 2020, 20 Holstein heifers (8 to 15 mo old) from Ruann Dairy (Riverdale, CA) were randomly divided and submitted to two different treatments (crossover design). Gonadotrophin-releasing hormone (GnRH; Fertagyl®, Merck, 129µg, IM) was given to synchronize the follicular wave emergence. Treatment 1×FSH consisted of a single intramuscular (IM) injection of 100mg of FSH (Folltropin®, Vetoquinol) 36h after GnRH. The FSH consisted of a 2.5-mL injection of 400mg of FSH diluted in 10mL of 0.5% HA. OPU was performed 48 to 50h after FSH. Treatment 5×FSH consisted of 100mg of FSH divided into 5 equal IM injections (10-14h intervals) 36h after GnRH. The FSH consisted of 5×1-mL injections of 400mg of FSH in 20mL of saline. OPU was performed 18 to 20h after the last FSH injection. All donors received both treatments at a 14-day interval and the recovered oocytes were fertilized with the same sexed female-sorted semen in both rounds. OPU, oocyte classification, IVM, IVF, and culture (IVC) were performed as described by Demetrio et al. (2020 Anim. Reprod. 17, e20200053). All oocytes went into IVM, except for degenerated oocytes. The number of 4-cell (or more) embryos on Day 3 of IVC divided by the number of oocytes in IVC after IVF is defined as the cleavage rate. The number of blastocysts (early to hatched) on Day 7 of IVP divided by the number of oocytes in IVC after IVF is defined as the blastocyst rate. Poisson-normal (count data) and Logistic-normal (proportion data) models were used to analyse the data. Treatment, donor (random effect), and sire were included in the models. The results are summarized in Table 1. There were no differences between the two treatments on the number of oocytes recovered per OPU (total and grade 1 and 2), percentage of grade 1 and 2 oocytes, cleavage rate, blastocyst rate and number of embryos (total and grade 1). Oocyte recovery and embryo production are highly donor dependent. Stimulation of the follicular growth before OPU with one single injection of FSH diluted in 0.5% HA 36h after GnRH can be efficiently used for IVP in Holstein heifers, without decreasing the number of oocytes recovered and/or embryos produced with the advantage of reducing labour and stress of handling cattle. Table 1. Number and quality of oocytes and cleavage and blastocyst rates Treatment OPU Oocytes per donor Grade 1 and 2 oocytes (%) Cleavage rate (%) Blastocyst rate (%) Total embryos per OPU Grade 1 embryos per OPU 1×FSH 20 17.0 45.7 84 39.8 6.2 3.8 5×FSH 20 19.9 46.5 82 35.6 6.3 4.0

Development and evaluation of a processing sector model for butter manufacture using a mass balance technique at two dairy processing sites

The butter manufacturing process at two different commercial dairy processing sites in Ireland was evaluated using a mass balance approach to develop, evaluate and validate a processing sector model of the flow of milk fat from intake to final product. The mass balance was represented as a function of fat intake = fat in products + fat losses + recycled fat. Representative samples of all products, namely whole milk, cream, skim milk, butter, buttermilk and cleaning‐in‐place streams (cream silo flush, butter churn residue and sludge), were collected from two different sites. Milk fat levels and product quantities were measured to obtain the fat outputs. Total fat losses at the end of butter production ranged between 1.90% and 2.25% of the total fat input for both sites. Three different scenarios were examined to evaluate the model: S1 (Animal Breed) high genetic merit (Elite) and national average (NA) Holstein Friesian (HF) cows were evaluated, for their effect on the net value of milk; S2 (Product Portfolio) a mixed product portfolio of cheese, butter and skim milk powder (SMP) was compared to a product portfolio comprised of butter alone; and S3 (Process Efficiency) the impact of varying process losses on net values of milk and the quantities of products produced was simulated. The value per 1000 L of milk for S1 was €410.69 and €393.20 for Elite and NA cow’s milk, respectively. For S2, the butter‐only product portfolio returned €355.10, whereas the mixed‐products portfolio returned €369.60. Lastly, S3 corresponding returns for 1%, 2.2% and 5% losses was €365.90, €361.47 and €351.12, respectively.

Health treatment cost, stillbirth, survival, and conformation of Viking Red-, Montbéliarde-, and Holstein-sired crossbred cows compared with pure Holstein cows during their first 3 lactations

Three generations of crossbreds from a 3-breed rotation of the Viking Red (VR), Montbéliarde (MO), and Holstein (HO) breeds were compared with their HO herdmates in 7 commercial dairy herds in Minnesota. The designed study enrolled 3,550 HO females in 2008 to initiate crossbreeding and a control of pure HO herdmates within each herd. Service sires were high-ranking, proven AI bulls selected for high genetic merit within each of the VR, MO, and HO breeds. Cows in this study calved from 2010 to 2017 and collection of data ended on December 31, 2017. The first generation of cows consisted of 644 VR × HO and 616 MO × HO crossbreds and their 1,405 HO herdmates. The second generation had 615 VR × MO/HO and 568 MO × VR/HO crossbreds and their 1,462 HO herdmates. The third generation had 466 combined HO × VR/MO/HO and HO × MO/VR/HO crossbreds and their 736 HO herdmates. Total health cost was the sum of veterinary treatment cost, pharmaceutical cost, and farm labor cost to treat 16 different health disorders. Conformation traits and body condition score were subjectively scored once during early lactation for each of the first 3 lactations of cows. Total health cost of the 2-breed crossbreds was significantly lower during first (-23%), second (-29%), and third (-21%) lactation compared with their HO herdmates. For the 3-breed crossbreds, total health cost did not differ during first lactation but was -26% lower during both second and third lactation compared with their HO herdmates. The stillbirth rate for calves born to 2-breed crossbred dams (4%) was significantly lower compared with calves born to their HO herdmates (8%) at first calving. Survival from first to third calving (+9%) and first to fourth calving (+11%) was significantly higher for the 2-breed crossbreds compared with their HO herdmates. Also, the 3-breed crossbreds had significantly higher survival to third (+11%) and fourth (+19%) calving compared with their HO herdmates. Across each generation of crossbreeding, the crossbreds had uniformly shorter stature, less angularity, and less body depth compared with their respective HO herdmates. The crossbred cows also had significantly less udder clearance from the hock but significantly more rear teat width and longer teat length compared with their respective HO herdmates. Furthermore, the crossbred cows had higher body condition score compared with their HO herdmates during each of their first 3 lactations.

The Role of Innate Immune Response and Microbiome in Resilience of Dairy Cattle to Disease: The Mastitis Model.

Simple SummaryA major concern for the development of livestock activities is represented by the gradual reduction of antibiotic usage in farm animals, which may disturb the fragile balance between animal health and production. Therefore, it is necessary to maintain the immunocompetence of farm animals within the structure of this new trend toward reduced drug usage. High-yielding dairy cattle often experience more disease prevalence associated with short life expectancy and reduced environmental fitness. These signs of immunosuppression can be linked to metabolic changes observed around calving, which confirms the crucial link between immunity and milk production levels. The immunocompetence of these animals should be re-appraised and new disease control strategies should be based on creating a more efficient immune system. This review summarizes the dairy cow’s metabolic response to stress and what role the innate immune system and microbiome play. The review also discusses how new approaches to animal health based on specific intervention at dry-off and in the first weeks after calving are needed as the relevant stressors are pivotal to disease occurrence.Animal health is affected by many factors such as metabolic stress, the immune system, and epidemiological features that interconnect. The immune system has evolved along with the phylogenetic evolution as a highly refined sensing and response system, poised to react against diverse infectious and non-infectious stressors for better survival and adaptation. It is now known that high genetic merit for milk yield is correlated with a defective control of the inflammatory response, underlying the occurrence of several production diseases. This is evident in the mastitis model where high-yielding dairy cows show high disease prevalence of the mammary gland with reduced effectiveness of the innate immune system and poor control over the inflammatory response to microbial agents. There is growing evidence of epigenetic effects on innate immunity genes underlying the response to common microbial agents. The aforementioned agents, along with other non-infectious stressors, can give rise to abnormal activation of the innate immune system, underlying serious disease conditions, and affecting milk yield. Furthermore, the microbiome also plays a role in shaping immune functions and disease resistance as a whole. Accordingly, proper modulation of the microbiome can be pivotal to successful disease control strategies. These strategies can benefit from a fundamental re-appraisal of native cattle breeds as models of disease resistance based on successful coping of both infectious and non-infectious stressors.

Efficient correction of a deleterious point mutation in primary horse fibroblasts with CRISPR-Cas9

Phenotypic selection during animal domestication has resulted in unwanted incorporation of deleterious mutations. In horses, the autosomal recessive condition known as Glycogen Branching Enzyme Deficiency (GBED) is the result of one of these deleterious mutations (102C > A), in the first exon of the GBE1 gene (GBE1102C>A). With recent advances in genome editing, this type of genetic mutation can be precisely repaired. In this study, we used the RNA-guided nuclease CRISPR-Cas9 (clustered regularly-interspaced short palindromic repeats/CRISPR-associated protein 9) to correct the GBE1102C>A mutation in a primary fibroblast cell line derived from a high genetic merit heterozygous stallion. To correct this mutation by homologous recombination (HR), we designed a series of single guide RNAs (sgRNAs) flanking the mutation and provided different single-stranded donor DNA templates. The distance between the Cas9-mediated double-stranded break (DSB) to the mutation site, rather than DSB efficiency, was the primary determinant for successful HR. This framework can be used for targeting other harmful diseases in animal populations.

Reconstitution and modernization of lost Holstein male lineages using samples from a gene bank

More than 99% of all known Holstein artificial insemination (AI) bulls in the United States can be traced through their male lineage to just 2 bulls born in the 1950s, and all Holstein bulls can be traced back to 2 bulls born in the late 1800s. As the Y chromosome is passed exclusively from sire to son, this suggests that variation is limited for much of the Y chromosome. Two additional male lineages that are separate from modern lineages before 1890 were present at the start of the AI era and had semen available from the USDA National Animal Germplasm Program (Fort Collins, CO). Semen from representatives of those lineages were used for in vitro embryo production by mating to elite modern genetic females, resulting in the birth of 7 bulls and 8 heifers. Genomic evaluation of the bulls suggested that lineages from the beginning of the AI era could be reconstituted to breed average for total economic merit in 1 generation when mated to elite females due to high genetic merit for fertility, near-average genetic merit for fat and protein yield, and below-average genetic merit for udder and physical conformation. Semen from the bulls is commercially available to facilitate Y chromosome research and efforts to restore lost genetic diversity.

Pipette and paper: Combining molecular and genealogical methods to assess a Nile tilapia (Oreochromis niloticus) breeding program

[Extract] Aquaculture selective breeding programs employ a closed nucleus mating strategy whereby animals displaying sought-after characteristics are mated to produce next generation offspring with increased pre-valence of desirable phenotypes. Offspring exhibiting high genetic merit for favorable traits are then usually chosen as candidate parents for the subsequent breeding cycle. The selective breeding process is replicated each succeeding generation in order to accumulate genetic gain within the breeding population. The long term success of these closed breeding systems is dependent on a number of factors: including, the heritability of a trait, the intensity of selection, the additive genetic variance observed in the founding population, and the amount of additive genetic variance maintained over subsequent generations (Falconer et al., 1996; Loughnan et al., 2016). If breeding practices are not properly managed, the number of animals with high relatedness will increase (Gjedrem and Baranski, 2009b), leading to a substantial loss of genetic diversity over subsequent generations (Pante et al.,2001). The maintenance of genetic diversity is critical to accommodate current and future changes in production environments, and if left unchecked, it can lead to inbreeding through increased homozygosity and deleterious fitness consequences associated with inbreeding depression (Pante et al., 2001). This loss of genetic diversity can also hamper progress within the selective breeding program as it limits the amount of genetic variance available for selection (Falconer, 1960).

A new Approach for Accurate Detection of Chromosome Rearrangements That Affect Fertility in Cattle.

Simple SummaryGlobally, cattle production has more than doubled since the 1960s, with widespread use of artificial insemination (AI) and an emphasis on a small pool of high-genetic-merit animals. Selecting AI bulls with optimal fertility is therefore vital, as impaired fertility reduces genetic gains and reduces production, resulting in heavy financial and environmental losses. Chromosome translocations, where large parts of the genome are inappropriately attached in abnormal patterns, are a common cause of reduced fertility; however, reciprocal translocations are significantly underreported due to the difficulties inherent in analysing cattle chromosomes. Based on our previous work, we have developed an approach for the unambiguous detection of abnormalities that affect fertility. We applied this method on the chromosomes of 39 bulls, detecting multiple abnormalities that affect fertility, including those that would be undetectable using traditional screening techniques. With UK dairy calving rates of only 50–60%, it is vital to reduce further fertility loss in order to maximise productivity. The approach developed here identifies abnormalities that DNA sequencing will not, and has the potential to lead to long-term gains, delivering meat and milk products in a more cost-effective and environmentally-responsible manner to a growing population.Globally, cattle production has more than doubled since the 1960s, with widespread use of artificial insemination (AI) and an emphasis on a small pool of high genetic merit animals. Selecting AI bulls with optimal fertility is, therefore, vital, as impaired fertility reduces genetic gains and production, resulting in heavy financial and environmental losses. Chromosome translocations, particularly the 1;29 Robertsonian translocation, are a common cause of reduced fertility; however, reciprocal translocations are significantly underreported due to the difficulties inherent in analysing cattle chromosomes. Based on our porcine work, we have developed an approach for the unambiguous detection of Robertsonian and reciprocal translocations, using a multiple-hybridization probe detection strategy. We applied this method on the chromosomes of 39 bulls, detecting heterozygous and homozygous 1;29 translocations and a 12;23 reciprocal translocation in a total of seven animals. Previously, karyotype analysis was the only method of diagnosing chromosomal rearrangements in cattle, and was time-consuming and error-prone. With calving rates of only 50–60%, it is vital to reduce further fertility loss in order to maximise productivity. The approach developed here identifies abnormalities that DNA sequencing will not, and has the potential to lead to long-term gains, delivering meat and milk products in a more cost-effective and environmentally-responsible manner to a growing population.

How can we improve embryo production and pregnancy outcomes of Holstein embryos produced in vitro? (12 years of practical results at a California dairy farm).

Genomic evaluations have revolutionized dairy cattle breeding, and the demand for embryos produced from very young heifers with high genetic merit has increased over time. The combination of low oocyte recovery, young age of donors, and milk production status can make the in vitro embryo production (IVP) of Holstein cattle incredibly challenging. Several factors need to be coordinated to obtain a live calf from an IVP embryo, but the quality of the oocyte at the start of the process is one of the key factors. Aspects related to oocyte quality, laboratory quality control, embryo quality and recipient selection are addressed here, based on the measures that the RuAnn Genetics Laboratory (Riverdale, California, USA) adopted in the last 12 years, with the goal of improving production of live, healthy calves from Holstein embryos. Follicular wave synchronization and stimulation with follicular stimulating hormone (FSH) is necessary to improve oocyte quality and consequently embryo production. Laboratory quality control and the use of high-quality supplies are essential to reduce variability in production and facilitate identification of other factors that might interfere with embryo production. High pregnancy rates can be achieved with good quality embryos selected at optimal time and stage of development, transferred by an experienced embryo transfer (ET) technician, to well managed recipients 7 or 8 days after estrus. Attention to detail at every step of the process is crucial to success.

Evaluation of production efficiencies at pasture of lactating suckler cows of diverse genetic merit and replacement strategy

Feed costs account for the largest proportion of direct cost within suckler beef production systems. By identifying the cow type with enhanced capability of converting grazed herbage to beef output across lactations, suckler cow systems would become more efficient and sustainable. The objective of this study was to estimate grass DM intake (GDMI) and production efficiency among lactating suckler cows of diverse genetic merit for the national Irish maternal index (Replacement Index) which includes cow efficiency components such as milk yield and feed intake. Data from 131 cows of diverse genetic merit within the Replacement Index, across two different replacement strategies (suckler or dairy sourced), were available over two grazing seasons. Milk yield, GDMI, cow live weight (BW) and body condition score (BCS) were recorded during early, mid and late-lactation, with subsequent measures of production efficiency extrapolated. Genetic merit had no significant effect on any variables investigated, with the exception of low genetic merit (LOW) cows being 22 kg heavier in BW than high genetic merit (HIGH) cows (P < 0.05). Beef cows were 55 kg heavier in BW (P < 0.001), had a 0.31 greater BCS (P < 0.05) and 0.30 Unité Fourragère Lait (UFL) greater energy requirement for maintenance compared to dairy sourced beef × dairy crossbred (BDX) cows (P < 0.001). The BDX had 0.8 kg greater GDMI, produced 1.8 kg more milk (P < 0.001), had a 0.8 UFL greater energy requirement for lactation and produced weanlings that were 17 kg heavier in BW than beef cows (P < 0.05). Subsequent efficiency variables of milk per 100 kg BW (P < 0.001), milk per kg GDMI (P < 0.001) and GDMI per 100 kg BW (P < 0.001) were more favourable for BDX. The correlations examined showed GDMI had moderate positive correlations (P < 0.001) with intake per 100 kg BW, net energy intake per kg milk yield, RFI and intake per 100 kg calf weaning weight but was weakly negatively correlated to milk yield per kg GDMI (P < 0.001). No difference was observed across genetic merit for beef cows for any of the traits investigated. Results from the current study showed that, while contrasting replacement strategies had an effect on GDMI and production efficiency, no main effect was observed on cows diverse in genetic merit for Replacement Index. Nonetheless, utilising genetic indexes in the suckler herd is an important resource for selecting breeding females for the national herd and phenotypic performance generated from this study can be included in future genetic evaluations to improve reliability of genetic values.

Effects of differences in level of post-weaning nutrition and in sire expected progeny differences for ribeye area on retail cuts yield in Hereford steers

Context Uninterrupted nutrient uptake and the use of bulls with high genetic merit for carcass traits may increase the likelihood of producing high-quality retail cuts for different markets. Aim The objective of this experiment was to evaluate the combined effects of level of nutrition during the 104-day post-weaning winter period (WADG; low-L: 0.2 vs high-H: 0.6 kg/calf per day) and level of expected progeny differences (EPD) for ribeye area (REA; high-H or average-Av) on carcass traits and retail cuts of Hereford steers. Methods Three crops of calves (n = 317) were selected according to REA (H-REA vs Av-REA), blocked for weaning weight (WW) and randomly allotted to one of the two WADG treatments (L-WADG vs H-WADG) for 104 days. Experimental design was a completely random block and the treatments were the combination of two factors (2 × 2). After winter (L-WADG and H-WADG groups), all calves grazed on improved pastures (herbage allowance: 5% of liveweight (LW) per day). The finishing was done on a feedlot and started when the group average of animals reached a full LW (FLW) of 350 ± 28 kg. Cattle were harvested at a constant final FLW of 525 ± 40 kg. Key results No interaction was observed (P > 0.05) between WADG and REA for carcass traits. Animals with H-WADG presented higher (P < 0.05) hot carcass weight (HCW) and dressing-out (%) than L-WADG. High REA and H-WADG steers showed higher weight (kg) in the rump and loin, striploin, sirloin, and lean component in the pistola cut (P < 0.01). Likewise, H-REA and H-WADG presented a greater proportion of rump and loin (P < 0.01) and lean (%) (P < 0.05) than Av-REA and L-WADG, respectively. Conclusions The combined effects of greater post-weaning winter gains and high REA EPD allow slaughter of younger steer with greater lean proportion and retail cuts. Implications No interaction between the REA and WADG allows producers to plan economic benefits through a higher WADG in the first winter phase as well as using superior bulls for carcass traits to achieve heavier retail cuts.

Comparative Study of Socio Economic Status and Constraints Faced by Members and Non-Members Milk Producers of Dairy Cooperatives in Rajasthan

The present study conducted in four milk union/ district of Rajasthan. The total sample size of milk producers of dairy cooperative society (DCS) and Non-member dairy cooperative society (NDCS) in the State was 240. All the related primary data were collected during year 2017-18. About 80 per cent selected house hold belongs to other backward class. The operational land holding of DCS member have higher than NDCS i.e. 5.19 ha. of DCS and 4.17 ha. of NDCS. The low milk production yield and unavailability of feed and fodder throughout year were major constraint faced by DCS household. In NDCS category also faced some other constraint like unavailability of vaccine and veterinary service. In concerns of economics constraints, majority of the dairy farmers faced high cost of feed and fodder, veterinary service and price offer of milk offer and lack of loan facility. Regarding marketing constraints, few were faced less knowledge about marketing strategies and lack of facility less advance payment for milk. Regarding technical constraints, most of the respondents, opined to have inadequate guidance of AI, feeding and health care of animal, high genetic merit bull as their constraint. The lack of purchasing power is serious social constraint followed by lower socio economic condition faced by NDCS.There is needed to make greater efforts to educate and assist the milk producers in respect to latest breeding, feeding and animal management technique.

10 Pregnancy rates following artificial insemination or embryo transfer in lactating Holstein cows

Excessive heat affects the fertility of high production lactating cows, and reduced pregnancy rates (PR) are observed during summer and early fall. Embryo production programs are used to produce more calves from high genetic merit animals, but could it also increase fertility by bypassing all the negative variables affecting the embryo development before Day 7 (oocyte development, ovulation, fertilization, early embryo development)? The data from AIs and embryo transfers (ET) between June 2017 and May 2019 were analysed. June, July, August, September, and October were called critical months (first-service AI conception rate dropped below 44%). The cows were located at Maddox Dairy in Riverdale, CA, USA, a Holstein herd that milks 3500 cows with a 305-day mature-equivalent milk production of 12 800 kg. First- and second-lactation cows were enrolled in a Presynch-Ovsynch oestrus-synchronization program and scheduled for the first AI at 86 days after calving or to receive an embryo 7 or 8 days after the expected heat. The embryos were produced invivo or invitro from Holstein donors and were transferred fresh or frozen. Blood was sampled on Day 30 after expected heat day (23 days after embryo transfer), and pregnancy was detected by the IDEXX PAG Bovine Pregnancy Test. Table 1 summarises the results, where ET PR% is the number of pregnant cows divided by the number of cows that received and embryo. All the cows synchronized for AI were bred, but only cows with the presence of a corpus luteum (CL) on ET day received an embryo. The presence of a CL was not detected in 28.7% (471/1642) of the cows (32.2% in the critical months and 25.7% in the others). Unfortunately, we could not detect the presence of a CL by ultrasonography every time we transferred embryos, so the nonovulation rate might be overestimated. The cows without a CL were considered open and used to calculate the adjusted PR (AdjPR%). Embryo transfer PR is superior to that of AI, especially during the critical months. Fresh invivo embryos have the most impact. When the cows without CLs are considered open, the difference between AI and ET is still evident for fresh invivo embryos. Besides producing animals with higher genetic merit, depending on the type of embryo used, ET can increase fertility in lactating Holstein cows, especially during the critical months. The other benefit of using ET is that cows that do not ovulate are synchronized right away, which is not the case for AI cows. Table 1.AI×embryo transfer in lactating Holstein cows1 from June 2017 to May 20192 Item Critical months (June to October) Other months (November to May) All year %PR n Adj PR% n %PR n Adj PR% n %PR n Adj PR% n Artificial insemination 41.2% 896 41.2% 896 47.7% 1767 47.7% 1767 45.5% 2663 2663 Fresh invivo embryo 62.7% 373 47.5% 493 69.5% 262 55.3% 329 65.5% 635 50.6% 822 Frozen invivo embryo 59.3% 221 44.8% 292 59.4% 256 47.3% 322 59.3% 477 46.1% 614 IVF fresh embryo 47.9% 167 36.2% 221 54.0% 363 43.0% 456 52.1% 530 40.8% 677 Total embryos 58.5% 761 44.2% 1006 60.2% 881 47.9% 1107 59.4% 1642 46.1% 2113 1Lactating Holstein cows, first and second lactation, first service, Presynch-Ovsynch, 85 DIM. 2PR%=the number of pregnant cows divided by the number of cows that received and embryo; AdjPR%=adjusted pregnancy rate.