Evaluation of the Progeny of Beef Sires Differing in Genetic Merit

End of project reportThe Irish Cattle Breeding Federation (ICBF) publishes breeding values (BVs) for beef bulls. Historically, BVs were expressed in index form relative to the base population. Sometime ago this changed to expression in units of measurement of trait. This change occurred in the course of this project and was accompanied by some re-ranking of bulls. BVs are published for growth, carcass grades and calving traits. Growth BV is expressed as carcass weight but there is no indication if this results from higher live weight gain or from a higher kill-out proportion and there is no indication of any consequences for feed intake or efficiency. • The objectives of the project were (i) to compare progeny of bulls of high and low growth genetic index, for growth, feed intake, slaughter traits and carcass traits, (ii) to partition the extra live weight of progeny of high growth index bulls into carcass and non-carcass parts, and (iii) to partition any extra carcass weight of progeny from high growth index bulls into its component fat, muscle and bone fractionsEuropean Unio

Performance and carcass traits of progeny of Limousin sires differing in genetic merit

peer-reviewedGenetic indices for growth and carcass classification are published for beef sires used in Ireland for artificial insemination (AI). The objective of this study was to compare growth and carcass traits of progeny of Limousin sires of low and high genetic index for growth. A total of 70 progeny (42 males and 28 females) out of predominantly Holstein-Friesian cows by 7 AI Limousin sires were reared together to slaughter. The 7 sires were classified as low (n=3) or high (n=4) index based on their published genetic index for growth. The male progeny were reared entire and all animals were slaughtered at about 20 months of age. Carcasses were classified for conformation and fatness, and a rib joint (ribs 6 to 10) was separated into fat, muscle and bone. Growth rate did not differ significantly between the index groups but tended to be higher for the high index progeny. This higher growth rate, combined with a significantly higher kill out proportion, resulted in carcass weight andcarcass weight per day of age being significantly higher for the high index progeny. Carcass conformation and fat class were not affected by genetic index, nor was the composition of the rib joint. Compared with males, females had a significantly lower growth rate and kill out proportion and, consequently, had a significantly lower carcass weight. The proportions of fat and bone in the rib joint were significantly higher, and the proportion of muscle was significantly lower for females than for males. It is concluded that carcass weight reflected sire group genetic index for growth but feed intake, carcass classification and rib joint composition were not affected

Studies relating to Polyunsaturated Fatty Acid (PUFA) Supplementation and Fertility in Cattle

End of project reportReproductive inefficiency has a significant impact on the economic performance of both dairy and beef herds, particularly in seasonal calving systems. Nutrition plays a fundamental role in reproduction. Furthermore, there is emerging evidence that supplemental dietary polyunsaturated fatty acids (PUFA) may increase cow fertility independent of their role as energy substrates. A number of studies have reported enhanced reproductive performance in dairy cows following dietary supplementation with sources of n-3 PUFA. However the possible mechanisms involved have not been identified and there is some inconsistency in the published literature on this topic. The objective of the research reported was to conduct a holistic examination of the effects of dietary long-chain n-3 PUFA supplementation on metabolic and reproductive responses in cattle. Such information is essential for the appropriate formulation of diets to enhance cow reproductive performance and in particular embryo survival

Studies relating to protein expression in the uterus of the cow

End of project reportEmbryo loss is a major cause of reproductive wastage in the cow. The majority of embryo loss occurs in the first 16 days after fertilisation when the embryo is critically dependent on the maternal uterine environment for survival. Despite the central role of uterine fluid in the normal growth and development of the embryo, there is limited information on the protein composition of these fluids. The main objectives of the studies in this thesis were to examine the protein composition of the bovine uterus during the oestrous cycle and to examine the relationship between the concentration of systemic progesterone and uterine protein expression in the cow. In the first study, the concentration of retinol-binding protein (RBP) in the bovine uterus was found to vary across the cycle and was 5-15-fold higher (P0.05) of the cycle, which was surprising given that previous studies have indicated that uterine RBP gene expression was positively associated with the concentration of systemic progesterone. In the second study, IGF binding protein 2 (IGFBP-2), IGFBP-3, IGFBP-4 and IGFBP-5 were identified in uterine fluid on days 3, 7, 11 and 15 of the oestrous cycle. There was a local effect on the concentration of IGFBPs where the concentration was greater on the ipsilateral side than that on the contralateral side for IGFBP-2 (P<0.05), 3 (P<0.01) and 5 (P<0.01) on day 15. This difference is a further indication of a local controlling mechanism regulating proteins between the uterine horns. Similar to RBP expression this study could find no significant relationship between the concentration of systemic progesterone and IGFBP concentrations on Day 7 of the oestrous cycle. In the third study, changes in the global pattern of uterine proteins between Days 3 and Day 15 of the oestrous cycle were examined using two-dimensional electrophoresis (2-DE). Six proteins were found to be upregulated on Day 15 compared to Day 3. Three proteins of these were identified as aldose reductase, plakoglobin and heat shock protein 27 while the other three proteins were identified as bovine serum albumin. Aldose reductase, an enzyme directly involved in the production of sorbitol and indirectly of fructose, was 10-fold higher (P<0.0001) on Day 15 compared to Day 3. Plakoglobin (Pg) was upregulated 2.3-fold (P<0.0001) on Day 15 compared to Day 3. Pg is a component of cellular junctions and its up-regulation may have a role in the uterine glandular epithelium. Heat shock protein 27 (Hsp27) was higher on Day 15 than on Day 3 (P<0.01) and Hsp27 was 1.4-fold higher in the ipsilateral compared to the contralateral uterine horn (P<0.01). Hsp27 may be secreted in response to potential stresses in the uterus or act as a molecular chaperone. On Day 7 there was no difference (P<0.05) in the pattern of proteins secreted between cows with low (2.7±0.10ng/ml) and high (4.8±0.13 ng/ml) concentrations of systemic progesterone on Day 7. The results of these studies have shown that dramatic changes occur in protein expression across the bovine oestrous cycle. Additionally, it emphasises the need for gene studies to be followed with protein studies as an adjunct or complementary tool. Proteins have a wide range of essential roles in the uterus and together these studies provide novel information on protein expression in the uterus of the cow

Biotechnology in Cattle Reproduction.

End of Project ReportTeagasc acknowledges support from the European Union 3rd and 4th Framework Programmes (CT-92-0163 and CT-95-0190)Over the next decade the Irish agri-food industry will have to compete in a rapidly changing world environment arising from increased competitiveness, decreased world market prices and increased consumer demands for higher quality, healthier and safer food. To become competitive in this environment the scale and efficiency of production at both farm and factory level will have to increase significantly and this must be achieved with due regard for the protection of the environment and the welfare of animals. New technologies will be needed to achieve this. Biotechnology will be central to the development of these new technologies. This project has been concerned with the identification and evaluation of biotechnology developments that have the potential to increase reproductive efficiency in cattle. This includes a range of technologies relating to the in vitro production, manipulation, cryopreservation and transfer of cattle embryos. The potential of other emerging technologies such as embryo and sperm sexing, cloning and biopharming or the production of commercially desirable proteins in cows milk are also addressed in this report.European Unoi

Global gene expression in endometrium of high and low fertility heifers during the mid-luteal phase of the estrous cycle

peer-reviewedBackground In both beef and dairy cattle, the majority of early embryo loss occurs within the first 14 days following insemination. During this time-period, embryos are completely dependent on their maternal uterine environment for development, growth and ultimately survival, therefore an optimum uterine environment is critical to their survival. The objective of this study was to investigate whether differences in endometrial gene expression during the mid-luteal phase of the estrous cycle exist between crossbred beef heifers ranked as either high (HF) or low fertility (LF) (following four rounds of artificial insemination (AI)) using the Affymetrix® 23 K Bovine Gene Chip. Results Conception rates for each of the four rounds of AI were within a normal range: 70–73.3%. Microarray analysis of endometrial tissue collected on day 7 of the estrous cycle detected 419 differentially expressed genes (DEG) between HF (n = 6) and LF (n = 6) animals. The main gene pathways affected were, cellular growth and proliferation, angiogenesis, lipid metabolism, cellular and tissue morphology and development, inflammation and metabolic exchange. DEG included, FST, SLC45A2, MMP19, FADS1 and GALNT6. Conclusions This study highlights, some of the molecular mechanisms potentially controlling uterine endometrial function during the mid-luteal phase of the estrous cycle, which may contribute to uterine endometrial mediated impaired fertility in cattle. Differentially expressed genes are potential candidate genes for the identification of genetic variation influencing cow fertility, which may be incorporated into future breeding programmes.Teagasc Walsh Fellowship Programm

Viability of in vitro produced cattle embryos.

End of Project ReportEmbryo transfer is being increasingly used in the cattle industry. As well as direct embryo transfers, many embryo-based biotechnologies have the potential to improve cattle production efficiency through enhanced breeding strategies, by facilitating the introduction of desirable traits such as disease resistance and through the production of desirable medical or pharmaceutical products in the milk. These biotechnologies are, however, dependent on a supply of viable in vitro produced (IVP) embryos. While the in vitro fertilization rate is high (80%) in cattle, only about 30 transferable embryos, or blastocysts, are produced from every 100 fertilized oocytes. A major factor affecting the viability of IVP embryos is their failure, in a high proportion of cases, to undergo normal development to the blastocyst stage in the manner of in vivo embryos. The major problem relates to a failure of the cells of IVP embryos to form a compact cell mass when they are 5 - 6 days old. This ultimately leads to developmental problems and compromised viability. Cell compaction is recognized as a critical event in early embryo development and has been associated with marked changes in protein synthesis and phosphorylation in the embryos of some species. This report is the first, to our knowledge, to describe the rate and pattern of protein synthesis and phosphorylation before, during and after compaction in both in vivo and in IVP cattle embryos. The main results are summarised below.European Union 4th Framework Programmes (Contract CT-95-0032

ONE HEALTH: Awareness to Action Antimicrobial and Anthelmintic Resistance Conference.

Given the serious global public health threat of antimicrobial resistance (AMR) I welcome the holding of this One Health conference focusing on AMR, and anthelmintic resistance. The Department of Agriculture, Food and Marine continues to focus on a joined-up approach to animal health under the One Health umbrella. 'One Health' is an approach to designing and implementing programmes, policies, legislation and research in which multiple sectors communicate and work together to achieve better public health outcomes. The challenge of AMR underpins the One Health concept. Ireland’s National Action Plan on Antimicrobial Resistance (iNAP), jointly developed with colleagues from the Department of Health, and the environment sector, recognises the urgent and growing problem of antimicrobial resistance for human health worldwide. It is currently being implemented through successful stakeholder leadership and collaboration. Anthelmintic resistance has been widely reported in parasites of a number of livestock species in Ireland, and is now an increasing problem nationally. Globally, resistance to all currently used antiparasitic veterinary medicinal products has been demonstrated. Resistance to anthelmintics is developing year-on-year, and is now a significant animal health issue. There is a responsibility on the agri-food industry to address its part in the major global challenge posed by AMR and anthelmintic resistance. This conference aims to both inform veterinary practitioners and farmers from the various animal sectors, and to also allow for discussion and debate around key interventions that can be put into practice to combat AMR and anthelmintic resistance. This conference places an emphasis on not simply increasing awareness, but also highlighting actions that can be taken to mitigate against the risk of further development and spread of both AMR and anthelmintic resistance. Tackling AMR and anthelmintic resistance collectively is critically important to achieving sustainable development of the agri-food sector. I wish to thank my colleagues in Teagasc, my department, Animal Health Ireland, University College Dublin and the Food Safety Authority of Ireland for organising this event. I hope you find this conference informative and that you leave with a better understanding of your respective roles and responsibilities to keep antibiotics and anthelmintics working effectively into the future

Protein Nutrition and Fertility in Cattle.

End of Project ReportThe objectives of the project were to determine the effects of dietary crude protein intake, on blood concentrations of ammonia and urea and on fertility, and on the possible biological mechanisms involved. Heifers were used in all experiments in order to avoid any confounding effects of lactation and, or, negative energy balance. The results are summarised as follows. • • • • 5 Blood urea and ammonia increased linearly with increases in dietary urea. Fermentable carbohydrate, in the form of molassed sugar beet pulp (MSBP), was more effective than barley in reducing blood urea concentration. Plasma ammonia concentrations were more variable but MSBP was again more effective than barley in reducing these. Embryo survival rate was not affected by either dietary crude protein (CP) or fermentable energy intake irrespective of whether animals were fed a silage diet supplemented with feed grade urea or were grazing pasture with a high crude protein content. Despite generating systemic urea concentrations of up to 25 mmol/L and systemic ammonia concentrations of up to 242 μmol/L no significant relationship between these parameters and embryo survival rate was established. Consistent with these results on embryo survival, elevated blood urea or ammonia had little effect on the biochemical composition of oviduct fluid, the environment of the early developing embryo. It can be concluded that elevations in systemic concentrations of ammonia or urea per se, particularly of the magnitude observed under normal feeding conditions, are unlikely to impair embryo survival in cattle as a consequence of disruptions to the oviductal environment

Fluctuations in Energy Intake and Fertility in Cattle.

End of Project ReportsReproductive failure in dairy cows results in fewer calves born, lower milk sales, slower genetic progress and consequently, significant financial loss to the industry. Dairy cattle breed improvement programmes have, at least until very recently, focused primarily on increasing the yields of milk or milk solids. The resulting genetic improvement has led to significant increases in milk yield per cow but this increase is now associated with a significant decline in cow reproductive wastage. An important part of the Teagasc research programme in this area is to determine the time at which embryo loss occurs and also to determine whether the extent of the embryo loss is affected by the energy nutrition of the cow and to devise strategies to reduce its extent. This project has focused on the relationship between changes in dietary energy intake near the time of insemination and the extent and pattern of embryo survival. The main results are summarised in this report and detailed results of the several experiments involved have been published in the papers listed at the end of this report. • • 4 The objectives of this project were to determine the effect of changes in energy intake near the time of insemination on embryo loss rate, on the timing of embryo loss and on the possible biological mechanisms involved. Cross bred heifers were provided with either high or low energy intakes that were based on pasture allowances calculated to provide either 0.8 or 2.0 times their maintenance requirements. These energy intakes were allocated for two weeks before and about five weeks after insemination. The effect of the changes in energy intake on embryo loss and on the time at which embryo loss occurred, relative to the time of insemination, was established. Possible associations between embryo loss and blood concentrations of progesterone, NEFAs, insulin and glucose were examined. A sudden reduction from a high to a low energy intake imposed for two weeks from the day of insemination reduced the subsequent embryo survival rate by 30 percentage points to a survival rate of 38%. When energy intake over this same period was either maintained or increased, embryo survival rate remained high (overall mean, 69%), within a range of 65-71%. The time at which embryo loss occurred was established. Embryo survival or pregnancy rates measured on days 14 and 30 after insemination and at full term were 68%, 76% and 72%, respectively. These results provide new information indicating that most embryo loss, at least in heifers, had occurred on or before day 14 after insemination. There was no evidence of any association between the shortterm changes in energy intake either before or after AI and blood progesterone concentration. Neither was there any evidence that the detrimental effect of the sudden reduction in energy intake on embryo survival was mediated through changes in the systemic concentrations of non-esterified fatty acids (NEFAs) or insulin. There was a suggestion, however, that the detrimental effect of the reduced energy intake may operate through a reduction in systemic glucose concentrations.Dairy Levy Farmer Fun