Embryonic and Early Foetal Losses in Cattle and Other Ruminants

Abstract

Embryo survival is a major factor affecting production and economic efficiency in all systems of ruminant milk and meat production. For heifers, beef and moderate yielding dairy cows, does and camelids it appears that fertilization generally lies between 90% and 100%. In high-producing dairy cows there is a less substantive body of literature, but it would appear that it is somewhat lower and perhaps more variable. In cattle, the major component of embryo loss occurs before day 16 following breeding with some evidence of greater losses before day 8 in high-producing dairy cows. In cattle late embryo loss, while numerically much smaller than early embryo mortality loss, nevertheless, causes serious economic losses to producers because it is often too late to rebreed females when they repeat. In multiple ovulating small ruminants, the loss rate is positively related to ovulation rate. Systemic concentrations of progesterone, during both the cycle preceding and following insemination, affect embryo survival rate with evidence that too high or indeed too low a concentration being negatively associated with survival rate. Uterine expression of mRNA for progesterone receptor, oestradiol receptor and retinol-binding protein appears to be sensitive to changes in peripheral concentrations of progesterone during the first week after artificial insemination. Energy balance and dry matter intake during 4 weeks after calving are critically important in determining conception rate when cows are inseminated at 70-100 days post-calving. Concentrate supplementation of cows at pasture during the breeding period has minimal effects on conception rates though sudden reductions in dietary intake should be avoided. For all systems of milk production, more balanced breeding strategies with greater emphasis on fertility and feed intake and/or energy balance must be developed. There is sufficient genetic variability within the Holstein breed for fertility traits. Alternative dairy breeds such as the Jersey or Norwegian Red could also be utilized. Genomic technology will not only provide scientists with an improved understanding of the underlying biological processes involved in fertilization and the establishment of pregnancy, but also, in the future, identify genes responsible for improved embryo survival. Its incorporation into breeding objectives would increase the rate of genetic progress for embryo survival.

Sire effect on early and late embryonic death in French Holstein cattle

“…a v. b, P < 0.05; a v. c, P < 0.01; a v. d, P < 0.001. during the last few decades is because of an increase in early rather than late embryonic death (Humblot, 2001;Grimard et al, 2006;Diskin and Morris, 2008). However, the identification of QTL linked to FF-EEM in Holstein cattle failed to date when using NRR on D28 .…”

“…However, to our knowledge, investigations allowing the determination of precise phenotypes of pregnancy failures after insemination on a large-scale basis and the possible impact of the sire have not been conducted. In cows, most of the pregnancy failures occur during the very beginning of pregnancy Diskin and Morris, 2008).…”

“…However, to our knowledge, investigations allowing the determination of precise phenotypes of pregnancy failures after insemination on a large-scale basis and the possible impact of the sire have not been conducted. In cows, most of the pregnancy failures occur during the very beginning of pregnancy Diskin and Morris, 2008).A combined use of progesterone measurements and pregnancy-associated glycoproteins allows the identification of the different phenotypes of pregnancy failures under field conditions (Humblot, 2001).The aim of this study was to investigate on a large-scale basis (i) the sire effects on the respective frequencies of early, late embryonic mortality (LEM) and FD from precise phenotyping of their progeny and (ii) the relationship between bull estimated breeding value (EBV, based on imprecise cow fertility phenotypes from previous years) and the above distribution of pregnancy failures. Collecting this information was also a first step to run subsequent wholegenome association studies (GWAS) for those traits.…”

Bovine P-selectin mediates leukocyte adhesion and is highly polymorphic in dairy breeds

“…The condition is caused through a variety of contributing factors, such as endometritis (Sheldon et al, 2009), irregularities in the oestrous cycle (Bulman and Lamming, 1978) and high rates of early embryo mortality (Diskin and Morris, 2008). Similar to mastitis, there is evidence for the involvement of selectins in all of these processes.…”

“…Around 40% of bovine embryos are lost by day 21 while a further 7-20% die between 4 to 12 weeks of gestation (Diskin and Morris, 2008). Endometrial SELP expression in the cow increases from Day 20 of gestation (Bai et al, 2015) and SELP polymorphisms in women are associated with recurrent pregnancy losses (Dendana et al, 2012).…”