Project

OVERVIEW

Good fertility is essential for the sustainability of livestock production. However, concomitant with intensive selection for increased milk yield, reproductive performance of dairy cows has declined in recent decades. This has become a major concern for farmers and the dairy industry. The causes of this decline in reproductive success are multi-factorial and fertility problems include: an increase in postpartum failure to return to cyclicity, poor expression of oestrus, and problems of oogenesis, embryo survival and susceptibility to uterine infections.

FECUND will address the problems of reproductive success in the cow using a interdisciplinary approach that will integrate in vivo and in vitro studies, biology, physiology, -omics technologies and bioinformatics to define new phenotypes, to deliver targets for genomic selection for improved fertility, and to improve reproductive biotechnology. FECUND will investigate the underlying reasons for differences in reproductive success between heifers and cows to define the genetic vs management factors involved and to better understand the impact of Energy Balance and classical Genetic Selection on fertility, focusing on the early phases of reproduction when most embryonic loss occurs.

 

BACKGROUND

Successful reproduction requires the development of viable gametes, fertilisation, establishment of pregnancy by implantation of the embryo, gestation of the foetus and the delivery of viable offspring. Thus, the reproduction process encompasses many molecular and cellular interactions which require that cows are in an appropriate metabolic state and that a complex series of physiological events occur correctly with appropriate timing. Improvement of reproductive success may be achieved by better animal management and through genetic selection for better fertility. To achieve these goals a better understanding of the reproductive process is needed, which would be aided by improved measurement of reproductive traits, better recording and the application of new reproductive techniques together with increased knowledge of gene function and regulation.

Currently selection for improved reproduction is addressed using traits that have low heritability and low accuracy, in part, because reproduction has been considered as a single trait. Research is therefore urgently needed to improve the precision of phenotype recording by better defining the key biological variables. Using measurements of progesterone it is possible to identify animals failing to return to cyclicity postpartum and to detect embryonic losses following implantation. However, there are still no methods to identify fertilization failure and embryonic loss prior to implantation, which is the period during which most losses occur. Many countries now include fertility in genetic evaluations, based on recording simple traits. Fertility has been traditionally been based on calving and insemination data or measures combining these with production data to calculate a “fertility index”. While using this information has reduced the rate of decline in fertility, the low level of reproductive performance remains a real problem for producers, and reproduction problems are among the most common reasons for culling dairy cattle. The rapid advances in -omics technologies, when appropriately combined with physiological measurements, will facilitate systematic studies to improve our understanding of reproductive physiology and fertility which can be applied to further improve the situation.