Understanding how targeted early life nutrition can advance the availability of high quality semen from genetically elite young bulls

The bull has a huge influence on the rate of genetic progress in cattle, particularly when used through artificial insemination. Novel research currently being conducted at Teagasc Grange is focused on understanding the underlying physiological and molecular mechanisms regulating the role of nutrition in stimulating sexual development.

The bull has a huge influence on the rate of genetic progress in cattle, particularly when used through artificial insemination. Nutrition of the bull calf during early life can have a large and lasting effect not only on subsequent growth potential but also on the onset of sexual maturity. For example, greater nutrient intake during the first months of life can stimulate the development of brain-testicular axis that regulates sexual development and reproductive function. The outcome of this is earlier onset of puberty and availability of high quality semen.

Indeed, recent research conducted at Teagasc Grange clearly shows the positive effect of early life nutrition (up to ~ 6 months of age) on advancement of puberty, with very well-fed bull calves reaching puberty approximately 4 weeks ahead of their contemporaries maintained on a lower plane of nutrition. Moreover, data also suggest that if a bull calf has been exposed to a low plane of nutrition during the first 6 months of life, improving nutritional status thereafter, will not appreciably advance puberty. Earlier sexual maturation leads, in turn, to earlier availability of high quality semen a key requirement for the use of genetically elite young sires within the relatively short breeding period typically practiced in seasonal calving herds. The positive effect of enhanced early-life nutrition on reproductive development is mediated through the complicated hormonal interplay between the brain, metabolic organs and the testes.

Novel research currently being conducted at Teagasc Grange is focused on understanding the underlying physiological and molecular mechanisms regulating the role of nutrition in stimulating sexual development. This work aims to uncover, in particular, key genes that could inform the development of targeted nutritional regimens (known as Nutrigenomics), as well those potentially exploitable within the context of the national genomic selection breeding program. Such an approach will help to ensure consistent early onset of puberty and semen availability in young genetically elite young bulls, thus shortening the generation interval for genetic improvement of both beef and dairy cattle.

This collaborative project, funded by Science Foundation Ireland (16/IA/4474), is led by Teagasc in partnership with University College Dublin, the University of Limerick and the Irish Cattle Breeding Federation.