Research in the field of bovine genetics in France aims to improve the performance of dairy cows. This research focuses, on the one hand, on the relationship between feeding heifers and cows, growth and reproductive performance and milk production. On the other hand, the relationship between diet during rearing and the age at the earliest first calving.
In Holstein (Prim'holstein) dairy systems with seasonal calving, Holstein heifers generally calve at an age of around 24 months. This period may vary depending on the date of the first insemination which may be delayed if sufficient weight is not reached (between 360 to 380 kg).
Currently, it is already possible to allow heifers that have not reached sufficient weight for insemination, via diet, to catch up with it without degradation of reproductive or production performance. Thus, increasing the growth of Holstein dairy heifers makes it possible to decrease their age at puberty, reducing their age at first calving and shortening the non-productive rearing period.