It is now possible to almost eliminate low-value male dairy calves by using just enough sexed semen to generate the required number of replacement dairy heifers.
Recent research indicates that sexed semen can be effectively used after observed heats or in conjunction with fixed-time AI synchronisation protocols.
Use of sexed semen on heifers and targeted cows to generate replacements will allow more beef semen to be used on all the other cows that are not suitable for generating replacements (low EBI, later calving etc), including at the start of the breeding season.
The resulting calf crop is composed of mostly dairy heifers and readily saleable beef-cross calves.
Selection of beef sires for use on dairy herds is often based on simply identifying an available, easy-calving and short-gestation beef bull.
Nevertheless, the genetic merit of beef sires used on dairy herds has a large impact on the beef merit of the offspring, and hence on the profitability of beef farms.
Dairy farmers often fear the risk of calving difficulties and longer gestations arising from using higher beef merit sires.
The Dairy Beef Index (DBI) enables dairy farmers to select beef sires with good carcase performance traits without compromising on calving traits.
A validation study indicated that, on average, the progeny of bulls selected based on DBI have similar calving difficulty compared with bulls selected just for calving traits.
Progeny from sires ranked highly on DBI had only 0.8% more calving difficulty and 0.4 days longer gestation compared with progeny from sires ranked highly on just calving traits.
Nevertheless, carcases from sires ranked highly for DBI had heavier (+9kg), better-conformed and leaner carcases compared with progeny ranked highly on just calving traits.
Mass uptake of sexed semen by Irish dairy farmers will diminish the number of male dairy calf births, and hence a new strategy to generate the next generation of high-EBI bulls for use in AI needs to be developed.
In addition, to achieve genetic gain in DBI, an intensive genetic selection programme will be required. One option is to use a combination of Assisted Reproductive Technologies (in vitro produced (IVP) embryos, sex-sorted semen) to intensively select for genetic improvement in elite dairy bulls and beef breed bulls suitable for use in the dairy herd.
A trial to evaluate IVP embryos was conducted in spring 2021, and the results will be presented at the open day.