The introduction and use of the economic breeding index (EBI) on dairy farms can only be described a success.
Recent updates to the EBI include a carbon sub-index, which will reduce the carbon footprint of Irish dairying.
There has also been the launch of the commercial beef value (CBV) of calves which links well with the Dairy Beef Index (DBI), incentivising dairy farmers to generate valuable calves for the
downstream beef industry.
EBI
The EBI will continue to be the tool to deliver on the pillars of on-farm sustainability.
Teagasc advises that all farmers should use sexed semen to generate some, or all of their dairy heifer calves.
Ideally, farmers should only consider the top 50% EBI females in their herds for mating to high-EBI dairy bulls when using sexed semen.
All remaining females should be considered for mating to beef bulls with a high DBI value from the start of the breeding season.
Teagasc believes farmers should select a team of high-EBI artificial insemination (AI) bulls from the Irish Cattle Breeding Federation’s (ICBF’s) dairy active bull list to breed their dairy herd replacements.
Farmers should use the team of bulls equally, with no more than 15% of matings to any individual bull to minimise genetic and fertility risks.
For a typical 100-cow dairy herd, at least eight bulls should be used, with no more than 15 straws to any individual bull.
Sexed semen
The increased availability of sexed semen has accelerated genetic gain in dairy replacements, which has also resulted in a marked increase in the number of beef-cross calves generated.
The advice from Teagasc for farmers using sexed semen is to ensure that inseminations with sexed semen are completed in the first three weeks of the breeding season.
Prioritise usage on maiden heifers, younger cows, earlier-calving cows and cows without health issues. Farmers should also use a large team of high-EBI bulls to minimise genetic and fertility risks.
Beef-on-dairy
To ensure saleable, profitable, and sustainable dairy-beef cattle are generated, Teagasc advises that farmers use beef AI bulls from the ICBF Dairy-Beef Active Bull List.
It’s recommended to firstly select bulls with a calving difficulty percentage range suitable for the females being mated (first calvers, second calvers, mature cows), and then select bulls with the highest beef sub-index value.
Teagasc also advises that dairy farmers use the ICBF HerdPlus sire advice tool, as it will simplify the process of bull selection and identify the optimum mating for both dairy and beef bulls.
The tool will allocate dairy bulls to cows based on their strengths and weaknesses, as well as manage inbreeding.
The tool also identifies the optimum beef AI bull mating to minimise calving issues and
maximise beef merit.
Future changes
Three characteristics dictate whether a trait should be considered for inclusion in breeding indexes like the EBI or DBI:
- Is the trait economically, socially or environmentally important?
- Are there genetic differences among animals for the trait in question?
- Can the trait be measured on a large number of animals or correlated with a measureable trait?
Some of the traits being explored currently relate to feed intake, methane emissions and nitrogen use efficiency.
All are important and genetic variation exists for all.
None of the traits are easily measurable, however, and how selection for these traits influences the production system as a whole has not yet been characterised.
While research on new traits is ongoing, improvements to the ongoing genetic evaluations for current traits is also important; one such trait is gestation length.
Breeding and reproductive programmes contribute approximately 50% of the observed improvements in productivity on Irish dairy farms over time.
Substantial scientific advancements have been made in recent years, which have translated into breeding and reproductive tools to exploit these developments.