Calving over 90pc of maiden heifer calves born alive at two years of age is achievable.
Doing so will minimise the number of heifer calves required on your farm and the proportion of your herd that are available for breeding to non-dairy bulls.
Choosing DAMS for the next generation of replacements
Maiden heifers are ideal candidates to select when breeding the next generation of replacement heifer calves.
They usually have the highest EBI and can be manipulated to mostly calve in the first two weeks of the calving season.
The calves born are high EBI, early born and compactly calved. The choice of suitable AI sires for replacement heifers has increased over the last number of years without compromising on EBI.
Select then from within the dairy cow herd for cows that are early calving, high EBI and performing well.
In compactly calved herds that are not increasing in size, this means that a proportion of the mature cows can be bred to beef AI from the start of the breeding season.
Using the Dairy Beef Index (DBI) to select beef AI bulls
The DBI is a breeding goal to promote high quality beef cattle bred from the dairy herd with minimal consequences on the calving difficulty or gestation of the dairy cow.
The DBI ranks beef bulls, for use in the dairy herd, according to their genetic merit for calving and carcass performance traits:
Expressed in euros (€), each €1 increase in DBI can be interpreted as a €1 expected increase in profit for that bull's progeny;for example, bull A has a DBI of €100 and bull B has DBI of €20. The progeny born to bull A are expected to generate €80 more profit compared to progeny sired by bull B. Calving traits account for 64pc of the average DBI value. The DBI selects for shorter gestation, easier calving and less calf mortality:
On the recommended bull file, lower values for all calving traits are more desirable;
If a bull's calving difficulty figure is 4pc then 4pc of his calves are likely to require considerable assistance at birth. Increasing calving difficulty indicates that more calves will require considerable assistance at birth.
Beef traits account for 36pc of the average DBI value. The DBI selects for higher carcass weight and conformation, and more animals that meet minimum factory specifications (280 kg, O=). The DBI also recognises that some breeds are paid a premium slaughter price and the DBI selects for reduced feed intake, as well as quieter and polled cattle.
On the recommended bull file, higher values for carcass weight and conformation are more desirable.
When selecting beef AI sires using the DBI it is important to consider what components are contributing to an individual sire's DBI value. For example the DBI, calving and beef sub-indexes of two similar DBI beef sires listed on the March 21, 2019 bull list are presented in the table.
Both sires have similar DBI values (€84 and €83 respectively). However the calving value of Sire A is €69 while that of the Sire B is €49 reflecting his slightly more difficult calving figures. Sire A is more suited for use on dairy heifers while Sire B will be best used on cows with a proven track record of easy calving where he will sire calves of superior beefing merit.
Sire B however will produce calves that themselves have potentially more beef value. He can be safely used on dairy cows without compromising on the risk of increased calving difficulty.
Teagasc is collating lists of suitable sexed semen and well proven high DBI AI beef bulls for use on dairy cows and heifers this year. Contact your local dairy adviser for further information.
George Ramsbottom is a Teagasc dairy specialist based in Oak Park, Co Carlow