Page 53 - NZ Herefords Magazine 2019 Edition

Beef + Lamb NZ Genetics Industry Focus

Dairy Beef Progeny Test at

Limestone Downs: 2018 UPDATE

WORDS REBECCA HICKSON, MASSEY UNIVERSITY PHOTOGRAPHS SUPPLIED

THE DAIRY BEEF PROGENY TEST at Limestone Downs aimed
to demonstrate the effectiveness of BREEDPLAN EBVs in a dairy
beef system and identify the types of bulls suited for dairy beef.
The dairy farmer typically wants easy-calving, short-gestation
cows that generate high value calves without compromising
their cows. PhD candidate Lucy Coleman reports the bulls used
(which had birth weight EBV lighter than breed average) were
not negatively affecting the cows’ performance in the dairy herd.
There was no difference in lactation or rebreeding performance
of cows at Limestone Downs that had calved Angus or Hereford
calves, and there was no effect of calf birth weight on lactation
or rebreeding performance either, despite a 30kg range in calf
birth weight in the experiment. Finishing steers from the first cohort of progeny at Limestone Downs.
The bulls used over the mixed-aged cows in the dairy
beef progeny test have been a resounding success for calving
difficulty, with less than 1% of cows assisted at calving, a similar
rate to what the farm would usually have seen using Friesian sires.
Similarly, we have demonstrated a good relationship between
birth weight EBV and calf birth weight, and gestation length EBV
and gestation length. Similarly, 200 day weight EBV was a good
predictor of weaning age – calves with greater 200 day EBV
reached weaning weight (85kg) earlier. It is clear dairy farmers
can select Hereford bulls for dairy cows, knowing that selection
for improved birth weight, gestation length or 200 day weight
EBVs will result in the desired improvements in their calves.
Post-weaning growth performance of the dairy beef calves
in relation to their 200 day weight EBV was less convincing,
with no relationship observed between 200 day weight EBV and
weight of progeny at 200 days. This is probably explained by Photo 1
the potential bias created in favour of low-EBV bulls by weaning
progeny at a fixed weight rather than a fixed age, and because
early-weaned dairy-beef calves experience a markedly different
environment from beef calves pre-weaning. Fortunately, by 400
days of age, there is again a relationship between 400 day
weight EBV and progeny live weight, with 1kg of 400 day weight
EBV translating to an extra 0.2kg in mean progeny live weight
at 400 days (compared with an expectation of 0.5kg). Finishing
farmers can purchase dairy-beef calves from higher growth
sires to get heavier cattle at 400 days of age.
Sire means for birth weight differed by 10.6kg between the
heaviest and lightest sires, whilst sire means for 400 day weight
had a 33kg range, demonstrating the importance of selecting Photo 2
appropriate sires to achieve the desired performance for calves.
Generally, low birth weight bulls were also lower 400 day weight ABOVE: High and low EMA carcasses from the heifers: 94 cm2
sires, but three bulls were in the top 20 for both birth weight and EMA in a 255 kg carcass (Photo 1) versus 54 cm2 in a 261 kg
400 day weight (out of 65 bulls used over mixed-aged cows). Given carcass (Photo 2). A nice demonstration of the difference in meat
the experimental design was to achieve a wide spread of breeding distribution among similar weight animals.
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