Page 53 - NZ Herefords Magazine 2019 Edition
P. 53

Beef + Lamb NZ Genetics                                                                   Industry Focus

          Dairy Beef Progeny Test at

          Limestone Downs: 2018 UPDATE


          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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