During a recent discussion on the need to supervise calving cows I was challenged over the potential risk from calves being born backwards etc. Unfortunately the discussion then moved onto the merits of the various calving alerters, cameras, etc rather than what I should have said –
“The real question with all malpresentations, apart from perhaps twins, is why did they occur?” Malpresentations are almost entirely due to the inability of the calf to easily turn around and be in the correct position a few days prior to being born. This occurs from a combination of –
- The calf being too big, heavy, blocky – all measured by Calving Ease Direct EBVs and
- The size of the cow’s womb and pelvis – all measured by Calving East Maternal/Daughters.
Hence selecting heavily for high positive EBVs for calving traits will significantly reduce and potentially eliminate malpresentations.
Three areas of management which can also influencing malpresentations are –
- Exercise in late pregnancy, bounces the calf around and helps it to get in the correct position for calving.
- Muscle strength/tone in the cow also helps to position the calf. Good muscle tone is dependant on adequate calcium, which itself is controlled by blood magnesium levels. Hence the advice to feed pregnant cows and extra 50 g/day of a high magnesium mineral beginning 2 weeks before calving is due to start.
- The vigour of the calf itself is also critical even before calving starts. One of the key nutrients here is adequate vitamin E/selenium in the ration of pregnant cows. Adequate supplementation will also improve the vigour of the calf once it is born, helping it break out of the water bag and avoiding losses from sheeted calves. It will also ensure the calf is on it’s feet and suckling ASAP. Calf vigour is so critical to profitability that we desperately need a relevant EBV, which has been available in many other countries of many years.
Basil Lowman, firstname.lastname@example.org
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