Rearing great calves; an investment in the future of your herd

Rearing great calves; an investment in the future of your herd
By Travis Scott, Anexa FVC Veterinarian

Rearing good young stock is extremely important for the future of your herd, as well grown heifers will be much more likely to get in calf early and have good production throughout their life. One of the secrets to producing great calves lies in minimising the number of growth checks that they suffer. All management changes should happen gradually and at the right time; this requires a little bit of forward planning so that things go as smoothly as possible.

Invasive husbandry practices like dehorning are going to be stressful for calves and will temporarily suppress their intakes. Dehorning calves while they are still on milk will result in a smaller growth check than if they are dehorned after they are weaned. It’s also faster and safer for you to handle them when they are smaller.

Weaning calves off milk can cause problems as their rumen may not be developed enough to get all their nutrients from solid feed. Weaning on weight is a good way of ensuring that later born calves stay on milk long enough and don’t get left behind. The DairyNZ recommendation is to wean calves at 80 – 100kg, depending on their breed.

Calves should have had access to high quality roughage right from birth to stimulate rumen development. Historically people fed hay or straw, but studies have shown that high protein meal is the best way to get the rumen going. Calf meal will usually also contain something to prevent coccidia, which can cause ill-thrift and scouring in young animals.

As soon as calves start eating pasture, they will be picking up worms. It takes most worm species at least three weeks between being eaten and starting to shed eggs; therefore, we recommend drenching young stock once a month. A dual action oral drench such as Arrest C is a very cost-effective way to achieve good parasite control and minimise the build-up of resistance in young stock.

The wet weather for the past six months has meant that pasture quality isn’t as high as we might like. This makes the milk and meal components of a calf’s diet even more important, and it might pay to hold off any weaning decisions until we’ve had a bit more sunshine.

When you do decide to wean calves off meal, make sure it’s done gradually. If calves have got a properly developed rumen, there shouldn’t be a noticeable change to their growth rates, as they will be able to eat enough grass to compensate for the loss of the meal. A pre-ruminant calf is sometimes described as being round or ‘apple’ shaped when viewed from behind, and as their rumen develops they take on a ‘pear’ shape; it appears wider, lower down.

Remember that the meal has been preventing coccidia, and any scouring after meal is stopped should be investigated. Try to avoid weaning off meal at the same time as moving stock to run-off or to grazing, as the doubling down of stressors can make them even more susceptible to disease.

Before calves leave your property, they should be up to date with all their vaccinations. This means two shots for blackleg and lepto, plus two shots for BVD if that is part of your BVD control strategy. You should be contacted by your local clinic soon to make sure that these are all done in time.

Weighing calves just before they go off grazing is a great way to check your own calf rearing, but also to ensure that expectations with your grazier are clear. If you send well grown calves off grazing, you should expect well grown heifers to come home, but if you send under-grown calves they may never be able to catch up to targets. If you can identify animals that might need a bit of extra help and preferentially feed them from the get-go then their prospects are much brighter than if they are identified later.

CALF VACCINATION SEASON

Why do we vaccinate against Leptospirosis?
Leptospirosis is a horrible debilitating disease that is spread through urine from various animals, including your dairy cows. It is also a zoonotic disease, meaning that cow urine can cause disease in humans.

Vaccination is one part of the puzzle in protecting your cows, yourself and your staff, but you need to vaccinate early. A recent Massey University study showed that vaccination needs to happen before calves are exposed to the disease. Once an animal contracts Leptospirosis, it will shed the bacteria despite vaccination, which might give you a false sense of security. You will vaccinate the animals and think they are protected but, the vaccine does not remove an already existing infection and therefore these animals pose a risk to you, your staff and any unvaccinated animals on farm.

The best timing to start vaccination is when your youngest replacement animal is eight weeks of age, with a booster to follow 4 weeks later. A good ‘rule of thumb’ is to vaccinate your calves twice before Christmas to give them early protection against Leptospirosis. They will need annual booster vaccinations after these two initial shots to keep their immunity up, which usually means that you give your calves a third vaccine in winter to line them up with your heifers and herd.

Make sure you complete a Leptospirosis risk assessment with your vet to fill in the other parts of the puzzle. There are other aspects of lepto control to consider, for example, don’t smoke, eat or drink in your cow shed, keep on top of your rodent control and keep pigs well away from your cow shed. This is a serious health and safety issue for you and your staff. You need to take the necessary precautions to protect your animals and your team.


Date Added: Wednesday, 8th November 2017


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