Heifer worming crucial for herd health and productivity
Worming high-risk groups of cattle, such as first and second calving cattle, is crucial for long-term herd productivity, a leading cattle vet has advised.
While the evidence of worms' effect on productivity in older cows is well established - reductions in milk yield of as much as two litres per day are common - the impact on the heifer can often be much greater.
Wood Veterinary Group partner Chris Watson points out that the stress of calving, followed by transfer from rearing to milking groups, can seriously disadvantage heifers. They become more prone to disease, and their ability to consume adequate levels of ration can be seriously affected, with knock-on effects on milk production.
"The risks that any parasite burden could add to this are not worth taking," Mr Watson advises. "Worming them is likely to have a very positive feedback for health and profit.
"Second-lactation animals will have had more grazing experience and a chance to develop greater natural immunity. However, because the payback for their rearing period has not even been covered by the first lactation, it is worth trying to get every advantage from the second lactation.
"With any significant parasite burden the effects will be just the same - lower food intakes, more weight loss in early lactation and reduced performance."
But don't let heifers detract your attention from the rest of the herd, says Helen White, Technical Services Manager for Merial Animal Health. "The cow's immune system takes time to respond to the presence of worms; furthermore, this response varies between individual animals and against different species of parasites.
"In the case of infections with Cooperia species of gut worm - common in young cattle during the first grazing season - immunity will be reasonably good but only towards the end of that season," Ms White explains, "hence it is important to worm heifers.
"But it's a different story with Ostertagia ostertagi, the other common gut worm species," she cautions. "Immunity takes much longer to develop, as much as two seasons, and even then it's not total.
"Older cattle frequently harbour worm burdens which can number hundreds of thousands; unless clinical disease appears, they'll frequently go undetected."
Mr Watson adds that it's worth considering a whole-herd policy for both gut worms and external parasites, as there is frequently a payback for the cow's health and production.
"A whole-herd protocol of worming cows at calving has a lot to be said for it: it is simple, and more likely to be adopted and carried out thoroughly," concludes Mr Watson.
