Left sided displacement of the abomasum (LDA) is a production disease of dairy cows and is associated with high milk yields. Most cases occur within a week of calving and a drop in daily milk yield and appetite are typical symptoms. When more than 2% of cows within a herd develop LDAs after calving, a review of management over the period of risk is required.
The risky transition period begins three weeks before calving and also continues for three weeks afterwards with a peak in risk when calving actually occurs.
Cows should enter the risk period in a body condition score of 3. Body condition is easiest to manipulate when cows are in late lactation before drying off and the target at this stage is 2.75. Dry cows should then be managed to maintain condition on a diet of mainly straw, as they will put on condition readily when on a higher plain of nutrition.
On reaching the risk period, maximising dry matter intake alongside prevention of milk fever is crucial. And since intakes of grazed grass are unpredictable, this is easiest to achieve when cows are housed.
Fresh feed should be available constantly for risk cows and when calving dates are accurate and cows are in appropriate body condition they will not get too fat at this time. Frequent feeding and pushing up of the remaining ration stimulates cows to take extra meals. High risk cows should never be without food and when waste feed does not have to be cleared away, the cows are being underfed.
It’s worth bearing in mind when a cow moves group she spends additional time socialising with other cows to establish a pecking order. When the new group is large, more social interactions are expected to take place and there will be more competition for feeding, drinking and lying space, even in the best housing. Therefore, it’s helpful to group risk cows separately from the main herd so they can spend more time eating.
When a separate group for cows in the first three weeks of lactation is not practical, just a few extra days of individual care after calving can make a big difference.
Once a calf is born, there is effectively empty space in the cow’s abdomen. This increases the potential volume of the rumen which more than doubles the healthy cow’s appetite. The rumen is the engine of the cow and for high performance it needs to reach expanded size as soon after calving as possible. When the cow does not eat, an LDA develops when the abomasum floats up to fill the space between the rumen and the body wall on the left hand side. This limits the amount of dry matter the rumen can hold and hence reduces milk yield.
Examination by a vet is essential to confirm the diagnosis. Whatever method of correction is chosen, it’s crucial cows are given a second chance to eat and fill their rumen because they missed out on the first opportunity for this when they calved.
Ideally house these cows in an individual pen to eliminate competition until they have regained their appetite. Avoid changing diet and feed a ration the cow would be expected to eat, but supplement with some long fibre. Provide ample fresh feed to stimulate appetite and check the water supply. It’s also worth discussing with a vet what went wrong at calving to improve future management plans.Simon Archer works at the Scarsdale Vet Group, Derby