Extra care needed to reduce risk for first calvers
FIRST calvers need extra care four weeks before and eight weeks after calving to reduce lameness risks, the time when damage is most likely to occur.
Bristol Universitys John Webster said an MDC study of first calving heifers showed that they suffered less lameness when housed in straw yards and fed drier diets, than when in cubicles.
In the study, which is underway, heifers are assessed by picking up their feet and measuring sole lesions or bruising four weeks before calving and four, eight, 16 and 24 weeks after calving. Currently these heifers are between 16 and 24 weeks calved.
While all heifers showed some foot damage associated with calving and onset of lactation, those in cubicles and fed on wetter diets suffered more sole lesions (see table).
In cubicles heifers had lesions that were 50% more severe on the wet than the dry diet, said Prof Webster. The dry diet was 50% dry matter, while the wet diet had water added, so was 25% DM.
In straw yards feet had effectively returned to normal 16 weeks after calving. "Even in cubicles, the study found heifers were getting better by 16 weeks after calving.
"But the real risk factor is calving itself." Calving disrupts horn formation in the foot. The reason for this is not fully understood. However, it could be affected by the way the animal partitions nutrients or by hormones. But it is unlikely to be poor nutrition because demand for nutrients is lower before calving than when milking.
"Calving is inevitable, but we can do much to reduce external stresses on feet during the vulnerable period of four weeks before to eight weeks after calving. It is only a short period," he said.
He suggests maximising lying time by keeping heifers separate from cows, housing them in straw yards for the critical 12 weeks around calving or calving at pasture and providing a comfortable path to the milking parlour.
Any animal that suffers from severe sole ulcers should be removed from the cubicle house and kept in well-bedded straw yards, and given at least six weeks to recover, added Prof Webster.
Average changes in lesion scores in four groups of 10 heifers around calving
Timing (weeks) Cubicles Straw yards
wet feed dry feed wet feed dry feed
-4 2.1 1.8 1.2 2.1
+4 7.8 12.1 6.8 3.3
+8 12.7 18.7 6.7 4.8
+16 10.2 15.6 2.7 2.0
*one bruise is given a score of 1. The worst score for a lesion is eight. When the score is 12.1, three animals in the group have sole ulcers.