Broken legs in dairy heifers
This season there have been several herds in our area that have experienced front leg fractures in first calving heifers.
The fractures have occurred around calving time or within a couple of weeks after calving. Often there is no history of trauma; the heifer is simply found in the yard or paddock with a broken leg, usually above the elbow. Affected herds have had up to six or seven cases each.
The cause of the condition is multi-factorial but, in New Zealand (NZ) at least, there is usually a strong correlation with copper deficiency. Copper is required in young, growing animals to form strong bones; copper deficiency can result in thin, weak bones that easily fracture. The humerus bone is particularly vulnerable due to its weight-bearing function.
Copper deficiency can be the result of a lack of copper in the diet (common on NZ soils) or due to the presence of other minerals in the soil such as zinc, iron, sulphur and molybdenum that interact with the copper and prevent it from being absorbed in the animal’s gut. The use of zinc for facial eczema prevention may be a contributing factor in some cases.
The problem is investigated by clinically examining affected animals and blood and/or liver tests to determine copper levels and check for any other factors. Pasture testing is also a useful tool to check for other mineral interactions. When the likely cause has been identified then supplementation can be put in place to correct deficiencies. It takes time for the weakened bones to recover so management practices need to be put in place to protect the heifers such as milking once a day and running a separate heifer herd.
Treatment options for heifers that have sustained fractures are limited. Less severely affected animals may be salvaged with conservative treatment but often they have to be destroyed on humane grounds. Veterinary advice should be sought in all cases.
Contact us if you have had any unexplained fractures in your herd.