Long bone deformity appears to have a higher occurrence amongst beef suckler herds. Calves are born with a dwarf like appearance as a result of the shortening of the long bones in the legs, giving them a characteristically short, bow-legged appearance. They may also have dished faces and domes heads. In very severe cases calves can struggle to stand and suckle.
While the reasons behind it are not clear we do know it is not a genetic defect and appears to be nutrition related. Almost all cases tend to appear in cows with high silage intakes of both grass/clover and either pit/baled. There is evidence that it may also be related to a lock up of manganese- an essential element for the development of bone, cartilage and other connective tissues.
This year almost 30% of all beef and sheep silages analysed by our SAC lab have been below 25% DM. Although cases appear to be more prevalent in cows fed high quality silage these wet silages could cause issues, especially when fed ad-lib or where silage accounts for more than 75% of their total dry matter intake.
The greatest risk period has been pinpointed as the 4th and 5th month of pregnancy. For example those due to calve in June, are most at risk between December and January. The best approach for many herds during this period is to top up restricted supplies of silage with ad-lib straw. Where straw is in short supply an alternative option would be to leave the calves on the cow and feed some of the concentrates to the cow rather than the calf.
Mary McDowell, SAC Consulting Livestock Nutritionist
Sign up to the FAS newsletter
Receive updates on news, events and publications from Scotland’s Farm Advisory Service