The bent-leg syndrome in sheep. I. The effect of pregnancy and age of the ewe on concentrations of plasma minerals.

The effect of age of the ewe and pregnancy on concentrations of plasma calcium, phosphorus and magnesium and its relationship to the bent-leg syndrome in lambs, were investigated. This study included Merino ewes (n = 74), Dohne Merino ewes (n = 127), S A Mutton Merino ewes (n = 123) and S A Mutton Merino lambs (n = 145). Over a period of 8 years, 52 S A Mutton Merino ram lambs out of a total of 602 ram lambs weaned (8,6%), developed the bent-leg syndrome compared to the 2 ewe lambs out of 591 ewe lambs (0,3%) weaned. It was found that both the age of the ewe and pregnancy had no contributing effect in the development of this syndrome. The ewes of which the offspring developed the bent-leg syndrome, had an inverse plasma Ca:P ratio. Approximately 15% of the S A Mutton Merino ewes which gave birth to offspring which developed the bent-leg syndrome, had more than one lamb which developed this condition over the past 8 years. It is suggested that these ewes are carriers of certain genetic factors which can cause excessive phosphorus absorption. No differences in the concentration of plasma calcium, phosphorus and magnesium were found between ewe and ram lambs.