VITAMIN-B12 LEVELS IN EWE COLOSTRUM AND MILK AND IN LAMB SERUM

Vitamin B-12 was measured in samples of normal ovine colostrum and mil k and in sera of lambs and ewes taken at various stages of lactation, from lambing up to 16 d. Colostrum obtained within 24 h of lambing con tained high concentrations of vitamin B-12, but within a few days the levels fell. The lambs received high levels of vitamin B-12 from their dams' colostrum but a parallel decrease of vitamin B-12 levels in lam bs' serum and ewes' milk was subsequently observed. Milk vitamin B-12 was analysed by the microbiological method (Lactobacillus leichmannii, ATCC 7830) and a radioisotope dilution (RID) technique. Milk vitamin B-12 concentrations were greater with the microbiological technique co mpared with the RID method. The radioassay method has been shown to be as reliable as the microbiological method for measuring vitamin B-12 in ovine milk except for very low levels.