Abstract

The invention relates to measuring the decrease in phosphorylation of the fatty acid binding protein (FABP) found in the milk fat globule membrane (MFGM) of bovine or human milk to detect growth hormone treatment in animals. MFGM of cows treated with recombinan+bovine somatotropin (bST) displays weaker FABP autophosphorylation activity than non treated cows. MFGM isolated from cows treated with bST have significantly reduced levels of phosphorylated FABP. The bST test of the present invention can be used not only to determine whether the animal producing the milk has been treated with bST, it can also be used to determine the efficacy of bST on milk production. Dairy managers could thus base their decision on whether to continue bST treatment on such a test.