The distribution of serum transferrin types in dairy cattle and their relationship to milk and butterfat production

Abstract

The serum transferrin type was identified for 1102 dairy cows. The gene frequency distribution among nine herds of predominantly Friesian type cattle was TfA 40.7 per cent, TfD 55.9 per cent, and TfE 5.4 per cent. In one herd of 31 Red Poll cattle the distribution was TfA 32.3 per cent, TfD 33.8 per cent, and TfE 33.8 per cent. There was no significant difference between the observed and expected distribution of the various genotypes. Cows of genotype D/D produced significantly more milk than those of type A/A, but their butterfat test was lower and the average butterfat production of the two groups was identical. There was no significant difference in lactation length.