Prediction of Milk Yields from Serum ß-Lactoglobulin Concentrations in Pregnant Heifers

¹ Department of Dairy Science, University of Wisconsin-Madison, Madison 53706

The serum concentration of ß-LG at wk 26 of pregnancy was determined in Holstein heifers of known genetic merit to evaluate use of a single blood sample as an index to predict their subsequent milk yield. Concentrations of ß-LG varied widely (16 to 1200 ng/ml) in the serum of the heifers at this stage of pregnancy. Subsequent measures of lactation performance showed that heifers with high ß-LG concentrations in pregnancy produced more milk than those with low ß-LG in serum. Previous studies have shown that the concentration of ß-LG in serum shows a log-linear increase during pregnancy, which is consistent with correlation to the growth of the mammary parenchyma. Therefore, the logarithm ß-LG concentration was used as the index in this study. The correlations of this index were .46, .54, and .48 for first lactation 305-d yields of milk, fat, and protein, respectively. The results suggest that serum concentrations of ß-LG estimated from a single blood sample at this stage of pregnancy can be used to predict milk yield. Analysis showed that an explanation of future milk yield was significantly improved by use of serum ß-LG and parent average. Serum ß-LG can be used as a physiological marker to prescreen heifers for lactation potential.

Key Words: milk yield • ßbeta;-lactoglobulin • cattle

Submitted on May 6, 1994
Accepted on September 8, 1994