Abstract
Lactoferrin was determined by the immunological method of Laurell in bovine colostrum and milk from 1 to 547 days after parturition (60 samples). Iron which was closely contacted with the bacteriostatic effect of lactoferrin, and nitrogen distribution were also measured.
Lactoferrin contents in bovine colostrum, transitional milk, matured milk, and milk in later lactation were 80.9±45.0, 54.0±21.7, 40.4±25.0, and 455mg/100ml skim milk, respectively, with considerable differences among samples from individual cows. The lactoferrin to whey protein ratios in colostrum, transitional milk, matured milk and milk in later lactation were 3.3, 6.9, 7.2 and 5.2%, respectively.
Iron contents in colostrum, transitional milk, matured milk and milk in later lactation were 1.77± 123, 92±43, 53±14 and 73μg/100ml, respectively. The weight ratio of iron to lactoferrin was high in colostrum, then decreased with elapsing of lactation days and was very low in milk in later lactation.
Significant correlation was observed between the concentrations of lactoferrin and whey protein nitrogen (r=0.666). No correlation, however, was observed between the lactoferrin and iron concentrations. Iron is likely to be contained at approximately constant level in matured milk.
