The composition of the colostrum of some beef cattle breeds according to time of post partum

This research was carried out to investigate the changes of main components of colostrum with 0-4 days after calving by five beef cattle breds, kept i n Hungary. After calving and 24 hours later beef cattle breeds had higher dry matter c ontent in colostrum compared to that of dairy breeds; but the dairy breeds were superior to the beef cattle breeds from the second day. This relates t o the colostrum of the beef cattle breeds more concentrated than the dairy breeds during the first 24 hours but they reached that values earlier which were characteristic to the normal milk. Examining the protein content of c olostrum there were similar tendencies in change of dry matter content with difference that the protein content of colostrum of beef cattle breeds was higher than that of the dairy breeds between the 2(nd) and 4(th) days, too . On the first and the second days the fat content of colostrum of the suck lers decreased which was related to the higher dilution in beef cattle bree ds. The sugar content of colostrum of the beef cattle breeds has increased between the calving and the 4(th) day post partum, and reached the values c haracteristic to the normal milk - (4.8-5.0%) - on the 5(th) - 6(th) day. T here was not significant difference between the beef and the dairy breeds, neither in sugar nor in the ash content. The ash content of colostrum reach ed the values characteristic to the normal milk, 7-8 days after calving. The whey protein and the non protein nitrogen content of colostrum of the b eef cattle breeds were higher than that of the dairy breeds, significantly. Decreasing of these fractions in the beef cattle breeds were more moderate than the dairy breeds as in case of the total protein content, according t o time. Our calculations show that whey protein content of the beef cattle breeds reached that values which were characteristic to the normal milk, af ter the 5(th) day post partum. Not having found a decided difference in the casein content of colostrum between the beef and the dairy breeds. The cas ein content of colostrum of blonde d' Aquitaine and Limousin higher than th at of the other kind of beef cattle breeds, which manifests itself in the r atio of whey protein and casein, too. At the same time the ratio of whey pr otein and casein in both Angus types differ from the other beef cattle bree ds in favour of the whey protein. The calculated immunglobulin-G values of colostrum milked immediately after calving were usually much higher at sucklers than at the dairy breeds. Thi s was true especially between the 1(st) and the 4(th) days which was connec ted with the more moderate decrease of IgG fraction in the beef cattle bree ds. Similarly the data of the literature the IgG content of the fresh milke d colostrum was determined primarily by the breed. According to our examina tions this determination becomes more unimportant moving off the time of ca lving. The energy content of colostrum at Black Angus and Red Angus rose among the other kind of beef cattle breeds. The average energy content of the colost rum of blonde d' Aquitaine and Limousin was connected with the high protein content of their colostrum. The energy content of colostrum of Hungarian S immental was the lowest.