Bovine Milk Orotate: Differences between Cows and Changes during Lactation

Abstract

Orotate in the morning milk of 250 cows from 5 dairy breeds averaged 81.1 .mu.g/ml but exhibited large variability as indicated by a SD of 48.6 and a range from 19-664 .mu.g/ml. Much of this variability in milk orotate is probably due to variation between individual cows. Some variation was due to breed, number of lactations and stage of lactation. Jersey and Guernsey cows produced milk with lower orotate than Ayrshire, Brown Swiss or Holstein cows. Cows with more lactations had lower orotate concentrations. Stage of lactation affected orotate concentration; this was reverified by periodic monitoring in individual cows at various stages of lactation. Orotate in 1st-drawn colostrum averaged 13.2 and 5.8 .mu.g/ml for 7 uniparous and 8 multiparous Holstein cows. Within 2 wk these animals had increased to 60 .mu.g/ml with uniparous animals rising more rapidly. For 8 other Holstein cows monitored biweekly from 2 to 44 wk of lactation, orotate rose to 76 .mu.g/ml by wk 10 and remained fairly constant through wk 38. The cow with the highest concentration of milk orotate produced milk with 4-10 times more orotate than these 8 animals at all stages of lactation; the average from 10 through 38 wk was 558 .mu.g orotate/ml and a sample approached 800. During the dry period, orotate concentration in lacteal secretions decreased to that in 1st-drawn colostrum.