Calf's sex, parity and the hour of harvest after calving affect colostrum quality of dairy cows grazing under high tropical conditions.

High-quality colostrum is an important factor influencing neonatal calf health, and quality assessment is essential to obtain good health results. This research evaluated the effects of the calf's sex, the parity of the cow and the hour of colostrum harvest after parity on the fat, nonfat solids, protein and Ig contents in Holstein colostrum for cows under high grazing conditions in the tropics. The effects of the calf's sex and parity on somatic cell count (SCC) at the first milking postpartum were determined. A comparison was made between a laboratory method and a farm method for the estimation of the fat and protein content of colostrum. Thirty-three cows were sampled in the study. The calf's sex was shown to have an effect on the amount of colostrum, on the concentration of fat, and on the amount of milk produced by lactating Holstein cows; all were higher in cows that gave birth to a female calf. Colostrum protein decreased after the first hour postpartum, and the Ig concentration had a tendency to decrease after 4 h. The cows that had parity 1-2 had lower Ig concentrations and total production of Igs, and higher SCC at the first milking postpartum. Ekomilk was a reliable method to measure the colostrum fat on the farm.