Effect in the milk production and post-partum performance on the physicochemical composition of cow milk from Zebu breeds

Abstract

This study aims to evaluate the influence of the milk production and parturiation order on the physicochemical composition of milk from Zebu breeds. The milk samples were collected during the Zebu Breed Milk Tournament of the 46th Agricultural Exhibition in Parnamirim, state of Rio Grande do Norte, and subsequently analyzed. The sampling of milk for the analysis was performed during the three days of the tournament. All samples were stocked individually in sterilized plastic flasks. Each flask was analyzed the composition (fat, protein, lactose, total solids, defatted dry extract), ureic nitrogen and somatic cell count. To analyze the database, the cows were divided into three different groups according to their average production level during the three days of the tournament. This analysis was done using the SAS Statistical Software. There was not significant difference (P>0.05) between the average fat and somatic cell count among the groups. The milk average levels of protein and lactose of group I were significantly smaller (P<0.05) than the ones of groups II and III. Fat concentration, protein, lactose, total solids, somatic cells and ureic nitrogen were positively correlated to daily milk production and paturiation order. The parturiation order presented the highest positive correlation (r=0.2245) when compared to milk production, while ureic nitrogen exhibits the highest correlation with parturiation order (r=0.4981). Parturiation order and daily milk production affect physicochemical composition of milk. Key-words: physicochemical characteristics, somatic cell count, raw milk