Ocorrência do leite instável não ácido em vacas da raça Gir leiteiro

Abstract

The objective of the study was to investigate the occurrence of unstable nonacid milk (UNAM) in gir dairy cows. The research was conducted on the experimental farm of the Agricultural Research Company of RN. A total of 60 individual milk samples were obtained from 13 cows, at morning milking, from July to September 2022. Cup tests and California Mastitis Test (CMT) were performed to exclude cows with mastites. The milk samples werw subjected to composition analyzes (fat, protein, lactose, non-fat solids and total solids) ,somatic cell count (SCC), density, titratable acidity (TA), pH and alcohol test (AT) 72°, 74° and 78°. The data were subjected to analysis of variance, while the means were compared using the Tukey and Duncan test at 5% significance. The samples were group into normal milk (13,34%), acidic milk (78,33%) and UNAM (8,33%). UNAM was the smallest part of the 48,33% of AT positive samples. Only TA differed (P<0.001) between normal milk (TA ≥14≤18°D e AT Negativo) and UNAM (TA ≥14≤18°D e AT Positivo) in relation to acid milk (TA >18°D e AT Negativo ou Positivo). UNAM had clotting at graduations 74°(37.5%) and 78°(62.5%), UNAM did not occur at the lowest graduation used of 72°. Therefore, the occurrence of unstable non-acidic milk (UNAM) in dairy cows was low. The acidity results were high in individual milk, Which may have been caused by the natural acidity, lactation stage and/or breed of the animal. Future research is suggested to understand the factors that influence the occurrence of UNAM and its impact on dairy zebu breeds.