Evaluation of milk productivity and milk quality of goats of different genotypes depending on the number of lactations

Abstract

The results of assessing the dynamics of milk productivity of goats of different genotypes depending on the number of lactations in 305 days are presented. The level of average monthly milk yields was studied. Four groups of Saanen and Nubian breed goats of 10 animals each were formed for the experiment. Starting from the 1st month of lactation in all groups, milk yield increased continuously until the 4th month, and then went down by the end of lactation. The maximum average monthly milk yields were in the 2nd-4th months of lactation in all four groups of female goats. Average monthly milk yields were highest for goats of all genotypes and lactations in the 4th month. Saanen goats dominated over Nubian goats in the first lactation by 14.43 kg, or 15.96%, in the third by 4.23 kg, or 4.48%. The parameters of physicochemical and microbiological composition of the milk of Saanen and Nubian goats of different lactation numbers were studied. The content of the main milk nutrients: protein, fat and milk sugar, as well as minerals is higher in the Nubian goat breed in both lactations. The density and acidity of goat milk were in accordance with the GOST (All Union State standard). The freezing point of goat milk samples of both breeds and lactations ranged from 0.50-0.57 °C. The somatic cell content in the milk of goats of both genotypes ranged from 128 to 1500 thousand/cm3 and conformed to the standards. Bacterial contamination of milk of the goats of both breeds and lactations did not exceed permissible sanitary standards.