Forty-four crossbred primiparous cows participated in this study, namely: 15 1/2 animals corresponding to 1/2 Holstein (HO) x 1/2 Gyr; 15 3/4 animals corresponding to (3/4 HO x 1/4 Gyr) and 14 7/8 animals corresponding to (7/8 HO x 1/8 Gyr) raised under similar handling and feeding conditions. The sample collection was carried out between January and March 2013. To compare the quality of milk among breeds genetic compositions, the study was set up in a completely randomized design. Data of variables fat, protein, lactose contents, fat free dry matter (DDE), urea, somatic cell count, electrical conductivity, pH, titratable acidity and production were submitted to analysis of variance using the Tukey test at 5% probability for comparison of means between treatment 1 (1/2 HO x 1/2 Gyr), treatment 2 (3/4 HO x 1/4 Gyr) and treatment 3 (7/8 HO x 1/8 Gyr). Statistical analyses were performed using the SISVAR® - UFLA software. Correlation analysis between variables was performed using the ASSISTAT software. The results demonstrate that the genetic makeup of the different races holstein / Gyr primiparous cows did not affect the quality of the milk produced. The values ​​of the chemical constituents of milk have been considered suitable for human consumption. Titratable acidity and milk production were higher for 3/4 Holstein/Gyr animals.

 

Key words: Protein, electrical conductivity, titratable acidity, Holstein, Gyr.