Abstract

This study aimed to evaluate the chemical composition and somatic cells count (SCC) of milk from Holstein / Braunvieh (HB) cows of five different grade crossing (genetic groups): Seven ½ blood HB, 14 5/8 blood HB, 16 3/4 blood HB, 86 7/8 blood HB and 28 15/16 blood HB cows were used. Six samplings at seven-day intervals were performed. The quality of milk was assessed according to the fat, protein, lactose and defatted dry solids (DDE), urea and casein levels and somatic cells count. There was no significant difference (P>0.05) in fat content of milk among blood levels; however, the other nutrients in milk differed (P<0.05) among blood levels studied (lactose, DDE, protein, casein, urea). SCC was higher in milk produced by cows of 3/4 blood HB genetic composition. Variations in milk production among genetic groups were also verified, with 1/2 blood HB animals being more productive compared to other genetic compositions. Correlation of genetic composition, production volume, days in lactation, number of deliveries and SCC with the chemical components of milk was found. A positive correlation between genetic composition and DDE and negative with production volume and number of deliveries was found and the SCC value of 13.41% was above the recommended by Brazilian legislation for milk quality.

Key words: Casein, fat, genetics, mastitis, urea.