COMPOSITION, PHYSICAL AND TECHNOLOGICAL PROPERTIES OF RAW MILK AS AFFECTED BY CATTLE BREED, SEASON AND TYPE OF DIET

The aim of the study was to describe the differences in composition, physical and technological properties of raw milk as affected by breed of cattle, season and type of feeding. The study was conducted from June 2005 to February 2007 on bulk milk samples (BMS) collected from 8 commercial dairy herds consisting of Czech Fleckvieh (CF, 4 herds) and Holstein (H, 4 herds) dairy cows. Half of herds in each breed was grazing (G) during summer season while the other half was not (N). Samples were collected regularly two times in winter (W) and two times in summer (S) period resulting in a total of 64 bulk milk samples (BMS) examined. Milk yield in CF (5385.50 kg) was lower (P<0.05) than in H (7015.15 kg). Milk fat in CF was higher (P<0.05) than in H breed being 3.9 and 3.72 g/100 g, respectively. CF cows had higher (P<0.05) content of crude protein, casein, true protein and non-protein nitrogen (NPN) than H. Content of fat, crude protein, casein, true protein and whey protein was lower (P<0.05) in summer (S) than in winter (W). Milk yield in grazing herds (G, 5197.50 kg) was lower (P<0.05) than in non-grazing herds (N, 7203.75 kg). Content of fat was higher (P<0.05) in G (3.89 g/100 g) than in N (3.73 g/100 g). Concentration of lactose, urea, crude protein, casein, true protein, whey protein was lower (P<0.05) in G than in N. In conclusion, the Czech Fleckvieh breed had a lower milk yield but produced milk with higher concentration of the main milk components than the Czech population of the Holstein breed. Large seasonal variations were determined in concentrations of the main milk components. The most pronounced changes in milk composition were caused by the type of feeding with a clear decrease in milk yield and content of lactose and all studied protein fractions and higher content of fat in grazing herds compared to non-grazing herds.