Association between the polymorphism of bovine beta 4-defensin gene and milk traits in Holstein-Friesian cows as computed for standard (305 days) and the whole lactation

摘要

Associations were studied between the polymorphic forms of bovine beta 4-defensin gene and milk traits in cows during the standard (305 days) and the whole lactation. The study was carried out in the years 2004-2007 on 207 Holstein-Friesian cows yielding on the average 9600 kg milk/year. The animals were in their first to fifth lactation, maintained in loose barn and fed ad libitum with TMR (total mixed ration) composed of maize silage, wilted grass silage and concentrates supplemented with minerals and vitamins. The diets were formulated according to the INRA standards. Milk production data were collected from the individual cows' records during their consecutive lactations. The RFLP-NlaIII method was used to identify the polymorphic forms of beta 4-defensin gene (C and T). A total of 616 records of standard and 837 of the whole lactation for milk, milk fat and milk protein yield and fat and protein content of milk were statistically evaluated using one-trait repeatability animal model with DMU package.The cows of CC genotype yielded more milk than cows of genotype CT during both the standard (+181 kg, P <= 0.05) and the whole lactation (+241 kg, P <= 0.05). The CT cows produced milk with higher protein content (P <= 0.01 and P <= 0.05 for standard and whole lactation, respectively), but the protein yield did not differ significantly between the two genotypes in question. Moreover, no significant differences were identified in fat content of milk between the CC and CT genotype, but the fat yield was higher (P <= 0.05) in homozygous CC cows.