engleski

Effects of the β-lactoglobulin genotype on milk production parameters of Jezeropivska sheep breed

Effects of β-lactoglobulin (β-Lg) genotypes on milk traits (duration of lactation and milk yield) and milk composition (content of fat, protein, lactose and solids nonfat - SNF) of a Montenegrin autochthonous sheep breed were studied. The study was carried out on 44 ewes of Jezeropivska sheep breed. This is the most numerous autochthonous breed of sheep in Montenegro, which is traditionally raised in mountain area of Durmitor and Sinjajevina, and partly in the central part of the country. According to the recent investigations, genetic polymorphisms in β-Lg, a major whey protein in milk of ruminants, are closely related with milk production parameters and technological properties. Polymorphisms within ovine β-Lg gene were detected using PCR-RFLP method - RsaI restriction endonuclease. Two genetic variants (A and B) and three genotypes (AA, AB and BB) of β-Lg were identified. The analysis showed a prevalence of strong A allele (0.63) compared to the weak B allele (0.38), while the frequencies of genotypes were 0.364, 0.523 and 0.113 respectively. Milk yield and milk composition parameters were obtained by using the standard procedures of milk recording during lactation. There were no statistically significant differences in duration of lactation and total milk yield between these three genotypes, while daily milk yield was significantly influenced (p<0.05) by genotypes. Study showed that variant B of β-Lg was linked with higher milk production. Daily milk yield was the highest (0.70 kg) in ewes of BB genotype β-lactoglobulin than AB (0.60 kg) and AA (0.54 kg) genotype. The effect of genotype of β-Lg on protein and lactose content were significant (p<0.05), while it is not significantly influenced fat and solid non-fat content. In Jezeropivska sheep breed genotype AA was linked with the higher protein content (5.86%). The protein content in the milk of AB and BB genotype was the same (5.64%). Significant association between AB genotype of β-lactoglobulin gene with higher lactose content (4.67%) was found. The results presented in this study could be useful in improvement of the concept of conservation and sustainable use of this autochthonous sheep breed, while gene of β-Lg as a potential marker in improving milk traits of sheep.

Jezeropivska sheep ; milk yield ; milk composition ; β-lactoglobulin ; genotype

nije evidentirano