association of kappa-casein gene polymorphism with some biochemical blood indicators in guilan native cattle of iran (bos indicus)

evaluation of the blood and milk biochemical parameters always is considered as effective key factor for animal health and dairy products. in order to assess the association of kappa-casein (k-cn) genetic variants with blood biochemical indicators, blood samples were randomly and individually collected from 126 iranian guilan native cattle. blood plasma was used to measure blood glucose, urea, cholesterol, triglycerides and thyroxine concentrations. the genomic dna was extracted from the whole blood by the modified salting out method. the 350 bp fragment of kappa-casein gene was amplified using polymerase chain reaction restriction fragment length polymorphism (pcr-rflp) and a pair of specific primers was digested by hinfi restriction enzyme. in general, two alleles of a and b with the frequencies of 0.726 and 0.274 and two genotypes of aa and ab with frequencies of 0.452 and 0.548 were detected, respectively. the chi-square test result showed that the studied population was not in hardy-weinberg equilibrium. results of statistical analysis revealed that there was significant difference between glucose, cholesterol and thyroxin levels in both sexes which are associated with the greater levels of testosterone and thyroid hormones in bulls than cows. however, there was no significant difference between males and females for urea and triglyceride levels (p>0.05). there was no significant difference between aa and ab genotypes of kappa-casein (k-cn) gene in guilan native cattle for the blood parameters measured (p>0.05). according to the current results, kappa casein gene singly cannot be an appropriate marker to study the blood parameters in native cattle of guilan.