Effect of leptin genetic polymorphism on lameness prevalence in Tunisian Holstein cows

Abstract

Lameness is the third most important infection affecting dairy cattle in modern stabling barns. Environmental (food, stables and injuries) and genetic factors are responsible for this pathology. This study aims to investigate the screening of leptin genetic polymorphism and its effect on lameness prevalence. DNA was extracted from 412 blood samples from Holstein cows (lame and healthy). Genotyping was performed by the PCR-RFLP using the Sau3AI restriction enzyme. Prevalence of parity, calving season, age at calving, test-day milk yields, calving year and leptin/Sau3AI genotype was evaluated by the logistics procedure. Results showed that allelic frequencies are 0.68 and 0.32 respectively for the A and B allele. Frequencies for the AA, AB and BB genotypes are 0.52, 032 and 0.16 respectively. All factors included in the logistic regression model significantly affect the prevalence of lameness in Holstein cows (P<0.01). The probability of lameness incidence varied between 37 % and 99 % respectively for the second and the third parity. The lameness incidence recorded in multiparous is higher than primiparous cows. This recorded incidence is greater in winter and autumn than in the summer and spring. The genetic polymorphism affects the prevalence of lameness in Holstein cows. The incidence of lameness in AB genotype is lower than that in BB and AA genotype. These results can be a way to improve length of productive life for cattle breeds in Tunisia.