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.