The association between single-strand conformation polymorphism (SSCP) in the gene of insulin-like growth factor-I receptor (IGF-IR) and age at first calving (AFC), calving interval (CI), lactation length (LL), and milk yield (MY) was studied using 106 graded Holstein females. The polimerase chain reaction (PCR) with specific initiating oligonucleotides, resulted an amplified fragment of 335pb. The population genotypes frequencies were 82.1% and 17.9%, for AA and AB genotypes, respectively. The frequency of A allele was 0.91 and 0.09 of B allele. No association between the identified polymorphism and AFC, CI, and MY was observed. The LL was positively associated (P<0.05) with the absence of B allele. Animals carrying the AA genotype presented a longer lactation period.
beef cattle; reproductive efficiency; post-calving; candidate gene
