Relación entre polimorfismos genéticos intragénicos y características de producción de leche y fertilidad en vacas Holstein Fresian

Abstract

The positive effect of the administration of growth hormone (GH) on milk production and the presence in selected dairy cattle lines of higher prolatin (PRL), thyrotropin (TSH) and GH concentrations, prompted an examination of the presence of restriction fragment lengh polymorphism (RFLP) in the GH factor-1/pituitary-specife transcription factor Pit-1 gene uring the enzyme Hinfl and to indestigate association between this polymorphism with milk production and reproduction records (measured as lactating days, days open, calving Interval and number of inseminations required to conception) using a small sample as a preliminary análisis. Mil kwas sampled from 46 Holstein-Fresian cows. A strategy employing polymerase chain reaction (PCR) was used to amplify a 451-bp fragment from milk and hair DNA simples.Digestion of PCR products with Hinfl revealed two alleles: allele A was not digested (451-bp fragment), and allele B was cut at one restriction site, generating two fragments of 244 and 207 bp, this fragments seems to be identical to other studies using semen DNA simples. Three genotype were obseeved; frequencies were 10.8.35.2 and 55% for AA, AB and BB respectively which seems to be different from others studies. Two models were used to test for the association with production and reproduction traits, one using EBV and other using YD as dependent variables. The genotype were included as a fixed effect in two models either. The presence of A allele was found to be superior for milk production and inferior for reproduction traits in both models.The implications of adverse effects of this allele, the posible metabolic path way of the products of this gene, and the differences between the two models used, was discussed.