Use of postpartum body condition score to identify the most fertile beef cows raised in extensive operations
The assessment of postpartum body condition score in beef cattle may be a useful tool to recommend technologies to improve reproductive efficiency based on nutrition and reproductive management. The variability and repeatability of body condition scores between 60-90 d postpartum were investigated in order to verify the possibility that such assessments could indicate the inheritance of fertility in beef cows. In three consecutive years a total of 3721 cows predominantly Hereford purebreds and crossbreds, kept on natural pastures in seven farms in the southern region of Rio Grande do Sul, Brazil, were evaluated. More than 60% of these cows had intermediate to superior body condition score (scale of five classes), varying significantly among farms and years studied. A low repeatability of scores in the same animal in two or three consecutive years was found, refuting the possibility of direct selection for higher fertility as a function of body condition score. Although the scoring system does not define fertility phenotypes, it allows the identification of the one in every 200 cows with the characteristic of being pregnant and maintaining high body condition scores during three consecutive years, which may serve as base animals for future genome association studies employing single nucleotide polymorphisms.