Impact of Mutations in PRLR on Hair Weight, Prolactin Levels, Feed Intake, and Growth in Beef Cattle in Hot, Humid Climates

The study investigated the impact of mutations in the prolactin receptor gene (PRLR) on hair weight, growth, and feed efficiency in beef cattle raised in a hot, humid climate. The study involved 77 calves with different PRLR genotypes: 64 with slick mutations (SLICK), 6 wild-type (WT), and 7 with a large deletion (NULL). Results showed that SLICK calves had the least hair weight after 3 months and the highest average daily gain and body weight at the end of the trial, while NULL calves had the greatest hair weight and lowest growth metrics. SLICK calves also had higher residual feed intake, indicating lower efficiency, compared to WT and NULL. The study concluded that PRLR genotype significantly affects post-weaning growth, likely due to differences in hair growth and temperature regulation.