Weight gain is a key performance trait for beef cattle; however, attention should be given to the production costs for better profitability. Therefore, a feed efficiency trait based on performance can be an interesting approach to improve performance without increasing food costs. To identify candidate genes and genomic regions associated with residual body weight gain (RWG), we conducted a genome-wide association study (GWAS) with 720 Nellore cattle using the GRAMMAR-Gamma association test.
We evaluated the adenine nucleotide translocator (ANT) and cytochrome oxidase subunit III (COX III) mRNA expressions in the muscle and liver of Japanese quails presenting high and low feed efficiency (FE), and subjected them to three different environmental temperatures: comfort, heat stress (38°C), and cold stress (10°C). ANT mRNA expression was lower in the liver of heat-stressed animals. In the muscle, higher ANT and COX III mRNA expressions were observed in high-FE and cold-stressed animals.
Selection for the wide range of traits for which most beef breed associations calculate expected progeny differences focus on increasing the outputs of the production system, thereby increasing the genetic potential of cattle for reproductive rates, weights, growth rates, and end-product yield. Feed costs, however, represent a large proportion of the variable cost of beef production and genetic improvement programs for reducing input costs should include traits related to feed utilization.