Body conformation traits assessed based on visual scores are widely used in Zebu cattle breeding programs. The aim of this study was to identify genomic regions and biological pathways associated with body conformation (CONF), finishing precocity (PREC), and muscling (MUSC) in Nellore cattle. The measurements based on visual scores were collected in 20,807 animals raised in pasture-based systems in Brazil. In addition, 2775 animals were genotyped using a 35 K SNP chip, which contained 31,737 single nucleotide polymorphisms after quality control. Single-step GWAS was performed using the BLUPF90 software while candidate genes were identified based on the Ensembl Genes 69. PANTHER and REVIGO platforms were used to identify key biological pathways and STRING to create gene networks. Novel candidate genes were revealed associated with CONF, including ALDH9A1, RXRG, RAB2A, and CYP7A1, involved in lipid metabolism. The genes associated with PREC were ELOVL5, PID1, DNER, TRIP12, and PLCB4, which are related to the synthesis of long-chain fatty acids, lipid metabolism, and muscle differentiation. For MUSC, the most important genes associated with muscle development were SEMA6A, TIAM2, UNC5A, and UIMC1. The polymorphisms identified in this study can be incorporated in commercial genotyping panels to improve the accuracy of genomic evaluations for visual scores in beef cattle.

The objective of this work was to evaluate the influence of environmental factors on the lactation curve parameters and milk yield of Holstein cows. Data on lactations conducted from 2010 to 2019 in the state of Paraná, Brazil, obtained from the official dairy control service, were used. The parameters of the lactation curves were estimated using the Wood model and NLIN procedure of the SAS software. The influence of the environmental factors lactation order and calving region and season on the parameters of the lactation curves and on milk yield was evaluated using the MIXED procedure of SAS. First-lactation cows reached peak lactation later and showed a more persistent lactation. Milk yield increased with lactation order. The highest lactation peaks occurred in lactations started in winter and in fall, at 305 days. Cows raised in the center-east region of the state of Paraná had the highest milk yield at the peak and at 305 days of lactation. Lactation order and calving region and season influence the shape of the lactation curve of Holstein cows, with an increase in milk yield when lactation cycles begin in winter-spring.