Visual body-scores selection and its influence on body size and ultrasound carcass traits in Nellore cattle1

Abstract

Genetic parameters, genetic trends, and genetic progress of carcass traits were estimated for 12,447 Nellore individuals from different Brazilian herds. The following carcass traits were analyzed: visual body scores of conformation (CONF), precocity (PREC), and muscularity (MUSC); rump width (RW) and rump length (RL), body size (frame); and ultrasound evaluation of ribeye area (REA), backfat thickness (BFT), and rump fat thickness (RFT). Heritability estimates (± SE) for CONF, PREC, and MUSC were 0.23 ± 0.02, 0.33 ± 0.03, and 0.31 ± 0.02, respectively. The heritability estimates (± SE) for RW, RL, and frame were 0.25 ± 0.05, 0.16 ± 0.04, and 0.31 ± 0.03, respectively. Ultrasound of the REA, BFT, and RFT presented mean heritability estimates (± SE) of 0.38 ± 0.03, 0.44 ± 0.04, and 0.47 ± 0.04, respectively. The visual body score of CONF had high genetic correlations with RW, RL, and frame (0.74 ± 0.09, 0.82 ± 0.08, and 0.83 ± 0.04, respectively), indicating a high association of CONF with the measurements related to body structure. The REA had no correlation with BFT and RFT (-0.09 ± 0.04 and -0.03 ± 0.04, respectively) and showed only a moderate genetic correlation with MUSC (0.39 ± 0.05). The BFT and RFT had moderate genetic correlations with PREC (0.36 ± 0.07 and 0.29 ± 0.07, respectively) and no correlation with frame (-0.02 ± 0.03 and 0.05 ± 0.05, respectively), suggesting that selection for frame had no effect on the subcutaneous fat content of the carcass. Low genetic trends and low genetic progress were obtained for REA (0.026 cm, 0.02%), BFT (0.0031 mm, 0.05%), and RFT (0.0013 mm, 0.02%), with no significant values of genetic progress detected throughout the studied period. The CONF, PREC, and MUSC presented high genetic trends (0.030 points, 0.030 points, and 0.029 points, respectively) and high genetic progress (0.60%, 0.56%, and 0.59%, respectively), indicating a significant genetic progress for these traits throughout the evaluated period. Carcass traits evaluated by ultrasound and visual body scores are eligible for selection and can be used in genetic improvement programs in Nellore cattle; however, visual body score selection for carcass traits can result in slower genetic progress for carcass quality when compared to selection performed by ultrasound.

Gene co-expression networks associated with carcass traits reveal new pathways for muscle and fat deposition in Nelore cattle

“…Studies involving Bos indicus animals have shown a lower propensity for subcutaneous fat deposition and Longissimus muscle area when compared to Bos taurus breeds [2, 3]. Compared to other Nelore studies, our phenotypic values for REA (mean value = 59.75 cm 2 ) can be considered on the average, taking into account that studies in Nelore cattle show amounts varying from 40 to 100 cm 2 [1, 2, 20, 21]. On the other hand, the BFT phenotypic values (mean value = 7.00 mm) were higher than that found in the literature for Nelore, with mean values ranging from 1.93 to 4.84 mm and, even higher than presented in some Bos indicus x Bos taurus crossbreed studies [1, 3, 20–22].…”

Non-invasive methods for the determination of body and carcass composition in livestock: dual-energy X-ray absorptiometry, computed tomography, magnetic resonance imaging and ultrasound: invited review

“…, 2010 ), and, for example, in Angus cattle (Ravagnolo et al , 2010), Nelore cattle (Bonin et al. , 2010 ) or Angus–Brahman crossbred cattle (Elzo et al , 2010 ).…”

“…Expectedly, real-time US data of muscle depth in sheep or breast muscle thickness in broilers showed medium-to-high direct heritability estimates between 0.2 and 0.51 (Jones et al , 2004, Wolf and Jones, 2007; Grosso et al , 2010 , Maximini et al , 2012 ; Table 4 ), whereas heritability estimates – depending on age – varied in a similar range between 0.31 and 0.42 for loin muscle (or rib eye) area (between 12 th and 13 th ribs) in Bos indicus (Bonin et al , 2010 ; Pinheiro et al , 2011 ), Angus–Brahman (Elzo et al , 2010 ) and multi-breed beef cattle (Jeyaruban and Johnston, 2014 ). Heritability estimates for back fat thickness (between 12 th and 13 th ribs) showed slightly lower values ranging from 0.06 to 0.32 (Bonin et al , 2010 ; Elzo et al , 2010 ; Pinheiro et al , 2011 ) as well as for rump fat thickness with values from 0.26 to 0.29 (alone Pinheiro et al , 2011 ). The advantage of US scanning can be concluded from the above references.…”

Genome‐wide association study and pathway analysis for fat deposition traits in nellore cattle raised in pasture–based systems

“…Alternatively, ultrasound techniques can be used to measure carcass traits in live animals, such as BFT (Grigoletto et al, 2020;Santana et al, 2015). In addition to enabling data collection at an early age, this technique minimizes costs, facilitates measurement protocols and is highly genetic correlated (>0.85) with traits measured in slaughter plants, and therefore, useful indicators to be used in breeding programs (BONIN et al, 2015;Greiner et al, 2003). Grigoletto et al (2020) have identified important candidate genes associated with ultrasound-based BFT and RFT in Montana Tropical Composite cattle.…”