Genetic correlations among indicator traits for carcass composition measured in yearling beef bulls and finished feedlot steers

Abstract

among indicator traits for carcass composition measured in yearling beef bulls and finished feedlot steers. Can. J. Anim. Sci. 85: 463-473. Genetic correlations were examined among 10 live growth and ultrasound traits measured in yearling beef bulls (n = 2172) and four carcass traits measured in crossbred finished feedlot steers (n = 1031). Heritabilities ranged from 0.13 (bull ultrasound longissimus muscle width) to 0.83 (yearling bull hip height). Genetic correlations indicated that selecting yearling bulls for increased growth rate and hip height would lead to higher carcass weight, increased longissimus muscle area and reduced levels of carcass marbling in steers. Bull ultrasound fat depth was positively associated with both carcass fat depth and marbling score. Most ultrasound longissimus muscle size measurements in bulls were positively associated with each other and with carcass longissimus muscle area in steers, but the magnitude of the genetic correlation with carcass measurements depended on the bull longissimus muscle size trait in question. This suggests that longissimus muscle shape in bulls may be related to carcass weight, fat and muscle traits in steers. Results confirm that while ultrasound is a valuable tool for the genetic improvement of carcass traits in beef cattle, genetic correlations between live bull ultrasound and steer carcass traits less then unity suggest that selection would benefit from multiple trait evaluations in situations where reliable carcass data are available. Les corrélations génétiques indiquent qu'en sélectionnant les bouvillons d'un an d'après un taux de croissance plus rapide et la hauteur aux hanches, on obtiendrait des carcasses plus lourdes, un longissimus d'une plus grande superficie et de la viande moins persillée. L'épaisseur du gras des bovins mesurée aux ultrasons présente une corrélation positive avec l'épaisseur du gras de la carcasse et le persillé. La plupart des mesures du longissimus obtenues aux ultrasons chez les bovins sont positivement corrélées les unes aux autres ainsi qu'avec la superficie de ce muscle dans la carcasse des bouvillons, mais l'importance de la corrélation génétique avec les mesures de la carcasse dépend du paramètre concerné des dimensions du longissimus chez l'animal adulte. On en déduit que la forme du muscle chez les bovins adultes pourrait dépendre de caractères régissant le poids de la carcasse, le gras et les muscles chez les bouvillons. Les résultats confirment que si l'analyse aux ultrasons a son utilité pour parvenir à une amélioration génétique des paramètres de la carcasse chez les bovins de boucherie, quand les corrélations génétiques entre les mesures prises sur l'animal vivant aux ultrasons et les paramètres de la carcasse des bouvillons ont une valeur inférieure à l'unité, la sélection profiterait d'une évaluation multifactorielle dans l'éventualité où on possède des données fiables sur la carcasse.

Genetic associations between carcass traits measured by real-time ultrasound and scrotal circumference and growth traits in Nelore cattle1

“…When analyzing the genetic correlations between subcutaneous fat and height measured at different body locations, such as hump height or wither Ultrasound and carcass genetic parameters for Nelore height, Aass (1996) and Smith et al (2007) also found moderately negative genetic correlations of −0.29 and −0.20 between these traits, respectively. However, some authors (e.g., Waldner et al, 1992;Bergen et al, 2005) reported that the genetic correlation between HH and BF was close to zero (−0.07 and 0.01, respectively). Therefore, our results suggest that long-term selection for taller animals would tend to produce animals with less subcutaneous fat (i.e., later maturing in terms of carcass finishing).…”

Research Article Estimation of variance components for carcass and production traits in Guzerat cattle

“…Nevertheless, the Guzerat breed has made a great contribution to Brazilian cattle production, improving productivity, hardiness, precocity and meat quality (Junior et al, 2013). Traits such as rib-eye area, backfat and rump fat thickness, intramuscular fat percentage and visual score for finishing have been continuously assessed in breeding programs because they are related to meat quality, carcass yield and cutability, and organoleptic properties (Bergen et al, 2005;Neto et al, 2009;Junior et al, 2013;Cafe et al, 2018), while other traits such as dry matter intake, average daily gain, metabolic weight, residual feed intake and margin are related to production efficiency (Basarab et al, 2003;. Traditionally, genetic breeding programs in Brazil have only considered traits related to reproduction and adaptability; more recently these programs have included carcass characteristics, mainly in Nellore, with the aim to predict the genetic merit and expected progeny differences (Neto et al, 2009), but Guzerat has remained sidelined in this area.…”

Genome-Wide Association Study for Carcass Traits in an Experimental Nelore Cattle Population

“…The longissimus muscle area (LMA) is an efficient indicator of the carcass yield, carcass muscularity [3], carcass weight, fat and muscle traits in steers [4]. The subcutaneous fat covering over the longissimus muscle acts minimizing evaporative weight loss of the carcass in the cooler besides been an efficient carcass-finishing indicative [5].…”