Animal performance and carcass characteristics of Nellore young bulls fed coated or uncoated urea slaughtered at different weights

Abstract

-The objective of this study was to evaluate animal performance and carcass characteristics of 64 Nellore young bulls at 22 months of age finished in a feedlot and slaughtered at five body weights (350; 455; 485; 555 and 580 kg) fed diets containing coated or uncoated urea. The experimental design adopted was completely randomized, set in a 4 × 2 factorial arrangement, and for the variables assessed in the control animals, it was 5 × 2. No effect of interaction between slaughter weights and diets were observed, so the variables were analyzed separately, compared by polynomial contrasts and by the F test, respectively. The time animals remained in the feedlot to reach slaughter weights was 66, 88, 145 and 194 days. Average daily gain (ADG) showed quadratic behavior, with a maximum of 1.44 kg/day with animals of 491.7 kg. Dry matter intake (DMI) (kg/day) was similar in all the treatments, but it decreased linearly as body weight increased. The bionutritional efficiency worsened linearly as body weight rose. The elevation in slaughter weight resulted in linear decrease in the percentage of beef round and increase in forequarter. Backfat thickness and rib eye area of the longissimus increased linearly and the percentages of muscle and protein in the carcass reduced and those of fat and ether extract increased linearly as body weight increased. Average daily gain, DMI, feed efficiency and carcass characteristics were not affected by diets containing coated or uncoated urea. However, animals fed coated urea presenter better crude fiber and neutral detergent fiber intake.

Boneless yield of carcass of feedlot-finished young Bos indicus L. bulls

“…Likewise, absolute weights of trimmed primal cuts from the pistola hindquarter of the right 1/2 carcass increased linearly with slaughter weight, as a consequence of the greater muscle growth and deposition of adipose tissue in the carcass, as observed in the work of Pazdiora et al (2013). These results are similar to those found by Pascoal et al (2010), who attributed them to a better conformation and to an increase in carcass weight and fat deposition.…”

“…Likewise, no significant effect of coated-urea addition was detected on the weight and yield of primal meat cuts, bones, and trimmings. These results may be attributed to similar slaughter weights (518.0 kg), carcass weight (278.1 kg), fat thickness (4.47 mm), and physical composition of animal carcasses (muscle 58.2 %, fat 25.8 %, and bone 15.8 %) (Pazdiora, Resende, Faria, Siqueira, Almeida, Sampaio... & Prietto, 2013).…”

“…Authors as Pazdiora et al (2013) for example found greater representativeness of the forequarter as the slaughter weight of the animals increased, which might have been a result of the sexual dimorphism of uncastrated animals, where a more accelerated muscle development of the forequarter is observed in comparison with the pistola hindquarter. However, Pascoal et al (2010) found no differences for percentage of forequarter cuts relative to carcass weight in Braford cattle slaughtered with a carcass weight of 184, 205, and 229 kg.…”

“…Knuckle, topside, tenderloin, flank steak, rump, topside, and shin had their percentages decreased as body weight increased, and this response contributed to the linear reduction of the sum of all trimmed cuts from the pistola hindquarter relative to the weight of the cold right 1/2 carcass, likely due to the decreasing representativeness of the pistola hindquarter as slaughter weight of the animal increases (Pazdiora et al, 2013). This might have been due to sexual dimorphism of uncastrated animals, as mentioned previously.…”

Performance of crossbred steers post-weaned in an integrated crop-livestock system and finished in a feedlot

“…Carcass yield may be affected by several factors, such as weight of the gastrointestinal content, type of diet, age and weight at slaughter, degree of finishing, breeds, and crossings (Patterson et al, 1995). The weight at slaughter also interferes directly in the carcass yield because heavier animals show greater fat deposition, and, consequently, they have a higher yield (Pazdiora et al, 2013). British breeds and their crosses have a higher fat deposition and higher carcass yield than continental breeds, mainly due to the higher amount of fat in the carcass (Patterson et al, 1995).…”