Feedlot performance, feed efficiency reranking, carcass traits, body composition, energy requirements, meat quality and calpain system activity in Nellore steers with low and high residual feed intake

Abstract

a b s t r a c tThe aim was to evaluate growth, carcass traits, feed efficiency reranking, body composition, calpain system activity and meat quality in Nellore steers that were phenotypically ranked for high and low residual feed intake (RFI). Seventy-two Nellore steers (16-21 month-old, 334719 kg BW) had free access to a feedlot diet for 70 d (feeding period 1, P1). Daily dry matter intake (DMI), body weight gain (ADG) and ultrasound carcass traits were measured individually. The 12 lowest and the 12 highest RFI steers were classed as low-and high-RFI groups and were fed for a second feeding period (feeding period 2, P2). Spearman's rank correlation was performed for RFI and gain-to-feed ratio (G:F) measured over P1 and P2. The carcass traits, meat quality and calpain system activity were evaluated at slaughter, and body composition was determined. In P1, low-RFI steers had greater G:F (0.159 vs. 0.134; Po0.001), lower DMI (9.30 vs. 11.1 kg/d; Po0.0001), lower RFI (À 0.80 vs. 0.85 kg/d; Po0.0001), and tended to have lower rates of rump fat gain (4.48 vs. 6.05 mm; P¼ 0.06), but no differences were observed for ADG, BW, and other traits measured by ultrasound (P40.05). In P2, no differences between RFI classes were observed for G:F and DMI as a percentage of BW (P40.05), and small differences were observed for DMI (8.25 vs. 8.99 kg/d, Po0.05) and RFI (À 0.28 vs. þ0.29 kg/d, P¼0.06). The ranking correlations for RFI and G:F measured consecutively in P1 and P2 were low to moderate (r¼ 0.11-0.40). Low-RFI steers had lower requirements of metabolizable energy (ME) for maintenance (131 vs. 160 Mcal/kg EBW 0.75 d À 1 , Po0.05), but no differences were observed for fat and protein gain, retained energy and efficiency of ME use for gain (P40.05). No differences between low-and high-RFI steers were observed for carcass traits at slaughter; however, low-RFI steers had 8.1 kg less gastrointestinal fat than high-RFI steers. There were no RFI effects on meat shear force and the activities of m-calpain, m-calpain and calpastatin (P40.05). High-RFI steers had greater MFI in 1 d aged LM (53.9 vs. 40.8, Po0.05). The variation in feed efficiency between high-and low-RFI Nellore steers is related to differences in energy requirements and deposition of fat on internal organs. The ranking for feed efficiency is altered as cattle become older. The selection for improved RFI in Nellore cattle may reduce feed requirements for beef production without affecting meat tenderness and enzymatic activity of the calpain system.

Visceral organ weights, digestion and carcass characteristics of beef bulls differing in residual feed intake offered a high concentrate diet

“…In the current study no effect of RFI on, or correlations with, carcass fat score were detected, which is supported by the absence of an effect of RFI on final ultrasonic subcutaneous fat depth. These findings agree with those of Gomes et al (2012) for carcass backfat in steers. However, Nkrumah et al (2004) and Basarab et al (2007) found that RFI had a significant positive correlation (r = 0.25, 0.22; respectively) with carcass fat grade.…”

“…Additionally, Bonilha et al (2009) found that low RFI bulls had 14% lighter kidneys than high RFI bulls, although this was not evident in the current study or in that of Basarab et al (2003). In contrast, Mader et al (2009) and Gomes et al (2012) using steers, found no effect of RFI on the weights of any of the visceral organs measured. More recently, Bonilha et al (2013) found no effect of RFI on weights of any visceral organs except kidney weight, where low RFI bulls had 12% lighter kidneys than high RFI bulls.…”

“…In the current study, RFI tended to be negatively correlated with kill-out proportion, whereas Mader et al (2009) found that RFI tended to be positively correlated (r = 0.28; P = 0.08) with dressing percentage. Despite these results, other studies have found that RFI was not correlated with dressing percentage (McDonagh et al, 2001;Gomes et al, 2012). Disparites in the effect of RFI on kill-out proportion between studies may arise from factors influencing kill-out proportion such as variation in level of gut fill due to differences in diet composition or duration of a pre-slaughter fast.…”

Desempenho, metabolismo e emissão de metano de bovinos Nelore em terminação recebendo óleos funcionais em substituição ou combinação com monensina sódica na dieta

“…Além disso, esse efeito pode ser atribuído ao maior consumo de matéria seca e energia pelos animais ineficientes, e o consumo alimentar além das exigências pode levar ao aumento na deposição de gordura interna. De acordo com Gomes et al (2012), animais eficientes apresentaram menor quantidade de gordura no trato gastrointestinal menor quantidade de gordura pélvica e inguinal. A gordura interna pode ser um importante componente na variação da eficiência em novilhos Nelore e que como a indústria não paga diretamente por esses componentes de carcaça, a redução da conversão alimentar para gordura visceral pode ser desejada (GOMES et al, 2012).…”

Melanina na pele e metabólitos da vitamina D3 no plasma associados com polimorfismos nos genes MC1R (loco Extension) e DBP influenciam maciez e cor de carne de bovinos Nelore sem efeito sobre cálcio plasmático e muscular

“…Médias e coeficientes de variação para as características de maciez e cor de carne nos diferentes tempos de maturação (Tabela 4) se encontraram próximas, com poucas exceções, àquelas observadas em outros trabalhos (Tabela 5) usando animais da raça Nelore, Tabapuã, Brahman e Brangus (CURI et al, 2010;GOMES et al, 2012;LOBO-JR. et al, 2012;MAZZUCCO et al, 2010;PFLANZER;FELICIO, 2011;PINTO et al, 2010PINTO et al, , 2011PRINGLE et al, 1997;RIBEIRO et al, 2012;RILEY et al, 2003;SHACKELFORD et al, 1991;SMITH et al, 2009 A maior média para MFI aos 14 dias de maturação neste trabalho (Tabela 4), quando as estruturas celulares da carne estão bem fragilizadas, poderia ser um resultado da velocidade e/ou do aparelho usado durante a homogeneização das amostras (HOPKINS et al, 2000(HOPKINS et al, , 2004. Médias menores para os valores de L* em todos os tempos e médias maiores para os valores de b* nos dias um (1) e sete (7) de maturação (Tabela 4) quando comparados aos outros trabalhos (Tabela 5) poderiam estar associadas com as diferenças de maturidade dos animais, espessura de gordura da carcaça, declínio de pH e temperatura da carcaça e composição físico-química do músculo (FIEMS et al, 2000;ORELLANA et al, 2009;WISE, 1999).…”