Different measures of energetic efficiency and their phenotypic relationships with growth, feed intake, and ultrasound and carcass merit in hybrid cattle1

Abstract

Residual feed intake (RFI) has been proposed as an index for determining beef cattle energetic efficiency. Although the relationship of RFI with feed conversion ratio (FCR) is well established, little is known about how RFI compares to other measures of efficiency. This study examined the phenotypic relationships among different measures of energetic efficiency with growth, feed intake, and ultrasound and carcass merit of hybrid cattle (n = 150). Dry matter intake, ME intake (MEI), ADG, metabolic weight (MWT), and FCR during the test averaged 10.29 kg/d (SD = 1.62), 1,185.45 kJ/(kg0.75 x d) (SD = 114.69), 1.42 kg/d (SD = 0.25), 86.67 kg0.75 (SD = 10.21), and 7.27 kg of DM/kg of gain (SD = 1.00), respectively. Residual feed intake averaged 0.00 kg/d and ranged from -2.25 kg/d (most efficient) to 2.61 kg/d (least efficient). Dry matter intake (r = 0.75), MEI (r = 0.83), and FCR (r = 0.62) were correlated with RFI (P < 0.001) and were higher for animals with high (>0.5 SD) RFI vs. those with medium (+/-0.5 SD) or low (<0.5 SD) RFI (P < 0.001). Partial efficiency of growth (PEG; energetic efficiency for ADG) was correlated with RFI (r = -0.89, P < 0.001) and was lower (P < 0.001) for high- vs. medium- or low-RFI animals. However, RFI was not related to ADG (r = -0.03), MWT (r = -0.02), relative growth rate (RGR; growth relative to instantaneous body size; r = -0.04), or Kleiber ratio (KR; ADG per unit of MWT; r = -0.004). Also, DMI was correlated (P < 0.01) with ADG (r = 0.66), MWT (r = 0.49), FCR (r = 0.49), PEG (r = -0.52), RGR (r = 0.18), and KR (r = 0.36). Additionally, FCR was correlated (P < 0.001) with ADG (r = -0.63), PEG (r = -0.83), RGR (r = -0.75), and KR (r = -0.73), but not with MWT (r = 0.07). Correlations of measures of efficiency with ultrasound or carcass traits generally were not different from zero except for correlations of RFI, FCR, and PEG, respectively, with backfat gain (r = 0.30, 0.20, and -0.30), ultrasound backfat (r = 0.19, 0.21, and -0.25), grade fat (r = 0.25, 0.19, and -0.27), lean meat yield (r = -0.22, -0.18, and 0.24), and yield grade (r = 0.28, 0.24, and -0.25). These phenotypic relationships indicate that, compared with other measures of energetic efficiency, RFI should have a greater potential to improve overall production efficiency and PEG above maintenance, and lead to minimal correlated changes in carcass merit without altering the growth and body size of different animals.

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

“…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. The contrasting results for carcass fatness traits may arise from different measures of classifying carcass fatness.…”

Consumo alimentar residual e sua relação com medidas de desempenho e eficiência e características in vivo da carcaça de cordeiros

“…Em relação ao PVI, PVF e PM, os resultados aqui obtidos estão em concordância com os relatos de que o CAR não está ligado às medidas de tamanho corporal, como previamente descrito por Arthur et al (2001b) e Carstens et al (2002. Para TCR e TK, semelhante ao encontrado por Nkrumah et al (2004) consideração os pesos vivos e o ganho de peso dos animais, e estes se mostraram similares neste experimento, justifica-se a ausência de significância para essas medidas.…”

“…Nkrumah et al (2004) descreveram correlações muito parecidas entre CA e GMD, TCR e TK para bovinos mestiços, com coeficientes de, respectivamente, -0,63, -0,75 e -0,73. Para animais Nelore, Santana (2009) estimou correlações de -0,85 para CA e GMD, e de 0,50 entre CA e PVI, este último muito próximo ao exposto para cordeiros neste estudo.…”

Remote Noninvasive Assessment of Pain and Health Status in Cattle

“…24 Researchers evaluating residual feed intake (RFI) found distinct differences in feeding behaviors among high and low RFI calves using both the GrowSafe and Insentec monitoring systems. 60,61 Since feed inputs represent one of the largest costs in producing beef, monitoring behaviors that may identify calves with less than ideal feed efficiencies may be beneficial. 62 Monitoring the feeding behavior of an animal over a period of time allows establishment of a baseline against which deviations in subsequent behavioral patterns can be evaluated.…”