Association among residual feed intake, residual body weight gain, residual intake and body weight gain and temperament of Nellore cattle

Abstract

A study was conducted to investigate association among residual feed intake (RFI), residual body weight gain (RG), residual intake and body weight gain (RIG) and temperament of Nellore (Bos indicus) young bulls (n = 44; 387 + 22 kg initial body weight; 22 + 1 mo of age). Animals were evaluated for temperament at feedlot entry (d 0). Individual temperament scores were calculated by averaging steer chute score (5-point scale: 1 = calm, no movement; 5 = violent and continuous efforts) and exit score (calculated by dividing exit velocity results into quintiles; 1 = slowest steers; 5 = fastest steers). Animals were also classified according to temperament type [adequate temperament (ADQ) or excitable temperament (EXC)]. Animals were maintained in individual drylot pens (8 m²) and individual feed intake was measured during the trial period (d 0 to 109; finishing phase) to determine daily dry matter intake (DMI). Body weights (BW) were measured on d 0 and d 109 to determine the average daily gain (ADG). The DMI and ADG were used to determine the RFI. Residual body weight gain was calculated based on the regression of BW0.75 and feed intake. Residual intake and body weight gain was determined from linear combination into RFI and RG. Data were analyzed using PROC MIXED in SAS with fixed effects of temperament; animal was experimental unit. No differences (P > 0.05) were detected for RFI (-0.05 vs. 0.01, for ADQ and EXC steers, respectively; SE = 0.18) and RIG (0.04 vs. -0.05, for ADQ and EXC steers, respectively; SE = 0.20) between temperament types. However, ADQ steers had greater RG (P = 0.02) than EXC steers (0.05 vs. -0.10, for ADQ and EXC steers, respectively; SE = 0.06). In conclusion, residual gain is associated with temperament and it is independent of differences in feed intake in Nellore cattle.