Feed utilization, blood metabolites and ingestive behavior in Sahiwal calves divergently selected for low and high residual feed intake
Veterinarski arhiv (Tisak)
A. KuMAR: Feed utilization, blood metabolites and ingestive behavior in Sahiwal calves divergently selected for low and high residual feed intake. Vet. arhiv 89, 481-503, 2019. ABSTRACT This study aimed to evaluate differences in feed utilization between low and high residual feed intake (RFI) in Sahiwal calves by comparing performance, ingestive behavior and blood metabolites. Eighteen, growing, female Sahiwal calves (aged 10-14 months; body weight (BW) 100-125 kg) were fed ad libitum on a
... ad libitum on a total mixed ration for 90 d. RFI varied from -0.53 to 0.40 kg dry matter (DM)/d with a mean RFI of -0.27 to 0.17 kg DM/d in low and high RFI Sahiwal calves, respectively. Calves with low RFI consumed 26% less DM and required 35% less metabolizable energy for body maintenance (MEm) compared to high RFI, yet gained at a similar rate. Low RFI calves digest feed more efficiently than less efficient calves. Conventional efficiency measures also showed better efficiency in low RFI than high RFI calves. Low RFI calves spent less time in feeding, rumination, and chewing. Higher plasma concentrations of insulin-like growth factor-1 (IGF-1), growth hormone (GH), and creatinine, and lower concentrations of albumin, plasma urea nitrogen (PUN), and triglycerides were observed in the low RFI group than the high RFI group. However, plasma total protein, glucose, cholesterol, non esterified fatty acid (NEFA), beta-hydroxy butyric acid (BHBA), calcium (Ca), and phosphorus (P) concentrations were similar in both groups. In summary, low RFI calves utilized feed more efficiently by spending less time and energy in feeding, and the variability in blood metabolites might be due to differences in body metabolism.