PSIII-16 Limit feeding a high concentrate diet to newly-weaned calves does not negatively affect growth performance.

Abstract The objective of this experiment was to determine the effects of feeding a limit-fed concentrate-based diet compared to an ad libitum forage-based diet on growth performance and applied energetic measures in newly weaned steer calves during the receiving period. Single-sourced Charolais × Angus steers [n = 60; initial body weight (BW) 227 ± 0.5 kg] were used in a 61 d receiving study. Steers were utilized in a randomized complete block design and were blocked by location in the feedlot. After determining initial BW, steers were randomly assigned to 1 of 10 pens (n = 5 pens/treatment with 6 steers/pen). Steers were allotted on d 1 into 1 of 2 treatments: ad libitum forage-based diet [(ALF) 1.03 Mcal/kg diet] or limit-fed concentrate-based diet [(LFC) 1.36 Mcal/kg diet]. The LFC diet was fed at 76% of the dry matter intake (DMI) of the pen receiving the ALF diet within the same block. Steers were weighed on d 1, 14, 34, 54, and 61 to determine growth performance and applied energetic measures. From d 55 to 61, LFC steers were fed the ALF diet to account for gastrointestinal (GI) tract fill. A cost analysis was conducted to understand growth performance in relation to the cost of feeding each diet. All data were analyzed using the GLIMMIX procedure of SAS 9.4. From d 1 to 54, no differences (P ≥ 0.85) were observed between treatments for BW or average daily gain (ADG). By design, LFC steers had reduced (P = 0.01) DMI by 12% compared to ALF steers. The LFC steers improved (P = 0.04) gain efficiency by 12% compared to ALF steers. The ALF steers (P = 0.01) reduced the estimated maintenance coefficient by 23% compared to LFC steers, which had an estimated maintenance coefficient similar to the base coefficient of 0.077 Mcal/ BW, kg0.75. From d 1 to 61, there were no differences (P ≥ 0.45) observed between treatments for BW or ADG. The LFC steers had reduced (P = 0.01) DMI by 12% and improved (P = 0.04) gain efficiency by 14% compared to ALF steers. The ALF steers (P = 0.03) reduced the estimated maintenance coefficient by 15% compared to LFC steers, which had an 8% reduction in the estimated maintenance coefficient compared to the base coefficient. Under the conditions of this experiment, feeding the LFC diet resulted in a $0.19/kg of gain in savings compared to the ALF diet. Collectively, feeding a limit-fed concentrate-based diet to newly weaned steer calves during the receiving phase resulted in similar growth performance measures and improved gain efficiency, but reduced estimated maintenance coefficients to a lesser degree compared to feeding an ad libitum forage-based diet.