344 Replacing a High-roughage Receiving Diet with a High-energy Finishing Diet Improved Growth Performance and Feed Efficiency with No Impact on Health of High-risk Newly-received Calves

Abstract

This study evaluated impacts of feeding a finishing diet throughout both the receiving and finishing period compared to a receiving diet with adaptation to the finishing diet on health, performance, ruminal pH, and rumination of high-risk feedlot cattle. Five truck-load blocks of steers and bulls (n = 400) were used in a generalized complete block design and assigned to receive: 1) finishing diet for the entire feeding period (FIN) or 2) receiving diet for the first 56 d, followed by transition to the finishing diet (REC). All cattle were consuming the same diet on d 74. A subset of cattle (n = 48) were randomly selected to quantify ruminal pH, temperature, and rumination time. Ultrasounds were completed on d 0, 74, and 146 to determine fat thickness. Cattle fed REC had greater (treatment × day; P < 0.01) DMI from d 1 to 67 but less DMI from d 74 to 82, and DMI did not differ from d 83 to 174. Energy intake (treatment × day; P < 0.01) was greater for FIN from d 14 to 75. Cattle consuming FIN had greater (P ≤ 0.01) ADG and BW and improved (P < 0.01) gain:feed from day 0 to 74. At d 174, BW of FIN was 9.6 kg greater (P = 0.02). On d 74, FIN had greater (P ≤ 0.05) fat thickness but did not differ (P ≥ 0.61) at d 146. There was no difference (P ≥ 0.31) in health outcomes. Ruminal pH (treatment × day; P < 0.01) was greater for FIN on d 2 and 61, and rumination time was less (P < 0.01) for FIN from d 0 to 28. Overall, these results suggest providing a finishing diet to high-risk calves upon arrival may be a viable alternative to a traditional receiving diet.