PSII-25 Dose effect of rumen-protected choline on growth performance of receiving beef cattle.

Abstract Bollatti1, J.M., Andreola R.1, Zenobi M.2, K. Estes2, C. Zimmerman2 1Biofarma Experimental Center for Animal Nutrition, Cordoba, Argentina; 2Balchem Corp., Montvale, NJ, USA 07645 Dose Effect of Rumen-Protected Choline on Growth Performance in Receiving Beef Cattle Nutritional strategies that enhance growth and feed efficiency in newly received cattle are essential for optimizing performance during the receiving period. This study evaluated the dose-response effects of rumen-protected choline (RPC; ReaShure, Balchem Corp., Montvale, NJ) supplementation on growth performance in receiving beef cattle over a 45-day period. A total of 243 cattle (Angus/British crossbreed from commercial auction yards, n=203; Indicus crossbreed from a ranch, n=40) were transported in four trucks and assigned to 28 pens in a completely randomized block design. Blocking was based on arrival source and initial body weight (BW), and cattle within each block (n=7) were randomly allocated to one of four RPC doses (0, 20, 40, or 60 g/d) for the first 21 days. All cattle received a common diet, containing 38 mg/kg DM of monensin, transitioning from a high-forage receiving diet to a finishing diet by day 22. Cattle were processed upon arrival, including vaccination, deworming, and recording of initial BW. Intermediate BW was recorded on days 14 and 21, while final BW was measured on day 45 following a 16-hour feed restriction. Dry matter intake (DMI) was calculated weekly after discounting refusals, and feed efficiency (gain-to-feed ratio, G:F) was calculated. Data were analyzed using the MIXED procedure of SAS with pen as the experimental unit, and block as random effect. Linear and quadratic contrasts assessed dose effects, and overall RPC supplementation was compared to the control (0 g/d). RPC supplementation increased average daily gain (ADG) over 45 days (P = 0.04), demonstrating both immediate and sustained benefits. ADG improved linearly in the first 14 days (P = 0.09), and feed efficiency showed a quadratic response across 45 days (P = 0.05). No significant effects on DMI were detected (P > 0.15). Detailed results, including means and significance levels, are presented in Table 1. These results suggest that short-term RPC supplementation enhances early growth performance in receiving cattle, with carry-over benefits lasting through 45 days. Further research should refine optimal RPC dosing strategies and the appropriate duration of supplementation to maximize its benefits.