406 Awardee Talk: Extended Effects of Sequential Weaning and Backgrounding Management in Southeastern U.S. Beef Calves on Performance, Health, and Immunological Responses Through the Feedyard
Authors: Justice S Maggie , Mullenix Kimberly , Dillard S Leanne , Rodning Soren P , Chamorro Manuel , Tigue Alex , Smith Brandon B , Zessin Peyton , Boone Madison L , Henson Mason , West Micayla H , Agar Michael A 
Published: November 2023

Abstract
Understanding post-weaning management strategy impacts on calf performance and health can help producers add value to their operations and further strengthens the viability of the beef supply chain. A series of research and Extension studies were conducted to: 1) validate perceptions and determine motivations for pre- and post-weaning calf management strategies used in Southeast US cow-calf operations and 2) assess the collective effects these practices have on calf health and performance through the feedyard phase. An interactive, online survey (n = 214 responses) was distributed to Alabama beef producers to assess factors influencing the use of pre- and post-weaning management and management systems. Key challenges producers face in their operations who practice managed weaning and backgrounding strategies include input costs, land availability and market predictability. Developing demonstration data models to address cost-benefits of weaning and backgrounding may help producers evaluate areas of challenges identified in this survey. Subsequently, a two-year study was conducted using 427 Angus-crossed steer calves (294.2 kg) from three Auburn University research farms. Calves were assigned to one of three weaning methods for a 14-d experimental period: fenceline, nose-flap, or abrupt weaning. Response variables included initial and final body weight following the 14-d period, vaccination, and acute phase protein response. In both years of the study, fenceline weaned calves had the greatest average daily gain at 1.08 kg/d (P &lt; 0.0001) and abruptly weaned calves had the lowest average daily gain losing 0.15 kg/d during the 14-d observation period. After the weaning study, calves were brought to a centralized farm and began a 60-d backgrounding period where they were assigned to one of three nutritional management strategies in a 3×3 factorial design: cool-season baleage, bermudagrass hay, or grazing mixed warm-season annuals. All diets were supplemented with 1% BW of DDGS. Body weights and blood samples were again collected throughout the backgrounding period. In the backgrounding period, fenceline weaned calves had the greatest average daily gain (P = 0.02) in the first 30 d of the backgrounding period regardless of backgrounding diet type. Calves fed the hay-based diet also had a greater average daily (P &lt; 0.0001) than both the grazing and baleage groups in the first 30d of backgrounding. From d 30 to 60 of backgrounding in each year, steers on grazing and baleage diets supported greater ADG (P &lt; 0.0001) than hay diets during the last 30-d of the backgrounding period (0.74 kg/d and 0.77 kg/d vs. 0.31 kg/d, respectively). Following the backgrounding, steers were transported to a commercial feedyard where they remained for the finishing phase. Effects of backgrounding management on feedyard performance were only observed during the first 35d in the feedyard. Results indicate that weaning and backgrounding management strategies can influence calf performance during the transition period into the feedyard phase.