This Is AuburnElectronic Theses and Dissertations

Extended effects of sequential weaning and backgrounding management in southeastern U.S. beef calves on performance, health, and immunological responses through the feedyard




Justice, Susan (Maggie)

Type of Degree

PhD Dissertation


Animal Sciences


Beef calf management strategies used during the weaning and post-weaning period can have extended effects on growth performance and health in all sectors of the production chain. 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. From an educational perspective, it is important for Extension and industry professionals to understand how post-weaning management strategies are used by beef operations in the Southeast U.S. and the potential success of those practices. The objective of this set of studies was to: 1) determine commonly used calf management strategies in Southeast cow-calf operations and 2) assess the collective effects these practices have on calf health and performance through the feedyard phase. An online survey with 24 total questions was developed and distributed to cattle producers in the state of Alabama. Questions addressed if producers do or do not use managed weaning and backgrounding strategies. A total of 214 complete responses were received with 94% of respondents considering their operation to be a cow-calf operation. 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 the cost-benefit relation of weaning and backgrounding management may help producers evaluate areas of improvement identified in this survey. Extension educators can apply this data to create resources and programs centered on backgrounding to improve the understanding of potential benefits from adequate post-weaning management in beef calves. A two-year study was conducted using 427 steer calves (216 year 1, average BW 297 kg; 213 year 2, average BW 291 kg) from three Auburn University research farms. Calves were assigned to one of three different weaning method groups for a 14-d experimental period: fenceline, nose-flap, or abrupt weaning. Body weights were collected as a measure of growth performance. Blood samples were collected to measure vaccination and acute phase protein response. After the weaning period, calves were transported to a centralized farm and began a 60-d backgrounding period where they were randomly assigned to one of three nutritional management strategies in a 3×3 factorial design: cool-season annual baleage and 1% BW dried distillers’ grains (DDGS), bermudagrass hay and 1% BW DDGS, or grazing mixed warm-season annuals and 1% BW DDGS. Body weights and blood samples were collected throughout the backgrounding period. In both years of the study, fenceline weaned calves had the greatest average daily gain at 1.08 kg/d (P <0.0001) and abruptly weaned calves had the lowest average daily gain losing 0.15 kg/d during the 14-d observation period. In Year 1, steers had a significantly greater (P <0.0001) gain across all treatments than calves in Year 2, with Year 1 calves gaining 7.7 kg more during the weaning period than Year 2 calves. 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 bermudagrass hay-based diet also had a greater average daily (P <0.0001) than both the grazing and baleage diet groups in the first 30 d of backgrounding. From d 30 to 60 of backgrounding in each year, calves on the hay-based diet had the lowest average daily gain (P <0.0001). Steers on both the warm-season annual grazing and cool-season annual baleage diets demonstrated greater average daily gains (P <0.0001) during the last 30-d of the backgrounding period (0.74 kg/d and 0.77 kg/d respectively). Following the backgrounding period steers were transported to a commercial feedyard in Montezuma, KS where they remained for the finishing phase. During this phase performance was tracked through periodic weigh-ins and finally through carcass performance. Results indicate that weaning and backgrounding management strategies may influence calf performance during the transition period into the post-weaning phase.