Cotton Byproduct Assessment for Improving Beef Cattle Feeding Recommendations

Abstract

Beef cattle producers in the southeastern US have access to byproducts from multiple industries, including the cotton ginning industry. These byproducts, specifically whole cottonseed and cotton gin trash, are subject to changes in nutrient quality and physical characteristics and as the cotton ginning industry advances in genetic selection to improve lint yield and ginning processes. These changes warrant periodic evaluation of the byproducts available to beef cattle producers to update feeding recommendations. A series of experiments were conducted to evaluate beef cattle whole cottonseed feeding recommendations, gossypol intake, protein utilization characteristics, and gin trash feeding strategies. A whole cottonseed intake study using a crossover design in the Calan Gate® system was conducted to evaluate intake differences between a commonly grown cottonseed variety, DP1646, and a low-gossypol cottonseed variety, ULGCS. Six Angus-cross calves (two steers and one bull per group, average BW = 281 kg) were assigned to two treatments: 1) ad libitum DP1646 and bermudagrass hay, and 2) ad libitum ULGCS and bermudagrass hay. Each group underwent a 7-day acclimation period followed by a 7-day intake measurement period. Groups were then crossed over to the opposite treatment for a second acclimation and intake measurement period. Cattle consuming ULGCS had a greater (P = 0.0011) intake than cattle consuming DP1646. Cattle consuming ULGCS also had less total gossypol intake (P < 0.0001), and less free gossypol intake (P < 0.0001) compared to cattle consuming DP1646. An in situ digestibility study was conducted to evaluate potential digestibility differences between DP1646 and ULGCS. Two ruminally-cannulated steers were allowed free-choice access to whole cottonseed for a 7-day acclimation period prior to the start of the trial. Greater (P < 0.0001) ruminal DM digestibility was observed for ULGCS than for DP1646. Ninety-eight cotton varieties and breeding lines were obtained from the Auburn University Cotton Breeding Program and analyzed for relative distribution of degradable intake protein (DIP) to determine potential variation among cotton seed from a beef cattle feeding perspective. The varieties and lines tested had a range of DIP from 36.01% to 73.99% of total CP. A 60-day gin trash intake study was conducted using the Calan Gate® system to determine potential intake and animal performance differences between loose and baled gin trash. Twenty-four non-lactating crossbred cows and heifers (average BW = 613.41 kg) were assigned to one of two treatments: 1) ad libitum baled gin trash with 2.27 kg of 50:50 corn gluten feed and soybean hull pellets per day and 2) ad libitum loose gin trash with 2.27 kg of 50:50 corn gluten feed and soybean hull pellets per day. Body weight and body condition scores were collected at days 0, 30, and 60 of the study. Cattle consuming loose gin trash had a greater (P < 0.0001) intake than cattle consuming baled gin trash. Overall daily DM intake was close to 2.0% of animal body weight during the trial. There were no differences (P ≥ 0.6962) in body weight between gin trash feeding treatments or days of study. Throughout these studies, it was observed that whole cottonseed and gin trash can be used to support beef cattle at various stages of production if utilized correctly.