PSX-19 - Variation in nutritive value of whole cottonseed from the Regional Breeding Testing Network

Abstract: Whole cottonseed serves as a readily accessible, nutritional, and cost-effective supplementary feed for beef cattle. Standard estimates indicate that whole cottonseed contains approximately 52% neutral detergent fiber (NDF), 24% crude protein (CP), and 18% crude fat. For more than 15 years, the Regional Breeders Testing Network (RBTN) has conducted a multi-environment trial (MET) for breeders to evaluate germplasm to include whole cottonseed. The trial presents opportunities to analyze variations among cultivars concerning their nutritional value. Therefore, the purpose of this study was to assess the variability in nutritive value of whole cottonseed from the 2023 RBTN MET. Samples from 20 RBTN cotton varieties were obtained and assayed for NDF, ADF, ADL, and CP. Samples were also subjected for batch culture in vitro true digestibility (IVTD) and crude fat. In our study, NDF (total cell wall content) was less than previously reported book values (45.8% vs. 51.6%). Crude protein was consistent with book values (25.0% vs. 24.4%) and had the lowest degree of variability among the nutrients tested. However, crude fat (the primary energy source in whole cottonseed) in our samples was greater than values previously reported (20.2% vs. 17.5%) and had a high degree of variability. Our findings indicate that the nutritional value of whole cottonseed may differ depending on the variety acquired. This research lays the groundwork for pinpointing the genetic factors responsible for regulating its nutritional value.