Cottonseed characteristics related to beef cattle consumption: Protein degradability, digestibility, and gossypol content

Abstract

Our objectives were to (1) evaluate effects of whole cottonseed (WCS) storage conditions on protein and digestibility characteristics and (2) characterize protein degradability, gossypol content, and seed characteristics of cotton ( Gossypium hirsutum L.) in the southern United States. Seed with 0% heat damage (NN), 50% heat damage (N/B), or 100% heat damage (BB) was analyzed for in situ digestibility and protein degradability in Exp. 1. In Exp. 2, seed from 88 cotton breeding lines was obtained from a public cotton breeding program and analyzed for CP, undegradable intake protein (UIP), degradable intake protein (DIP), gossypol concentrations, and seed size. In situ DM disappearance was greatest ( P < 0.001) for NN after 48 h, and N/B was greater ( P < 0.05) than BB. Cottonseed that was not burned had a greater ( P = 0.01) amount of N degradable at a definable rate (B fraction) than BB, and the undegradable fraction (C fraction) tended to be less ( P = 0.06) for NN than BB and N/B. Cotton breeding lines had a mean CP value similar to those reported by the NASEM (2016), whereas DIP, UIP, and gossypol values had greater variability than CP in the present study. Correlations between seed size and protein were low, but there was a positive correlation with free gossypol. Heat-damaged WCS has decreased DM disappearance and N disappearance. Characterization of DIP, UIP, and gossypol in cottonseed may provide baseline selection criteria for cotton breeding programs, as well as aid in ration formulation strategies. Measuring WCS quality can help cotton breeders, animal scientists, and livestock producers develop seed value and feed recommendations for use.