Effects of Fermentation and Enzymatic Hydrolysis of Cottonseed Protein on Rumen Fermentation Characteristics, Intestinal Barrier Function, and Hepatic Metabolism in Suckling Lambs

The research aimed to examine the effects of fermentation and enzymatic hydrolysis of cottonseed protein on body weight changes, serum biochemistry, rumen function, intestinal health, and liver metabolism of suckling lambs. A total of twelve 7-day-old healthy male Hu sheep body weights (5.27 ± 0.48 kg) were randomly distributed into two groups. Starter feed regimens containing microbial fermentation of cottonseed protein (MFCP) or enzymatic hydrolysate of cottonseed protein (EHCP) were administered to lambs during the initial 60-day period. Results showed that compared with EHCP group, the serum glucose, ruminal acetic, propionic, butyric and valeric acids concentrations, jejunal immunoglobulin G content and mRNA expressions of <i>Claudin 1</i> and <i>Occludin</i>, as well as the relative abundance of <i>actinobacteriota</i> and <i>pseudoscardovia</i> in the rumen were significantly increased in the MFCP group (<i>p</i> < 0.05), whereas an opposite trend was observed in the jejunum. <i>α</i>-amylase and trypsin enzymatic activities were observed between the two groups. Relative to EHCP treatment, the MFCP group exhibited 69 elevated and 103 reduced hepatic metabolites, and these metabolites displayed distinct enrichment patterns within specific metabolic networks, including <i>fructose and mannose metabolism</i> (<i>p</i> = 0.003), <i>arachidonic acid metabolism</i> (<i>p</i> = 0.017), <i>glycerophospholipid metabolism</i> (<i>p</i> = 0.036), and the <i>cAMP signaling pathway</i> (<i>p</i> = 0.047). Overall, microbial fermentation of cottonseed protein may be beneficial for strengthening intestinal barrier function and facilitating hepatic lipid metabolism and immune regulation, while enzymatic hydrolysis of cottonseed protein enhances gastrointestinal digestive enzyme activity, thereby promoting nutrient digestion of suckling lambs.