Improved quality of cottonseed meal: effect of cottonseed protein isolate on growth performance, nutrient digestibility, and intestinal health in growing pigs.

Cottonseed meal (CSM) is abundant in proteins that have the potential to substitute for conventionally utilized protein supplements for animals. However, the presence of anti-nutritional factors in CSM, particularly free gossypol, has limited its application. This study evaluated the nutritional value of a cottonseed protein isolate (CPI) derived from CSM using an alkaline extraction and acid precipitation process and explored its effect on intestinal health in growing pigs. 32 Duroc-Landrace-Yorkshire castrated male pigs (initial body weight 19 ± 2 kg) were divided into 4 treatment groups: nitrogen-free diet, corn-soybean meal diet (CSD), cottonseed meal diet (CSMD, where CSM replaced 35% of the nitrogen in CSD), CPI diet (CPID, where CPI replaced 35% of the nitrogen in CSD). Our study revealed that, as compared to the CSM, the CPI exhibited significantly higher crude protein content and lower levels of crude fiber, neutral detergent fiber, acid detergent fiber, and free gossypol (P < 0.01). Interestingly, CPI feeding significantly decreased the ratio of gain to feed (G:F) in growing pigs (P = 0.012). Moreover, CPI also showed an improved apparent and true digestibility of protein, as well as enhanced nitrogen utilization in growing pigs (P < 0.05). The metabolizable energy of CPI was significantly higher than that of CSM (P < 0.01). Additionally, CPI showed higher apparent ileal digestibility and standardized ileal digestibility for amino acids such as arginine, aspartic acid, glutamic acid, and serine (P < 0.05). Importantly, CPI feeding improved the intestinal health in pigs as indicated by increases in villus height and digestive enzyme activities (P < 0.05), as well as increases in the production of short-chain fatty acid and beneficial microbiota (0.05 ≤ P < 0.10). The results not only showed an improved quality of CPI as compared to the CSM but also indicated a beneficial effect of CPI on growth performance and intestinal health in growing pigs. These attributes should make it an attractive candidate to substitute for conventionally utilized protein supplements like soybean meal.