棉粕和木薯粉混合发酵乳酸菌株的筛选及其对绵羊瘤胃体外发酵的影响OA

This study aimed to screen lactic acid bacteria(LAB)strains for fermenting cottonseed meal(CSM)and to optimize the fermentation process through the addition of cassava meal,thereby enhancing its potential as sheep feed.A total of 48 strains were isolated from various sources,including pickled vegetables,Jiangshui fermented grain slurry,yogurt,and sheep rumen fluid,and seven LAB strains were identified via 16S rDNA sequencing.The growth rates of the different LAB strains were compared,and a factorial experimental design was employed to investigate the effects of different LAB strains and ratios of CSM to cassava meal on sensory indicators,pH,ammonia nitrogen,crude protein,and the gossypol degradation rate in fermented CSM.This was conducted to determine the optimal strain and CSM-to-cassava meal ratio.Additionally,in vitro rumen gas production tests were conducted to assess the rumen fermentation parameters of a total mixed ration for sheep,using the fermented feed as the primary protein source.Based on multiple fermentation evaluation indicators,a CSM-to-cassava meal ratio of 8꞉2 achieved the highest gossypol degradation and favorable fermentation efficiency.Among the strains,one Lactobacillus paracasei strain isolated from yogurt exhibited high free gossypol degradation,rapid growth,lower post-fermentation pH,and suitable ammonia nitrogen and crude protein levels,making it the optimal strain for fermenting CSM in this experiment.The in vitro rumen gas production results showed that the 72-hour gas production of the fermented CSM group and the fermented CSM+cassava meal group were significantly higher than that of the control group(P<0.05).Additionally,the pH of the fermented CSM+cassava meal group was significantly lower than that of the fermented CSM group(P<0.05).This study demonstrates that,with a CSM-to-cassava meal ratio of 8꞉2,fermentation with the L.paracasei strain effectively degrades gossypol,improves CSM quality,and enhances nutrient degradation in the sheep rumen,providing a theoretical basis and practical guidance for the production application of fermented feed.