基于主成分分析的精料、茶渣、全株玉米青贮对瘤胃体外发酵的组合效应评价研究OA

[Objective]This study aimed to evaluate the combined effects of different ratios of concentrate,tea residue,and whole-plant corn silage on in vitro ruman fermentation,identify the optimal combination ratios use principal component analysis(PCA),and provide a reference for the use of tea residue as feed.[Method]A two-factor design was employed,with three concentrate-to-roughage ratios(20∶80,35∶65,and 50∶50)and four tea residue inclusion levels(0,5%,10%,and 15%),resulting in 12 treatment groups with four replicates each.Rumen in vitro fermentation tests in Simmental cattle were conducted,with gas production recorded over 48 h and fermentation parameters measured.PCA was used to evaluate the effects of different feed combinations.[Result]①When the concentrate-to-roughage ratio was 50∶50,pH of in vitro rumen fermentation broth was significantly higher than that in the other groups(P<0.05).The concentration of ammonium nitrogen in fermentation broth of 10%tea residue group was significantly lower than that of 0 tea residue group(P<0.05).There was a significant interaction between the concentrate-to-roughage ratio and the tea residue addition rate on the ammonia nitrogen concentration of in vitro rumen fermentation broth(P<0.05).Under all three concentrate-to-roughage ratios,the ammonia nitrogen concentration of in vitro rumen fermentation broth in 10%tea residue group was significantly lower than that in 0 tea residue group(P<0.05).When the concentrate-to-roughage ratio was 50∶50,the propionic acid concentration in fermentation broth was significantly lower than that in the other groups(P<0.05),while the acetate to propionate ratio(A/P)was significantly higher than that in the other groups(P<0.05),and the propionic acid concentration in 15%tea residue group was significantly lower than that in 0 and 5%tea residue groups(P<0.05).The valeric acid concentration of fermentation broth in 50∶50 concentrate-to-roughage ratio group was significantly lower than that in 35∶65 group(P<0.05).The valeric acid concentration of fermentation broth in 15%tea residue group was significantly lower than that in 0 and 5%tea residue groups(P<0.05).A/P of fermentation broth in 10%and 15%tea residue groups was extremely significantly higher than that in 0 and 5%tea residue groups(P<0.01).There was a significant interaction between the concentrate-to-roughage ratio and the tea residue addition rate on A/P of in vitro rumen fermentation broth(P<0.05).Under a 50∶50 concentrate-to-roughage ratio,A/P of fermentation broth in 10%and 15%tea residue groups was significantly higher than that in 0 and 5%tea residue groups(P<0.05).②Correlation analysis results indicated that 8 pairs of indicators showed significant correlations(P<0.05),and 32 pairs of indicators showed extremely significant correlations(P<0.01),making the data suitable for PCA.③A model evaluating the combined effects of concentrate,tea residue,and whole-plant corn silage was constructed via PCA,the highest composite score was achieved when the ratio of concentrate∶tea residue∶whole-plant corn silage was 35∶5∶60.[Conclusion]Under the conditions of this experiment,a diet ratio of concentrate∶tea residue∶whole-plant corn silage of 35∶5∶60 in Simmental cattle yielded the optimal combination effect.Tea residue could be considered as a source of roughage in Simmental cattle.However,high concentrations(10%-15%)of tea residue had a certain inhibitory effect on in vitro rumen fermentation.