杂粕替代豆粕及低蛋白饲粮对驴体外营养物质降解率及盲肠发酵特性的影响OA

This study aimed to investigate the effects of replacing soybean meal with miscellaneous meals and low-protein diets on the in vitro nutrient degradability and cecal fermentation characteristics in donkeys.Four-year-old,healthy Dezhou donkeys with a body weight of(235.0±5.0)kg were selected as donors of cecal fluid for in vitro culture.A two-factor completely randomized design was adopted.Factor one was normal protein level(12.5%,CP1)and low protein level(11.0%,CP2).Factor two was the proportion of soybean meal replaced by miscellaneous meals(rapeseed meal,corn germ meal,etc.),set at six levels:0(D0),20%(D20),40%(D40),60%(D60),80%(D80),and 100%(D100),resulting in a total of 12 treatments with six replicates per treatment.Except the CP1D0 treatment,other treatments were supplemented with lysine(Lys)and methionine(Met)to levels similar to those of the CP1D0 treatment.The results showed that compared with the CP1 treatment,CP2 treatment exhibited no significant differences in the degradability of dry matter(DM),neutral detergent fiber(NDF),and acid detergent fiber(ADF)in the stomach-small intestine-cecum,gas production at 24 hour and 48 hour,as well as concentrations of propionic acid,butyric acid,isobutyric acid,valeric acid,and acetic acid/propionic acid(P>0.05).The pH value,ammonia nitrogen(NH3-N),bacterial crude protein(BCP),and acetic acid concentrations were extremely reduced(P<0.01).The degradability of organic matter(OM)and crude protein(CP)in the stomach-small intestine-cecumin of D0～D60 treatments were extremely higher than that in the D100 treatment(P<0.01).The pH value and NH3-N concentration in the D60 treatment were extremely higher than those in the D80 and D100 treatments(P<0.01),the acetic acid content was extremely higher than that in the other treatments(P<0.01),and the valeric acid content was significantly higher than that in the D0 and D20 treatments(P<0.05).There were no significant differences among the D0～D100 treatments in the degradability of DM,crude fat(EE),NDF,and ADF in the stomach-small intestine-cecumin,BCP concentration,gas production at 24 hour and 48 hour,and total volatile fatty acid(TVFA)concentration(P>0.05).The interaction between dietary protein level and soybean meal substitution ratio had a significant effect on degradability of OM and propionic acid content(P<0.05),and an extremely effect on pH value and acetic acid content(P<0.01).The study shows that reducing the dietary protein level from 12.5%to 11.0%is feasible provided that Lys and Met are supplemented.Replacing 20%～60%of soybean meal with miscellaneous meals has no negative impact on nutrient digestibility in donkeys and can effectively conserve soybean meal protein feed resources.