Effects of fumaric acid supplementation on methane production,ruminal fermentation and microbial flora in goats fed diets varying in dietary effective fiber and starch

摘要

The effects of dietary supplementation of fumaric acid on methane production,rumen fermentation characteristics,microbial flora and in situ DM degradability of feedstuffs were examined in goats fed diets varying in dietary physically effective NDF (peNDF) and rumen degradable starch (RDS).Four goats fitted with permanent cannulates were used in a 4×4 Latin square design with a 2×2 factorial arrangement of treatments: low or high levels of dietary peNDF plus RDS (peFS,234 plus 153 g/kg DM in the low-peFS diet and 255 plus 175 g/kg DM in the high-peFS diet),across without or with fumaric acid supplementation (24 g/d per goat).The basal diet composed of alfalfa hay,the concentrate and corn silage,and fed as total mixed ration to the goats.The peFS in the diets was modulated by varyingly processing alfalfa hay either chopped (high-peNDF) or ground (low-peNDF),and corn either crushed (low-RDS) or ground (high-RDS).Fumaric acid supplement decreased methane production (L/d and L/kg DM,P＜0.05) while dietary peFS had no effects.However,the reduction of methane production in the low-peFS diet was larger than in the high-peFS diet (31.72％vs 17.91％,L/d).While dietary peFS had no effects,fumaric acid supplement decreased ruminal total volatile fatty acid concentration (TVFA,P＜0.01) and increased ruminal pH (P＜0.05).Increasing dietary peFS and supplementing fumaric acid to goats,shifted VFA pattern toward more propionate (P＜0.01) and less acetate (P＜0.01).Additionally,interactions between dietary peFS and fumaric acid supplementation were observed for the ratio of acetate to propionate (P＜0.05) which was more predominant when fumaric acid was supplemented to low- peFS diet.No difference was found in ruminal in situ DM degradation of concentrate or alfalfa hay by dietary peFS or fumaric acid supplement.Goats showed a lower ruminal methanogen abundant (P＜0.05) by supplementing fumaric acid and a higher B.fibrisolvens abundant (P＜0.05) with dietary peFS increasing.The present study demonstrated that fumaric acid reduced the enteric methane production through increasing ruminal propionate production and depressing methanogen abundance without negatively effecting on in situ DM degradability of feedstuffs.In addition,the methane-suppressing effects of fumaric acid were diet dependent,and were higher efficiency when goats received low- peFS diet.