Abstract/Summary

BACKGROUND: As the agro-industry produces considerable amounts of by-products globally, it is acknowledged to address the environmental issues related to their disposal and the resource competition between food for humans and feed for animals. The aim of this study was to explore in vitro, the effects of various by-products from the agro-industry on rumen fermentation and methane emission. Samples were collected from various food processing industries, including red, green apple pomace (RAP, GAP), hempseed cake (HC), coffee hulls (CH), coffee grounds (CG), spent mushroom compost (SMC), distillers dried Grains with solubles (DDGS). In doses of 100, 200, 300, g/kg, tested by-products were incubated in rumen fluid, where by-products replaced equal amounts of the substrates. RESULTS: Gas production (GP) and dry matter digestibility (DMD) decreased linearly in most of tested by-products with the growth of doses (P < 0.001), while NH3-N concentration increased linearly. Linear decreases were observed in CH4 production with increasing doses of all by-products (P < 0.05). The reduction of CH4 production range from 21.4% to 33.6% at the dose of 100-300 g/kg, but reductions were only observed in dose of 100 g/kg when CH4 productions were corrected by digested dry matter (P < 0.05). RAP, GAP, HC were higher than CH, CG, SMC for the comparison of key parameters including DMD, GP and volatile fatty acids. Better methane-mitigating effects were observed in RAP, GAP and HC than that of Control group and CH, CG and SMC. CONCLUSION: Most of by-products tested were proved to be a potential option for replacing conventional feed ingredients but should not exceed the dose at 200 g/kg.