Difference in the rate of fermentation of brewers’ grain silage caused by mixing rations of wheat bran or wheat screenings in Mongolia

摘要

Brewer's grain(BG)is one of the most important feed resources,especially as a source of protein.But its usage in Mongolia is restricted during the summer because of its high moisture content,or ease of decay,and high cost of transportation.So there is a need to develop an improved method to store and conserve its nutritional values until the following spring when the demand for BG increases.A study was,therefore,undertaken to determine differences in the fermentation quality of brewers' grain silage based on the use of different types and amounts of additives for different periods.Five treatments were studied: 100％BG(BG100 for short.82.0％moisture),90％BG: 10％wheat bran(WB,WB10,74.2％moisture),80％BG: 20％WB(WB20,66.2％moisture),90％BG: 10％wheat screenings(WS,WS10,73.5％moisture)and 80％BG: 20％WS(WS20,65.6％moisture).The pH,proportions of lactic acid and volatile fatty acids,including acetic(C2),propionic(C3),butyric(C4),valeric(C5)and caproic(C6)acids,were determined at 0,3,7,14,21 and 28 days(d).Fermentation quality of WB20 was the best and fastest as the pH decreased to below 4.2,the proportion of lactic acid increased to more than 1.5％at 3d,and proportion of C2+C3 and C4 acids did not increase by more than 0.2 and 0.1％,respectively,until 28d.The next best treatment was WB10,as the quality was almost the same as that of WB20,though the proportion of lactic acid reached 1.5％at 28d.The third best treatment was WS20,as the proportion of lactic acid neared the recommended level at 28d.But,based on the cost of different methods,WB10 was recommended for herders as it was relatively less expensive.