The Impact of the Application of Brewer's by-Product Roasted Barley Husks on Selected Parameters of Rumen Fermentation of Dairy Cows. In Vitro Study

Abstract

The aim of the study was to evaluate the effect of brewer's by-product roasted barley husks additive (RBH) on the cow's rumen fermentation process, in in vitro conditions. Ruminal fluid for the research was collected from 9 dairy cows selected on the basis of analogues. Animals were fed total mixed ratio (TMR). The substrates for in vitro experiment were composed on the basis of TMR. Control substrate contained only TMR. Substrates D1, D2, D3 contained TMR with the addition of respectively: 5, 10 and 15% of dry matter of RBH. Substrate D4 contained only RBH. Samples of ruminal fluid were incubated for 8 hours, in anaerobic conditions, at 39°C. A desirable effect of applying RBH was observed in groups D3 and D4the production of volatile fatty acids (VFA) increased. Furthermore, positive effects were observed in groups D2 and D4-acetic acid production decreased (by up to 7%). Reduced methane production (up to 10%) was observed in experimental groups which indicates that animals would have smaller energy losses. Most beneficial changes in the VFA profile and the highest growth of non-glucogenic and glucogenic acids ratio (NGR) were recorded in D3 group samples. Positive results in this matter are promising as the roasted barley husks are a by-product of beer production and its usage has both economic and ecologic benefits. Obtained results in the in vitro study are the prerequisites to carry out an in vivo experiment.