Effect Effect of different levels of monensin and a commercial probiotic on fermentative parameters of feedstuffs by bacteria isolated from rumen in vitro condition

The aim of this study was investigating the effect of antibiotic (sodium monensin) and trade probiotic on fermentation process and estimation of gas production parameters of feedstuffs (alfalfa hay, barley grain and alfalfa+ barley 50:50) in vitro condition. Experimental treatments were included control treatment (basal feeds without additive), basal feeds
supplemented with sodium monensin antibiotic and the trade probiotic at levels of 500 and 1000 mg per kg of DM. Gas production in vitro was used for determining gas production
parameters. Results showed both levels of sodium monensin and 1000 mg/kg of monensin decreased fermentable fraction (b) and rate (c) of gas production of alfalfa, respectively. Also, rate (c) of gas production of barley was significantly decreased by supplying a higher level of monensin (1000 mg/ kg). In comparison with level of 500 mg/kg probiotic, the higher level of probiotic increased rate of gas production of alfalfa+ barley mixture. There was no significant (p>0.05) effect of treatments on organic digestibility and metabolisable energy. Supplementation of antibiotics in diet containing 100% hay decreased fermentative parameters of feedstuffs in rumen. Adding the higher level of monensin to diet containing 100% grain decreased significantly gas production rate. Using probiotics in diet containing mixed hay and grain can increase rate of gas production by stimulating ruminal bacteria.