Effect of adding different levels of propolis extracts on digestibility, gas production and in vitro ruminal fermentation parameters

A study was conducted to evaluate the effect of adding different levels of ethanol, methanol and their 50:50 (v/v) binary mixture of propolis extract on in vitro gas production parameters, dry matter and organic matter digestibility, protozoa counts and methane production in a completely randomized design. Crude propolis sample was collected from Ramian region and its extraction was taken by ethanol, methanol and their mixture. Experimental treatments were including: 1) control containing basal diet with forage: concentrate ratio of 50:50 (without any extract), treatments 2 till 5 (control treatment + 25, 50, 100, 200 µl levels of ethanol extract, respectively), treatments 6 to 9 (control treatment + levels 25, 50, 100, 200 µl of methanolic extract, respectively), treatments 10 to 13 (control treatment + 25, 50, 100, 200 µl levels of binary solvents mixture extract, respectively). Results showed that the highest and lowest potential gas productions were related to treatment containing 200 µl and 25 µl of methanolic extract, respectively (P<0.05). Treatment containing 200 µl of binary solvents mixture extract had the highest metabolizable energy, organic matter digestibility and short chain fatty acid concentration (P<0.05). There was significant difference between treatments on dry matter and organic matter digestibility (P<0.05). Hence, treatments containing 25 and 100 µl of methanolic extract had the highest and control treatment had the lowest dry matter and organic matter digestibility, respectively (P<0.05). Using 25 µl and 200 µl levels of binary solvents mixture extract reduced Halotrish more than other levels and other extract. However, treatments containing propolis extract reduced methaneproduction remarkably. Generally, it can be concluded that propolis methanolic extract has potential to improve ruminal fermentation efficiency. However, more research is warranted to manipulate rumen microbial fermentation.