Effect of tannin supplememt from tea processing by-products on in vivo digestibility, growth rate and enteric methane emission from fattening beef cattle
The experiments were conducted on 24 crossbred bred cattle (323.1 ± 30.4 kg) using for the trial of 90-dayslasting experiment in order to determine methane emission by addition of tannin from tea by-products. Cattles were housed in farm housing condition then were individually arranged to respiratory chambers to measure methane gas emissions. The diets consisted of basal diets with addition of 0.0%; 0.3%; 0.5% and 0.7% tannin from tea by products on dry matter basic. Animals were fed ad libitum experimental diets for 15 days of adaptation prior to testing. Results showed that the effect of different levels of tannin supplementation on the level of CH4 and CO2 emissions of experimental cattle was from 268 to 306 liters/day, there was a significant difference in the amount of methane released (P<0.05). The control had the largest emitted methane at 306 liters/day. The supplementation tannin at 0.3-0.5% DM, did not affect on DM intake, and in vivo digestibility but improve the growth rate (by 2.2-8.1%) and reduce methane emission intensity (by 7.9-26.2%, calculated as CH4/kg LWG. It was concluded that the optimum level of tea tannin supplement in fattening beef cattle diet was of 0.4% (0.38-0.41%, DM basic).
