The objective of this study was to detennine the effect of crude protein levels in concentrate on enteric methane production from Vietnamese local fattening cattle. Animals (24 steers, initial live weight 150.3 +/- 11.8 kg) were arranged in a randomized complete block design with four treatments of protein levels in concentarate of 10, 13, 16 and 19 percent. Concentrate was fed at 1.5 percent of body weight, and roughage was 5 kg/d native grass and ad libitum rice straw (fresh basis). Enteric methane production was estimated by using tier 3 method of IPCC (2006) via the RUMINANT model. Results showed that dry matter and crude protein intake was increased with increasing protein levels in concentrate
average daily weight gain was increased from 0.58 to 0.77 kg/day when crude protein levels in the concentrate were increased from 10 to 19 percent. Enteric methane production ranged from 0.078 to 0.086 kg/day and methane efficiency ranged from 1.94 to 2.15 kg CO2eq/day, however no differences among crude protein levels were found (P0.05). Enteric methane production and methane efficiency per kg dry matter intake and per 100 kg body weight was tended to reduce in cattle fed a diet with 16 percent CP in the concentrate compared to other protein levels (P0.05). In conclusion, diet with 16 percent CP in the concentrate can be fed to Vietnamee local cattle to increase their performance and to reduce enteric methane production.