Feeding dairy cows for decreased ammonia emission

Greater demands will be placed on animal production in order to minimise emissions of ammonia and other wastes. Ammonia originates in the nitrogen part of faeces and urine. Thus, a good method to decrease ammonia is to reduce nitrogen residues in manure by appropriate feed rations. This was done in a study concerning the effects of decreased protein supply on ammonia release from dairy cattle manure. Rations with 14 and 19% of protein in the total dry matter ration were compared. Also, two feeding routines were included, separate feeds and a total mixed ration. The ammonia release was estimated on 24-h samples of manure (faeces and urine) from individual cows. At low protein levels, the ammonia emission decreased by 2/3 compared with the high level. No effects on milk production (mean 31 kg) or on milk composition were observed in this short-term experiment. Nitrogen efficiency, i.e. milk nitrogen in percent of consumed nitrogen, was 39% at low protein level compared with 29% at high level. Ration composition will be important in the efforts to reduce negative environmental influences resulting from milk production. The applied measuring technique seems to be a good tool in estimating the influences of diet on gaseous emissions. (C) 2002 Elsevier Science BY. All rights reserved.