Effect of feed protein content on ammonia volatilisation of pig effluents in the barn, during storage and spreading

Abstract

The aim of this study was to evaluate the effects of three strategies of protein feeding (12, 16 and 20%) on animal performance, nitrogen excretion and ammonia emission in the laboratory and in the field. The animals (15 castrated males) were housed individually in metabolism cages and were fed one of the three diets. The experiment lasted 21 days and urine and faeces were collected separately. Samples of each type of effluent (urine alone, fresh slurry and 18-day old slurry) were placed in a laboratory system designed to measure ammonia emission for 7 days. In the field, measurements of ammonia volatilisation were made during storage and surface-application of slurry. Lowering dietary crude protein while maintaining normal growth rate reduced urinary nitrogen and total amount of effluent, because of a lower water consumption. Ammoniacal nitrogen content, total nitrogen content and pH decreased when dietary crude protein decreased. This consequently reduced ammonia emission during all the stages of the management of the effluents. Over the whole process of the slurry ammonia emission was reduced by 63% when dietary protein decreased from 20 to 12%.