Investigation on the effects of vermiculite-based feed additives on ammonia and nitrate emission from pig slurry and pig growth performances

The aim of the present study was to evaluate the effects of vermiculite-based feed additives used in fattening pigs on the concentrations of nitrogen compounds in manure and atmosphere and upon measures of pig production efficiency. The trial was conducted in a fattening unit representative of Italian commercial units. The pigs were routinely fed twice a day with a feed ration identical for all the pigs except for the addition of the vermiculite additive (group A). During the fattening period, the evolution of atmospheric ammonia concentration, total nitrogen, ammonia and nitrates of slurry and pigs live weight gain were evaluated. The inclusion at very low dosage of vermiculite-based feed additives in fattening pigs increased the nitrification activity in the treated slurry. No reduction of the ammonia emission was obtained. The average growth rate of the treated group was higher, whilst the feed conversion rate was similar in both groups.