Effect of type of slatted floor and degree of fouling of solid floor on ammonia emission rates from fattening piggeries

The influence on ammonia emission to the atmosphere, of five types of slatted floor and of the degree of fouling of the solid floor was investigated in houses for fattening pigs. In the experiment there were two concrete slatted floors (SI with slats 10 cm wide and 2 cm gaps; S2 with slats 7 cm wide and 1.8 cm gaps); a cast iron slatted floor (S3 with slats 2.5 cm wide and 1.5 cm gaps) and two floors whose metal slats were triangular in cross section (S4 with 1 cm wide slats and 1 cm gaps; S5 was the same as S4, but partially covered over an area of 0.8 x 0.7 m with studs 5 cm high and 3.2 cm diameter, spaced at 20 cm). Three partially slatted compartments (all 25% slatted and 75% bare solid concrete) for 36 fattening pigs each were used. Air was drawn from outside through underground heat exchange tubes and entered the compartments via a ceiling of perforated plastic sheeting. The five types of slats were changed around between the three compartments (three in, two out) every three weeks during two growing periods of 15 weeks each, one during the winter and one during the summer. Ammonia concentrations in incoming and outgoing air and ventilation rate were measured continuously to calculate the ammonia emission to the atmosphere. The area of the solid floor wetted with urine was assessed visually. The excreting and lying locations of the pigs were determined from video recordings. S5 showed the lowest occurrence of excretions on the solid floor. Also in S5 the lowest number of pigs were lying on the pen partition side (the side with naps) of the slatted floor. The ammonia emissions were calculated relative to S1. These were 106% for S2, 95% for S3, 73% for S4 and 64% for S5 (SED 16%). The solid floor was fouled more during the summer than during the winter (P < 0.05); fouling increased towards the end of the growing period (P < 0.001). Opting for slatted floors from metal with more open space than concrete slatted floors, such as the floor with triangular section metal slats, significantly reduces ammonia emission from the slats. Partially covering the slatted floor with studs prevents pigs from lying in this area so that they use this area for excretion, giving less fouling and ammonia emission from the solid floor. (C) 1997 Silsoe Research Institute.