Effects of different litter depths on environmental parameters and growth performance of growing finishing pigs

Deep litter systems represent low cost alternatives to raise growing-finishing pigs, reducing slurry accumulation, although pig???s thermal comfort may be negatively affected by the heat produced inside the litter. This study compared environmental and performance parameters for growingfinishing pigs raised on deep litter systems having distinct depths and on solid floor. The experiment was conducted in a region of temperate climate of Brazil, comparing three treatments: litter having rice husk 0.5m (T1); and 0.25m deep (T2); and solid concrete floor (T3). The first litter was used in two lots and replaced by a second litter used in other two lots, during 52 weeks. Each lot included five pigs in a 7m2 pen, from 60 to 145d of age. Environmental parameters were determined at weekly intervals, including: atmospheric temperature; relative humidity; temperature at the center of the pen, in the surface(TSF); and at half of the depth (THD), only for T1 and T2. Feed consumption and weight of pigs were measured every four weeks. Atmospheric temperature and relative humidity were not influenced by the treatments (P>0.05). Mean TSF was 22.8 ?? 3.6oC, being lower for T3 (P<0.05), but with no difference between T1 and T2 (P>0.05). TSF was higher for new than for used litters (P<0.001) and for the first than for the second litter (P=0.03), apparently increasing in lots raised during termophilic phases. Mean THD was 33.8??10.8oC, being higher for T1 than for T2 (P<0.05). THD was also higher for new than for used litters (P<0.001) and for the first than for the second litters (P<0.05). No growth performance parameter differed across treatments (P>0.05). Despite the potential unfavorable thermal comfort under high temperatures, deep litter systems can be used to raise pigs in the growing-finishing phases due to the absence of negative effects for growth performance