Response of growing pigs to different evaporative cooling systems

Résumé

Study was conducted for seven weeks to compare the response of growing pigs to shower and wallow cooling systems. Growing cross breeds of Landrace x Large White pigs (weight 20-25kg) were used. Treatment 1, 2 and 3 were pigs without shower/wallow (control), pigs on wallow and pigs under shower, respectively. Forty-eight pigs comprising four pigs/replicate were replicated four times to the three treatments in a completely randomized design. The shower was activated for 5 minutes every hour from 11am to 5pm. During the period, the performance response, physiological parameter, temperature humidity indexes, microbiological and behavioral response of the growing pigs were observed. Significant differences were observed in the final weight of pigs in T3 (49.50 kg) compared to pigs in T1 (46.75 kg) and T2 (46.00kg). Although, pigs in T1 had the highest significant feed intake of 14.15kg compared to 10.81 kg and 10.38 kg that were observed for pigs in T2 and T3 respectively, the feed conversion ratio of pigs in T3 (3.82) was better. The temperature humidity index in the pen suggested that the pigs were at intense heat stress, thus requiring cooling (THI ranged from 81.12 to 86.39). The respiratory rate of the pigs ranged from approximately 41 min^-1 to 51 min0^-1 while the weekly rectal temperatures ranged from 37.3°C to 39.4°C in all the treatments. The microbial analysis of the water in wallow and shower showed an increase in microbial population to be 26.0 x 10⁴±3.54 and 12.0 x 10⁴±1.32 while the fungi populations were 2.0 x 10⁴±0.86 and 1.0.x 10⁴±0.57 respectively. Pigs in T1 were found to exhibit more habitual lateral lying position, increased frequency of visiting water trough and defecating in resting areas. Huddling, defecating in wallow and frequency of using wallow was predominant in T2 pigs. It can be concluded that pigs in wallows may be more predisposed to infectious diseases due to high microbial load, however, pigs under shower responded positively to cooling via improved performance.