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Moisture Production from Grower-finisher Pigs – Field Measurements Compared with Theoretical Values

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  Paper number  024183,  2002 ASAE Annual Meeting . (doi: 10.13031/2013.9177) @2002
Authors:   Shala K. Christianson, B.Sc., Graduate Student, Stéphane P. Lemay, Ph.D, P.Eng., Claude Laguë, Ph.D, P.Eng., John F. Patience, Ph.D, and Ernie M. Barber, Ph.D, P.Eng.
Keywords:   swine, moisture production, latent heat, dry feeders, wet/dry feeders, prediction

Moisture production (MP) measurements were taken for four grower-finisher cycles (23- 110 kg) in a modern swine barn. Values from various guidelines were determined for identical pig weights and ambient temperatures, and comparisons were made between the measured and predicted values to determine the validity of the guidelines currently being used. When comparing the measured MP with theoretical MP values, CIGR (1984) yielded the best estimates although the average MP was underestimated on average by 9% for all cycles. CIGR (2002) and Bond et al. (1959) also underestimated the average MP by 21 and 32%, respectively. The ks factor for slatted floors was decreased from 0.91 to 0.85 in the CIGR (1984) MP equations. However, the average calculated MP did not reflect the measured average MP of all pigs in the first experiment more closely for the 43-45 kg or 97-101 kg weight range, but the measured average MP was reflected more closely for the 73-77 kg weight range. This indicates different ks factors may be suitable for different weight ranges. As well, a diurnal pattern of MP by the pigs was observed. However, the MP equations do not account for this pattern and therefore should not be used for dynamic modeling. Predictions for animal activity were compared to the MP diurnal pattern and the patterns were similar, particularly at the larger pig weights. This animal activity equation may be suitable for dynamic modeling of MP. Dry and wet/dry feeders were used for this experiment, with two cycles using each feeder type. No feeder effect was found on the MP. As well, incomplete air mixing patterns in the rooms and slow relative humidity instrument response time were found to affect the MP measurements when the ventilation rate increased by not fully accounting for the increase of moisture entering the room through the ventilated air.

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