Heat and Moisture Production of Poultry and Their Housing Systems: Molting Hens

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Chepete, H. Justin
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Xin, Hongwei
Distinguished Professor Emeritus
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Agricultural and Biosystems Engineering

Since 1905, the Department of Agricultural Engineering, now the Department of Agricultural and Biosystems Engineering (ABE), has been a leader in providing engineering solutions to agricultural problems in the United States and the world. The department’s original mission was to mechanize agriculture. That mission has evolved to encompass a global view of the entire food production system–the wise management of natural resources in the production, processing, storage, handling, and use of food fiber and other biological products.

In 1905 Agricultural Engineering was recognized as a subdivision of the Department of Agronomy, and in 1907 it was recognized as a unique department. It was renamed the Department of Agricultural and Biosystems Engineering in 1990. The department merged with the Department of Industrial Education and Technology in 2004.

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  • Department of Agricultural Engineering (1907–1990)

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Heat and moisture production rates (HP, MP) of modern 68- to 75-week-old Hy-Line W-36 laying hens during molting were measured using large-scale indirect calorimeters that mimic commercial production settings. The measurements were performed continuously during acclimation, fasting, restricted feeding, and post-molt. Total HP (THP) was partitioned into latent and sensible HP (LHP, SHP) that incorporated influence of fecal moisture evaporation. THP during fasting (averaging 4.8 W/kg) and restricted feeding (averaging 6.0 W/kg) averaged 29% and 13% lower than that during post-molt (averaging 6.8 W/kg). Correspondingly, LHP averaged 1.9 W/kg and 1.8 W/kg and was 31% and 34%, respectively, lower than that (averaging 2.7 W/kg) during post-molt. Likewise, SHP averaged 2.9 W/kg during fasting and was 28% lower than during post-molt (averaging 4.1 W/kg). The average SHP under restricted feeding and post-molt was similar (4.2 vs. 4.1 W/kg, respectively). Respiratory quotient (RQ) averaged 0.71, 0.76, and 0.92 during fasting, restricted feeding, and post-molt, respectively. Heat production rates during the light period were significantly higher (P < 0.05) than those during the dark period. Daily mean and diurnal LHP as percentages of THP were similar during fasting and post-molt but they were 10% lower during restricted feeding. The results of this study provide a new thermal load database for design of housing ventilation systems for laying hens undergoing molting phase.


This article is from ASHRAE Transactions 110, no. 2 (2004): 274–285.

Thu Jan 01 00:00:00 UTC 2004