Heat and Moisture Production of Molting Laying Hens

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Chepete, H.
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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 the molting stage were measured using large-scale indirect calorimeters that mimic commercial production settings. The HP and MP were measured continuously during acclimation, fasting, restricted feeding, and postmolt or normal periods. Total HP (THP) was partitioned into latent and sensible HP (LHP, SHP), which incorporated the influence of fecal moisture evaporation. THP during fasting (averaging 4.8 W/kg) and restricted feeding (averaging 6.0 W/kg) periods averaged 29 and 13% lower than that during postmolt period (averaging 6.8 W/kg). Correspondingly, LHP averaged 1.9 W/kg and 1.8 W/kg and was 31 and 34% lower than that during postmolt period, which averaged 2.7 W/kg. Likewise, SHP averaged 2.9 W/kg during fasting period and was 28% lower than during postmolt period, which averaged 4.1 W/kg. The average SHP between restricted feeding and postmolt periods were similar (4.2 vs. 4.1 W/kg, respectively). The respiratory quotient (RQ) averaged 0.71, 0.76, and 0.92 during fasting, restricted feeding, and postmolt periods, respectively. HP values during the light period were significantly higher (P<0.05) than those during the dark period. The daily mean and diurnal LHP as a percentage of THP were similar during fasting and postmolt periods and were comparatively 10% lower during restricted feeding period. The results of this study provide a new thermal load database for design of building ventilation systems for laying hens undergoing molting phase.


This is an ASAE Meeting Presentation, Paper No. 024071.

Tue Jan 01 00:00:00 UTC 2002