Degree Type


Date of Award


Degree Name

Doctor of Philosophy


Agricultural and Biosystems Engineering

First Advisor

Hongwei Xin


An extensive literature review and comparative analysis of heat and moisture production (HP, MP) of various poultry types (layers, broilers, and turkeys) and their housing systems indicated that total heat production (THP, W/kg) has increased over the years by about 15 to 44% (1968 to 2000) for broilers, and by 36 to 63% (1974 to 1998) for tom turkeys. The metabolic rate equations derived from the literature data were 8.55 M0.74 (1968) and 10.62 M0.75 (1982 to 2000) for broilers; 6.47 M0.77 for pullets and layers (1953 to 1990); and 7.54 M0.53 (1974 to 1977) and 9.86 M0.77 (1992 to 1998) for turkeys. HP and MP of modern pullets (W-36 and W98) and W-36 laying and molting hens were measured. THP was partitioned into latent and sensible HP (LHP, SHP) for the bird (excluding moisture evaporation from the feces) or the room (including fecal moisture evaporation). The W-98 pullet produced higher THP than the W36 counterpart. Modern pullets showed higher THP (12--37%) than those 20 to 50 years ago. At the beginning of egg production, THP of the modern layers was 12% higher than that predicted by the CIGR (1999) model and the difference diminished with time. Evaporation of fecal moisture elevated room LHP by 8--79% and reduced the room SHP by 4--33% with reference to bird LHP or SHP. THP for molting hens ranged from 4.4 to 5.6 W/kg, 5.4 to 6.5 W/kg, and 6.7 to 6.9 W/kg during fasting, restricted feeding and post molt periods, respectively. LHP ranged from 1.7 to 2.1 W/kg, 1.5 to 2.0 W/kg, and 2.4 to 2.9 W/kg during the respective periods. The corresponding SHP ranged from 2.6 to 3.5 W/kg, 3.9 to 4.6 W/kg, and 3.9 to 4.4 W/kg, respectively. Results of this study provide an updated thermal load database for design and operation of poultry housing ventilation systems, as well as bioenergetics information for the scientific literature. Ventilation curves based on the new HP and MP were developed for 37week old W-36 hens housed at currently practiced stocking density and a recommended stocking density. The result revealed little influence of stocking density on supplemental heat requirement.



Digital Repository @ Iowa State University,

Copyright Owner

Hakgamalang Justin Chepete



Proquest ID


File Format


File Size

174 pages