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GROWTH AND PRODUCTION OF LAYERS RAISED IN A CONTROLLED THERMAL ENVIRONMENT COMPARED TO THOSE IN AN ENVIRONMENT NON-CONTROLLED
Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.org
Citation: Proceedings of the Seventh International Symposium, 18-20 May 2005 (Beijing, China) Publication Date 18 May 2005 701P0205.(doi:10.13031/2013.18409)
Authors: H. Minagawa and R. S. Gates
Keywords: Layer, thermal environment, growth, production, economic optimization
For intensive livestock and poultry production in animal buildings, economic optimization
techniques are needed. In this research, we investigated a relationship between the growth and
production of laying hens and their thermal environment to obtain a growth and production
model of layers that is based on economic optimization of environmental control for egg
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Two groups of five laying hens, White Leghorn, were examined and confined to a cage
individually in a barn. The barn was not equipped with an air conditioner, only protected from
rain, wind, and solar radiation. The air temperature of one group was controlled with a heater in
an adjacent room in the barn and that of the other group was not controlled. Hence the noncontrolled
group was dependent on the thermal environment of the barn. The hens were raised
from an age of 17weeks on Oct 26, 1995 to 47 weeks on May 29, 1996. We measured air
temperature, humidity, feed intake, water intake, and number and weight of eggs daily, as well as
weekly factors of waste production and body weight.
During the experiment the controlled group was kept at a thermal environment of air temperature
and relative humidity; (15 C 2 C) and (42% 6%), respectively represented by (average
s.d.). The non-controlled group attained an air temperature of (5 C 5 C) and a relative
humidity of (68% 5%) for the entire period. During the age of 19 weeks to 47 weeks, except
for two weeks at the beginning, the average daily feed intake was not different (P>0.1) between
the two groups. However the average daily measurements of water intake, egg weight, waste
production, body weight were greater in the controlled group. Across all ages the average feed
requirement, (dividing daily feed intake by daily egg weight), was 1.97 for the controlled group
and 2.04 for the non-controlled group. The feed efficiency was greater by 3.6% in the controlled
group. The small gain is due to hens of the controlled group using feed energy for egg production
and also weight gain. For both groups, the feed requirement decreased linearly with an increase
of air temperature and was not affected by relative humidity.