Investigation of heat stress during a typical broiler growout in Akure, Nigeria

 

There is little data on the thermal micro-environment and heat stress in poultry production systems in Nigeria. More knowledge can prepare managers to provide suitable environmental management systems. Thermal stress on broilers is an important factor in the hot, humid, non-windy tropical environments of Nigeria.

Air temperature, relative humidity and wind speed were measured inside and outside an open sided a naturally ventilated poultry house in Akure (7° 15’N, 5° 17’E), Nigeria for the period 3rd - 22nd February 2003. Birds were raised in stacked three-tier cages and were 4 weeks old when the measurement started.

A temperature humidity index (THI) chart for broiler (Swick, 1988), was used to categorize the thermal heat stress regimes experienced by the broilers. Out of the five categories of thermal regimes on this chart only three (comfort, moderate heat stress and high heat stress) were characterized in this study.

Results reveal that the birds in the cages at the lowest level were comfortable for about 4 % of the study period, while those in the middle and topmost cages were comfortable for about 12 and 34 % of the study period respectively. Observation also show that the birds in the cages at the lowest level were only moderately stressed for about 64 % of the study period, while those in the middle and topmost cages were moderately stressed for about 60 and 43 % of the study period respectively. Birds in the cages at the lowest level were highly stressed for about 32 % of the study period, while those in the middle and topmost cages were highly stressed for about 28 and 23 % of the study period respectively. Panting and skin temperature were also observed to increase with increasing ambient temperature above 27 ° C.

These results show that these broilers raised using stacked cages in naturally ventilated open-sided poultry houses in Akure were provided inadequate conditions for the bird’s comfort and performance. Economic losses to the farmers raising birds under this system in Nigeria are still being quantified.

These data sets will be useful in growth models as well as the design of low cost environmental management systems for improved poultry production in Nigeria.                      

##