Effect of environmental cooling on certain biochemical responses in broilers

Investigations were undertaken to study the effect of different thermal environments of growth attributes of broilers. One hundred fifty-day old chicks of both sexes were kept each in control, foggers, exhaust fan and cooler groups during hot and dry, and hot and humid periods to assess the effect of cooling on growth efficiency of broilers in terms of blood cholesterol and ascorbic acid. The average cholesterol content (mg/100 ml) of blood plasma was highest in the control groups of both the periods. The birds of the control and exhaust groups were more stressed as compared to birds in fogger and cooler groups where the cholesterol content was least. The average values for the ascorbic acid content of blood plasma (mg/100 ml) were highest in the cooler groups of both the periods showing the greater resistance of these birds against the thermal stress. The increased amounts of ascorbic acid in the cooler groups were positively correlated to the heavier body weights of the birds in this particular group. In contrast, the birds in the control and exhaust groups had minimum amounts of ascorbic acid content at all ages irrespective of sexes. Therefore, from the above results of cholesterol content and ascorbic acid concentration, it is concluded that hot and humid period at Ludhiana is the most stressful and evaporative cooling is the most efficient method for alleviating summer stress in broilers.