Sex and genotype dependence on the effects of long-term high environmental temperatures on cellular enzyme activities from chicken organs.

The effects of long term hyperthermia on enzyme levels in the chicken heart and breast muscles, brain, kidney, liver and lung, in relation to sex and degree of feathering, were studied. The enzymes studied were alanine and aspartate amino-transferases, alkaline phosphatase, creatine kinase, lactic dehydrogenase and gamma-glutamyltransferase. Double heterozygote frizzled naked neck and normally feathered male and female broilers were exposed to 24 degrees C (control group) and 32 degrees C (experimental group), for 5 weeks, starting at the age of 3 weeks. The birds were killed, the tested organ removed, homogenized and cell-free supernatant was obtained by centrifugation. Enzyme activities were measured with an autoanalyser and specific activities were calculated. Prolonged heat stress resulted in changes of enzyme activities in all the tissues studied. No significant differences were seen in the cellular enzyme levels from the various organs between male and female birds unexposed to heat stress. Following heat stress, however, greater changes in enzyme levels were seen in the brain, heart muscle and kidney of males compared to females. No significant differences were seen in the cellular enzymes studied in the tissues between the normal and frizzled naked neck chicken. Following prolonged heat stress, there were some differences in the degree of response between the frizzled naked neck and control groups. These differences did not show a consistent or clear pattern indicative of the degree of stress in each of the groups.