A study of the effects of environmental light and temperature on selected blood and urinary factors in broilers

Two experiments were conducted to investigate the effect of light, temperature, and age on some blood parameters and ammonia excretion by male broiler birds. Light treatments were 16L:8D and 24L:0D while temperature treatments were 20^°C and 35^°C within each light treatment. Samples were taken at 2, 4, and 6 weeks of age. Results show that light and temperature had no significant effect on blood concentrations of sodium, potassium, chloride, CO₂, anion gap, or ammonia, kidney asparaginase activity, plasma corticosterone levels, or total ammonia excreted in the feces. However it was found that blood ammonia levels at 2 weeks of age were significantly higher when compared to levels obtained at 4 and 6 weeks of age. It was concluded that this was due to the effect of the high protein diet fed to birds to 3 weeks of age. Kidney asparaginase activity was also significantly higher at 2 weeks of age which could reflect the effect of the high protein diet and the rapid turnover and restructuring of proteins in the body while birds are growing at a very fast rate. Plasma corticosterone levels tended to be higher at 2 weeks of age when compared to levels at 4 and 6 weeks. Birds on 24L:0D light treatment had higher corticosterone levels than birds on 16L:0D light treatment but not significantly so, which might indicate the tendency for continuous light to over-stimulate the adrenal gland directly or indirectly and initiate changes in blood chemistry and the normal physiological status of the body. Atmospheric ammonia was higher in 16L:0D light treated birds at all ages compared to the 24L:0D treated birds. This difference is thought to be due to prevailing conditions in the litter which tended to be more wet in pens with birds under continuous light thus suppressing uric acid and other nitrogenous compounds breakdown to ammonia by anaerobic bacteria.