The effect of environmental conditions on broiler performance
1- Body weight was significantly affected by temperature at 49 days in all three experiments. Body weight was higher at the lower temperature (2591 vs 2518 g).2- Body weight was significantly affected by the light regime at 6 weeks of age. Body weight was higher with intermittent light (9L : 3D) compared to continuous light (23L : 1D) (2223 vs 2164 g).3 - As expected, given the differences in body weight at 49 days, at 6 weeks of age daily weight gain was significantly affected by temperature, and by light regime (52.5 vs 50.8 and 50.4 vs 51.8 g respectively).4- Ammonia concentrations increased greatly with the age of the birds. The mean concentrations in experiments 1 and 3 all fell below the recommended for animal threshold limit value of 20 ppm ( but in experiment 2 the mean concentrations of ammonia were higher (28 ppm) than the recommended TLV of 20 ppm.5- Ammonia concentration was significantly greater in rooms with a litter depth of 30 mm (32 ppm) compared with 45mm, (24.2 ppm).6- Ammonia concentration was greater than 'Litterite' than wood shavings after the third week (11.2 vs 7.9 ppm)7- Inspirable dust concentration was significantly greater in rooms at the higher temperature in all the three experiments (10 vs 13.3 mg/m3) and in rooms with near-continuous light in experiment 1 (8.5 vs 5.7 mg/m3).8- Settled dust concentration was significantly greater in rooms at higher temperature in all experiment 2 and 3 (614.5 vs 474.35 mg/m2).9- Ammonia concentration was higher (but NS) in rooms at the higher temperature (21°C) compared with rooms at the low temperature (19°C) in all three trials (19.3 vs 22.3 ppm).10- Stocking density significantly affected ammonia concentrations in the 5th week and from 3-7 weeks of age (8.9 vs 13.3 ppm) (8.5 vs 11.2) respectively. Overall, the lower temperature (19 C), intermittent light, a litter depth of 45mm and a low stocking density (16 birds/m2) led to reduced ammonia and dust concentrations, an increased body weight, and daily weight gain and reduced mortality (NS).