Effect of temperature and dietary energy on layer performance.

DeKalb XL White Leghorn hens 20 wk of age housed at 16.1, 18.9, 22.2, 25.0, 27.8, and 31.1 C were fed diets containing 2,645, 2.755, 2,865, and 2,976 kcal MEn/kg. Feed intake was 5.9 g lower (P less than .05) when dietary energy was increased from 2,645 to 2,976 kcal MEn/kg and was 21.7 g lower when temperatures were increased from 16.1 to 31.1 C. The MEn intake of hens at temperatures ranging from 16.1 to 31.1 C was 61.2 (P less than .05) kcal/hen per day lower in treatments with the higher temperatures. The MEn intake of hens was also 16.7 kcal/day higher (P less than .05) when energy density in the diet was raised from 2,645 to 2,976 kcal MEn/kg. Egg production was not affected by either temperature or dietary energy density. Egg weight increased .78 g (P less than .05) with increases in dietary energy density from 2,645 to 2,976 kcal MEn/kg and decreased 3.18 g (P less than .05) when temperatures were raised from 16.1 to 31.1 C. Mean body weights and body weight gains were significantly (P less than .05) higher in treatments with higher energy density and lower in treatments with higher environmental temperatures. Feed conversion was increased .41 g feed/g egg mass (P less than .05) at higher temperatures (16.1 and 31.1 C) and increased .17 g feed/g egg mass at higher energy densities (2,645 and 2,976 kcal MEn/kg). Maintenance requirements were estimated at all temperatures.