Energy metabolism of growing broiler chickens kept in groups in relation to the environmental temperature. 1. Feed intake, heat production and energy utilization]

In 5 experiments with young broiler chickens kept in groups at environmental temperatures (ET) of 35, 30, 25, 20 and 15 degrees C feed intake, live weight development and heat production were ascertained between their 5th and 57th days of life. Feed intake and live weight were ascertained separately according to sex. With live weight being the same, feed intake increased with decreasing ET. There was no maximum feed intake up to the 57th day of life at between 20 and 25 degrees C. At the end of their 57th day of life the male and the female chickens had achieved the following live weights (in the sequence of decreasing ET 35-15 degrees C): 1342; 2014; 2829; 2946; 2374 and 1367; 1900; 2512; 2496 and 2200 g/animal resp. The highest live weight gain of the chickens was achieved at between 25 and 20 degrees C with 60-70 g/d for male and with 50-60 g/d for female animals. Heat production (HP) increased progressively with age. The highest HP was registered at 20 degrees C ET.