EFFECT OF CYCLING TEMPERATURE ON GROWTH, ENERGY-METABOLISM AND NUTRIENT RETENTION OF INDIVIDUAL MALE TURKEYS

1. Each week, from 12 to 20 weeks of age, male turkeys of a heavy stra in were subjected to cool (C; 16 degrees C), hot (H; 29 degrees C), an d cycling temperatures, and fed on a standard diet ad libitum for 4 d. Lighting was intermittent, 3 h on, 3 h off. Food was given when light s were on. Those given cycling temperatures (3 h C; 3 h H) were given food and light during the cool (eat-when-cool, EC) or hot (EH) periods . 2. Birds in all treatments gained similar amounts of weight from 12- 14 weeks of age. Thereafter, birds in C maintained gains, the body wei ght gains of birds in EC and EH declined moderately and birds in H los t weight. 3. Birds in C produced more metabolic heat. Those in H showe d increased, heat production as they became older. 4. Protein retentio n was greater in turkeys in C, EC and EH. It was lower in H, becoming negative between 18-20 weeks of age. Birds in H suffered body fat loss es which increased with age. 5. Birds in EH and EC gained similar amou nts of body weight. Birds in EH exhibited lower heat production and gr eater energy retention than those in EC. 6. Body temperatures were hig her in H than in the other environments.