Influence of early quantitative food restriction on long bone growth at different environmental temperatures in broiler chickens

1. This investigation was carried out to study the influence of early quant itative food restriction (40% of ad libitum intake from 7 to 14 d of age) a nd environmental rearing temperature (thermoneutral, cold and hot) on long bone (tibia, femur and humerus) development in broiler chickens. 2. Tibia, femur and humerus were obtained at the ages of 14, 21, 28, 35 and 42 d; and the variables studied were: length and width (mm, expressed as a bsolute values), bone breaking strength (kgf) and bone weight/bone length i ndex (BW/BL, mg/mm). 3. All bone variables increased with bird age. Food restriction reduced bon e length and width but did not affect bone weight. High environmental reari ng temperature reduced bone length and width at 42 d of age. Bone strength was not affected by environmental temperature but the calculated BW/BL inde x was reduced by heat exposure. 4. The findings suggest that food restriction and high environmental rearin g temperature reduce long bone growth; bone breaking strength was affected by bird age but not by food restriction nor rearing ambient temperature.