Relating Weight Gain and Feed:Gain of Male and Female Broilers to Rearing Temperature

The effects of environmental temperature on growth and feed:gain were studied in three trials each for male and female broilers. Chicks were reared in a common environment to 21 d of age. At 21 d, they were randomly allocated to 10 environmental chambers. Each chamber was maintained at a constant temperature; the chambers ranged from 12 to 30 C in two-degree increments. The dewpoint was maintained at 18 C, except that relative humidity was not permitted to exceed 82.9%. Body weight was determined at 21 d. Weight gain and feed:gain were determined at 28, 35, 42, and 49 d. The data were analyzed statistically, and regression equations were obtained for weight gain and feed:gain for each sex. Equations were based on body weight and temperature, and the body weight equations were plotted as grams gained per bird per day. Feed:gain increased with increasing weight. The temperature that resulted in the most favorable feed:gain decreased with increasing weight. These results support lower rearing temperatures for optimum growth and feed:gain by large broilers than those of other reports in the literature.