Broiler Growth in Diurnally Cycling Temperature Environments

MAXIMUM growth and feed efficiency are not attained when broilers are grown in environmental temperatures constantly above or below an optimal range for their age (Barott and Pringle, 1947Barott and Pringle, 1949Barott and Pringle, 1950; Joiner and Huston, 1957; Squibb et al., 1959a; Prince et al., 1961; Adams et al., 1962; Huston, 1965). After four weeks of age, requirements become less stringent with a constant temperature within the range 15 to 27°C. (approximately 60–80°F.) appearing to give the best weight gains and feed efficiency (Milligan and Winn, 1964; Prince et al., 1965). There are few data, however, on the effects of fluctuating temperatures on broiler growth. Reece et al. (1969) have reported that cycling the temperature from 4.4 to 15.6°C. diurnally during the eight week growing period results in increased mortality but does not appear to influence the percentage condemned, with or without the presence of Mycoplasma gallisepticum. It has been suggested that…