Performance of large groups of chicks using operant conditioning to control the thermal environment

In 4 trials, 408, 320, 160 and 400 one-day-old [male] chicks were housed on litter in pens measuring 1.8 x 2.4 m. Eight pens were used for each trial. For the first 6 days, temp. was maintained at 28 degrees C and on day 7 reduced to 16 degrees . Four pens were equipped with microswitches; the remaining 4 pens were each continuously heated by 2 infrared lamps. When chicks pressed the microswitch, infrared lamps were turned on for 1 min during the learning phase (operant conditioning) (day 7) and for 4 min during the experiments (from day 8). Trials 1 and 2 were concluded at 28 days, and trials 3 and 4 at 21 days. No significant differences in body weight gain, feed conversion efficiency, body composition and mortality rate were found between operant-conditioned chicks and those continuously supplied with heat. Chicks provided with continuous heat were exposed to 3 times as much supplementary heat as operant-conditioned chicks..