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

In four trials, 408, 320, 160, and 400 chicks were housed on litter in pens 1.8 x 2.4 m. Eight pens were used for each trial. For the first 6 days the environmental temperature was maintained at 28 C; on Day 7 the temperature was reduced to 16 C. Four pens were equipped with microswitches; the remaining four pens were each heated by two infrared lamps in constant operation. When chicks struck the microswitch, infrared lamps were turned on for 1 min during the learning phase when chicks were being conditioned to the experimental setup and 4 min during the experimental phase during which data were collected for analysis. Feed intake, gain, and mortality were recorded. Trials 1 and 2 were concluded at 28 days and Trials 3 and 4 concluded at 21 days. At the conclusion of the trials protein, fat, and water content of the birds were determined. Additional analysis for ash content was performed for Trials 1 and 2 only. No significant differences (P greater than .05) in gain, feed conversion, body composition, and mortality rate were found between treatments. Chicks provided with continuous heat were exposed to three times as much supplemental heat as operant conditioned groups yet feed efficiency was unaffected.