Within-session decreases in lever pressing responses in pigs under feeding scheme of livestock industry

Abstract

The present study examined within-session decreases in lever pressing responses in domestic pigs bred under the ordinary feeding scheme of the livestock industry. Two castrated male pigs were trained to obtain 3.4-g food pellets by lever pressing responses. Under the continuous reinforcement schedule in 90-min sessions, pigs' response rates were completely steady for the first 30 min (about 500 pellets) and then gradually decreased. The decrease of response rates was equally well described as a linear function of cumulative food intake and that of passed time.