The learning ability and memory retention of broiler breeders: 1 effects of reduced balanced protein diet on reward based learning

Learning and mental abilities of farm animals are important for their adaptation to new environments and could serve as an indicator for welfare and performance. This study assessed the learning ability and memory retention of broiler breeders through a T-maze test with a reward v. no reward set-up. Feed supplemented with or without meal worms served as a reward. Two trials were conducted with either parent stock (PS) breeders or pure line A (PL) breeders and with the same dietary treatment namely a control (C) group fed with standard commercial diets and a reduced balanced protein (RP) group fed with RP diets (25% reduction of CP and amino acids). To maintain similar target BW, the RP group received on average 10% more feed. A tonic immobility (TI) test was performed to estimate the fearfulness of PS breeders. Most breeders were capable of completing the T-maze tests, but the C group needed less time compared with the RP group when their own feed was given as a reward. However, when meal worms were provided as an extra incentive, the RP group completed the maze significantly faster than the C group. Compared to the C breeders, the RP breeders remained longer in a TI state, indicating a higher level of fearfulness. Long-term memory retention in the T-maze test was observed in both groups. It is concluded that the RP diet had no influences on the learning ability of the reward v. no reward discrimination test and its memory retention of broiler breeders. The increased amount of time the RP breeders needed to solve the test was probably due to a higher sense of fear. Furthermore, the RP diet enhanced the motivation of breeders to obtain an alternative feed such as meal worms.