The influence of early life socialisation on cognition in the domestic pig (Sus scrofa domestica)

Abstract

Previously, the benefits of early-life socialisation on later-life social development have been reported in pigs. Here we investigated the effect of pre-weaning socialisation on the later-life cognitive ability of pigs using a range of techniques. Pre-weaning, 101 piglets had access to a neighbouring pen from ~ 15 days of age and interacted with non-littermates (socialised). An additional 89 piglets remained isolated within their home pen (controls). After weaning, 100 individuals were selected for a range of cognitive tests including a food reward T-maze test, reversal learning T-maze test, a social preference T-maze test, and a puzzle box test. Performance during the food reward test was not influenced by treatment. Treatment effected improvement over the course of the reversal learning test, with controls showing a significant decrease in trial duration after the first two trials. During the social preference test, socialised pigs spent significantly more time in the presence of larger stimulus pigs than controls and were quicker to leave the middle of the maze, suggesting improved social skills. Neither sex nor treatment was observed to influence pig’s ability to solve the puzzle box. Thus, overall, evidence from the social preference test suggests an effect of pre-weaning socialisation on aspects of social cognitive development.

Cognitive tasks as measures of pig welfare: a systematic review

“…This is a relatively low but not unexpected sample size due to the high workload and time commitment associated with the cognitive task experimental paradigms. Notably, Weller et al ( 64 ) and Sneddon et al ( 65 ) had the highest number of animals per treatment group, 50 and 42, respectively.…”

“…Judgment biases and learned approach/aversion were the most used paradigms among the 11 cognitive tasks identified, but several other less common yet creative methods have been employed. For example, Weller et al ( 64 ) tested pigs’ innovation (i.e., ability to solve a new problem or find a new solution to an existing issue) by exposing them to a puzzle box they had to resolve to access a reward. Pigs’ betting tendencies were also studied via the Pig Gambling Task, with barren-housed or low birthweight pigs preferring “low-risk, low-reward” over “high-risk, high-reward” gambles ( 66 , 67 ).…”

“…Most studies explored in this review rely on food rewards as incentives for training and testing (e.g., ( 59 , 63 , 64 )), but performances in cognitive tasks can be affected by anhedonic processes. Anhedonia is a depression-like condition where responsiveness to rewards such as palatable food can be decreased when an individual is in a negative affective state ( 85 ).…”

Social behavior in farm animals: Applying fundamental theory to improve animal welfare

“…Several factors including diet, environmental enrichment, developmental stress, and personality may affect individual cognitive performance, and therefore decision making during contests (80,85,86). The effect of the social environment on cognitive development is a key area of interest in livestock studies (87)(88)(89)(90)(91), and these systems provide opportunities to design experiments investigating how social experience shapes assessment strategies and information use during contests (80).…”