Individual distance during resting and feeding in age homogeneous vs. age heterogeneous groups of goats

Abstract

The aim of this experiment was to investigate the individual distance during resting and feeding in homogenous and heterogeneous age groups of young and adult goats. Thirty-six young (<2 years) and thirty-six adult goats (>3 years) were allotted into 6 groups of young goats (YOUNG), 6 groups of adult goats (ADULT) and 6 heterogeneous age groups (HETERO), with 4 individuals in each group. Each group was tested in an experimental pen (12.0m×2.0m) for three days where a 24h video recording was conducted on the last day. The distance between all goats in the group (6 possible pairs) during resting was scored every 10min for 12h (from 18.00h to 06.00h) and during feeding every second minute for 2h after each feeding (09.00h and 15.00h).There was no significant effect of age composition or activity per se, but there was a clear interaction between age composition and activity regarding individual distance. Individual distance was significantly larger during feeding than during resting in the HETERO groups, but there was no such effect in the YOUNG and ADULT groups. The goats in the YOUNG groups had shorter individual distance when feeding than the HETERO and ADULT groups (1.71±0.12m, 2.93±0.09m and 2.87±0.16m respectively), but there was no significant difference between HETERO and ADULT. In the HETERO treatment, the individual distance between pairs of young goats was significantly lower than between pairs of adult goats and pairs of young–adult goats irrespective of activity (1.49±0.24m, 2.13±0.24m and 2.65±0.12m respectively). Variation in individual distance was lower during resting than during feeding in the YOUNG treatment, but not in the HETERO and ADULT treatment. To conclude, the individual distance was shorter during resting than feeding in the heterogeneous age groups, but this difference was not present in the adult or young, homogenous age groups. There were no differences in individual distance during resting between the different age groups. Overall, young goats appear to be more tolerant to having other individuals of similar age in close proximity and keep the longest distance to adult goats.