Effects of mixed-species stocking and space allowance on the behaviour and growth of red deer hinds and ewes at pasture

Abstract

Our objective was to test whether the effects of space allowance on social interactions, activity patterns and growth rates of hinds reared at pasture in single-species groups, were modified by mixing them with ewes. Thirty individuals of each species were assigned to two single-species groups of 10 animals (hinds: H1 and H2, ewes: E1 and E2) and to two mixed-species groups of 5 hinds and 5 ewes (M1 and M2). For 28 days, H1, E1 and M1 were kept at high space allowance (HSA: 267 m 2/animal) and H2, E2 and M2 at low space allowance (LSA: 67 m 2/animal) and for the following 28 days, the space allowance was reversed. Mean interindividual distances in single-species groups were lower at LSA than at HSA (hinds: 10.0±0.3 vs. 15.4±4.8 m, P<0.05; ewes: 7.9±0.5 vs. 11.0±2.5 m, NS). In mixed-species groups, distances between standing individuals of the same species were less than between individuals of a different species (hinds: 8.8±1.6 vs. 11.0±1.0 m, NS; ewes: 5.3±1.1 vs. 7.5±2.3 m, NS; hinds-ewes: 14.6±0.9 vs. 20.6±1.0, P<0.05, at LSA and HSA, respectively). Agonistic encounters between hinds were more frequent at LSA than at HSA when reared in single-species groups (median number of agonistic interactions/hour: 10.0 (9.6–12.8) vs. 5.0 (1.9–11.6), P<0.05). When reared in single-species groups, hinds were less synchronised during grazing at LSA than at HSA and they had shorter and more frequent meals. Such effects were not observed for ewes. Rearing the animals in mixed-species groups increased the effects of a restricted space allowance on grazing meals of hinds with a tendency to increase the number of meals and to reduce meal duration. In mixed-species groups, the effect of space allowance on ewes was more marked than when in single-species groups with ewes eating shorter and more frequent meals. The hinds reared in single-species groups grew slower at LSA than at HSA (185±63 vs. 225±42 g/day, P<0.01), whereas ewes grew at the same rates regardless of space allowance (175±53 vs. 185±54 g/day, at LSA and HSA, respectively, NS). In mixed-species groups, growth of both hinds and ewes was lower when space was restricted (hinds: 141±42 vs. 211±56 g/day, ewes: 170±47 vs. 202±32 g/day, at LSA and HSA, respectively, all P<0.05). In conclusion, restricting the space allowance resulted in behavioural changes and lower performance which were intensified by mixed-species stocking.