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

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 i ndividuals of each species were assigned to two single-species groups of 10 animals (hinds: H1 and H2, ewes: Fl and E2) and to two mixed-species group s of 5 kinds and 5 ewes (M1 and M2). For 28 days, H1, El and M1 were kept a t high space allowance (HSA: 267 m(2)/animal) and H2, E2 and M2 at low spac e allowance(LSA: 67 m2/animal) and for the following 28 days, the space all owance was reversed. Mean interindividual distances in single-species group s 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 enc ounters 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 gro ups, hinds were less synchronised during grazing at LSA than at HSA and the y had shorter and more frequent meals. Such effects were not observed for e wes. Rearing the animals in mixed-species groups increased the effects of a restricted space allowance on grazing meals of hinds with a tendency to in crease the number of meals and to reduce meal duration. In mixed-species gr oups, the effect of space allowance on ewes was more marked than when in si ngle-species groups with ewes eating shorter and more frequent meals. The h inds reared in single-species groups grew slower at LSA than at HSA. (185 /- 63 vs. 225 +/- 42 g/day, P < 0.01), whereas eu es 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 a ll P < 0.05). In conclusion, restricting the space allowance resulted in be havioural changes and lower performance which were intensified by mixed-spe cies stocking. (C) 1999 Elsevier Science B.V. All rights reserved.