Ewe-ewe and ewe-lamb behaviour in a hill and a lowland breed of sheep: a study using embryo transfer

Domestic sheep have a strong social tendency. The nature of this gregariousness, however, varies with season, breed, sex and age. In this study the social behaviour of two breeds of ewe (Suffolk and Scottish Blackface) was investigated over two years in two different environments. In addition, to examine whether lamb behaviour would affect the behaviour of the ewe, an embryo transfer study was carried out between the two breeds resulting in four combinations of ewe and lamb (Blackface ewe with Blackface lamb, n = 25; Blackface ewe with Suffolk lamb, n = 24; Suffolk ewe with Suffolk lamb, n = 25; Suffolk ewe with Suffolk lamb, n = 25). All ewes and lambs grazed together in Field 1 (year 1) and Field 2 (year 2). Field 1 was 9 ha and rather uniform; Field 2 was 21.4 ha and had two distinct regions: an upland and a lowland area. Blackface ewes preferentially associated with their own lamb whereas Suffolk ewes associated equally with their own lamb or another Suffoke ewe, there was no effect of lamb breed (percent observations with own lamb as nearest neighbour, Field 1: Blackface ewes = 50.2%, Suffolk ewes = 43.5%, P < 0.05; Field 2. Blackface ewes = 73.1%, Suffolk ewes = 43.5%, P < 0.001). Blackface ewes were also significantly closer to their lambs than Suffolk awes, regardless of year or lamb breed (Blackface ewes = 6.10 m, Suffolk ewes = 11.54 m, P < 0.001). When own lamb was not the nearest neighbour ewes associated with other ewes of the same breed as themselves (With same-breed ewe = 88.4% of observations, with other-breed ewe = 11.6%, P < 0,001). In Field 1 the distribution of both breeds in the field was similar to one another but ewes maintained subgroups composed predominantly of their own breed (P < 0.001), The mean distance between eu es was the same for both breeds, however subgroups were significantly smaller for Blackface ewes (7.53 and 9.26 ewes for Blackface and Suffolk respectively, P < 0.001). In Field 2 Blackface ewes were found mainly in the upland region of the field whereas Suffolk ewes were almost exclusively in the lowland areas. Mean distance between ewes increased markedly for Blackface ewes when compared to ewe-ewe distance in Field I but was unchanged for Suffolks (11.29 vs. 4.36 m for Blackface and Suffolk ewes respectively, P < 0.001). Subgroup size also declined for Blackface ewes in comparison to Field I but increased for Suffolks (Blackface = 3.10, Suffolk = 11.31 ewes, P < 0.001). Lamb breed had no effect on the social behaviour of either breed of ewe. The two breeds had differing behaviour in their relationship to their own lamb. Their relationship to other ewes, however, was significantly modified by the environment although the Blackface breed was less gregarious than the Suffolk under both conditions. (C) 1999 Elsevier Science B.V.