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 gregarious ness, however, varies with season, breed, sex and age. In this study the so cial behaviour of two breeds of ewe (Suffolk and Scottish Blackface) was in vestigated over two years in two different environments. In addition, to ex amine whether lamb behaviour would affect the behaviour of the ewe, an embr yo transfer study was carried out between the two breeds resulting in four combinations of ewe and lamb (Blackface ewe with Blackface lamb, n = 25; Bl ackface ewe with Suffolk lamb, n = 24; Suffolk ewe with Suffolk lamb, n = 2 5; Suffolk ewe with Suffolk lamb, n = 25). All ewes and lambs grazed togeth er in Field 1 (year 1) and Field 2 (year 2). Field 1 was 9 ha and rather un iform; Field 2 was 21.4 ha and had two distinct regions: an upland and a lo wland area. Blackface ewes preferentially associated with their own lamb wh ereas Suffolk ewes associated equally with their own lamb or another Suffok e ewe, there was no effect of lamb breed (percent observations with own lam b 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 Suf folk awes, regardless of year or lamb breed (Blackface ewes = 6.10 m, Suffo lk 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 on e 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 b reeds, however subgroups were significantly smaller for Blackface ewes (7.5 3 and 9.26 ewes for Blackface and Suffolk respectively, P < 0.001). In Fiel d 2 Blackface ewes were found mainly in the upland region of the field wher eas Suffolk ewes were almost exclusively in the lowland areas. Mean distanc e between ewes increased markedly for Blackface ewes when compared to ewe-e we 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 de clined for Blackface ewes in comparison to Field I but increased for Suffol ks (Blackface = 3.10, Suffolk = 11.31 ewes, P < 0.001). Lamb breed had no e ffect on the social behaviour of either breed of ewe. The two breeds had di ffering behaviour in their relationship to their own lamb. Their relationsh ip to other ewes, however, was significantly modified by the environment al though the Blackface breed was less gregarious than the Suffolk under both conditions. (C) 1999 Elsevier Science B.V.