Hand-feeding and gentling influence early-weaned lambs' attachment responses to their stockperson

Artificially reared herbivores are highly dependent on the stockperson at a n early age in order to learn to drink from an artificial milk provider. Th is period of training may be a determinant for the animals' subsequent resp onses toward humans. However, long-term responses may also depend on the hu man contact (e.g., visual, physical interactions, gentling, and handling) p rovided to the young lambs after this training period. We examined whether different levels of subsequent contact (no visual and physical contact, str oking, and feeding reward) affect long-term attachment responses of lambs t o the caretaker that provided the subsequent contact, after a common initia l training period for artificial feeding provided by another person. Ewe la mbs (n = 45) were artificially reared from multinippled buckets in groups o f three. All the lambs were trained by a stockperson (S1) to suck from the bucket (4.4 +/- .3 sessions of 3 min per animal for the first 2 d of life). Subsequently, 15 lambs received no further human contact (T0). Fifteen oth er lambs received only stroking from a second stockperson (S2) for 6 min th ree times a day during the first 4 wk (T1). The remaining 15 lambs (T2) wer e stroked and bottle-fed by S2 during the same posttraining period as for T 1. Tests were performed at 4, 6 (just before weaning), 9, and 13 wk of age in an unfamiliar arena marked in a grid pattern. The test procedure include d three successive parts: 1) isolation for 1 min; 2) S2 presence for 2 min; and 3) isolation for 1 min. The T0 lambs spent a similar amount of time in the grid square close to S2 regardless of whether he was present. The T1 a nd T2 lambs spent more time close to S2 than T0 (P < .01), and T2 spent mor e time close than T1 (P < .05). In the presence of S2, T2 vocalized less (P < .01) than T0, and T1 did not differ from either T2 or T0. The T2 lambs a lso crossed fewer squares than T0. When S2 left the arena, T2 vocalized mor e (P < .01) than T0 and more (P < .05) than T1, and T1 had a tendency to vo calize more (P = .08) than T0. Differences persisted with increasing age. H uman contact, especially stroking and feeding, during the 4 wk following in itial training strongly and durably influenced the lambs' response not only to the appearance but also to the disappearance of a familiar stockperson. This last result supports the idea that lambs could form a social bond wit h their stockperson.