Evaluation of sibling bonding in Nubian goat kids in the first three months of age

Abstract

Domestic goats (Capra hircus) form lasting social relationships from bonds formed in early life. Mother/infant relationships have been most extensively explored from the standpoint of the mother. This study investigated mother/infant and peer bonds formed by Nubian goat kids in the first three months of life. The hypothesis was that the mother/infant bond was stronger than the sibling/sibling bond. An open-field test (n = 22) and a two-choice selection chamber test (n = 30) were used. Each individual was presented both tests, repeated in each of four age classes: (1) 1-3 wks, (2) 4-6 wks, (3) 7-9 wks and (4) 10-12 wks. Preference in the open-field test was determined by proximity during four activities: resting, nursing, grazing and moving. Preferences in the selection chamber were determined by choice in six replicate trials of each choice pair: dam vs. sibling, dam vs. strange kid, strange doe vs. sibling and herdmate kid vs. strange kid. In the open-field test, preference for proximity of sibling was dependent on activity. Resting and nursing always occurred with the sibling. The sibling was preferred during grazing in age class 1 (T = -2.29, P = 0.03) and in age class 4 (T = -3.11, P = 0.005). Grazing was either near a sibling or a herdmate kid. Siblings were not preferred during moving activities. In the chamber test, kids approached either the dam or sibling significantly more frequently than the strange kid or doe. The sibling bond superceded the mother/infant bond in age classes 2 and 3. Preference for herdmate kid over strange kid increased with age. The hypothesis that the mother/infant bond is stronger than the sibling bond was rejected. The mother/infant bond is strong, but is superceded by the sibling bond most of the time. Age-related changes in the mother/infant bond may be related to changes in the ability of the mother to provide milk and in maturing social relationships of the kid. Domestic goats in confinement may differ from their wild relatives in their expression of some behaviours due to the effect of nutrition and limited space.