The psychoendocrine evaluation of infant attachment recently demonstrated that early rearing experience modifies the endocrine profiles and the social interaction between a lamb and its attachment figure. While lambs are able to discriminate familiar and non-familiar conspecifics (mother or lamb), only lambs reared with their mother develop such clear social discrimination or preference. Lambs reared without mother displayed no preference for a specific lamb from its own group. Other differences were reported in exploratory and emotional behaviours. Moreover, lambs reared with their mother only present lower plasma cortisol and higher plasma oxytocin levels than lambs reared with same age conspecifics only. Because these behavioural and endocrine responses are supported by brain organisation, we decided to describe and compare the brain development of lambs reared in group with and without mother by using T1-weigthed- and diffusion tensor MRI at 1 week, 1, 2 and 4 months of age. Using texture analysis of the T1w MRI, we showed that the differentiation of the pituitary differed between the two groups. The extraction of diffusion parameters allowed to show that the white matter fractional anisotropy increased from 1 week to 4 months, whatever the group. Moreover, some differences were noticed between groups in specific brain areas. The impact of early rearing experience found in our study could reflect the consequences of social environment.