Mother–Young Relationships in Sheep: A Model for a Multidisciplinary Approach of the Study of Attachment in Mammals

Abstract

The onset of maternal responsiveness and the development of mother–young attachment in sheep are under the combined influence of hormonal and sensory stimulations. In the mother, the prepartum rise in oestrogen and vaginocervical stimulation caused by expulsion of the foetus act on the main olfactory system and on hypothalamic regions. This induces maternal care through the central release of oxytocin, modulated by opiates and corticotrophin‐releasing hormone. In parallel, activation of the main olfactory network enables the learning of individual lamb odour and maternal attachment. In the neonate, the first suckling episodes and the concomitant activation of the cholecystokinin, opioids and oxytocin systems facilitate the development of a preference for the mother. Gastrointestinal signals activate the brain stem, the hypothalamus and the amygdala. Within 72 h of parturition, the mother–young attachment shifts from proximal to distal recognition based on visual and auditory cues after which vocal cues become more salient. Although olfaction remains a key element in the display of selective maternal nursing, maternal attachment relies on a multisensory mental image of the lamb. These findings support the view that sheep are amongst the most appropriate animal models for the study of maternal and filial attachment in mammals.

Nonsocial Functions of Hypothalamic Oxytocin

“…In rodent pups, the first suckling episodes can activate OXT-secreting system through gastrointestinal signals, which facilitate the development of a preference for the mother [20, 21]. These early-life events can exert profound long-lasting effects on various behaviors such as fear/anxiety, stress responses, and reproductive functions [22].…”

Reproductive and sexual behaviour development of dam or artificially reared male lambs

“…Most of these studies were conducted in rodents, species in which the relationship between mother and offspring is not selective. Unlike rodent, sheep and goats are selective [8,9]. Sheep establish an offspring-mother bond within the first few hours after birth, and after that ewes reject alien lambs [8,10,11].…”

Fearfulness Affects Quail Maternal Care and Subsequent Offspring Development

“…The quality of maternal responses to offsprings’ early solicitations is particularly important for the establishment and the quality of the mother-offspring bond in birds [54] as in mammals [55]–[57]. Our observations during the beginning of the brooding period indicate that LTIs and STIs did not respond similarly to chicks’ solicitations, solicitations that we consider to be similar initially, as all our chicks came from the same strain and were distributed randomly between the females of each set.…”