Does the selection on temperament in merino sheep significantly affect the establishment of the ewe-lamb bond or lamb survival?

Samantha Bickell

    Research output: ThesisDoctoral Thesis

    153 Downloads (Pure)

    Abstract

    The selection of Merino sheep for a calm temperament has been previously proposed to improve lamb survival by improving the expression of maternal behaviour in calm ewes. However, the effects of the selection process on ewe and lamb behaviour and the establishment of a mutual bond are still unknown despite these temperament traits having been selected over 15 years. The aim of this thesis was to study in detail the extent to which the selection on temperament had affected the establishment of the ewe-lamb bond and lamb survival, and its means of transmission from mother to young. This study shows that selection for temperament in Merino sheep does not affect the early process of ewe-lamb bonding. In a two-choice recognition test, both calm and nervous ewes recognised their lambs at 6 hours after parturition. Likewise, calm and nervous lambs showed a preference for their own mother at 18 hours after birth even though differences in temperament were detected in the lambs at one week of age. Even in the presence of a novel object, known to be a strong stressor for the nervous ewes, calm and nervous ewes did not differ in their ability to recognise their own lamb in a two-choice test. Unexpectedly however, the nervous lambs expressed better discriminative abilities than the calm lambs in the presence of the novel object in the two-choice test. In addition, when the ewes were housed indoors in individual pens, both temperament lines expressed adequate maternal behaviour. Hormonal secretion patterns of oestradiol, progesterone and prolactin, hormones involved in the onset of maternal behaviour during the pre and post-partum period, were similar between the two lines, providing further evidence to suggest that both calm and nervous mothers had the capacity to express adequate maternal behaviour. Under outdoor lambing conditions with minimal human disturbance, calm ewes licked their lamb more and tended to stay longer on the birth site, while nervous lambs stood up
    Original languageEnglish
    QualificationDoctor of Philosophy
    Publication statusUnpublished - 2009

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