The contribution of the activity of the newborn Merino lamb to the attachment to its mother and subsequent survival

Abstract

Proc. Aust. Soc. Anim. Prod. 1996 Vol. 21 THE CONTRIBUTION OF THE ACTIVITY OF THE NEWBORN MERINO LAMB TO THE ATTACHMENT TO ITS MOTHER AND SUBSEQUENT SURVIVAL P.M. MURPHY and D.R. LINDSAY Dept of Animal Science, The University of Western Australia, Nedlands, W.A. 6907 Strong attachment to the mother is essential for the survival of the lamb and the lamb itself must play a role in the establishment of a strong and enduring attachment to its mother (Lindsay et al. 1990). If the lamb is more active and vocal immediately after birth, it should encourage stronger maternal behaviour, strong attachment, and enhance its chances of survival. Low lamb activity and vocalization will reduce maternal interest, inhibit strong bonding and reduce the chances of lamb survival. This experiment investigates this concept. Sixty Merino ewes were allocated to 1 of 3 groups in which their lambs received the following treatments: (1) control -0.9% saline (0.1 ml/kg) (2) ` high'vigour - stimulant (adrenaline 0.1 ml/kg) or (3) ` 'vigour low mild sedative (xylazine O.O04ml/kg in 0.9% saline to 0. lml/kg). Treatments were given as intramuscular injections at birth. Responses to treatments were measured by recording the standing, sucking and vocalization activities of the lambs and the response of the dams every 10 seconds during the first hour postpartum. By the end of the first hour there were no further responses to treatments. Data for behaviour were analysed by ANOVA and lamb survival data after 48 hours, 2 weeks and 9 weeks were analysed by chisquare. Table 1. Time spent by ewes grooming their lambs (minutes &EMe), separated (>3 metres) from their lambs (minutes f SEM) and the number of bleats (k SEM) between groups in the first hour post-partum The ` ' vigour treatment reduced the standing and sucking activity for the lambs below that of the low control lambs, but not vocalizations, while the ` high' vigour treatment did not stimulate activity or vocalization above that of the controls. Maternal behaviour was adversely influenced by low lamb activity in the first hour after birth (Table 1). Dams of lambs with low vigour spent less time grooming their lambs and separated from their lambs for longer than ewes from the other groups. Poor lamb vigour adversely affected the ewes' maternal behaviour and lamb mortality was increased (Table 2). Table 2. Lamb mortality to 48 hours, 2 weeks and 9 weeks of age Treatment Number of lambs Mortality birth to 48 hrs Mortality 48 hrs to 2 wks Mortality 2 to 9 weeks Total lamb mortality (%) Control 22 0 1 aA ` High' vigour 26 1 2' ` ' vigour Low 21 1 6' A Values in the same column with different superscripts are significantly different 1 2 (9)' 1 3 (12) ' 1 8 (38)b (2 d.f ; P < 0.05). Few lambs died from birth to 48 hours, suggesting that the treatments per se did not directly influence lamb survival. Lambs with poor vigour in the first hour had about 28% higher mortality to 9 weeks of age than lambs in the other groups. This was attributed to reduced maternal interest and the inhibition of strong and enduring attachments between ewes and their lambs. The lamb has an important role in the development of maternal behaviour and attachment to its mother during the first hour after birth. Low activity and vocalization may adversely affect this attachment and can lead to the death of the lamb. LINDSAY, D.R., NOWAK, R., PUTU, P. and McNEILL, D.M. (1990). In 'Reproductive Physiology in Merino Sheep. Concepts and Consequences' (Eds C.M. Oldham, G.B. Martin and I.W. Purvis) p.191205. (The University of Western Australia: Perth). 486