Ewe maternal behaviour score relationships with lamb survival: A dissertation submitted in partial fulfilment of the requirements for the degree of Bachelor of Agricultural Science with Honours at Lincoln College

Abstract

This paper reviews factors which affect the survival of the newborn lamb including some discussion ,on the incidence and cause of perinatal lamb mortality. Environmental conditions and physiological factors such as temperature regulation greatly influence lamb survival and are considered but the main concern of this review is how maternal behavioural traits at parturition affect the newborn lamb. Variation in ewe maternal behaviour is recognised but few .data exist to demonstrate whether ewe behaviour is related to lamb survival. Preliminary analyses of 1050 ewe behaviour records (1 to 5 score based on observations during tagging of lambs within 24 hours of birth) of six breed types and three age groups over one year were made. Least Squares Analysis of Variance showed that maternal behaviour was better by 0.26 of a score on average for each year increase in ewe age and by 0.18 of a score on average for each unit increase in litter size. Breed effect only reached statistical significance when two factor interactions and partial regressions involving breed were not included in the least squares model. When correction was made for litter size, age and breed of ewe, LW/LB increased by 0.03 on average for each unit increase in behaviour score. A small field trial involving differential nutrition (medium vs high) of 155 F-gene carrier ewes for 8 weeks over winter established a 5.5 kg liveweight difference. This nutrition treatment resulted in a 0.42 increase in the average maternal behaviour score in the lower nutrition group.