7th World Congress on Genetics Applied to Livestock Production, August 19-23, 2002, Montpellier, France GENETIC VARIATION IN MATERNAL BEHAVIOUR SCORE AND LAMB SURVIVAL J.M. Everett-Hincks, N. Lopez-Villalobos, H.T. Blair and K.J. Stafford Institute of Veterinary Animal and Biomedical Sciences, Massey University, Palmerston North, New Zealand INTRODUCTION New Zealand sheep farmers have focussed selection pressure on fecundity traits in recent times. The relationship between lambing rate and lamb survival is poorly understood in highly fecund ewes. Lamb survivability is a problem with up to 30% lamb losses recorded between pregnancy scanning and tailing (Aspin 1997). These lamb losses are not acceptable from a production and animal welfare perspective. There has been some subjective selection for maternal behaviour traits thought to improve lamb survival. An example of such a trait is the maternal behaviour scoring system as described by O’Connor et al. (1985). A better understanding of the relationships between production traits such as lamb survival and these adaptation traits, is critical for the development of sustainable breeding programmes (Simm et al. 1996). The aim of this study was to estimate genetic parameters for maternal behaviour score, litter survival as a trait of the dam and lamb survival as a trait of the lamb. MATERIALS AND METHODS Animals. Data were edited to remove missing records and any data recording errors. The final dataset used in this study consisted of 1954 ewes with MBS records and 2193 ewes with litter survival records. A total of 4137 lambs were used to obtain lamb survival records. MBS was recorded on Coopworth ewes while litter survival was recorded on Coopworth (n=1947) and ½ East Friesian ½ Coopworth (n=246) ewes. Lamb survival was recorded for progeny of Coopworth ewes, which included Coopworth (n=3691), ½ East Friesian ½ Coopworth (n=214) and ¾ Coopworth ¼ East Friesian (n= 232) lambs. All animals were from a single sheep farm with records from 1997 to 2000. Measurements. The shepherd recorded maternal behaviour score (MBS) on a 5-point scale (low, 1 to high, 5) based on the distance a ewe retreats from her lambs when the shepherd is tagging them (O’Connor et al. 1985). Litter survival as a trait of the dam (LSD) was measured from parturition to weaning. It was calculated by dividing rearing rank (number of lambs reared to weaning) by birth rank (number of lambs in litter) and was recorded as a percentage Session 14. Behaviour and welfare Communication N° 14-14