The aim of the present investigation was, to examine whether outdoor wintering of lambing ewes is a successful and animal friendly production system. The welfare and growth performance of winterborn lambs in outdoor husbandry were assessed in two winter periods (1995/96, 1996/97) when a total of 353 lambs were born into three different husbandry systems. System 1 consisted of 75 lambs from 26 (winter 1) and 29 (winter 2) ewes and was wintered outdoors with access to a lambing shelter with a straw bedded floor. System 2 included 120 lambs from 52 (winter 1) and 54 (winter 2) ewes which were born in an uninsulated barn with access to an outdoor yard. System 3 was kept in an uninsulated barn with no access to the outside and consisted of 158 lambs from 52 (winter 1) and 54 (winter 2) ewes. The lambs were of five different genetic origins which were equally distributed over the three husbandry systems. The genetic groups included purebreds from the hardy ‘Rhönschaf’ (RHO) and from the ‘German Blackface’ (GBF) mutton breed and the reciprocal crosses of these breeds (GBF ✕ RHO, RHO ✕ GBF). The fifth group were crossbreds between rams of the small-framed French mutton breed ‘Charmoise’ (CHA) and Rhönschaf-ewes (CHA ✕ RHO). The time period between parturition and first standing (‘time to stand’) and the time period from birth to first sucking (‘time to suck’) were considered as vigour traits. Vigour was visually assessed and scored. The rectal temperature was measured 3 h post partum. Live-weight gains were estimated from birth to 25 and 42 days of life. No differences between the different husbandry systems were observed in the measured traits. Outdoor-born lambs showed the same vigour and were able to maintain homeothermy as well as those born indoors. Ewes sought the shelter prior to lambing which might have favoured the early vigour of lambs and thus, their ability to maintain homeothermy. The visually assessed vigour score was in good accordance with the vigour traits time to stand and time to suck. The breed of the ewe had a significant effect on lamb vigour, lambs from hardy RHO ewes showing a better vigour than lambs from GBF ewes. Hybrid vigour estimates of time to stand and time to suck were 0·17 and 0·20, respectively, but were not statistically significant.
Crossbred lambs between GBF and CHA mutton rams and hardy RHO ewes had a good vitality and growth performance. Outdoor wintering with a lambing shelter did not adversely influence survival of newborn lambs or their subsequent growth performance.