Vachon, M., Morel, R. and Cinq-Mars, D. 2007. Effects of raising lambs in a cold or a warm environment on animal performance and carcass traits. Can. J. Anim. Sci. 87: 29-34. A 2 × 2 × 2 factorial arrangement was conducted over two consecutive winters to compare growth and carcass traits of ram and ewe lambs in a cold or warm environment (noninsulated, unheated vs. an insulated and heated barn with minimum inside temperature (T) between 5 and 10°C). Each winter, 14 pairs of lambs of each sex were randomly allocated to either a cold or warm environment (average weight of 23.8 kg ± 0.6 and 22.4 kg ± 2.0 in 2003 and 2004, respectively). They were fed hay and concentrate ad libitum until they reached 42 to 48 kg body weight (BW) when they were slaughtered. Carcass traits were then evaluated. The average temperature in the cold environment was -7. 49 and -4.74°C in 2003 and 2004, respectively, vs. +6.25 and +10.50°C, respectively, in the warm environment. There were no differences (P > 0.05) in growth performance and carcass traits between lambs raised in a cold or a warm environment. However, there was a tendency for lambs raised in a cold environment to have higher average daily gain (ADG) (P = 0.06) and to take less time to market (P = 0.09). Results suggest that it is possible to raise lambs in a cold environment without having any detrimental effect on performance and carcass quality. Aucune différence significative (P > 0.05) n'a été observée pour les performances zootechniques, ni pour la qualité des carcasses entre les agneaux élevés en environnement tempéré ou froid. Par contre, les agneaux en environnement froid ont eu tendance à faire un meilleur gain moyen quotidien (P = 0.06) et prendre moins de temps pour atteindre le poids du marché (P = 0.09). Les résultats suggèrent qu'il est possible d'élever des agneaux dans un environnement froid sans pénaliser les performances zootechniques ni la qualité des carcasses.