Agneau de Lait is the French term for "young milk-fed lamb" which are 2 to 3 months old. In France, "milk-fed lambs" are slaughtered before they are weaned at an age of 30 to 40 days when they weigh between 8 to 10 kilograms (18 to 22 pounds). Agneau de Lait also refers to suckling lamb or baby lamb. baby lamb or milk-fed lamb.