Lamb
Authority: USDA Food Safety and Inspection Service
USDA guidance sets whole-cut lamb -- chops, roasts, leg of lamb -- at the same safe minimum internal temperature as beef and pork: 145°F (62.8°C), followed by a mandatory 3-minute rest before carving. Ground lamb requires a higher 160°F (71.1°C) with no rest time required.
| Parameter / Specification | Standard Value | Unit |
|---|---|---|
| Whole-Cut Safe Temp | 145 | °F (62.8°C) |
| Required Rest Time | 3 | minutes |
| Ground Lamb Safe Temp | 160 | °F (71.1°C) |
Lamb vs. Mutton
"Lamb" and "mutton" both come from domestic sheep, but the terms refer to the animal's age: lamb is meat from a sheep in its first year, hogget comes from a sheep in its second year, and mutton comes from older sheep. The exact cutoffs vary by country -- in Britain the definition is tied to whether the animal has any permanent incisor teeth, while Australia's 2019 standard defines lamb as under 12 months old or having no permanent incisors in wear yet.
Mutton was a mainstay of the American diet in the early 20th century, but its consumption declined sharply after World War II, and today the meat industry markets most sheep meat simply as "lamb" regardless of the animal's exact age at slaughter.
Why Whole Cuts and Ground Meat Differ
The same whole-cut versus ground-meat safety split that applies to beef and pork applies to lamb: whole muscle cuts like chops, roasts, and leg of lamb only need to reach 145°F because bacterial contamination on intact meat is concentrated on the exterior, which the cooking process reaches directly and thoroughly.
Grinding changes that. The process mixes any surface bacteria throughout the meat rather than leaving it on the outside, which is why ground lamb -- like ground beef and pork -- requires a higher internal temperature of 160°F to ensure heat has reliably penetrated to wherever bacteria may now be distributed.