Possible Clues:

• Characteristic of fleshy part of head after a time, perhaps
• Quality of some grub in each can brought into dining room
• Dining not good in officers' room -- quality lacking in vegetables
• Brawniness; substance
• Dine at home in place for meals — what's the quality of the beef?
• Taking food mostly in soldiers' canteen for quality of brawn
• Stick a sharp point into stew to reveal quality of beef?
• Have meal at home in dining room - the quality of the beef!