This section is from the book "Practical Dietetics With Special Reference To Diet In Disease", by William Gilman Thompson. Also available from Amazon: Practical Dietetics with Special Reference to Diet in Disease.
Veal, especially when obtained from animals killed too young, is usually tough, pale, dry, and indigestible; but when the animals are slaughtered at the right age the meat is sometimes tender, and is regarded by many as nutritious. It differs considerably from beef in flavour, and contains more gelatin. Veal broth is nutritious, and affords a wholesome variety in the dietary for the sick. When too much is given it may excite diarrhoea. Veal is much more used for invalids in Germany than elsewhere, although it figures less conspicuously in hospital dietaries there now than formerly. Bauer declares it to be more digestible than beef, but Pavy says, referring to both veal and lamb, "they are meats that it is desirable to avoid, generally speaking, in case of dyspepsia," and this opinion is prevalent in America as well as in England. Veal contains more water and less fat and protein than ox flesh.
Mutton is rated as more digestible than beef by English writers upon dietetics. That can hardly be said to be the case in this country, where the quality of beef has been so much improved of late years, and where average mutton is not so tender as in England. For example, Balfour writes in his work upon the Senile Heart (1894): "We also recommend meat with short fibre, such as chicken, rabbit, game, mutton, or well-grown lamb, in preference to such meats as beef, whose fibres are long and tough." Fat mutton is richer in fat than beef, and is certainly less digestible than lean beef.
Undoubtedly tough mutton is quite as difficult of digestion as tough beef, and it is harder to obtain it tender. Mutton fat contains a larger percentage of stearic acid, which makes it firmer and less digestible than beef fat. Fat mutton is more likely to disagree with those whose digestion is enfeebled. When properly assimilated after digestion, mutton possesses equal nutrient value with beef.
Mutton should not be eaten until the sheep is at least three years old, and the best English mutton is obtained from animals which are six years of age. Mutton broth is wholesome and suitable for the sick. It may be given in typhoid and other fevers. It is somewhat constipating.
Lamb, when very tender and of just the right age, is quite as digestible as beef or mutton, but the flesh contains too large a proportion of fat - more than is present in veal. Good lamb is expensive, and, on account of the uncertainty of the character of the meat, it is not usually to be recommended for invalids.
Venison is a tender meat with short fibres, which is very digestible when obtained from young deer, but it is regarded as somewhat stimulating to the stomach, and it is often eaten when aged to a degree which, while some think it improves the flavour, unfits it for dyspeptics. The meat corresponds very closely in chemical composition to lean beef.
Pork is a tender-fibred meat, but it is notoriously indigestible on account of the high percentage of fat present, which may exceed 37 per cent, or considerably more than the quantity of its nitrogenous material. Pork ribs may have as much as 42 per cent of fat. The fat is composed chiefly of palmitic and oleic glycerides.