'Modern Meat' raises tough questions for consumers to chew on; Modern Meat: Antibiotics, Hormones, and the Pharmaceutical Farm, by Orville Schell. New York: Random House. 337 pp. $17.95.

''Over the past several decades,'' writes Orville Schell in this new book, ''the ways in which livestock are produced in the industrialized world have undergone a dramatic transformation....

''While the short-term benefits in the form of greater efficiency in mass production and thus lower meat costs to consumers are undeniable, assessing the long-term risks has been a much more elusive undertaking. In many instances drugs and chemicals have been approved before the long-range consequences of their use are completely understood.''

Cattle and hog rancher, journalist, and writer of articles and books on China , Schell thoroughly exposes the hazards of modern-day methods of livestock production on the ''pharmaceutical farm.'' In ''Modern Meat'' he investigates the practice of using hormones to fatten livestock in abnormally short periods of time. He questions the liberal addition of antibiotics to livestock feed to control diseases and sedate animals - a practice, he notes, banned in some European countries because of its perceived health risk. And he documents his work with convincing scientific data comprehensible to the layman.

Readers are forced to consider the following questions, among others: How much can the consumer trust farmers and ranchers to do their part in safely regulating meat production? Can the US Food and Drug Administration be relied upon to faithfully monitor existing laws? Is the meat industry alert enough to possible long-term risks? Is adequate research done before a drug is marketed? And what are the effects of these additives on the farm animals themselves?

Schell then probes another dimension of the meat industry so unbelievable that his stories could grow hair on steer horns.

There's the account of the inventor of plastic hay, who suggests his creation be used as a substitute for the good-old-fashioned stuff. And there's a tour of the Flavor Corporation of America - where synthetic feed-additives for animals are produced to stimulate the appetites of overfed, reluctant eaters.

'' 'Aromabuds,' '' writes Schell, ''which purportedly combined flavors and aromas, came (I was told) in twenty-four varieties (reminiscently similar to Howard Johnson's legendary twenty-eight flavors) and included such unlikely animal taste sensations as ''Chocolate Milk,'' ''Delicious Apple,'' ''Jamaica Rum,'' ''Licorice Stick,'' and ''Roasted Almond.''

This book gives a startling introduction to today's mass-producing factory farms, where life is increasingly ''depersonalized'' for pigs and cows that are numbers in slots, denoted by their highest dollar value. Pigs, confined in dark, cramped quarters, never set hoof beyond the barn door. Cows munch a steady diet of citrus peel and shredded cardboard.

''Modern Meat'' is not without distortions, the greatest flaws being Schell's unrestrained personal bias and overdramatization of issues. Schell offers us a 1 ,000-volt, emotionally charged account of the fate of America's family farms and the abuses in the meat industry.

He overblows the issue of diethylstilbestrol (DES) (a growth promotant for cattle banned in 1979), for instance, in a drawn-out 13-chapter examination. Only one side of the issue is represented. Little notice is given to the fact that the doses of DES being given to cattle were minute and that the ban was, and still is, controversial amoung scientists.

Nonetheless, this is a book that serves a fundamental purpose by alerting consumers and industry persons to the problems, especially during a time when industry regulations are becoming increasingly lax.