Meat value of cow carcases
Cow beef is mainly boned out for manufacturing and its main value is the lean content. Most of this is exported.
The best primal cuts from well finished cows can have acceptable eating quality and are commonly sold as "budget" table beef. Eating quality can be quite acceptable but is not as consistently good as beef from yearling animals.
Cows are lighter muscled than steers and when they are in good condition they can carry a lot more waste fat.
Cows generally have a mature skeleton which does not vary greatly in weight as they gain or lose weight from season to season. As lean cows gain weight, muscle fills first and then as they get heavier, muscle growth slows and fat accumulates.
This means very lean carcases of British and Bos indicus types may have depleted muscles, resulting in a high proportion of bone and a poor yield of saleable lean. Their primal cuts also lack the eating quality of fatter cows. These carcases have a low value in normal times but during dry seasons they are often in oversupply and can be worthless.
Moderately fat cows are heavier and generally are expressing their muscle potential. They are much more valuable as they yield reasonable amounts of meat and generally carry a moderate but not excessive fat cover. Their primal cuts are often sold as "budget" table beef.
This is why improving cows from light to moderate fatness and weight can add a lot to their value.
Heavy, fat cows can carry large amounts of fat and require a lot of trimming to produce the lean beef required for manufacturing. This makes them more costly to process and reduces their carcase value, hence the price penalties that usually apply.
Some cows are quite lightly muscled and when they are fat they carry very large amounts of waste fat.
Cows of the heavier muscled breeds, especially the larger European breeds, carry a lot more meat and do not get as overfat at heavier weights. This greatly increases their value.