It is rather common for a nutritionist to be invited to visit a farm before designing a specific nutrition program. In fact, in my opinion, this must be a prerequisite set by the nutritionist. At any rate, an experienced eye will quickly decide whether a true custom-made program is possible. And, although nutrition can cope or even help with a mediocre farm health status, or even untrained staff and below-par facilities, the one thing that cannot fix is a mixed genetic population.
Certain farms enjoy breeding and cross-breeding their own genetics, which I consider a noble exercise, but when it becomes a self-indulging purpose, it negates any nutrition effort to feed commercial (terminal) animals efficiently. It is not rare for a farm to have four or even more breeds of animals, all intermixed in the same facilities, while cross-bred animals are constantly and even randomly produced. I understand there is a certain thrill there and, in fact, I know this is how the first genetics advances were achieved. But I am focusing here in commercial operations that produce their own market animals and not modern genetics businesses.
When faced with a mixed population, a nutritionist cannot create any reasonable nutrition program to feed any animal efficiently. At best, a medium animal is envisioned, resulting in the paradox where no such animal exists and as such some animals are underfed whereas the rest are overfed. It is a lose-lose situation that has no fix. Remember that, in modern farms, individual animal feeding is impossible, whereas even group feeding is becoming increasingly difficult.
Thus, if the plan is to improve animal efficiency, the first thing that needs to be done is to establish genetics and keep them constant. Any experimentation needs to be done separately from the commercial population. It is only then that a nutritionist should be invited to “feed” these animals. Otherwise, a guesstimate in making up a nutrition program is as good as any and, lamentably, this is how many try to make a living.