Given that Safehold agriculture and terraforming explicitly hinges on gene-modded species, it may be erroneous and even presumptious to base one's assumptions on historical Terran models.
Take, for example, pork. Pigs are much more prolific than cattle, and produce significantly more meat for a given amount of feed - much (if not most or even all) of which can consist of byproducts and/or waste. Chickens are even more efficient in that they produce dozens or even hundreds more offspring and utilize feed even more effectively - and both species can be largely self-sufficient (though in the case of chickens at least some protection might be needed. It is certainly not difficult for me to imagine a scenario where these animals, properly modified, could be the linchpins of a terraforming scheme. IIRC, it has been said that pigs were part of what might be termed a "Euroforming" scheme in our own history, where they were seeded on islands by sailors exploring the New World - though perhaps these colonies were merely escapees from settlers who did not thrive.
Applying the same science of genetic modification to cattle to increase efficiency, output and aid terraforming would seem a logical step as well. Whether or not it would be trivially easy to allow them to ingest native Safeholdian fodder is not for me to say but given the nature of the turn-key environment Langhorne and the Archangels seem to have striven to impart to the world it doesn't seem like a stretch to imagine. Free-range cattle terraformig ranches a la the old West seem to me to be at least plausible.
Thus my questioning as to whether certain arguments are necessarily applicable to Safehold.
..and none of which addresses my initial ponderment - though short of an ex-cathedra proclamation it seems best to rely on the text
Thanks all for an interesting discussion thus far.