If you are unable to reliably provide suitable pasture or foraging space, at least once a day feed your livestock, (in addition to fermented grain), either greens or hay and some other source of protein. Black Soldier Fly Larvae is a good choice.
Black Soldier Flies resemble mud dauber wasps, with translucent wings and primarily black bodies. They are about 3/4 inch long and have two antennae, but no mouthparts. They do not bite or eat, and they are not interested in people’s houses or sneaking indoors.
We have had success attracting Soldier Flies using deep tubs with ventilation holes cut in at the top and a harvesting tube inserted at the bottom. A small amount of kitchen scraps will attract the flies, and the females will lay 500+ eggs inside pieces of corrugated cardboard attached to the inside of the tub.
The larvae hatch in about four days and begin eating the food scraps in the tub. They grow to about an inch long, and exit the tub after about 22 days. Send the remaining foodstuff in the tub to your compost pile and feed the larvae to your chickens, ducks, hogs, and fish. They are about 42% protein and yummy!
Oh…just FYI – people can eat them, too. Just saying…