I use field peas in my rations. They are the only lentil that does not need extruded before adding them in. They are a great replacement for sow/boar and grower/finisher rations of Soy Bean Meal. However, feeding them to nursry pigs could cause a little slower growth.
Did you call feed stores or feed mills? I'd be surprised if you couldn't find someone who knew what you were talking about. The folks around here at the feed stores don't know much, but the old timer at the mill knows most everything.
What about a southern cowpea like black-eyed peas. They can handle the heat but I don't know about the soil type. They provide a larger bushy plant about 30" cubed as well as the peas. We use them in the south for human and livestock feed as well as making hay from the vines. They are great protein and as legumes improve the soil by fixing nitrogen.
The easiest way to get seed is to buy dry ones in the grocery store and plant them. They germinate almost as well as feed store seeds do.
The owner of the feed store I use had the best answer. He said I have tons of
free feed on my property and he was right. Many mesquite trees. My free roaming equine eat the pods/beans as far up on the trees as they can reach!
Can't believe I didn't think of it. The indians have used mesquite beans/pods so
many ways. I feel so dumb!!
Here in the desert of central Arizona the growing season is 12 months a year. Certain plants for certain seasons. (Two seasons -- warm and warmer!) But, I've never been into gardening. Perhaps that could change in the winter when we're out of the hundred degree temps.