Non GMO feed may be difficult to source. Corn and soybeans are used in animal feed. 90% + of all the corn and soybeans produced in the US are GMO varieties. Why is that? What is the purpose or benefit of GMO? GMO corn and soybeans are modified to be resistant to certain herbicides (weed and grass killers). Why is that important? Prior to GMO, cropland was plowed/tilled to kill all existing plants and vegetation prior to planting a crop. That process uses a lot of fuel, a lot of labor, contributes to pollution, lessens air quality, takes more time and money, decreases soil moisture, lessens the health of the soil, allows conditions for loss of soil due to wind and rain (LOTS of soil in many cases from runoff and erosion). Soil loss is never good. There is no real loss, it just goes into the water and streams and ends up somewhere else. Then the crop was planted into the tilled soil. As grasses and weeds emerge, they must be removed to allow the crop to thrive and produce for harvest. That requires more soil disturbance by using field hands (people) with hoes to chop the weeds or tractors with cultivators (mini-plows of sorts) to till the soil again to remove the weeds and grass. That process again uses a lot of fuel, contributes to pollution, lessens air quality, takes more time and money, decreases soil moisture, lessens the health of the soil, allows conditions for loss of soil due to wind and rain. That process would be repeated multiple times until the crop formed a large enough canopy over the soil to shade the ground and inhibit new grass and weed emergence.
GMO crops allow the farmer to plant a crop into the previous year's stubble without tilling the soil or with minimum tillage of the soil - avoiding many of those extra costs and damages to the soil, air and water that the old methods of farming produced. As weeds and grasses emerge, the crop is sprayed with an EPA approved herbicide that kills the weeds and grasses, but does not damage the crop. With less fuel, less pollution, less damage to the environment, better soil health and other good effects. Spraying uses far less fuel and smaller equipment than cultivating resulting in much less impact on environment. Those are the advantages of GMO crops.
I know of a chicken company that started producing non-gmo chickens. Sounds good to some people. If there is a demand for a product and the company can get a premium for that product, economics might say to produce that non-gmo chicken. They had problems buying and getting delivery on enough non-gmo corn and soybean meal to keep the chickens fed and found that the economics were not working in their favor. They stopped producing non-gmo chickens.
You may already know and understand all this. But I wanted to point out that there are advantages to GMO including positive effects on natural resources and environment. What do you see as the attraction to non-gmo fed beef?