A feed ratio is a measure of profitability of animal husbandry, expressed as the ratio between the cost of food and the price of the final product.
For example, in pig farming, the hog/corn ratio is the number of bushels of corn equal in value to 100 pounds of live hogs.
Since corn is a major input cost to hog producers, the higher the price of hogs relative to corn, the more profit there is in feeding hogs.
[1] In dairy farming, the milk-feed price ratio is a measure of the value of 16% protein ration to one pound of whole milk.
As with the hog/corn ratio, this relationship is an indicator of the profitability of milk production.