(4) Serious losses may occur where profit was expected through a rise in the price of foodstuffs. Scarcity in food supplies, due to an unfavorable season, often compels the stockman to sacrifice animals that he has been raising for two or three years. It is sometimes asserted that, although society suffers from short crops, the farmer is benefited, because the increase in price is greater than the decrease in yield. One year, for example, the decrease in the production of maize was 30%, while the increase in price was 50%. If, therefore, the crop had been sold it would have brought more than the crop of the previous year. The farmers, however, require about 80% of the maize crop in the production of their live stock, so that when there was a decrease of 30% in the yield of maize, many had none to sell, while others had to purchase maize at increased prices or use other crops, such as oats, which they might otherwise have sold. Still others would be compelled to sell, at reduced prices, their partially fattened animals. There is a constant fluctuation in the price of animals and animal products, due to variation in yield and hence in price of food supplies. It requires continual vigilance on the part of the stockman to secure food supplies at such cost as will enable him to secure a profitable return from his animals. CHAPTER XVI RETURNS FROM ANIMALS In any well-considered plan of farm operations it is essential to have some basis for estimating the amount of food required to carry live stock through the year in order to know, on the one hand, what portion of the crops raised are available for sale and, on the other hand, what food supplies must be purchased. A requisite of any successful farm enterprise is a proper consideration of these market conditions. While domestic animals consume a variety of foods, and each class of animals has special food requirements, the basis of calculation of the needed supplies is fortunately not complicated. Twenty-five pounds of dry matter are required per day for each thousand pounds of live weight of horses, cattle and sheep, and for swine about 40 pounds for each thousand pounds of live weight. It may be more convenient to calculate the food requirement of swine on the basis of increase in live weight, allowing five pounds of dry matter for each pound of increase. Some further details as to food requirements will be found in the paragraphs which follow. COST OF PRODUCING HOGS