All feeds do not contain these nutrients in the same proportions. Some feeds, like corn, are deficient in protein, while others, like tankage, contain a large percentage of protein.
From the foregoing it is easily seen that the problem of the hog raiser is to use a combination of feeds which will provide the proper proportions of the various nutrients. While the pigs are young, bone and muscle producing foods are especially necessary. Toward maturity the percentage of fat producing foods may be increased.
=Corn, pasture and other supplements.= Corn is the most widely used feed for pigs. As has been stated, it is essentially a fat producing food and must be properly supplemented. Clover or alfalfa pasture supplies the protein and part of the mineral matter which the corn lacks. Rape furnishes good pasture for hogs, almost equal to clover and alfalfa. Rye, blue grass, cow peas and soy beans together with various pasture mixtures have value as hog pastures. Where pigs are fed in a dry lot, tankage may be used to supply the protein. Pasture-fed pigs are thriftier and make cheaper gains than those fed in a dry lot. Skim-milk or buttermilk together with tankage makes an ideal supplement to corn. Middlings and shorts may also be used.
=Mineral matter.= To insure pigs getting enough mineral matter it is recommended that the following mixture be kept before them at all times:[7]
Wood ashes or coal screenings 1 bushel Air-slaked lime 8 quarts Salt 8 quarts Rock phosphate 3 quarts Copperas (iron sulphate) 1 quart
The first four ingredients should be mixed thoroughly and the copperas dissolved in warm water and poured over the mixture.
=Feeding and care of the sow.= In starting in the swine industry with one or more gilts, it should be borne in mind that a sow should not be bred until she is eight or ten months of age. Every hog raiser should aim to have his sows produce two litters a year, farrowing in April and October.
Not more than two-thirds of the grain ration should be corn. Some feeders prefer to use ground oats and middlings exclusively. In any event, heating and fattening foods should be avoided. In addition to the grain ration, roots and clover or alfalfa hay or skim-milk should be fed. Sows on good pasture require little grain except just before farrowing.