Nutritive Requirements of Swine

THE HOG excels other livestock as an economical converter of feed into body tissue, the products of which are largely meat and fat. Fundamentally, the nutritive requirements of swine are not so complicated as those of other classes of livestock. The swine ration is largely made up of concentrated feeds with only a small proportion of roughage, aside from good pasture. Hogs grow rapidly and most of them reach market weight at 7 to 10 months of age. They also reproduce at a much younger age than most farm animals. Welldeveloped gilts are usually bred to farrow their first litters at approximately 1 year of age. The growth of swine follows the same general law as that of other animals, but they grow much faster in proportion to their body weight than the larger farm animals. Growth curves showing the rate of increase have been published by various investigators. The curves given in figure 1 show a somewhat faster rate than most of the other United States data. These curves are based on records kept on litters used in record-of-performance tests at the Agricultural Research Center, Beltsville, Md., for the autumn farrows of 1936 and 1937 and the spring farrows of 1937 and 1938. The sows and the pigs of all four farrows were handled under essentially identical conditions except for the diflierences due to season of the year. Besides the ration of yellow corn and a protein mixture with mineral supplements incorporated, the sows grazed on rye pasture. The pigs were weaned either at 8 or at 10 weeks and a large proportion were placed on the record-of-performance test. For the most part, the animals were removed from the feed lot when they attained a weight of approxi-