602 FEEDS AND FEEDING 



915. Protein requirements of swine. Since pigs grow rapidly, they 

 need an abundant supply of protein in their rations, to furnish the build- 

 ing material for the rapidly developing muscular tissues and the internal 

 organs as well. Furthermore, the supply of protein must not only be 

 ample in amount, but also the proteins must be of the right quality. 

 This last requirement is of much greater importance in the feeding of 

 swine than with cattle, horses, or sheep. This is because swine are 

 commonly fed chiefly on the cereal grains, and the proteins of all grains 

 are unbalanced in composition, being low in certain of the necessary 

 amino acids. Moreover, many of our common protein-rich swine feeds 

 do not balance the proteins of the cereals efficiently. For example, grain 

 with only wheat middlings, linseed meal, gluten feed, or corn germ meal, 

 makes a very unsatisfactory ration for young pigs not on pasture. 

 (118, 938) This is probably due primarily to the unbalanced nature of 

 the proteins such rations furnish, tho these supplements are also low in 

 calcium. (98, 119) On the other hand, skim milk, buttermilk, whey, 

 tankage, and fish meal, all of which are animal products, supplement the 

 cereals in a most efficient manner, for they supply proteins which are 

 rich in the very amino acids deficient in the grains. 



Fortunately for economy in pork production, all good pasture crops, 

 such as alfalfa, clover, and rape, are not only rich in proteins and in 

 calcium, but their proteins are quite high in those amino acids which are 

 low in the grains. Therefore, pigs on good pasture make quite good gains 

 on corn supplemented by only linseed meal, wheat middlings, or corn 

 germ meal. (969, 973) 



Legume hay has an important place in swine feeding, due to its rich- 

 ness in protein and calcium, and also because the proteins are quite well 

 balanced. (1009) The high value of alfalfa hay and hay from other 

 legumes for brood sows in winter is emphasized later. (1016) 



Pigs can not be expected to consume much dry roughage, owing to the 

 nature of their digestive tracts. However, even for them legume hay is 

 often an exceedingly important feed. For example, if pigs not on pas- 

 ture must be fed grain supplemented by such feeds as linseed meal or 

 wheat middlings, without any feed of animal origin, better gains will 

 be secured if a little legume hay is added to the ration. Also, even such 

 a good ration as corn and tankage is improved by adding a little alfalfa 

 hay to it, or still better, both alfalfa hay and linseed meal. (1010) For 

 fattening pigs, ordinarily not over 3 to 5 per ct. of the feed should be 

 hay, or the ration will be so bulky that the gains will be lessened. 



916. Mineral requirements. Swine suffer much more commonly than 

 horses, cattle, or sheep from a lack of calcium in their rations. This is 

 because they are fed largely upon the cereals, and also on account of 

 the rapidity of their growth and the confinement under which they are 

 often reared. It is well known that frequently pigs become crippled 

 during growth or on shipment to market, and brood sows often break 

 down while suckling their pigs. These troubles may be due, in part, at 



