348 FEEDS AND FEEDING, ABRIDGED 



This table points out several facts of great importance to the pork 

 producer. While the amount of feed eaten per head daily increases 

 as the pigs grow larger, the amount consumed per 100 lbs. live weight 

 decreases rapidly. In other words, young pigs have a greater capacity 

 for consuming feed than older ones per 100 lbs. live weight. The 

 average gain per day started at 0.8 lb. for pigs weighing under 50 lbs. 

 and gradually increased until those weighing 250 to 300 lbs. showed 

 a daily gain of 1.5 lbs. The last column, perhaps the most important, 

 shows that as the pigs grow older, they require more and more feed 

 for 100 lbs. gain, the gains thus constantly becoming more expensive. 

 The greater production from the younger pigs is due chiefly to the 

 fact that they consume more feed per 100 lbs. live weight and conse- 

 quently have a greater surplus from which to make gain after their 

 bodies are maintained. Also, 100 lbs. of gain made by 150-lb. pigs 

 has somewhat less food value than the same amount made by 250-lb. 

 pigs, for the gain of the younger pigs contains more water and less 

 fat. Due to the increased cost of the gains as they mature, most pigs 

 are now marketed when weighing only 250 lbs. or less. 



Nutrient requirements of swine. — Since pigs are commonly fattened 

 for market before maturity, they are growing rapidly as well as storing 

 fat in their bodies. Consequently their ration should supply ample 

 protein and mineral matter for normal growth. The requirements of 

 pigs of various ages, as shown in studies by the junior author of the 

 numerous trials at American experiment stations, are given in the 

 Modified Wolft'-Lehmann standards. 



We have seen in Chapter IV that since horses, cattle and sheep eat 

 large quantities of hay, which is relatively rich in calcium (lime), 

 their rations ordinarily contain plenty of this mineral nutrient. Pigs, 

 however, are not fitted to consume much roughage and are fed chiefly 

 on the cereal grains, which are low in calcium. There is, therefore, 

 much more danger that their rations may not contain sufficient calcium 

 for thrifty growth of the skeleton and body tissues. Pigs on such pas- 

 ture as alfalfa, clover, or rape, and those fed skim milk or tankage as 

 supplements to corn or other grains, will ordinarily receive sufficient 

 calcium. When fed in the dry lot on cereal grains and their by- 

 products, they should be given additional calcium in the form of ground 

 limestone, bone ash, or ground rock phosphate. An abundant supply 

 of calcium is especially necessary for young pigs and brood sows. 

 When rations are so balanced that they furnish sufficient protein to 

 meet the feeding standards, they will also supply enough phosphorus 

 for rapid growth. This is due to the fact, brought out in Chapter V, 

 that the common feeds which are rich in protein are also high in 

 phosphorus. 



