694 FEEDS AND FEEDING 



breeding powers. In summer the boar should run in a pasture lot, and 

 in winter he should have the freedom of a small yard adjoining the pen. 

 About 1 Ib. or less of concentrates daily per 100 Ibs. live weight is suf- 

 ficient in summer for fairly mature boars on good pasture. During 

 service the boar requires more feed than at other seasons. In winter 

 mature boars should be given only enough concentrates to maintain their 

 weights. Young boars need enough concentrates to keep them growing 

 thriftily. 



The most common mistake made in feeding boars is to overfeed them 

 and allow them to become so fat that their breeding powers are seriously 

 injured. Two weeks before the breeding season begins, the ration 

 should be increased somewhat, so the boar will be gaining in weight when 

 service begins. The amount of concentrates to be fed during the breeding 

 season will depend on how much the boar is used. In general he should 

 be fed enough to prevent his losing much weight. Many breeders prefer 

 not to feed much corn to boars during this time and use concentrate 

 mixtures made up of farm grains and a considerable proportion of 

 protein feeds, such as wheat middlings or bran, linseed meal, tankage, 

 and chopped legume hay. 



1028. Gestation period; breeding studies. It has been generally stated 

 that the average gestation period of sows is 112 days, or 16 weeks, but 

 Carmichael and Rice report that the average of 549 gestation periods 

 of sows of various breeds at the Illinois Station was 114.6 days. 19 The 

 shortest gestation period was 98 days and the longest 124 days. How- 

 ever, about three-fourths of the sows farrowed between the 113th and 

 117th days. Altho it is commonly believed that old sows carry their pigs 

 1 to 3 days longer than young sows, there was little evidence of this in 

 these studies. There was also little correlation between the length of 

 the gestation period and the weight of the pigs at birth, or between the 

 sex of the pigs and the length of the period. On the average there were 

 8.1 pigs in the litters, weighing a total of about 20 Ibs. In litters with 

 few pigs, the weight at birth tended to be a trifle larger than in litters 

 with more pigs than the average. There seemed to be a tendency for 

 the larger litters to contain a slightly larger proportion of dead or im- 

 mature pigs than in the smaller litters. Of a total of 5,657 pigs, 51.9 per 

 ct. were males and 48.1 females. 



Immature sows tended to produce fewer and smaller pigs than older 

 animals. On the average, sows one to one and one-half years old had 7.5 

 pigs, while those two years old or older had 8.6. The average birth 

 weight of the pigs from the younger sows was 2.44 Ibs. and of those from 

 the older sows, 2.61 Ibs. Similarly, Iddings found at the Idaho Station 20 

 that gilts bred at 8 months averaged 7.7 pigs per litter ; sows 24 months 

 old averaged 9.6 pigs; and aged sows 10.6 pigs per litter. Carlyle 21 

 found that sows 4 years old or more bore 9 pigs to the litter on the 

 average, the litter weighing 26 Ibs., while 1-year-old sows averaged less 



"111. Bui. 226. 20 Breeder's Gaz., 64, 1913, p. 241. a Wis. Bui. 104. 



