Size of Litters 



97 



important factor causing this variation. In Table XVI 

 are presented the findings made by Rommel from a study 

 of the farrowing records of 6145 sows recorded in volume 

 36 of the American Poland China Record. 



TABLE XVI. SIZE OF LITTERS OP Sows OP DIFFERENT AGES 



These results show that the two-year old sows, recorded 

 in volume 36, produced larger litters than did the year- 

 lings, and the three-year old sows larger litters than the 

 two-year olds. There was a regular increase in the size 

 of litters as the age of the sows increased. It is believed 

 that these averages are based on a sufficient number of 

 litters to make them reliable and fairly indicative of the 

 fertility of sows of different ages. These results should 

 not, however, be interpreted to mean that the average 

 sow necessarily produces an increasing number of pigs 

 to the litter up to and including her fifth year. Ordinary 

 herd selection would mean the elimination of the low pro- 

 ducers at an early age and the retention of the more pro- 

 lific. The older sows in the average herd are, therefore, 

 selected individuals, while the younger ones contain many 

 whose performance records will not entitle them later to 

 permanent places in the breeding herd. 



With the purpose of securing information on how age 



