Investigations ivith Swine. 



497 



aged less than 8 pigs, weighing but 15 Ibs. From the records of 

 1,477 pure-bred sows of 8 breeds Rommel 1 found that on an average 

 there were 9 pigs to the litter, 50.1 per ct. males and 49.9 per ct. 

 females. 



811. Milk yield. At the Wisconsin Station 2 Carlyle studied the 

 milk of 12 sows of 3 breeds. The pigs were kept from the dam ex- 

 cept for short periods at 2-hour intervals by day and 4 by night, 

 when they were put with her to suckle. They were weighed collect- 

 ively before and after that operation, and the increase credited as 

 milk drawn from the dam. With extreme difficulty samples of milk 

 were obtained for analysis. The average yield of milk of 4 sows of 

 each breed during 84 days between farrowing and weaning, deter- 

 mined in the above manner, is given below: 



Yield of milk by sows between farrowing and weaning. 



We learn that these sows gave from 4.9 to 6.3 Ibs. of milk daily, 

 the total for 84 days, by which time they went dry, ranging from 

 429 to 532 Ibs. A 4-yr.-old, 532-lb. sow with 10 pigs gave 669 Ibs. 

 of milk, while a 5-yr.-old, 490-lb. sow with 8 pigs gave only 337 Ibs. 

 Carlyle states that some sows yield almost twice as much milk as 

 others. 



812. Composition of sow's milk. On analysis the milk of the 

 sows reported in the preceding article showed the composition re- 

 corded in the following table, average cow's milk being added for 

 comparison : 



Average composition of sow's milk. 



1 U. S. Dept. Agr., Bur. Anim. Indus., Cir. 112. 

 33 



2 Bui. 104. 



