FERTILITY 



93 



eight and three-tenths. The records for 325 five-year- 

 old sows give the average size of litter as eight and seven- 

 tenths. The total number of sows examined, ranging 

 in age from one to five years, was 6145 and the average 

 size of litter for the whole number was seven and four- 

 tenths. 



The number of animals included in these investiga- 

 tions and the unquestioned accuracy of the records make 

 these figures valuable. It is clear that the sows increase 

 in fertility from one to five years. From the standpoint 

 of the practical breeder, it would seem that sows from 

 two to four years of age will be most profitable from the 

 standpoint of prolificacy. 



92. Relation of age to fertility in sheep. The greater 

 fertility of the older females has been noted in ewes by 

 the Wisconsin Experiment Station in Bulletin No. 95. 

 Observations made at that station on the percentage of 

 increase from ewes of different ages show that two-year- 

 old ewes gave an annual increase of 158 per cent, three- 



THE EFFECT OF THE AGE OF EWES ON PER CENT OF IN- 

 CREASE AND SEX OF LAMBS 



WISCONSIN EXPERIMENT STATION, BULLETIN 95 



