THE DEVELOPMENT OF THE DAIRY HEIFER 209 



Of 287 breeders replying to this question, 75 per 

 cent answered in the affirmative. This indicates a wide- 

 spread belief in the favorable influence of a bulky ration 

 while young upon the digestion of the mature animal. Our 

 investigations give no positive data along this line. It has 

 been observed, however, that a heifer that has been receiv- 

 ing a heavy grain ration up to calving time will consume, 

 when first put upon a typical dairy ration, only about one 

 half as much roughness as a heifer that has been raised 

 upon roughness. However, this marked difference soon 

 disappears. After about two months on the same ration, 

 we have been unable to observe any difference in the power 

 of digestion. However, more accurate means must be em- 

 ployed to determine this point definitely. The digestive 

 apparatus has great powers of adapting itself to the char- 

 acter of the food consumed, and for this reason it is probable 

 that the effects of the ration fed during the period of growth 

 are not permanent. 



Age at first Bulling. Question 12. At what age, on the 

 average, do the heifers first come in heat? 



The influence of breed counts for considerable in this 

 connection. The average age given for Jerseys was 8 

 months, Guernseys 11 months, Holsteins 11.4 months, and 

 Ayrshires 12.8 months. Our investigation has shown a wide 

 variation in this respect due to the ration fed. As might 

 reasonably be expected, the animals receiving a liberal grain 

 ration reach sexual maturity sooner than those on a ration 

 with no grain. Our data show an average difference for 

 the two groups of 65 days for the Jerseys, 126 days for the 

 Holsteins, 100 days for the Ayrshires ; an average of 92 days 

 for the 32 animals included. 



