22 MAINE AGRICULTURAL EXPERIMENT STATION. 



These tables present a number of points of interest to the 

 breeder of cattle. We note : 



I. The average age of the herd bulls used to sire the 967 

 calves included in the statistics was just under three years. 

 The median age of these herd bulls was approximately two and 

 a half years. This means that one-half of the calves were 

 sired by bulls tinder two and a half years old at time of ser- 

 vice. Seventy-five per cent of all the calves (as shown by the 

 third quartile age) were sired by herd bulls less than about 

 three years and nine months old at time of service. Less than 

 15 per cent of the calves were sired by bulls five or more 

 years old. Let us consider for a moment what these facts 

 mean. A bull must be at least three years old before the 

 breeder can possibly have had any opportunity to test the 

 milk producing capacity of his daughters. But ^8.p per cent 

 of all the calves covered in these statistics zvere sired by bulls 

 under three years of age. In other words, in the breeding 

 operations of a large number of Maine's most progressive and 

 wide-awake breeders (for such the cooperators in this record 

 scheme are) more than half of the calves produced in a given 

 interval of time are sired by bulls about whose ability to trans- 

 mit milking qualities absolutely nothing definite can by any 

 possibility be known. It is doubtless entirely fair to assumie 

 that essentially the same conditions regarding cattle breeding 

 methods obtain in other places generally. Is it remarkable 

 that progress is so slow? 



2. In the female half of the herd the conditions are better. 

 We see that if we exclude heifers bred for their first calves, 

 the average age of the breeding cows is approximately five and 

 a half years. This is an age when, on the average, cows are 

 nearly if not quite at their best as regards milk production. 



3. Out of 878 calves 166, or 18.9 per cent were the first 

 calves of heifers. The average age of these heifers when suc- 

 cessfully served for these first calves was approximately one 

 one year and seven months. Three-quarters of the heifers were 

 successfully served for their first calves before they were 2.1 

 vears old. 



