5 MAINE AGRICULTURAL EXPERIMENT STATION. 



Calculated total milk (on the basis of all 29000 



•11 ■ \ = -^ ' ^= 454-6 lbs. 



cows now milking) 63.79 



Average per cow =: 32.5 lbs. 



From the above figures it is possible to make precise and 

 definite comparisons between these two herds. We note, in 

 the first place, that Herd B was operating with more than 10 

 per cent, greater efficiency at the time the records were made 

 than was Herd A. Bringing both herds to the same basis of 

 efficiency (100 per cent),^ however, it is plain that the cows 

 in Herd A are much belter cows than those in Herd B, the 

 average production per cow on the same efficiency of operation 

 basis being about 16 lbs. per day higher in the former than in 

 the latter. This is the fact. Herd A is one of the best herds 

 of pure-bred Holstein Friesian cattle in the state, nearly every 

 cow having an A. R. O. record. Herd B is only a fair average 

 herd. 



Table 2 has many uses besides that of herd comparison here 

 illustrated. It may be used for the comparison of individual 

 cows. It forms a much more scientifically accurate basis for 

 the age correction of advanced registry records than do the 

 rules of entry to advanced registry of any association in this 

 country. 



(c) ANALYSIS OF BILTMORE RECORDS. 



This matter will be considered in a later section of this Re- 

 port (cf. p. 26 ). 



II. The Study of Inbreeding in Dairy Cattle. 



During the past year the work on the theoretical side of 

 this problem has been extended along two lines. The first" 



''Of course any other percentage could have been taken instead of 100. 

 The essential thing is to compare both herds on the same percentage 

 basis of operation efficiencj'. One hundred per cent is as good, and in 

 some regards perhaps better than any other basis on which to make the 

 comparison. 



"Pearl, R. Studies on Inbreeding. VI. Some further considerations 

 regarding cousin and related kinds of mating. Amer. Nat., Vol. XLIX, 

 pp. 570-575, 1915. 



