ANNUAL REPORT, 1934 19 



Third, the records of the mixed Holstem and Jersey herd of the Massachusetts 

 Agricultural Experiment Station for the years 1920 to 1933 inclusive were studied 

 by similar methods. They included a total of 42 cows with 136 lactations. The 

 results gave a range of efficiency from a low of 18.12 percent to a high of 39.60 

 with an average of 29.35. That is to say, on the average, these cows returned 

 29.35 pounds of total digestible nutrients in the form of milk for every 100 pounds 

 of total digestible nutrients fed. 



The following four points seem well established. 



1. There was a gradual rise in efficiency of feed conversion with age from two 

 years to about nine years. 



2. The cows that showed a low efficiency at two years were low all through 

 their lives, and those high at two years were high throughout their lives. 



3. Percentage efficiency of feed conversion is apparently an inherited quality. 



4. As would be expected, there was a positive correlation between amount 

 of production and efficiency; that is, the higher producing cows were the more 

 efficient converters. 



Inheritance of High Milk Production in the May Rose Family of Guernsey 

 Cows. (V. A. Rice.) A study was made of all the direct male offspring of the 

 Guernsey bull, May Rose King, through his 15 sons, their sons, grandsons, etc. 

 In this way it is possible to trace the lines of high production back to their source, 

 and to ascertain which lines of breeding at the present time are the more homozy- 

 gous for high m'lk production. 



Further studies along this line will reveal the methods of breeding which have 

 given rise to these more homozygous strains. 



A Study of Bull Indexes and the Formulation of the Intermediate Bull Index. 



(V. A. Rice.) The Mount Hope Index, based on the theory of partial dominance 

 of high milk production and low fat percentage, the Gifford Index, using merely 

 the daughters' records, and the Intermediate Index, suggested by the author, 

 with the offspring placed halfway between the cows' level of production and the 

 assumed index, both for amount of milk and percentage of fat, were studied for 

 their accuracy and reliability from the standpoint of prognosticating the produc- 

 tion of future daughters of a bull after his index has been achieved through the 

 production records of his first ten daughters. The results showed that all three 

 methods were remarkably accurate, but that the Intermediate method was the 

 best. 



Further studies were made to determine the value of the Intermediate Index in 

 foretelling the production of the daughters of young untried bulls. The method 

 was to obtain indexes on the sire and two grandsires of the young bull, which were 

 used as the transmitting level of these male animals. The transmitting level 

 for the dam and two granddams was the average of (1) the cow's own record, 

 (2) the index of her sire, and (3) the cow's own index calculated from her daughters' 

 records and the indexes of the sires of said daughters. It was found that a figure 

 comprised of 6/10 of the average of the parental indexes and 4/10 of the average 

 of the grandparental indexes was, on the average, within 6 percent of accuracy. 



The Comparative Efficiency of Lambs in Utilizing Feed. (Ralph W. Phillips.) 

 Ten lambs were fed individually for four months and accurate records and analysis 

 of all feeds consumed were obtained, the object being to determine what individual 

 differences exist in the efficiency with which lambs transform feed into meat. 

 The lambs were approximately seven months old when the feeding trial began, 

 and all received the same ration. 



