li»CO] DAIRY FARMING DAIRYING. 175 



liiftations could be estimated from the production in one of tlie lactations. Only 

 the first S months of each lactation were considered. The correlation between 

 the 5-lactation milk total and the amount of milk given by the cows as two- 

 year-oMs was found to be +0.74. The correlation was higher when a later 

 lactation was taken as the basis of estimate. Similar deterniiiuitions are given 

 for the relationship between butter fat percentage in the individual lactations 

 and the average percentage of all tive. 



" The average correlation coefficient for the 7-day test of IIolstein-Friesian 

 cattle and the 365-day test, of which the 7-day test is a part, is +0.57. Tlie 

 average correlation coefficient for the 7-day test and 365-day test, of which 

 the 7-day test is not a part, is +0.55." 



The author reports 19 coefficients of correlation between the annual milk 

 production of Registry of ]\Ierit Jersey cows and the score assigned by judges to 

 the cont\)rmatiou of a particular body part, and to total score. The latter cor- 

 relation is highest, being +0.194. Many of the coefficients are practically zero, 

 but only one is negative. " The parts of the conformation having a distinctly 

 significant relation to milk production of the cow were the milk veins, size, and 

 condition of udder, the size and shape of rear udder, the shape and size of 

 barrel, and the general appearance of the cow." 



The 21 calves born in the cross-bred herd between October 15, 1918, and 

 October 26, 1919, are listed, and the milk yields of 6 cro^-bred heifei's are pre- 

 sented in the form of graphs showing the changes in successive months of lac- 

 tation. " The milk yield of the breeds seem to occupy the following i-elation : 

 The low milk yield of the Aberdeen Angus is recessive to the higher milk yield 

 of the Jersey. T'he Jersey milk yield is recessive to the higher milk yield of 

 tlie IIolstein-Friesian." 



Tiiere are al.so included a revision of the e.stimates of the " transmitting quali- 

 ties " of Guerasey sires given in the previous report, and abstracts of Bulletin 

 281 noted below, and of Pearl and INIiner's paper on the milk of Ayrshire 

 cows already noted (E. S. R.. 42, p. 69). 



Studies ill milk secretion. — VII, Trail sniitting qualities of Jersey sires 

 for milk yield, butter fat jierceiitage, and butter fat, R. Pearl, J. A\'. Gowkn, 

 and J. R. IMiner {Maine Sta. Bui. 2Sl (lUID), Pl>- ^!>-1(j4^ lUlx- 3; pp. 1 6 0-20 ■',).— 

 The authors arrange 225 Jersey bulls in the order of their estimated " trans- 

 mitting qualities " as determined for each sire by the difference between the pro- 

 duction of his daughters and that of their dams. Only year records were used, 

 and each bull considered had at least two Registry of Merit daughters out of 

 llegistry of Merit dams. To eliminate differences due to variations in age at 

 testing, the records of each cow were corrected to a standard age by assuming 

 that the ratio between her observed yield and her standard-age yield would be 

 etpial to the ration between the average of all cows tested at her age and the 

 average of all cows tested at the standard age. Eight years was taken as the 

 standard age of milk production and two years as the standard age for percentage 

 of fat. Corrected amounts of butter fat were not computed for individual c()ws, 

 but each group of dams and each group of daughters was credited with a butter- 

 fat yield determined by nudtiplying the group's average milk yield as of eight 

 years by the group's average fat percentage as of two years. 



A bull whose daughters averaged higher in both milk yield and butter fat 

 percentage than their dams is considered a superior sire; one whose daughters 

 tiveraged less in both respects is considered inferior. On this basis there were 

 28 superior and 40 inferior sires. These two groups are subjected to a more 

 detailed study with respect to their origins. The inferior sires were found to be 

 a»mewhat more inbred as measured by Pearl's coefticieuts (E. S. R., 38, p. 209), 



