776 EXPERIMENT STATION EECORD. [Vol. 37 



or stage of lactation are less than 100 per cent efficient. The manner in which 

 the table is to be used is shown by examples. 



The study of inbreeding in dairy cattle. — A preliminary report is made of 

 a study of inbreeding in American Jersey cattle. Tabulated data and diagrams 

 are presented showing the coefficients of inbreeding for random samples of the 

 general population of both Jersey bulls and cows and of samples of the animals 

 in the Register of Merit. From these it is concluded that American Jersey 

 cattle at the present time may be said, in general and on the average, to be 

 about one-half as intensely inbred, when account is taken of the eighth ances- 

 tral generation, as would be the case if continued brother X sister breeding 

 had been followed. That, in general and on the average, Register of Merit 

 animals are less intensely inbred than the general population of Jersey cattle. 



Physiology of cattle breeding. — In a study of the normal duration of oestrum 

 in cattle it was found that of 834 successful services which are tabulated over 

 79 per cent occurred within 10 hours after the discovery of heat No significant 

 differences appeared between the distributions for the different breeds. 



A study of 712 cows from the herds of about 150 leading dairymen of Maine 

 shows that on the average these cows were dry about 4 days short of 2 months 

 prior to calving. About 14 per cent of them were dry more than 79 days and 

 about 29 per cent were dry less than 40 days. 



In a study of the age of cattle used as breeders by dairymen in the State, 

 it was found that of 967 calves included in the statistics 58.9 per cent were 

 sired by bulls less than 3 years of age at time of service. Less than 15 per 

 cent of the calves wore sired by bulls 5 or more years old. The bearing of 

 these facts on the progress in dairy cattle breeding is evident, since it is 

 Impossible to test the milk producing capacity of a bull's daughters before he 

 is 3 years old. The average age of breeding cows in the study was approxi- 

 mately 5.5 years. Out of 878 calves 166 were the first calves of heifers. The 

 average age of these heifers when successfully served for these first calves 

 was approximately 1 year and 7 months. Three-quarters of the heifers were 

 succes.sfully served for their first calves before they were 2.1 years old. 



The Kerry: Its advantages under present conditions, Cheviot (Hark Lane 

 Express, 118 (1917), A'o. .}-J8.'?, pp. 206. 207. figs. 2).— The advantages of the Kerry 

 cattle as compared with the dairy type of Shorthorns and other dairy breeds 

 under present war conditions are pointed out, and notes are given on the origin 

 of the Kerry breed and of the type of the breed known as Dexter Kerry. 



Studies from the survey on the cost of market milk production, K. B. 

 MussER, G. C. White, B. A. McDonald, and H. F. Judkins (Conn. Agr. Col. 

 Ext. Serv. Bui. 7 (1917), pp. 27). — Results are given of a survey of 193 repre- 

 sentative dairy farms in Connecticut made for the purpose of determining the 

 cost of producing milk for the year ended April 30. 1917, and for the month of 

 April, 1917. 



It was found thiit the cost of producing milk on 178 of these farms for the 

 year ended April 30, 1917. was 5.53 cts. per quart. There was an average loss 

 for the year per cow for the 178 farms of $18.42. The cost of producing milk 

 on 179 farms for the month of April, 1917, was 6.29 cts. per quart, with labor 

 at the yearly rates. 



The 28 highest-producing herds produced milk on the average for 2.06 cts. 

 per quart below the 25 lowest-producing herds. The greatest percentage of 

 pure-bred bulls and milk records were in the 28 herds with the highest-produc- 

 ing cows, while the .smallest percentage was in the 25 lowest-producing lierds. 

 The 28 highest-producing herds showed a profit above the net cost of production 

 of $10.86 per cow per year, while the lowest-producing herds showed a loss of 

 $33.75. The average milk production of the 3,258 cows on those 178 farms was 



