176 EXPERIMENT STATION RECORD. [Vol.38 



tion between the time in the heat period at which the cow is served and the 

 sex of the offspring. Tabulated results of 1,313 matings show that of the 

 calves resulting from service under three hours after appearance of heat 51 

 per cent were bulls, of calves resulting from service over three hours and under 

 eight hours 51.7 per cent were bulls, and 46.9 per cent of the calves were bulls 

 when the cows were served over eight hours after the apptarance of oestrum. 



The analysis of milk records. — In continuation of this studj' (E. S. R., 37, 

 p. 775), the effect of certain Advanced Registry Jersey bulls on the average 

 niillc, fat test, and net milk-fat production of their daughters as compared wiih 

 the dams of these daughters is considered. From tabulated data of 23 well- 

 known Jersey sires, it appears that about one-half of the bulls in this group got 

 daughters which, on the average, were poorer producers than the dams of those 

 daughters. In some cases the deleterious effect of the bull on the productive 

 qualities of his offspring was extremely marked. On the other hand, certain of 

 the bulls in this group exercised an extraordinarily beneficial effect upon the 

 productive qualities of the breed. 



New cooperative project. — An outline is given of a cooperative plan by which 

 it is hoped to furnish to the dairy cattle breeders of the State definite and de- 

 pendable information as to whether their bulls are transmitting productive qual- 

 ities to their progeny. 



Breeding experiments. — Notes are given on the progress being made in the 

 attempt to build up an experimental herd of crosses between low-milking and 

 high-milking breeds, and between low-testing and high-testing breeds of cattle. 



Report of the second Jerscij sires' futurity test of the Aroostook Jersey 

 Breeders' Association. — A report is given of the second of these sires' futurity 

 tests (E. S. R., 35, p. 70), which was held at the Aroostook farm in October, 

 1916. 



The change of milk flow with age as determined from seven day records 

 of Jersey cows, R. Pearl and S. W. Patterson {Maine Sta. Bui. 262 (1917), pp. 

 145-152, fig. i).— Results are given of a study of the milk fiow of Jersey cows 

 as affected by age. The basis of the study was the seven-day milk records of 

 5,821 Jersey cows as published by the American Jersey Cattle Club.^ 



It is concluded that milk production changes with age in a definite manner. 

 This change follows a logarithmic curve of the form y=a+bx'+c log x where 

 |/=production and a?=age. Maximum production is reached at approximately 

 the age of eight years and seven months. 



The dairy record (Minnesota Sta., Rpt. Grand Rapids Substa., 1916, pp. 

 60-64, fig. 1). — A progress report is given of an experiment in breeding up a 

 herd of grade Guernseys from common and mixed-blood cows with pure-bred 

 Guernsey bulls. In 1905, when the project was begun, the average milk fat pro- 

 duction per cow was 196 lbs. In 1916 this production had increased to 300.7 

 lbs. The average milk production per cow of 41 cows in the herd in 1916 was 

 6,281 lbs. The average fat content of the milk increased from 4.27 per cent in 

 1911 to 4.78 per cent in 1916. Summarized herd records from 1911 to 1916, 

 inclusive, and individual records for 1916 are tabulated. 



Data on stump-land pasture emphasize the advisability of brushing and seed- 

 ing down stump lands, as the net profit per acre from stump lands after being 

 seeded down to grass for several years will almost equal the original cost of 

 brushing and seeding, when grazed by dairy cows. 



Raising dairy heifers (Mo. Bui. Ohio Sta., 2 (1917), No. 9, pp. 291-298, figs. 

 2). — On the basis of previously noted studies in Wisconsin, Connecticut, Massa- 



1 Jersey Sires and Their Tested Daughters. Publislied by American Jersey Cattle 

 Club, New Yorlj, 1909. 



