140 Maine Agricultural Experiment Station. 1917. 



6. BREEDING EXPERIMENTS. 



The experiments in cattle breeding which are being car- 

 ried out with the University of Maine herd have proceeded 

 satisfactorily during the year. These experiments are along 

 the line of experimental hybridization. This is the only meth- 

 od now known by which one may hope to make an adequate 

 analysis of the laws lof heredity. 



In view of these considerations we are endeavoring as ra- 

 pidly as possible to build up an experimental herd of first gen- 

 eration crosses between low milking and high milking breeds, 

 on the one hand, and between low testing and high testing breeds, 

 on the other hand. It is gratifying to be able to report that 

 this experimental cross-bred herd is now nearly completed. 

 To February 9, 1917 a total of 42 animals have been produced 

 of which some 14 will probably be permanently retained in the 

 experimental herd. The remainder have been, or will be, sold 

 as fast as they pass the age of 200 days when certain records 

 are taken on them. To complete the herd, so that analytical 

 experiments may go forward, there are now required only six 

 heifers. Owing to the fact that a control of sex in the individ- 

 ual case is impossible, it is likely to take at least one or two 

 years more to complete the experimental herd. After these 

 six heifers have been obtained probably no more first generation 

 crosses will be bred. 



The breeds used in the formation of the experimental herd 

 are the Jersey, the Holstein-Friesian, and the Aberdeen Angus. 

 The Ayrshire and Guernsey breeds were used in some prelim- 

 inary work, but will not be continued. It is interesting to 

 note that one first generation hybrid animal is now in milk, 

 having borne a heifer belonging to the second hybrid genera- 

 tion on April 10, 1916. Another heifer belonging to the second 

 cross-bred generation was born August 17, 1915. It is the 

 second cross-bred generation which yields the important results 

 in Mendelian experiments. 



A complete list of the calves born in the experimental herd 

 between January 1, 1916, and February 9, 1917, is given in Table 

 6. In conjunction with the list given in the last report'' this 

 gives all the cross-bred calves obtained in the experiments. 



"Pearl, R. Report of Progress on Animal Husbandry Investiga- 

 tions in 1915. Me. Agric. Expt. Stat. Misc. Publ. 519, pp. 1-27, 1915. 



