4 MASS. EXPERIMENT STATION BULLETIN 307 



were housed in units of 250 at the new experimental poultry- farm. Artificial 

 lights have never been used. 



Modern methods for disease control, such as range rotation, complete separa- 

 tion of growing and adult stock, and cleaning and disinfecting of houses and 

 equipment, have been regularly employed. For many years all birds have been 

 tested yearly for pullorum disease, and in recent years chicken-pox vaccination 

 has been practiced regularly either at housing time or on the range at about 

 twelve weeks of age. Up to the fall of 1926 all birds in the laying houses were 

 self-fed laying mash in hoppers and grain twice daily in the litter. On November 

 19, 1926, self-feeding whole corn, oats, and laying mash was begun. 



The Qualities of an Improved Flock 



In general, an improved flock should consist of birds very uniform for all the 

 known desirable characters from the standpoint of fecundity; the birds should 

 be free from standard defects; there should be very high hatchability, low mortal- 

 ity, and a high degree of prepotency. 



An ideal hen should possess the following qualities: Standard weight; earl\- 

 sexual maturity; high intensity; no winter pause; non-broodiness; high persis- 

 tency; large egg size; first quality color, shape and shell texture of eggs; high 

 hatchability; strong vigor; trueness to breed standard; and prepotency. When 

 these requirements are considered individually in view of what is known regarding 

 their inheritance, the fact becomes very evident that the development of an 

 improved flock possessing all the desirable qualities is a gigantic undertaking 

 requiring large numbers of birds, careful observation, complete records, and a 

 knowledge of genetic principles involved. The measure of success in poultry- 

 breeding is the degree of uniformity in the flock with respect to all the characters 

 bred for. 



The Plan of Breeding 



The description of the plan of breeding may logically begin with the method 

 of selecting breeders. Since the male contributes to the inheritance of a greater 

 number of offspring than does the female, his selection may be considered first. 



Males have been selected in part each year by three different standards. Aged 

 males that were physically fit and that had sired a superior group of daughters 

 were used, and satisfactory matings were repeated as far as possible. Cockerel 

 breeders were selected each year both on their pedigree and on the performance 

 of their sisters with respect to characters affecting fecundity up to the breeding 

 season. Each male was selected on ph\sical characters as far as available birds 

 permitted. In the earlier years not much attention was paid to plumage color 

 or to physical defects in comb, shank, feathering, split wings, etc. During the 

 past five years great care has been exercised not to breed from either males or 

 females with physical defects, and some attention has been given to improving 

 plumage color. 



All hen breeders were selected on their fecundity characters and on the per- 

 formance of their daughters. Pullet breeders were chosen on pedigree and on 

 their performance up to the breeding season. Heavy body weight has always 



