Constitutional Vigor in Poultry Breeding. 62;^ 



variety are compared, is characteristic of the physically weak. (Figs. 7 and 

 8). The wing feathers of a chick grow first, then the tail feathers. These 

 should always be in proportion to the size of the body. A weak chicken 

 may fail to develop its body as rapidly as its wing feathers, which makes 

 the wings appear large and out of proportion to the size of the body. 

 (Fig. 6, B). Such a chicken should be so marked that it can not 

 by any possible chance get into the breeding flock, even if it should ap- 

 parently overcome its weakness. It should not be allowed to live 

 beyond the marketing age in any event, and in most instances should 

 be killed without attempting to raise it even to the squab broiler size. 

 Weakness is a trouble to be prevented rather than cured. 



When the chick has produced its first coat and is completely covered 

 with feathers, the contrast between the weak and the strong is very 

 apparent. (Figs. 7, 10 and 11.) The chick that lacks vigor of con- 

 stitution frequently requires several weeks longer to complete its 

 first plumage than does the stronger chick of the same age and variety. 

 Here, again, the weak should be eliminated. In Fig. 7, note the dif- 

 ference in the size of the bodies and the feather development of the 

 two weak chicks, BB, as compared with the two strong chicks, AA; 

 the difference in the expression of the eye of the strong and the weak; 

 also, shape of the head and beak, the size of the comb, and general atti- 

 tude. The two chicks in the center should be killed, or marked. 



Chickens in Figs. 10 and 11, A and B, show strong contrasts. These 

 chickens are of the same age and variety and were hatched, brooded 

 and fed under the same conditions. Note the difference in the alertness 

 and activity of the two groups. Group A find no difficulty in running 

 through the deep grass, and are piling up in the corner to get away. 

 Group B have small bodies and long wings, and are moving through the 

 grass with difficulty. Compare the plump, well-feathered bodies of 

 group A with the less developed, poorly feathered bodies of group B. 

 The difference in the appearance of the chickens to the eye was 

 far greater than is shown in the illustration. Chicks shown in group 

 B were given special care in a separate flock, while their sisters in group 

 A were allowed to run with a large flock on free range. From these 

 flocks were selected the hens used later in experiment. 



When the stock is brought from the range to be placed in winter- 

 quarters in the fall of the year, a rigid selection should again be made 

 and only those pullets and cockerels retained which satisfy all require- 

 ments for robust physical vigor. Weak chickens, if allowed to live, 

 should always be kept by themselves in small flocks in a brooder and 

 given special care. 



