104 



CIVIC BIOLOGY 



any branch of the industry, from pigeons and chickens to geese 

 and turkeys and native game birds, is likely to yield a sub- 

 stantial profit from the start. One of the chief problems of 

 present interest is that of breeding for egg production, the 

 accepted unit being the number of eggs laid in a year. Some 



recent American records are 

 shown in the table below. 



Variations in growth of flesh 

 or fat are similar to those in 

 milk and egg .production. This 

 means that one animal may 

 not digest or assimilate food 

 as well as another, or one may 

 use its energy in developing 

 nervous activity (which is not 

 edible) while the other is grow- 

 ing flesh and fat. Experiments 

 have shown that one animal 

 may thus require over 30 per cent more food to gain a pound 

 of flesh than another. Here selection and thorough breeding 

 are saving enormous losses and increasing productive efficiency. 



AMERICAN EGG RECORDS 



FIG. 50. Hen C. 521 



Bred by Professor James Dryden, 

 Corvallis, Oregon 



1 This is held to be the world record up to date. In attempting to make 

 a record of this kind it is necessary to have official control to guard against 

 any possible mistakes or falsification, if the records are to stand. 



