182 POULTRY PRODUCTION 



2 to 3 per cent, solution of a standard stock dip. This is a 

 safe precaution in all cases where eggs are secured from 

 flocks with whose history one is not perfectly familiar. It is 

 unnecessary in cases where the eggs come from stock that 

 has been strong and vigorous for years and without serious 

 outbreak of disease of any kind. It should be recognized as 

 simply a precautionary measure to eliminate any disease 

 germs that may be on the outside of the egg, and not in any 

 measure a sure preventive of chick diseases. 



Incubation Periods. — ^The number of days necessary for 

 the incubation of the eggs of the various species of poultry 

 are as follows: chickens, varying from 19 for light breeds to 

 21 for heavy breeds; turkey 28, varying from 26 to 30; all 

 ducks except the Muscovy 28, varying from 26 to 32; Mus- 

 covy ducks 33 to 35; goose 30, varying from 27 to 33; guinea, 

 varying from 26 to 30, and pigeon 17 from the day the second 

 egg is laid, but varying at times from 16 to 20 days. 



Comparative Reliability of Natural and Artificial Incubation. — 

 The great danger in artificial hatching is in overheating the 

 eggs, which, of course, the hen cannot do, though she all 

 too frequently leaves her nest and refuses to return. Over- 

 heating is much more serious in consequences than an equal 

 amount of underheating. A temperature of 105° F. or above 

 is dangerous, and eggs held for any considerable time at 

 107° F. will die. . Eggs may be held at 4° below the proper 

 hatching temperature (103°) for quite long periods with 

 apparently no more serious consequences than delaying the 

 hatch a few hours. 



With standard machines properly handled there is little 

 danger of overheating except during the last two or three 

 days, when the increased amount of animal heat given off 

 by the nearly developed chick makes the best machines 

 uncertain, and calls for carefiil watching. In incubator 

 hatching there are fewer eggs broken or chilled than in the 

 case of hen hatching. 



Relative Hatching Efficiency of Hens and Incubators. — ^The 

 time has passed when the question of the desirability of 

 having an incubator on a farm where upward of one hundred 

 and fifty chickens are raised annually is any more debatable 



