BY PHILIP B. HADLEY 55 



for the more alluring problems in breeding and feeding. It cannot be 

 believed, however, that all that can be said about incubation and brooding, 

 has been said. With the greater increase in the poultry industry in this 

 country, and the necessity of winter production of immense numbers of 

 birds to supply city markets, the problem of artificial brooding is becoming 

 of an ever increasing importance to all large poultry raisers. 



Closely related to this subject, since so great mortality is often present 

 among artificially brooded chicks, is that which we may call, for the lack of 

 a better term, Poultry Hygiene; and we may define this as the science 

 which deals with the laws of health of the chicks. It is a study of the 

 young birds' surroundings, with a view to ascertaining in what measure 

 these are conducive to health or to disease. Disease is not, strictly speak- 

 ing, caused by micro-organisms. In most instances, whether in human 

 beings or in chicks, disease is due as much to a weakened vitality as to out- 

 side infectious agents or materials. Disease is merely an offset to the 

 normal equilibrium of physiological conditions, which we call health, 

 either because the vitality is too weak, or because some outside stimulus is 

 too strong. In a great number of cases young birds in a weakened condi- 

 tion succumb to the action of organisms which are constantly present in well 

 birds. The problem of practical poultry hygiene would, then, have for its 

 aim the study of all those conditions which make for or against the vitality 

 and health of poultry. It is a problem whose aspects extend into every 

 phase of poultry work, from the formation of the egg in the oviduct to the 

 final disposal of the bird in the market. It has to do, first, with the problem 

 of egg infection, either with the coccidia which cause Blackhead and White 

 Diarrhea, or with other microorganisms which cause the rotting of eggs and 

 the premature death of young chicks in the shell. It may have to do with 

 the questions of incubation including the effect of moisture, of carbon 

 dioxide, of ventilation, of intermittant versus steady heat. Later, it 

 includes consideration of methods of brooding; and the relation thereto of 

 different methods of feeding and heating; also questions of infection through 

 dust or through contaminated food or water. Furthermore, the practical 

 poultry hygiene should include a study of the hygiene of the poultry yard, 

 its location, drainage, its constant or intermittent use, methods of cleansing, 

 disinfecting, etc., together with methods (especially in large poultry plants) 

 whereby certain divisions of the yard can be quickly and effectively isolated 

 from the rest in the case of such an epidemic as fowl cholera. The writer 

 has recently been called to inquire into a certain poultry epidemic in a 

 neighboring state in which a large poultryman lost three thousand birds 

 within two months through fowl cholera, and was advised to kill the balance 



