284 POULTRY CULTURE 



individual treatment for lice. Waterfowl which have access to water 

 in quantities sufficient for bathing or swimming are not likely to 

 be troubled with external parasites. When young ducklings and 

 goslings are brooded with hens and given water only for drinking, 

 they are often troubled with head lice. If the water in the drinking 

 vessel is deep enough to allow the bird to get the head well under 

 water, it will keep the lice off its head and neck in this way ; on 

 other parts of the body they are less dangerous, and the bird can 

 get at them with its bill. Young poultry hatched and reared, arti- 

 ficially are less afflicted by lice, but it is not well to take it for 

 granted that incubators and brooders are free from them ; young 

 birds in brooders will appreciate opportunities to dust themselves, 

 and so make assurance of freedom from the parasites doubly sure. 



Growth proves the materials and work of the poultry grower. 

 If the birds grow normally the sum total of factors affecting growth 

 must be approximately right, deficiencies being offset by advantages 

 in other directions, as faulty conditions by extra attention, slight 

 weakness in stock by very favorable conditions, etc. ; if growth is 

 not normal, one factor must be radically wrong or several factors 

 slightly wrong, and the total of deficiencies so great as to have a 

 marked effect on the general result. Normal growth of poultry 

 is continuous and rapid ; in the most rapidly growing common 

 kinds of poultry geese and the larger breeds of ducks the rate 

 of growth is so great that the fact that the birds are growing fast is 

 self-evident. In chickens and young turkeys growth is not so notice- 

 able, but it is plainly seen by comparing the birds, while small, with 

 younger birds, and, after they are weaned, either with younger birds 

 or with adults. 



Rate of growth. This has been determined experimentally only 

 for chickens and ducklings. Though the number of experiments 

 is small, it is probable that, these being apparently average in- 

 stances, the figures are very near the ordinary averages and may 

 fairly be taken as standards for roughly ascertaining whether the 

 rate of growth is normal. 



The rate of growth of chickens of different breeds and types is 

 surprisingly uniform for the first ten or twelve weeks. Differences 

 between individuals of the same stock are more marked than dif- 

 ferences in averages for different breeds. Leghorn chicks from 



