FIFTY-SECOND ANNUAL CONVENTION 69 



B, but it is not near as rich in vitamine D as it is in vita- 

 mine A. Therefore it is very important, I believe, that 

 dairy cows have plenty of pasture, and that they get out 

 in the sun. Probably some of the good effects of pasture 

 that we have known in the past have been due to the 

 action of sunlight. 



I would not think of maintaining dairy cows in barns 

 throughout the year. They should get out on pasture in 

 the sunlight and get fresh, green feeds. 



A very interesting development has been made re- 

 cently in experimental work with poultry, and also with 

 dairy cows, by the Wisconsin experiment station, our own 

 institution. It has been found in the case of poultry, that 

 with laying hens having ultra-violet light produced by 

 these quartz mercury lamps shining on these hens, they 

 can be pepped up so they will produce more eggs. You 

 have all known egg production can be increased by having 

 electric lights, but this is another thing. The ordinary 

 electric light simply fools the hen, makes her work about 

 sixteen hours a day instead of seven or eight. With ordi- 

 nary electric light she eats more, works longer and lays 

 more eggs, but by means of ultra-violet light it has been 

 possible to maintain a still higher production. Whether 

 it will be practical to use ultra-violet lights in poultry pro- 

 duction, I do not know. 



Professor Hart, who developed these interesting facts, 

 has also found in experiments with goats, using goats be- 

 cause he could get goats in the agricultural chemistry 

 building and couldn't get cows, some things of interest in 

 milk production. 



Now he has experimented with cows that were losing 

 lime steadily from their bodies, then has had the ultra- 

 violet light shine a few minutes a day on the backs of these 

 goats, and within eight days he has brought these animals 

 back to a condition where they are no longer losing lime 

 from their bodies; and he has been able to reduce the 

 rickitic power of that milk six to eight or ten times and 

 produce a milk that is very high in this anti-rickitic prop- 

 erty. 



