246 DAIRY CATTLE AND MILK PRODUCTION 



from the cow dropping particles of food into the basin. If 

 some arrangement is provided whereby the basins can be filled 

 at intervals when the animals need water, and then drained 

 out, this objection may be largely overcome. One of the 

 most satisfactory provisions for watering cows in the stable is 

 the use of a continuous cement manger. By this means the 

 objections above mentioned are overcome. The manger is 

 swept free of feed when it is desired to water the animals, and 

 the water remaining after the animals have drunk is drawn out 

 through a drain arranged for the purpose. 



Salt Requirements. All animals that consume large 

 quantities of vegetable food require salt. Carnivorous ani- 

 mals do not have this craving, neither do human beings that 

 live mostly upon meat. According to Bunge l the cause of 

 this salt requirement by herbivorous animals is the large quan- 

 tity of potassium which they consume with the plant food. 

 The potassium is excreted through the kidneys, but while in 

 the body a reaction takes place between the potassium and 

 the sodium chloride or common salt, and the resulting com- 

 pounds are excreted from the body. This leaves the body 

 short in the amount of sodium chloride needed, and results in 

 the well-known craving for common salt, or sodium chloride. 

 Common salt is needed, according to this view, to help expel 

 the excess of potash taken in with the vegetable food. 



Babcock's Investigations. Babcock 2 has reported ex- 

 tensive investigations on this subject. He kept cows in milk 

 without salt for periods up to one year. The composition and 

 quantity of the milk produced was not affected by withhold- 

 ing salt for short periods. Cows without salt showed a strong 



1 Bunge, Lectures on Physiological and Pathological Chemistry. 

 'Babcock, 22d Annual Report Wisconsin Experiment Station, p. 123. 



