80 ILLINOIS STATE DAIRYMEN'S ASSOCIATION 



fed otherwise, were given no salt for periods as long as a 

 year. After 2 to 3 weeks, they showed abnormal appetites 

 for salt, but their health was not usually affected for a 

 much longer time. Finally, a complete breakdown oc- 

 curred, marked by loss of appetite, lusterless eyes, rough 

 coat, and a very rapid decline in both live weight and yield 

 of milk. If salt was supplied recovery was rapid. In one 

 case potassium chlorid was given instead of common salt 

 (sodium chlorid). Recovery followed as quickly as when 

 common salt was supplied, showing that not the lack of 

 sodium but the lack of chlorin was responsible for the 

 troubles. 



Cows in milk and sheep need the largest amounts of 

 salt; fattening cattle, horses, dry cows, and stock cattle 

 require less; and pigs but little. The salt requirement will 

 vary considerably in different localities. Soils which con- 

 tain large quantities of salt doubtless produce feeds con- 

 taining more salt than those poor in this ingredient; and 

 also the water of streams and wells varies in salt content. 



Iodine. 



Especially in certain sections of the northwestern 

 states, during recent years heavy losses have been experi- 

 enced of new-born pigs, lambs, kids, calves and foals, due 

 to goitre or "hairlessness." The young so affected are born 

 dead or weak, are frequently hairless, and commonly have 

 enlarged necks. This is due to the thyroid gland in the 

 neck being diseased and enlarged, just as in the case of 

 humans suffering from goitre, brought about probably by a 

 lack of iodine in the feed or a failure to absorb and use the 

 traces of iodine usually present in the feed. Recent investi- 

 gations have shown that this trouble with the offspring can 

 be overcome by administering iodine in the form of potas- 

 sium iodide to the pregnant dams. 



Mineral Matter Required for Milk Production. 



It was formerly assumed that when dairy cows were 

 fed common well-balanced rations containing plenty of pro- 



