Nursing Sickness in Minks (Table 2)) 
Nursing sickness affects a significant number of female mink 
each spring. They lose their appetites and consequently their 
weight, and the milk flow shrinks. Death losses are heavy among 
the females as well as their young. The nature of this dise 
turbance is not known. The annual loss for the 1943-52 period 
is estimated at $107,000. 
Urinary Calculi (Urolithiasis) (Tables 20, 22, and 2h) 
Urinary calculi occur principally among cattle and sheep, but 
losses are also serious among ranch-raised mink.: In cattle the 
disorder is most common in range areas and in the feed lots, 
chiefly among steers. In sheep the principal losses are anong 
wether lambs being fattened in feed lots. 
The formation of stones, or calculi, in the urinary tract-often 
leads to blocking of urine excretion. While progress is being 
made in research on its causes and prevention, methods of control 
are still relatively ineffective. Its incidence is rather erratic, 
although feed supplies in certain areas are becoming recognized 
as predisposing factor. Within specific areas there is consider- 
able fluctuation from year to year that appears to be related to 
climatic conditions. The disorder is common on mink farms in the 
North Central States. 
Yellow Fat in Mink (Table 2h) 
Yellow fat, or steatitis, in mink is now considered to be of 
nutritional origin. Affected animals show browmish yellow pig- 
mentation in the body fat. The death rate is high and the pelt 
of poor quality. The disease occurs on diets high in unsaturated 
fats and low in vitamin E. Prevention appears to rest in reduc- 
tion of unsaturated fats in the diet and increase in vitamin E 
content. Additional research is needed to develop practical means 
of dietary control. 
Miscellaneous Nutritional Disorders 
Other nutritional deficiencies of various types occur to a 
significant extent in all classes of livestock. Because of their 
numbers anc complexity, they will be handled in a group. In 
several respects this miscellaneous group represents the true 
nutritional deficiencies in that a missing nutrient (or nutrients) 
is the seat of the trouble. There are also mutrient—excess dis- 
orders due to toxic effects of feed components. 
Some of the nutritionaledeficiency disorders are due to lack 
of sufficient quantities of any one of 15 or more vitamin factors. 
Among the more important vitamins found to be deficient are 
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