| Abstract: | Four experiments were conducted to determine the effect of nutrition on blood and milk cholesterol of Holstein cows. Whole cottonseed (WCS) and(or) niacin, dried brewers grains, supplemental vitamin E, and lasalocid had no effect on milk or plasma total cholesterol in lactating Holstein cows. Cows that were fed diets with rice bran or WCS had increased blood cholesterol compared to cows fed diets with no supplemental fat, and cows that were fed diets with high starch contents had lower plasma cholesterol. Plasma cholesterol was not related to milk cholesterol in these cows. When cows were fed whole cottonseed and(or) niacin, milk cholesterol was positively correlated to days in milk and lactation number. In cows fed diets with either dried brewers grains or soybean meal as the protein supplement, milk cholesterol was positively related to milk protein. There was also a large positive correlation between milk yield and age, and plasma cholesterol in these cows. A fifth experiment was conducted to determine the effect of lactation on plasma cholesterol of Holstein cows. When cows were not lactating, they had significantly lower plasma cholesterol compared to when they were 100 to 130 d in milk. In cows that were 100 to 130 d in milk, plasma cholesterol was positively correlated with milk cholesterol. Supplemental fat increased plasma cholesterol, but higher starch concentrations decreased plasma cholesterol. There were no significant effects of nutrition on milk cholesterol. |
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