Studies on the Composition of Bovine Blood as Influenced by Gestation, Lactation, and Age

Abstract

Summary The blood of heifers has been analyzed at weekly intervals, from the time of breeding through one year of lactation, for non-protein nitrogen, glucose, calcium and phosphorus. There is little variation in these blood constituents as influenced by gestation and lactation. Average values for non-protein nitrogen were 32.82; for glucose 52.12; for calcium 10.91 and for phosphorus 5.44 mg. per 100 cc. Blood glucose values are definitely related to age. Blood from calves less than one week of age contained 125 mg. of glucose per 100 cc. This value gradually decreased to 54.4 mg. per 100 cc. of blood at the end of a year. There is a diurnal variation in the glucose content of calves’ blood. Directly after feeding milk, blood sugar values increase sharply. Carbohydrate tolerance tests on animals of various age groups indicate very little response to sugar feeding in the older groups but a decided response in young calves.