HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by VanLandingham, A. H. Articles by Bowling, G. A. Search for Related Content PubMed Articles by VanLandingham, A. H. Articles by Bowling, G. A.

Studies on the Chemical Composition of the Blood of Dairy Cattle

I. The Effect of Age and Phosphorus Intake on the Calcium and Inorganic Phosphorus Content of Whole Blood of Dairy Heifers

West Virginia Agricultural Experiment Station, Morgantown, W. Va.

ABSTRACT

Three groups of growing dairy heifers were fed in such a way that all received approximately the same amount of digestible crude protein and total digestible nutrients in proportion to body weight. One of the groups was fed a normal ration while the others were fed rations low in phosphorus. Calcium and inorganic phosphorus was determined on composite samples of whole blood at monthly intervals throughout the experiment.

Under the conditions of the experiment as outlined the following conclusions were reached:

1. The inorganic phosphorus in the blood of animals fed a normal phosphorus ration shows a slight increase from the second to the fourth month, after which it remains fairly constant until the tenth month, when there is a gradual decline as the animals grow older.
   
2. The concentration of inorganic phosphorus in the blood is an important index of the severity of phosphorus deficiency in the ration. Low-phosphorus rations cause an immediate lowering of the inorganic phosphorus in the blood. The rate of lowering is roughly proportional to the severity of phosphorus deficiency in the ration. There is always a lowering of the inorganic phosphorus in the blood for a period of several weeks before any pronounced physical symptoms of a deficiency are apparent.
   
3. Anorexia, or loss of appetite, stiffness in front and rear quarters, and general emaciated condition are physical symptoms which usually follow a lowering of the inorganic phosphorus in the blood when animals are on phosphorus deficient rations.
   
4. The phosphorus requirement for growing dairy animals is not directly proportional to gain in body weight, but depends to a considerable degree upon the rate of skeletal growth as measured by the rate of gain in height at withers. There is a decrease in the requirement for growth in proportion to body weight with increase in age as the animals approach maturity.
   
5. An average daily phosphorus intake of approximately 25 grams (equivalent to about 3.8 grams per 100-pounds body weight) was sufficient, to maintain what appeared to be a normal supply of inorganic phosphorus in the blood up to 25 months of age. An average daily phosphorus intake of 8 grams (equivalent to 1.3 grams per 100-pounds body weight) was not sufficient to maintain a normal supply of inorganic phosphorus in the blood of growing dairy animals from 6 to 25 months of age.
   
6. Age and level of phosphorus intake were without effect upon the calcium content of whole blood of growing dairy heifers.
   

^1,2 Departments of Agricultural Chemistry and Dairy Husbandry, respectively.