54 Milk and Its Products 



will produce a seven -eighths -blood, and so on ad 

 infinitum. Since only the offspring of pure -bred 

 parents on both sides are eligible to registry in the 

 herd books of any of our dairy breeds, it follows that 

 no matter how far the process of grading up by the 

 use of pure -bred sires on grade females is carried, 

 pure breds, in the technical sense, can never be pro- 

 duced. Since pure -bred animals are sought after for 

 breeding purposes, the offspring of pure -bred animals 

 are, therefore, more valuable, and command a higher 

 price than do the offspring of grades. Hence, if the 

 value of the calves is taken into consideration, a pure- 

 bred herd is a more productive one, other things being 

 equal, than a grade herd. On the other hand, by the 

 grading -up process above referred to, continually 

 selecting the cows that are the best producers, it is 

 entirely possible, and by no means difficult, to estab- 

 lish a herd of grade cows that will equal, in the pro- 

 duction of milk, any herd of pure-bred animals. 

 Hence, if the main product alone is sought after, a 

 grade herd may produce as largely as a pure -bred 

 one; but if the by-product in calves is to be taken 

 into consideration, a pure -bred herd certainly has an 

 advantage over a grade herd of equal productive 

 capacity. 



Maintenance of the dairy herd. A dairy herd may 

 be maintained in two ways: First, by continued pur- 

 chase of mature animals to replace those whose period 

 of usefulness has passed. There are many conditions 

 under which this may be a wise practice. If it is 

 desirable to have the whole herd composed of cows 



