The Assembling of Herds 689 



pedigrees, including their show and dairy records, and upon 

 their individual appearance. In purchasing cattle the buyer 

 should recognize certain fundamental principles. 



1. Pedigree is of no value" unless supported by fertility. 

 In order to be fertile the animal must be physically sound. 

 If any chronic disease, such as tuberculosis, is present, the 

 fertility of the animal is lowered or destroyed. Some cows 

 and bulls with tuberculosis breed, it is true, but when a 

 large number of tubercular animals is assembled the group, 

 as such, shows low fertility. Besides, the disease is a gen- 

 eral menace to the herd. The, laws and customs of sale 

 now safeguard the buyer fairly well in many states. The 

 laws also forbid the sale of animals with such acute infec- 

 tions as anthrax. There are no laws, and no laws are pos- 

 sible of enactment, which can adequately protect the buyer 

 against the diseases of the genital organs which may inter- 

 fere with or destroy the reproductive power of the animal. 

 At the same time the genital infections constantly threaten 

 to pass from a diseased individual to another which is sound 

 or to one which carries a less perilous infection. 



2. The buyer should assume that the cattle in all herds 

 carry infections in their genital organs which may ulti- 

 mately lead to sterility, abortion, retained afterbirth, calf 

 scours, and other unwelcome phenomena. He should further 

 realize that there are vast differences in the virulence of 

 infections in the cattle of different herds and of different in- 

 dividuals in the same herd. In some herds the infections 

 are so mild that little or no visible harm comes from their 

 presence; in others the reproductive efficiency falls so far 

 below the ideal that the herd is economically a dismal fail- 

 ure. Between these extremes there is every gradation. 



3. The prospective buyer should not expect the average 

 seller to volunteer all information regarding diseases among 

 his cattle interfering with reproduction. Each herd of size 

 has cows which have aborted because of contagion, but no 

 breeder posts a sign on his stable giving notice to the public 

 that he has "contagious abortion" in his herd. Some bacte- 

 riologists come to the aid of the breeder by asserting that 



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