OHAPTEE XXVII. 



Farrow Cows, and Intermitted Breeding. 

 Weakened Contractility in the Udder-Supply Arteries. 



A sufficient supply of blood in the region of the ovaries 

 and the oviducts, is of course necessary to supply the blood 

 and heat from which the coupling results in cows at any 

 season of the year. But the intermission of breeding du- 

 ring alternate years or longer periods, by farrow cows, is 

 so peculiar a circumstance, that it cannot occur without an 

 equally peculiar cause ; and, after careful study and inquiry, 

 the conclusion is arrived at, that partial relaxation of the 

 udder-supply arteries is the cause of these intermissions of 

 breeding power, during one or more years, in farrow 

 cows. Rest in the breeding organs is necessary to allow 

 the cows to recover sufficient contractility in their weak- 

 ened artery-wall muscles, to enable them to again become 

 fit for breeding. 



In farrow cows, the relaxation of the udder-supply arte- 

 ries is light in extent; yet the enlargement of these arteries 

 is sufficient to preclude the augmentation of blood, and 

 blood heat in the ovarian blood-vessels, in the degree that 

 can give rise to coupling heat. Too large a proportion of 

 the blood is conveyed by the enlarged and partially re- 

 laxed udder-supply arteries to the milk glands, to admit 

 of a sufficient blood-supply to induce coupling heat being 

 diverted to the ovarian blood-vessels, to excite their natu- 

 ral functions of activity. This accounts for the failure to 

 breed in a succeeding season, of cows that bred in the pre- 

 vious year ; the partiallj? relaxed udder-supply arteries re- 



