[Probable conditioned prostaglandin deficiency in cows with ovarian cysts (author's transl)].

Blood and ovaries have been collected monthly for one year from 1358 cows at the slaughter-house. 4.4% of the cows presented cystic follicle ovaries (follicle with a diameter greater than or equal to 25 mm) and 5.7% presented cystic corpus luteum (internal cavity with a diameter greater than or equal to 10 mm). Analysis of fatty acid composition of red blood cells lipids has shown that in cows with cystic follicles (P less than 0.001) and in cows with cystic corpus luteum (P less than 0.01), the proportions of omega 3 family polyunsaturated fatty acids were higher than in normal cow. The sigma omega 3/ sigma omega 6 ratio was also higher (P less than 0.001) for cows with both types of ovarian cysts, particularly in spring, summer and autumn. An alimentary etiology of ovarian cysts pathogeny could be an increased intake of these fatty acids which are more abundant in young grass. The omega 3 polyunsaturated fatty acids are known to be inhibitors of the synthesis of PgF2 alpha which is involved in ovulation and luteolysis.