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Progestins in Corpora Lutea, Ovaries, and Adrenals After Estrus and Breeding of Normal and Abnormal Cows¹

Department of Dairy Science, Washington State University, Pullman

ABSTRACT

Progesterone and ⁴-pregnene-20 ß-ol-3-one (progestins) were separately determined in the corpus luteum, ovaries, and adrenals. A total of 77 animals was studied and 53 were considered reproductively normal at the time of slaughter. Progestin content of the corpus albicans prior to ovulation ranged from 0 to 24 µg. Progestin concentration per gram was high in the developing corpus luteum on the second and third days of the cycle, but the total quantity was generally less than 100 µg. until after the sixth day. Maximum quantities were observed at 14–16 days (six cows averaged 251 µg.). Decline in concentration and total progestins was not marked until near the time of an expected estrus. During pregnancy, the average level for seven cows was 161 µg. at 25–34 days and for six cows, 250 µg. at 37–42 days. The differences were also reflected in concentration, since the weight of the corpus luteum was, on the average, essentially constant. Neither size nor progestin content of the ovaries and adrenals varied appreciably among these cows. Adrenals of four cows 8–22 days post-partum were large (average 46 g.) and contained about four times more progestins than is generally observed (66 µg.). The progestin content of the corpus luteum of repeat breeders was not unlike normal animals in a similar stage of the estrous cycle. The corpora lutea and fluids from cystic follicles generally had less progestins than luteal cysts or the fluid they contained. One cow with a dead embryo at 20 days postbreeding had only 8 µg. of progestins in the corpus luteum.

¹ Scientific Paper No. 2055, Washington Agricultural Experiment Stations, Project 1359. This investigation was supported in part by funds for biological and medical research by the State of Washington, Initiative Measure No. 171.

² Present address: Department of Genetics, University of Wisconsin, Madison.