| Abstrakt: |
IN nonpregnant ewes, luteal function increases for about 9 days and starts to decline 12 to 14 days after estrus according to the following indirect measurements: (a) luteal weight and progesterone content and concentration (Stormshak et al., 1963); and (b) progesterone concentration in plasma from the ovarian vein (Edgar and Ronaldson, 1958; McClure and Ronaldson, 1962; Stormshak et al., 1963) and peripheral blood (Neher and Zarrow, 1954; Plotka and Erb, 1967). Similar data are available for nonpregnant cows (Gomes et al., 1963; Plotka et al., 1967; Dobrowolski, Stupnicka and Domanski, 1968) and sows (Gomes, Herschlet and Erb, 1965; Schomberg et al., 1966; Tillson and Erb, 1967). Stormshak et al. (1963) concluded that luteal progesterone content was indicative of the level of function of corpora lutea (CL) in terms of the amount of hormone released into the ovarian venous blood. This concept may be extended to peripheral blood in only a general way since simple correlations between levels of progesterone in these two sources of blood and luteal tissue have been discouragingly low (Gomes and Erb, 1965). The purpose of this paper is to extend the observations of previous research indicated above by subjecting similar data to step-wise multiple regression analyses and, in addition, include comparisons using rates of excretion of estrogen in urine. |
