Early effect of conceptus on plasma progesterone level in the cow.

摘要: Progesterone levels in jugular venous blood are being measured by us cycling (unmated) and inseminated (pregnant or non-pregnant) cows as part of a comparative study with normal difficult breeding histories. Hawk, Wiltbank, Kidder & Casida (1955) reported high incidence embryonic death during the period 16 to 25 days after insemination. The 3rd week gestation may indeed be critical phase regulation luteal function, since towards end this regression corpus luteum normally occurs absence conceptus. This note records that herd Friesian cattle cycle length 21\m=.\2days \m=+-\1\m=.\5s.d. presence conceptus uterus first exerted significant effect on peripheral plasma progesterone level 19th day Samples were collected between 07.30 08.00 hours from veins free venereal infection demonstrable lesions reproductive tract, at known stages oestrous pregnancy. (about 150 ml) was drawn into vessels containing sodium citrate cooled rapidly 4\s=deg\C. separated centrifugation 4\s=deg\C stored \p=m-\18\s=deg\C until analysis, performed usually within 2 weeks. Plasma samples (80 extracted described Lindner, Lunenfeld Shelesnyak (1967), concentration these extracts determined method Lindner Zmigrod which is based sequential paperand gas-chromatography hydrogen-flame detector, use radio-active internal recovery standard. Jugular cow 7 ovariectomy con¬ tained detectable, ifvery low, (0-17 μg|100 ; 3 weeks operation undetectable (<0-15 μg| 100 ml). circulating present 1 probably adrenal origin (Balfour, Comline Short, 1957), surgical stress have temporarily enhanced such secretion. Release ofprogesterone body fat depots also been contributing factor (cf. McCracken, 1963). reliability assay procedure tested replicate determinations added ovariectomized cow. results (Table 1) indicated satisfactory.