Plasma progesterone levels throughout the oestrous cycle and release of LH at oestrus in sheep with different ovulation rates

Abstract

The concentrations of progesterone in the peripheral plasma throughout the oestrous cycle and the preovulatory LH discharge were examined in Finnish Landrace, Galway and Fingalway (Finnish Landrace X Galway) ewes. Progesterone levels were significantly higher in Finnish Landrace ewes during the luteal phase of the cycle (Days 10--13) than in Galways of Fingalways in which the concentrations were similar. Luteal-phase progesterone levels were almost 50% higher during December than during October in all three breeds. The relationship between the number of CL and plasma progesterone was not a simple linear function. All aspects of the preovulatory LH discharge were similar in the three breeds with the exception of the timing of the LH release in relation to the onset of oestrus. This occurred earliest in the Galway and latest in the Finnish Landrace while the Fingalway was intermediate.

Genetic variation in spontaneous ovulation rate and LH receptor induction in mice

“…Furthermore, the induction of LH receptors by FSH is potentiated by oestrogen (Richards, 1978). The genetic differences in the number of ovarian or testicular LH receptors found in untreated animals (Purvis, Clausen & Hanson, 1978;Spearow, 1980; could, in part, be due to genetic differences in serum gonadotrophin concentrations (Bartke, Robertson & Dalterio, 1979;Bindon, Blanc, Pelletier, Terqui & Thimonier, 1979;Quirke, Hanrahan & Gosling, 1979;Spearow, 1980;Wolfe et ai, 1981 ) or the down-regulation of LH receptors by LH or hCG . The present study suggests that the 6-9-fold differences in LH receptor induction by diethyl¬ stilboestrol and FSH are a major source of genetic variation in the number of LH receptors found in untreated animals.…”

Comparison of the survival of fertilized eggs from adult ewes in the uteri of adult ewes and ewe lambs

“…The plasma was stored at -20°C until assayed. Duplicate plasma samples were used for progesterone determination by a conventional radioimmunoassay procedure which has been described elsewhere (Quirke, Hanrahan & Gosling, 1979). The sensitivity of the assay, as calculated from the errors in the blanks (2 s.d.)…”

Effect of cold and hot ambient temperatures on plasma progesterone concentrations in ewes with intact and denervated ovaries containing experimentally maintained corpora lutea

“…The peripheral blood concentrations of progesterone in the ewe vary with the season (Lamond et al, 1972;Rhind et al, 1977Rhind et al, , 1978Quirke et al, 1979), increased concentrations being associated with low temperatures (Wheeler & Barnes, 1983). If this increased progesterone concentration is a direct effect of low temperatures, high temperatures should be expected to induce low progesterone concentrations.…”