The ovaries of 3 groups of Merino ewes were examined for corpora lutea by laparoscopy every 17 days between 28.3.74 and 16.6.75. During the 1974 breeding season the mean body weight of the ewes was maintained at 37 kg. Between the 1974 and -1975 breeding seasons the nutrition of the ewes was varied to give groups of ewes with mean body weights of 37, 41 and 46 kg; groups of ewes of low, medium ...

Pregnancy is characterized by increased plasma adrenocorticotropic hormone (ACTH) and cortisol. Studies suggest that progesterone acts as an antagonist at mineralocorticoid receptors. Therefore, we tested the hypothesis that chronic progesterone, produced by treatment of nonpregnant ewes or during pregnancy, will result in increased plasma ACTH relative to the plasma cortisol concentrations. We...

The effect of level of dietary energy and protein intake on reproductive performance was studied in 110 Finn-cross ewe lambs and in 404 Finn-cross yearling ewes during late gestation. Nitrogen metabolism was studied in 26 ewe lambs and 23 yearling ewes. Increasing digestible energy and crude protein intake for ewe lambs and yearling ewes during late gestation increased (P<.05) ewe average daily...

Two commercially available progestogen products for cattle, melengestrol acetate (MGA) and norgestomet (SMB), were evaluated for their ability to induce synchronized estrus in anovulatory ewes. Seasonally anestrous ewes (n = 232) were randomly assigned to one of seven treatments: 1) control (C); 2) MGA only (OMGA; .3 mg of MGA/d); 3) MGA+zeranol (RMGA; 2.5 mg of zeranol); 4) MGA+PG-600 (PMGA; 4...

These studies test the hypothesis that pregnancy alters the feedback effects of cortisol on stimulated ACTH secretion. Ewes were sham-operated (Sham), or adrenalectomized (ADX) at approximately 108 days gestation and replaced with aldosterone (3 microg x kg(-1) x day(-1)) and with cortisol at either of two doses (ADX + 0.6 and ADX + 1 mg x kg(-1) x day(-1)); ewes were studied during pregnancy a...

These studies test the hypothesis that the increased adrenocorticotropic hormone (ACTH) and cortisol in pregnancy reflect a reset of regulated plasma cortisol concentrations. Ewes were sham operated (Sham) or adrenalectomized (ADX) at ∼108 days gestation. Adrenalectomized ewes were replaced with aldosterone (3 μg ⋅ kg-1 ⋅ day-1) and with cortisol at either of two doses (ADX + 0.6 and ADX + 1.0 ...

During the last trimester of pregnancy single and twin-bearing ewes were fed chopped oat hay ad libitum and supplements (300 g/day) of cottonseed meal (CSM) (T1) or barley grain plus urea and sodium sulfate (Bar+N+S) (T2), or CSM and oat hay restricted to the level consumed by the T2 ewes (T3). T1 ewes consumed 47% more hay and approximately 13% more digestible organic matter than T2 ewes. T1 e...

Thirty-nine multiparous ewes (19 Pelibuey and 20 Romanov × Pelibuey) treated with fluorogestone acetate impregnated intravaginal sponges were used to evaluate the effects of low pregnant mare serum gonadotropin (PMSG) doses and genotype on their reproductive efficiency under heat stress conditions. The sponge treatment lasted for 12 days, and 24 h before sponge removal, ewes of each genotype we...

St. Croix White hair sheep ewes were used to evaluate the effect of supplemental nutrition prior to breeding during the dry and wet seasons on St. Croix. Beginning 21 d prior to breeding ewes were fed supplement in addition to grazing guineagrass pasture (FEED). Other ewes in the flock grazed pasture only (CONTROL). This study was conducted during the dry (June and July) and wet seasons (Octobe...

Background: The Lori-Bakhtiari sheep breed is one of the most common native breed in the south-western parts of Iran. The peri-parturition period (2 weeks before to, 2 weeks after parturition), is generally of critical importance regarding the health, production and profitability of the ewes. OBJECTIVES: This study was carried out to compare the serum concentrations of glucose, non-esterified f...