Plasma concentrations of 15-ketodihydro-PGF(2alpha), cortisol and progesterone during manual twin reduction in thoroughbred mares

The aim of the present study was to highlight the effect of two different techniques of one embryo crushing on some hormonal changes. Ten twinning mares were submitted to the mobile or fixed manual crushing of one blastocyst within day 19 after the last mating. Blood sample was collected from 20 min before to 90 min, 24 and 72 h after the procedure was performed to analyse 15-ketodihydro-PGF(2alpha), cortisol and progesterone plasma concentrations. Singleton pregnancy diagnosis was checked 72 h after crushing and at term of pregnancy. Because the unwanted crushing of both embryos occurred in one mare during the attempt of manual separation of the twins, that mare was not included in the evaluation of crushing-induced hormonal changes. No significant differences in hormonal concentrations were observed after one embryo crushing and also when the effect of the mobile (n = 6) or fixed (n = 3) technique was specifically evaluated. When the effect of the two techniques on each post-crushing sampling time hormonal levels was analysed, only a higher cortisol level 30 min after the fixed compared with the mobile technique was observed. The crushing performed within 19 days of gestation does not induce significant changes in 15-ketodihydro-PGF(2alpha), cortisol or progesterone plasma concentrations. When the fixed technique was performed, only a temporary higher cortisol concentration was seen 30 min after crushing, suggesting that the fixed technique might be responsible for a slight level of stress for the mare.     

Food deprivation stimulates the luteolytic capacity in the gilt

The aims of this study were to study the effects of fasting on progesterone (P4) production in the pig and to verify whether fasting influences luteal expression of PGF(2alpha) receptor (FPr) and prostaglandin secretion. Superovulated prepubertal gilts were used; half of them were fasted for 72h starting on day 2 (F2) or 9 (F9) of the induced estrous cycle, respectively, while two groups (C2 and C9) served as respective controls. Plasma P4 and PGFM concentrations were determined by RIA while FPr mRNA expression in CLs collected at the end of fasting period was measured by real-time PCR. In experiment 1, plasma P4 concentrations in fasted gilts were significantly (P<0.01) higher than in controls starting from day 3 (F2; n=6) and 10 (F9; n=6). FPr mRNA expression was similar in F2 and C2 (n=6) CLs while it was significantly (P<0.05) higher in F9 than in C9 (n=6) CLs. In experiment 2, cloprostenol administered on day 12 significantly (P<0.05) increased FPr mRNA expression in CLs from both F9 (n=6) and C9 (n=6) gilts. At the time of cloprostenol injection PGFM levels were significantly higher (P<0.05) in the fasted group and cloprostenol-induced luteolysis in fasted but not in normally fed gilts. Results from this study indicate that fasting in prepubertal gilts induced to ovulate stimulates luteal P4 and PGFM production as well as FPr mRNA expression, thus increasing luteolytic susceptibility.     

Effects of Mating on Plasma Concentrations of Testosterone, Cortisol, Oestrone Sulphate and 15-Ketodihydro-PGF2α in Stallions

Very little information is available regarding the physiological mechanisms involved in the normal sexual activity in the stallion and, in particular, the endocrine control of reproduction is still not clearly understood. This experiment was designed to determine the short-term effect of sexual stimulation on plasma concentrations of testosterone, cortisol, oestrone sulphate and 15-ketodihydro-PGF(2alpha) in stallions. Semen samples were collected from 10 lighthorse stallions of proven fertility using a Missouri model artificial vagina. At the same time, blood samples were collected from the jugular vein with heparinized tubes, 20 and 10 min before oestrous mare exposure, at exposure and 10, 20, 30 min after dismounting. Testosterone concentrations showed a sharp rise 10 min after mating (p < 0.001), reached a plateau, and then showed a further increase 30 min after mating (p < 0.001). Cortisol concentrations increased 10 min after mating (p < 0.001) and remained at high levels in the subsequent samples taken. A peak of oestrone sulphate was observed 10 min after mating (p < 0.001). 15-Ketodihydro-PGF(2alpha) concentrations decreased rapidly at the moment of the exposure of the stallions to an oestrous mare (p < 0.05), returned to pre-mating concentrations and then decreased again 30 min after mating (p < 0.05).     

Responsiveness to Progestagen-eCG-Cloprostenol Treatment in Goat Food Restricted for Long Period and Refed

For 6 months, 10 adult Saanen crossbred goats were fed undernutrition diet (70% maintenance), and finally five goats were refed for 6 weeks with 150% maintenance. In all animals oestrus was synchronized using 45 mg FGA vaginal sponge for 11 days, 300 IU eCG and 50 microg cloprostenol 48 h prior to sponge removal. From oestrus onset, during a 24-h period, blood samples were collected for oestradiol and NEFA assay. Ovulation was verified by laparoscopy 3 days after sponge removal. Body mass loss was 18.62 +/- 3.03% of initial weight and in refed goats body weight recovery was 90.63 +/- 3.56%. NEFA level was higher in restricted goats (p < 0.05). Fifty per cent of underfed goats (2/4) and all refed goats (4/4) exhibited oestrus and ovulation. Significant relationship (p < 0.05) was found between weight loss and the interval sponge removal-oestrus onset (r = 0.91) or ovulation rate (r = 0.70). Only in the refed group was the ovulation rate related to the oestradiol amount (r = 0.99) (p < 0.05). Collectively results showed that a short period of improved feeding re-established the responsiveness of oestrus synchronization in chronically fasted goats.