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Ovarian response and cortisol and progesterone blood levels in superovulated heifers treated with dexamethasone
THERIOGENOIAXY
OVARTAN RESPONSEAND OOKI'ISOLANDP~S'IEKZJE -DIEVELS IN SUPEmTED
HEIFEPSTPEATEDWI'I%DEXAVETHASCUE
A. Bielanski Dept. of Herd Medicine and Theriogenology Western College of VeterinaryMadicine, Universityof Saskatchewan Saskatocpl,S&atches+xin, S7N OWO Canada Six&en heifers wsre superovulatedcp1day 10 Of their estrous cycle with twicxsdaily decreasingdoses of FSH-P (6,5,4,3mg). Estrus was induced by an injectionof 500 pg cloprostenolan day 3 of treatment. Eleven animalsware injectedintra~ouslywith 40 nqdexamathasone (Azium,Schering) for five days beginningcn the first day of sqxxovulatorytreatnent (groupDX). Five lifers served as controls, superovulatedbutnottreatedwithde~thasone (groupCG). All the animals mre inseminatedtwice at 12 hour intervals after the axset of heat.< Blood sanples forprcgesterone and axtisolradioiarnun oassay weretaken daily. On day 7or 8 afterestrus animalswere slaughpltered, eabryos were recoveredand ovaries ware examined for reve. 0varianPespcxlse Group CG DX
N 5 11
No. C.L. 110 2*
No. Er&ryos 75 1*
No. Follicles Wsight of > 10 mm < 10 Iml Ovaries (x + SE) 12 15
5 118*
50.35 + 10.35 12.14 + 5.21*
* Differencesbetween groups are significant (p < 0.001) Allofthe animals exhibitedestrus after treatsent,but in tba DX groupsyn@cms tendadtobe less intense. Levels ofprogestercne in the DX grow decreased frcana mean of 9.62 + 0.82 ng/ml at cloprostenol injecticmto below 0.5 ng/ml within 24lours where it rerrained until slaughter. Progestercnelevels in theCGgroqwerelcx+estat estrus and increasedto 17 + 2.83 ng/ml and 24.2 + 2.57 on day 7 and 8, respectively. Similarly~corti.sollevelsdecreased sharply in the DX group frcxn5.35 + 1.53 ng/ml to belch 1 ng/ml within 24 hours after first injectionof -&xamathasoneand remained low until slaughter. In contrast,cortisol in the CG group increasedcp1the seccnd day of FSH-P treatsent (4.37+ 0.86 ng/ml) and reached a peak on the day prior to estrus (11.1+ 7.69 ng/ml) and at estrus (11.4+ 3.23 ng/ml) with a slow decline to mean levels of 3.8 f 1.15 ng/ml-m day 7 or 8 after estrus. Results indicate thatdexa%thasone treatment_duringsuperovulation treatm?ntwith FSH-P can [email protected] abrogate ovarian respen.=. At the very least, the effect would appear to involve a reduction in folliculargrz&h. Ackncwledgenents: The experimantwas done at the Animal Diseases Research Institute,Nepean, Ottawa, Ontario. Sincere thanks to Dr. W.C.D. Hare, Dr. G. Randall and Mrs. L. Singh for advice, and Mrs. S. Miller and Mr. Y. Barbeau for technicalassistance.
17x
JANUARY
198.5 VOL. 23 NO. I
OVARTAN RESPONSEAND OOKI'ISOLANDP~S'IEKZJE -DIEVELS IN SUPEmTED
HEIFEPSTPEATEDWI'I%DEXAVETHASCUE
A. Bielanski Dept. of Herd Medicine and Theriogenology Western College of VeterinaryMadicine, Universityof Saskatchewan Saskatocpl,S&atches+xin, S7N OWO Canada Six&en heifers wsre superovulatedcp1day 10 Of their estrous cycle with twicxsdaily decreasingdoses of FSH-P (6,5,4,3mg). Estrus was induced by an injectionof 500 pg cloprostenolan day 3 of treatment. Eleven animalsware injectedintra~ouslywith 40 nqdexamathasone (Azium,Schering) for five days beginningcn the first day of sqxxovulatorytreatnent (groupDX). Five lifers served as controls, superovulatedbutnottreatedwithde~thasone (groupCG). All the animals mre inseminatedtwice at 12 hour intervals after the axset of heat.< Blood sanples forprcgesterone and axtisolradioiarnun oassay weretaken daily. On day 7or 8 afterestrus animalswere slaughpltered, eabryos were recoveredand ovaries ware examined for reve. 0varianPespcxlse Group CG DX
N 5 11
No. C.L. 110 2*
No. Er&ryos 75 1*
No. Follicles Wsight of > 10 mm < 10 Iml Ovaries (x + SE) 12 15
5 118*
50.35 + 10.35 12.14 + 5.21*
* Differencesbetween groups are significant (p < 0.001) Allofthe animals exhibitedestrus after treatsent,but in tba DX groupsyn@cms tendadtobe less intense. Levels ofprogestercne in the DX grow decreased frcana mean of 9.62 + 0.82 ng/ml at cloprostenol injecticmto below 0.5 ng/ml within 24lours where it rerrained until slaughter. Progestercnelevels in theCGgroqwerelcx+estat estrus and increasedto 17 + 2.83 ng/ml and 24.2 + 2.57 on day 7 and 8, respectively. Similarly~corti.sollevelsdecreased sharply in the DX group frcxn5.35 + 1.53 ng/ml to belch 1 ng/ml within 24 hours after first injectionof -&xamathasoneand remained low until slaughter. In contrast,cortisol in the CG group increasedcp1the seccnd day of FSH-P treatsent (4.37+ 0.86 ng/ml) and reached a peak on the day prior to estrus (11.1+ 7.69 ng/ml) and at estrus (11.4+ 3.23 ng/ml) with a slow decline to mean levels of 3.8 f 1.15 ng/ml-m day 7 or 8 after estrus. Results indicate thatdexa%thasone treatment_duringsuperovulation treatm?ntwith FSH-P can [email protected] abrogate ovarian respen.=. At the very least, the effect would appear to involve a reduction in folliculargrz&h. Ackncwledgenents: The experimantwas done at the Animal Diseases Research Institute,Nepean, Ottawa, Ontario. Sincere thanks to Dr. W.C.D. Hare, Dr. G. Randall and Mrs. L. Singh for advice, and Mrs. S. Miller and Mr. Y. Barbeau for technicalassistance.
17x
JANUARY
198.5 VOL. 23 NO. I