TY - JOUR
T1 - The efficacy of different hCG dose rates and the effect of hCG treatment on ovarian activity
T2 - Ovulation, multiple ovulation, pregnancy, multiple pregnancy, synchrony of multiple ovulation; in the mare
AU - Davies-Morel, Mina Clare Gwynne
AU - Newcombe, John R.
N1 - Davies Morel, M. C. G., Newcombe, J. R. (2008). The efficacy of different hCG dose rates and the effect of hCG treatment on ovarian activity: Ovulation, multiple ovulation, pregnancy, multiple pregnancy, synchrony of multiple ovaulation; in the mare. Animal Reproduction Science, 109 (1-4), 189-199.
IMPF: 01.89 RONO: 00
PY - 2008/12/1
Y1 - 2008/12/1
N2 - Despite the widespread use of hCG to advance ovulation in the mare there is little information on efficacy of dose rates and any contraindications of its use. This study aims to investigate the effect of dose of hCG on ovulation within 48 h and the effect of hCG on: ovulation, multiple ovulation (MO), pregnancy, multiple pregnancy (MP) rates and synchrony of MO; additionally whether any seasonal effect is evident. Sequential ultrasonic scanning was used to monitor the occurrence of ovulation, within 48 h of treatment, in 1291 Thoroughbred mares treated with either 750iu hCG or 1500iu hCG s.c. Ovulation rate, type (single ovulations (SO), MO, synchronous, asynchronous) and subsequent pregnancy were then monitored in 1239 Thoroughbred mares on a commercial stud over 3 years, 536 of which were treated with 750iu hCG at mating, all mares were also allocated into groups according to month of mating. No significant difference existed between the two dose levels of hCG and no significant difference existed between treated and untreated mares in overall ovulations (1.32 and 1.28 respectively), MO (31.7% and 27.7%), pregnancy (65.1% and 65.6%) or MP rates (10.8% and 11.8%). There was no significant association between month of year and pregnancy or MP rates for either treated or control mares, nor for MO for untreated mares. A significant (p <0.05) association was evident between month and MO in treated mares, MO being lowest in April (22.3%). 95.9% of treated mares multiple ovulated within 48 h compared with 90.7% controls, a near significant difference. In conclusion this study demonstrates that: (i) hCG dose of 750iu s.c. is just as effective in inducing ovulation within 48 h as 1500iu, (ii) 750iu hCG has no significant effect on ovulation, MO, pregnancy or MP rates; (iii) a significant (p <0.05) association exists between season and MO in hCG treated mares; (iv) a tighter synchrony (ovulation within 48 h) of MO is evident in hCG treated compared with control mares (p = 0.052).
AB - Despite the widespread use of hCG to advance ovulation in the mare there is little information on efficacy of dose rates and any contraindications of its use. This study aims to investigate the effect of dose of hCG on ovulation within 48 h and the effect of hCG on: ovulation, multiple ovulation (MO), pregnancy, multiple pregnancy (MP) rates and synchrony of MO; additionally whether any seasonal effect is evident. Sequential ultrasonic scanning was used to monitor the occurrence of ovulation, within 48 h of treatment, in 1291 Thoroughbred mares treated with either 750iu hCG or 1500iu hCG s.c. Ovulation rate, type (single ovulations (SO), MO, synchronous, asynchronous) and subsequent pregnancy were then monitored in 1239 Thoroughbred mares on a commercial stud over 3 years, 536 of which were treated with 750iu hCG at mating, all mares were also allocated into groups according to month of mating. No significant difference existed between the two dose levels of hCG and no significant difference existed between treated and untreated mares in overall ovulations (1.32 and 1.28 respectively), MO (31.7% and 27.7%), pregnancy (65.1% and 65.6%) or MP rates (10.8% and 11.8%). There was no significant association between month of year and pregnancy or MP rates for either treated or control mares, nor for MO for untreated mares. A significant (p <0.05) association was evident between month and MO in treated mares, MO being lowest in April (22.3%). 95.9% of treated mares multiple ovulated within 48 h compared with 90.7% controls, a near significant difference. In conclusion this study demonstrates that: (i) hCG dose of 750iu s.c. is just as effective in inducing ovulation within 48 h as 1500iu, (ii) 750iu hCG has no significant effect on ovulation, MO, pregnancy or MP rates; (iii) a significant (p <0.05) association exists between season and MO in hCG treated mares; (iv) a tighter synchrony (ovulation within 48 h) of MO is evident in hCG treated compared with control mares (p = 0.052).
KW - hCG
KW - synchrony of ovulation
KW - multiple ovulation
KW - multiple pregnancy
KW - pregnancy
KW - season
U2 - 10.1016/j.anireprosci.2007.10.005
DO - 10.1016/j.anireprosci.2007.10.005
M3 - Article
C2 - 18054451
SN - 0378-4320
VL - 109
SP - 189
EP - 199
JO - Animal Reproduction Science
JF - Animal Reproduction Science
IS - 1-4
ER -