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Administration of 6-methoxybenzoxazolinone (MBOA) does not augment ovulatory responses in St. Croix White ewes
S T Willard1, T Dickerson, R Dodson
1Department of Animal and Dairy Sciences, Mississippi State University, Box 9815-CVM Wise Center, Mississippi State, MS 39762, USA. swillard@ads.msstate.edu
Abstract:
The objective of this investigation was to examine the effects of 6-methoxy-benzoxazolinone (MBOA), a plant compound that resembles melatonin and alters ovarian function in rodents, in combination with PMSG on superovulatory responses in the cycling ewe. In Experiment I, St. Croix White ewes (n = 44) were synchronized (intra-vaginal progestin sponge) for 14days followed by hCG (750 IU) at 1 day after sponge removal (day 0). Ewes were assigned to one of six treatments administered on day -1: Control (no PMSG or MBOA; n = 7); PMSG (1000 IU i.m.; n = 7); Low MBOA (0.43 mg/kg i.m.; n = 7); High MBOA (1.15 mg/kg i.m.; n = 7); Low MBOA + PMSG (n = 8); High MBOA + PMSG (n = 8). In Experiment II, St. Croix White ewes (n = 24) were synchronized (progestin CIDR) for 14 days followed by hCG on day 1 after CIDR removal (day 0). Ewes were assigned to one of three treatments administered on day -1: Control (n = 8); PMSG (n = 8); Low MBOA+PMSG (n = 8). Laparoscopy was performed on day 9 to assess numbers of corpora lutea (CL) and visible follicles on each ovary. Blood samples were collected on day -13, -1, 0, 1, and days 6 or 7-12 for analysis of serum progesterone (P4) by RIA. Treatment groups receiving PMSG (alone or with MBOA) exhibited greater (P < 0.05) serum concentrations of P4 post-synchrony than Control and MBOA-only groups. Ovulation rate was lower (P < 0.05) for Control and MBOA-only treated ewes than ewes receiving PMSG. Ovulation rate in ewes treated with MBOA alone was similar (P > 0.10) to Controls, and PMSG treatment alone did not differ (P > 0.10) from MBOA + PMSG treatment. Ewes treated with PMSG alone did not differ (P > 0.10) in follicle number from High MBOA + PMSG treated ewes, however, Low MBOA + PMSG treated ewes had greater numbers of follicles at day 9 (P < 0.05) than the PMSG or High MBOA + PMSG groups in Experiment I; although, this was not replicated in Experiment II with numbers of follicles in the Low MBOA + PMSG group being similar (P > 0.10) to PMSG alone. In summary, the addition of MBOA in combination with PMSG as part of a synchronization-superovuation protocol in the ewe did not increase ovulation rate.
Insights
This study found that 6-methoxy-benzoxazolinone (MBOA) did not improve superovulation rates in ewes when combined with pregnant mare serum gonadotropin (PMSG). MBOA alone also did not enhance ovulation compared to controls.
Area of Science:
- Reproductive biology
- Animal science
- Endocrinology
Background:
- 6-methoxy-benzoxazolinone (MBOA) is a plant compound with melatonin-like properties.
- MBOA has been shown to affect ovarian function in rodents.
- Superovulation protocols are crucial for enhancing reproductive efficiency in livestock.
Purpose of the Study:
- To investigate the effects of MBOA, alone and in combination with PMSG, on superovulatory responses in cycling ewes.
- To determine if MBOA can enhance ovulation rates in a synchronized ewe population.
Main Methods:
- Two experiments were conducted using St. Croix White ewes synchronized with progestin sponges or CIDRs.
- Ewes received treatments including PMSG, MBOA (low and high doses), or combinations thereof.
- Laparoscopy assessed corpora lutea and follicle counts, while serum progesterone was analyzed via RIA.
Main Results:
- PMSG treatment, with or without MBOA, increased serum progesterone concentrations compared to controls.
- Ovulation rates were higher in ewes treated with PMSG than in control or MBOA-only groups.
- MBOA alone did not significantly alter ovulation rates compared to controls, and its combination with PMSG did not outperform PMSG alone in increasing ovulation rate.
Conclusions:
- The addition of MBOA to PMSG-based synchronization-superovulation protocols in ewes did not lead to an increased ovulation rate.
- MBOA alone did not demonstrate a significant effect on ovulation rate in this study.
- Further research may be needed to explore other potential roles or optimal combinations for MBOA in reproductive management.
