Reproductive performance of Creole goats subjected to estrus synchronization protocols differing in duration and GnRH administration.
Neither post-AI GnRH administration nor the duration of synchronization protocols significantly affected pregnancy rates in Creole goats, suggesting that insemination techniques are more crucial.
Where it sits
this study against the rest of the gonadorelin (gnrh) corpusSummary and findings
This study evaluated the effect of GnRH administration five days after artificial insemination (AI) on the reproductive response of Creole goats subjected to different synchronization protocols. A total of 39 goats were divided into short-term and long-term protocols, with 21 receiving GnRH. No significant differences in pregnancy rates were found between the protocols or treatments.
Abstract
Reproductive efficiency in goats is essential for improving productivity, with estrus synchronization and artificial insemination (AI) being strategic reproductive tools. Although post-AI GnRH administration has been proposed to improve luteal function and fertility, its effectiveness under different synchronization protocols in goats remains unclear. Therefore, this study evaluated the effect of GnRH administration five days after AI on the reproductive response of goats synchronized using short- and long-term protocols. A total of 39 Creole goats were distributed according to protocol type (short-term: n = 26; long-term: n = 13) and treatment (control: n = 18; GnRH: n = 21). In both groups, intravaginal sponges containing medroxyprogesterone acetate were inserted on Day 0. Artificial insemination was performed 64 h after device removal, and the depth of cervical semen deposition was recorded. Estrus expression was concentrated between 24 and 48 h after device removal in both protocols, with greater synchrony in the long-term protocol. No significant differences were observed in pregnancy rate between protocols (57.7 vs. 53.8%) or treatments (57.1 vs. 55.6%). Intermediate cervical semen deposition resulted in a greater pregnancy rate (69.2%) than superficial deposition (25.0%). Multiple correspondence analysis revealed associations between reproductive variability, insemination depth, and estrus expression patterns. In conclusion, neither post-AI GnRH administration nor protocol duration affected pregnancy rate. However, reproductive performance appeared to depend more on insemination-related factors than on hormonal treatments under field conditions in Creole goats subjected to cervical artificial insemination programs.
Background
This paper addresses the question of how GnRH administration affects reproductive performance in goats, particularly in the context of estrus synchronization and artificial insemination. Previous studies have suggested that GnRH may enhance luteal function and fertility, but its effectiveness in different synchronization protocols remains uncertain. Understanding these dynamics is crucial for improving reproductive efficiency in goat farming.
Methods
The study utilized a controlled design with 39 Creole goats divided into short-term (n=26) and long-term (n=13) estrus synchronization protocols. The goats received intravaginal sponges containing medroxyprogesterone acetate on Day 0, followed by artificial insemination 64 hours after device removal. The primary outcome measure was the pregnancy rate, while secondary measures included cervical semen deposition depth.
Results
The primary endpoint revealed no significant differences in pregnancy rates between the short-term (57.7%) and long-term (53.8%) protocols, or between GnRH treatment (57.1%) and control (55.6%). Intermediate cervical semen deposition was associated with a significantly higher pregnancy rate of 69.2% compared to superficial deposition at 25.0%.
Interpretation
These findings indicate that neither the duration of the synchronization protocol nor the administration of GnRH post-AI significantly influenced pregnancy rates. The results align with previous literature suggesting that insemination techniques may play a more critical role in reproductive outcomes. Limitations include the small sample size and the lack of long-term follow-up, which may affect the generalizability of the results.
Key findings
- Pregnancy rate was 57.7% for short-term and 53.8% for long-term protocols.
- Pregnancy rate was 57.1% for GnRH treatment and 55.6% for control.
- Intermediate cervical semen deposition resulted in a pregnancy rate of 69.2% compared to 25.0% for superficial deposition.
Limitations
- small sample size n=39
- no long-term follow-up data
- single-site study