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The effect of injection of GnRH or hCG during estrus cycle on ovarian follicular dynamics in Shami cattle

تأثير حقن GnRH أو hCG خلال دورة الشبق في ديناميكية الجريبات المبيضية للأبقار الشامية

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 Publication date 2011
and research's language is العربية
 Created by Shamra Editor




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Fifteen Shami cows available in Dier-Al-Hajar Station for improving Shami Cattle were used during 2009-2010 to evaluate the ovarian response of cows for gonadotropin releasing hormone (GnRH) or human chorionic gonadotropin (hCG) injected on day 5 of the estrus cycle during which dominant follicle is growing in the first follicular wave. Animals were divided randomly into three groups of five cows. Group 1 was left as a control and received no treatment while Groups 2 and 3 received on day 5 of the estrous cycle a single i.m. injection of 8 ?g of a GnRH agonist (Buserelin) and 3000 IU hCG, respectively. Transrectal ovarian ultrasonography was performed daily to monitor ovarian follicular dynamics and corpus luteum.


Artificial intelligence review:
Research summary
تتناول هذه الدراسة تأثير حقن هرموني GnRH و hCG على ديناميكية الجريبات المبيضية في الأبقار الشامية. تم إجراء التجربة في محطة بحوث دير الحجر لتحسين الأبقار الشامية خلال عامي 2009 و2010، حيث استخدمت 15 بقرة شامية تم تقسيمها إلى ثلاث مجموعات. المجموعة الأولى تركت دون معاملة كمجموعة شاهد، بينما حقنت المجموعتان الثانية والثالثة بهرموني GnRH و hCG على التوالي في اليوم الخامس من دورة الشبق. أظهرت النتائج زيادة معنوية في عدد الجريبات الصغيرة (2-5 مم) في المجموعتين المعالجتين بعد يوم واحد من الحقن مقارنة بالشاهد، بينما انخفض عدد الجريبات المتوسطة (5-9 مم) والكبيرة (≥ 9 مم) بعد يومين من الحقن. كما أظهرت النتائج أن حقن GnRH و hCG يؤدي إلى ظهور موجة مبيضية جديدة وحدوث الإباضة بعد 24-48 ساعة من الحقن. لم يتأثر قطر الجسم الأصغر الأصلي أو الثانوي بنوع المعاملة. توصي الدراسة بإجراء المزيد من الأبحاث لدراسة تأثير هذه الهرمونات على معدلات الحمل في الأبقار الشامية عند التلقيح الصناعي أو نقل الأجنة.
Critical review
تعتبر هذه الدراسة مهمة لفهم تأثير الهرمونات على ديناميكية الجريبات المبيضية في الأبقار الشامية، إلا أن هناك بعض النقاط التي يمكن تحسينها. أولاً، كان من الممكن زيادة حجم العينة لتحسين دقة النتائج. ثانياً، لم يتم التطرق إلى الآثار الجانبية المحتملة لاستخدام هذه الهرمونات على المدى الطويل. ثالثاً، كان من الأفضل تضمين مجموعة إضافية من الأبقار التي تتلقى علاجاً بديلاً أو تكميلياً لمقارنة النتائج بشكل أكثر شمولية. وأخيراً، كان من المفيد توسيع نطاق الدراسة ليشمل أنواعاً أخرى من الأبقار لمقارنة تأثير الهرمونات بين السلالات المختلفة.
Questions related to the research
  1. ما هو الهدف الرئيسي من هذه الدراسة؟

    الهدف الرئيسي هو دراسة تأثير حقن هرموني GnRH و hCG في اليوم الخامس من دورة الشبق على ديناميكية الجريبات المبيضية في الأبقار الشامية وإمكانية حدوث الإباضة.

  2. ما هي النتائج الرئيسية التي توصلت إليها الدراسة؟

    أظهرت الدراسة أن حقن GnRH و hCG يؤدي إلى زيادة معنوية في عدد الجريبات الصغيرة وانخفاض في عدد الجريبات المتوسطة والكبيرة، كما يؤدي إلى ظهور موجة مبيضية جديدة وحدوث الإباضة بعد 24-48 ساعة من الحقن.

  3. ما هي التوصيات التي قدمتها الدراسة؟

    توصي الدراسة بإجراء المزيد من الأبحاث لدراسة تأثير حقن هرموني GnRH و hCG على معدلات الحمل في الأبقار الشامية عند التلقيح الصناعي أو نقل الأجنة.

  4. ما هي النقاط التي يمكن تحسينها في الدراسة؟

    يمكن تحسين الدراسة بزيادة حجم العينة، دراسة الآثار الجانبية المحتملة لاستخدام الهرمونات على المدى الطويل، تضمين مجموعة إضافية من الأبقار لتلقي علاج بديل أو تكميلي، وتوسيع نطاق الدراسة ليشمل أنواعاً أخرى من الأبقار لمقارنة تأثير الهرمونات بين السلالات المختلفة.


References used
Alvarez, P., L. J. Spicer, C. C. Chase, Jr., M. E. Payton, T. D. Hamilton, R. E. Stewart, A. C. Hammond, T. A. Olson and R. P. Wettemann. 2000. Ovarian and endocrine characteristics during an estrous cycle in Angus, Brahman, and Senepol cows in a subtropical environment. J. Anim. Sci. 78: 1291–1302
Amaya-Montoya, C., M. Matsui, C. Kawashima,K. G. Hayashi, G. Matsuda, E. Kaneko, K. Kida, A. Miyamoto and Y. I. Miyake. 2007. Induction of Ovulation with GnRH and PGF2α at Two Different Stages During the Early Postpartum Period in Dairy Cows: Ovarian Response and Changes in Hormone Concentrations. J. Reprod. Dev. 53 (4): 867–875
Atkins, J. A., D. C. Busch, J. F. Bader, D. H. Keisler, D. J. Patterson, M. C. Lucy and M. F. Smith. 2008. Gonadotropin-releasing hormone-induced ovulation and luteinizing hormone release in beef heifers: Effect of day of the cycle. J. Anim. Sci. 86:83–93
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Twelve growing Shami heifers available in Dier-Al-Hajar Station for improving Shami Cattle during 2005-2007 weighing 250±11 kg and 400±21 days old were used to monitore the growth of dynamic of ovarian follicles (daily numbers, size, length and nu mber of waves, rate of growth and regression) and characteristics of estrus cycle (length, time of dominancy, diameter of Graffian follicle and estrus and ovulatory times), length of corpus luteum (CL) during the estrous cycle. Heifers were maintained under uniform conditions and fed according to their daily growth. Transrectal Ultrasound Echo System (7.5 MHz probe) was used to study the ovarian structures and to monitor the daily development and regression of ovarian follicles, the formation and regression of corpus luteum in the left and right ovaries during the estrus cycle. Results indicated that the growth turnover of ovarian follicles was observed and developed in a wave pattern in all Shami heifers and no significant differences in the number and sizes of ovarian follicles were found between right and left ovaries. A cohort of 5 to 7 small follicles with a diameter 2-5 mm developed together and one of them was selected to continue growing and becomes dominant and later on being regressed or ovulated during the estrus cycle. One to five follicular waves were observed per cycle and each wave was characterized by the development of one large (dominant) follicle and a variable number of smaller follicles. The estrus cycle with one follicular wave occurred only in heifers exhibited the first post pubertal cycles with an average length equaled to 8.67±0.33 days. Frequency of estrus cycle according to the number of follicular waves was 8.4, 25.3, 44.2, 20 and 2.1% in cycles having 1, 2, 3, 4 and 5 follicular waves, respectively. Furthermore , the length of estrus cycle was also related to the number of follicular waves and it was 21.87±0.62, 22.44±0.74, 26.4±0.72, 26.50±3.50 days in cycles having 2, 3, 4 and 5 follicular waves, respectively with significant differences (P < 0.05) in cycles with 2 or 3 vs. 4 and/or 5 waves. The functional duration of CL was extended to 9, 12 and 15 days in a short (17-19 days), intermediate (20-24 days) and long estrus cycle (≥ 25 days). The maximum diameter of dominant follicles in ovulatory waves was significantly larger (P < 0.05) than that of dominant follicles in nonovulatory waves. In conclusion, this study showed that the development of ovarian follicles in Shami heifers occurs in waves and the most common pattern is three waves per estrous cycle.
Twelve growing Shami heifers available in Dier-Al-Hajar Station for improving Shami Cattle weighing 115±3 kg and 178±4 days old were used to monitor the daily growth of ovarian follicles (daily numbers, size, length and number of waves, rate of gr owth and regression) using Transrectal Ultrasound Echo System (7.5 MHz probe) in 6-14 months-old heifers. Results indicated that ovarian follicles developed in a wave pattern in all Shami heifers when they were 6 months old and no significant differences in the number and size of ovarian follicles were found between right and left ovaries. A cohort of 4 to 7 small follicles with a diameter 2-5 mm developed together and one of them was selected for continual growth, became dominant and later regressed during the pre-pubertal stage.
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