اثرات تیمار با ملاتونین و تغییرات طول شبانه روز بر فراسنجه‌های تولید مثلی و هورمونی قوچ افشاری در خارج از فصل تولید مثل

نوع مقاله : مقاله پژوهشی

نویسنده

گروه علوم دامی، دانشگاه زنجان

چکیده

سابقه وهدف: تغییرات فصلی در قوچ بر اندازه بیضه، تولید مایع منی، غلظت تستوسترون پلاسما و رفتارجنسی اثر می-گذارد که به طور کلی این تغییرات از بهار به پاییز افزایش می‌یابد. تجویز ملاتونین در زمان مناسب از سال و یا به دنبال روزهای بلند، اثر روز کوتاه طبیعی را در بالا بردن فعالیت تولید مثلی در قوچ تقلید می‌کند. بنابراین، هدف از انجام این تحقیق، بررسی اثرات کاشت ملاتونین و تغییرات طول شبانه روز برکیفیت وکمیت اسپرم قوچ افشاری در خارج از فصل تولید مثل می‌باشد.
مواد و روش‌ها: دوازده رأس قوچ افشاری (6 قوچ بالغ و 6 قوچ یک ساله) به طور تصادفی به سه گروه آزمایشی اختصاص داده شدند: در گروه شاهد، حیوانات به مدت 60 روز از اوایل اردیبهشت تا اوایل تیرماه در معرض طول روز و شب طبیعی (16 ساعت روشنایی، 8 ساعت تاریکی) قرار گرفتند. در گروه ملاتونین، حیوانات با رژیم نوری گروه شاهد + دو ایمپلنت ملاتونین (هرکدام حاوی 18میلی‌گرم ملاتونین) تیمار شدند. در گروه سوم (رژیم نوری)، حیوانات در معرض 8 ساعت روشنایی و 16 ساعت تاریکی قرار گرفتند. ابعاد بیضه قوچ‌ها پنج بار با فاصله دو هفته اندازه‌گیری شد و نمونه منی یک بار در هفته جمع‌آوری گردید. فراسنجه‌های کمی و کیفی منی با کمک سیستم کاسا اندازه‌گیری شد. همچنین، برای اندازه‌گیری غلظت تستوسترن، نمونه خون از تمام قوچ‌ها در روز 0، 18، 30، 41 و50 پس از کاشت ملاتونین و اجرای دوره نوری گرفته شد. برای اندازه‌گیری غلظت ملاتونین پلاسما، نمونه خون از تمام قوچ‌ها در روز 30، 41 و 50 پس از کاشت ملاتونین و اجرای دوره نوری گرفته شد.
یافته‌ها: حرکت پیش‌رونده اسپرم در گروه رژیم نوری (16/0±71/4) و تیمار ملاتونین (16/0±41/4) نسبت به گروه شاهد (16/0±06/4) افزایش یافت (01/0=P). علاوه بر این، غلظت اسپرم در گروه ملاتونین (اسپرم/میلی‌لیتر 25/0±32/5) نسبت به گروه‌های شاهد (اسپرم/میلی‌لیتر25/0±17/4) و رژیم نوری (اسپرم/میلی‌لیتر25/0±12/4) به صورت معنی‌داری افزایش یافت (002/0=P). غلظت ملاتونین پلاسمای خون در گروه ملاتونین نسبت به گروه دوره نوری و شاهد در روزهای مختلف نمونه‌گیری افزایش یافت. غلظت تستوسترون پلاسما در روزهای مختلف نمونه‌گیری تحت تاثیر کاشت ملاتونین یا دوره نوری قرار نگرفت (05/0=P).
- نتیجه‌گیری: در مجموع، کاشت ملاتونین غلظت اسپرم و حرکت پیش‌رونده اسپرم قوچ‌های افشاری را افزایش داد در صورتیکه که اثری بر سایر فراسنجه‌های اسپرم نداشت. اجرای رژیم نوری موجب افزایش حرکت پیش‌رونده اسپرم گردید. کاشت ملاتونین و اجرای رژیم نوری اثری بر محیط و طول بیضه نداشتند. کاشت ملاتونین، غلظت ملاتونین پلاسما را افزایش داد در صورتیکه اجرای دوره نوری اثری بر غلظت ملاتونین پلاسما نداشت.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Effects of melatonin and a photoperiod regimen on semen characteristics and hormonal status of Afshari rams out of breeding season

نویسنده [English]

  • Athareh Rajaei
university of zanjan
چکیده [English]

Abstract
Target and background: It is well known that rams show a marked seasonal variation in many reproductive aspects, including testicular size, semen production, plasma testosterone concentration and sexual behavior –characteristics that generally increase from spring to autumn. These changes are mainly regulated by photoperiod with long days being inhibitory and short days being stimulatory. The administration of melatonin at the appropriate time of the year, or following a treatment of long days can mimic the stimulatory effect of natural short days in advancing the period of maximum reproductive activity in the ram. The objective of this study was, therefore, to determine whether treating rams with melatonin and photoperiod in mid-spring increased testicular and semen concentration parameters. The aim of present study was to investigate the effects of melatonin and changes in photoperiod regimen on semen characteristics of Afshari rams out of the breeding season.
Material and methods: Twelve rams were randomly allocated into three groups: In control group rams were exposed to natural day photoperiod. In Melatonin group rams were treated as the same as control group plus two 18 mg of melatonin implants one in the area under the skin of the left ear and another in the area below the right ear. In photoperiod regimen group rams were managed as the same as group 1 and 2 until 4 pm (8 hours light) and thereafter were kept in dark stall until 8 am. Plasma melatonin and testosterone concentrations were measured by commercial kits. Testicle dimensions were measured five times during experiment and semen samples were taken 2 days a week for 8 weeks.The data were analyzed in a randomized complete block design.
Results: The results showed that photoperiod regimen increased semen wave motion motility in compare to control group (P= 0.01). In addition, sperm concentration in melatonin treatment group (5.32±0.25) significantly increased in compare to control group (4.12±0.25) and photoperiod regimen group (4.15±0.25) (P=0.002). Plasma melatonin concentration in melatonin treatment group increased in compare to photoperiod regimen group and control group on different sampling days (P= 0.05). Plasma testosterone concentration was not affected significantly in experimental groups on different sampling days following melatonin or photoperiod treatments (P= 0.05).
Conclusion: In general, melatonin implants increased sperm concentration, and Photoperiod increased Progressive velocity of Afshari rams, but did not effect on other sperm parameters. melatonin implants increased plasma melatonin concentration but photoperiod did not effect on plasma melatonin concentration.

کلیدواژه‌ها [English]

  • : Afshari ram
  • melatonin
  • photoperiod regimen
  • testosterone
  • sperm parameters
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