فهرست مطالب

پژوهش های علوم دامی - سال بیست و نهم شماره 2 (تابستان 1398)
  • سال بیست و نهم شماره 2 (تابستان 1398)
  • تاریخ انتشار: 1398/06/01
  • تعداد عناوین: 9
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  • مختارعلی عباسی* صفحات 1-13
    زمینه مطالعاتی

     یکی از عوامل موثر بر صحت پیش بینی ارزش اصلاحی با استفاده از روش های سنتی وجود اطلاعات کامل شجره پدری است.

    هدف

    این مطالعه با هدف بررسی اثر نقص شجره پدر بر برآورد مولفه های (کو)واریانس، پارامترهای ژنتیکی و صحت انتخاب، یک جمعیت با دو صفت وزن شیرگیری با وراثت پذیری 15/0 و سرعت رشد روزانه با وراثت پذیری 30/0 و همبستگی های فنوتیپی، ژنتیکی و محیطی 5/0 شبیه سازی شد.

    روش کار

    بدین منظور کلیه اطلاعات شجره و عملکرد حاصل از 10 سال انتخاب و آمیزش در فایل ذخیره شد. در هر فایل شماره پدرها با دو روش تصادفی و متوالی و با نسبت های 0 تا100% از شجره حذف شد. فایل های حاصل با مدل حیوانی دو صفتی تجزیه و تحلیل شدند.

    نتایج

    در حالت حذف تصادفی و متوالی شجره پدر، واریانس فنوتیپی صفت وزن شیرگیری در سطوح مختلف نقصان شجره پدر تقریبا ثابت بود. واریانس ژنتیکی افزایشی کاهش یافته و تغییرات واریانس محیطی در جهت مخالف واریانس ژنتیکی افزایشی بود. در روش حذف تصادفی کاهش وراثت پذیری معنی دار بود. در روش حذف متوالی، فقط برای درصدهای حذف 50 تا 90 کاهش این دو پارامتر معنی دار بود. با افزایش میزان حذف تصادفی و متوالی شجره پدر از 0 تا 100 درصد، صحت انتخاب برای صفات وزن شیرگیری و افزایش وزن روزانه به ترتیب به از 767/0 به 493/0 و از 933/0 به 614/0 تقلیل یافت. مقدار همبستگی ژنتیکی بین دو صفت با افزایش میزان نقصان شجره پدردر روش حذف تصادفی کاهش معنی دار نشان داد. اما در روش حذف متوالی فقط برای درصد حذف 60 و 80 معنی دار (05/0P<) بود.

     

    نتیجه گیری کلی

    بطورکلی با افزایش میزان اطلاعات گمشده پدری مقادیر پارامترهای ژنتیکی دو صفت کاهش یافت.

    کلیدواژگان: پارامترهای ژنتیکی، شبیه سازی رایانه ای، شجره پدری گمشده
  • آذر شهبازی، عذرا جوان بخت* صفحات 15-29
    زمینه مطالعاتی

     صنعت مرغداری به جهت تامین بخش عمده ای از نیازهای غذایی و پروتئینی کشور، از جمله زیربخش های مهم بخش کشاورزی محسوب می گردد. از اینرو، در راستای افزایش بازده تولیدات این زیربخش و به تبع آن افزایش بازده بخش کشاورزی، لازمست عوامل موثر بر سطح تولید در این صنعت، شناسایی و ترکیب بهینه نهاده ها و صرفه های ناشی از مقیاس، مورد تحلیل و بررسی قرار گیرند.

    هدف

     در مطالعه حاضر به بررسی ساختار تولید و تعیین اندازه بهینه واحدهای پرورش مرغ گوشتی شهرستان مسجدسلیمان

    روش کار

     از طریق برآورد تابع هزینه ترانسلوگ به روش سیستم معادلات به ظاهر نامرتبط، پرداخته شده است. داده های موردنیاز با تنظیم پرسشنامه و مراجعه حضوری به مدیران تمام واحدهای پرورش مرغ گوشتی در این شهرستان به دست آمد.

    نتایج

     نتایج نشان می دهند که کشش های خودقیمتی تقاضا برای همه نهاده ها منفی است و مقدار اندک آنها حاکی از کم کشش بودن تقاضا برای نهاده ها و عدم امکان تغییر زیاد تقاضا در قبال تغییرات قیمت می باشد. در بین نهاده ها نیز تقاضای نهاده دان، با توجه به ضروری بودن آن در فرآیند تولید، کمترین حساسیت را نسبت به تغییر قیمت نشان می دهد. کشش های تقاطعی نیز نشانگر رابطه جانشینی بین اغلب نهاده های تولیدی به جز نهاده دان با جوجه یکروزه و نیروی کار است. با توجه به نتایج برآورد تابع هزینه متوسط ترانسلوگ، صنعت مرغداری در این شهرستان، از بازده افزایشی نسبت به مقیاس برخوردار است و اندازه بهینه واحدها با نگهداری 28000 قطعه جوجه، حاصل می شود، در حالیکه متوسط ظرفیت موجود آنها 20000 قطعه است. یعنی، این واحدها می توانند با افزایش متناسب نهاده های تولیدی و افزایش مقیاس تولید، از صرفه های ناشی از مقیاس بهره گیرند و تولید خود را با هزینه های کمتری، افزایش دهند. به عبارت دیگر، واحدهای تولیدی مورد مطالعه با 28000 قطعه از حداقل هزینه متوسط برخوردار خواهند شد.

     نتیجه گیری نهایی

    در نهایت، پیشنهاد می گردد برای تشویق تولید کننده به افزایش تولید، با اعمال سیاست های مناسب از نوسان قیمت بویژه افزایش قیمت نهاده ها جلوگیری نمود و از لحاظ فنی راه حلی پیدا کرد که امکان جانشینی بین نهاده ها در بخش تغذیه ی طیور فراهم گردد تا در صورت افزایش قیمت برخی نهاده ها، به دلیل عدم امکان جانشینی بین آنها، تولید، محدود نشود.

    کلیدواژگان: ساختار تولید، اندازه بهینه، واحدهای مرغداری، سیستم معادلات به ظاهر نامرتبط، مسجدسلیمان
  • نسیم بیابانی، فرشید فتاح نیا، گلناز تاسلی*، مهدی بهرامی یکدانگی، حمیدرضا میرزایی الموتی صفحات 31-42
    زمینه مطالعاتی

    برای استفاده بهینه از فرآورده های فرعی کارخانجات صنایع تبدیلی باید فرآیندهایی روی این محصولات صورت پذیرد تا  با سهولت بیشتری در تغذیه دام استفاده شوند. بسیاری از این فرآورده های فرعی مانند تفاله نعناع و تفاله کاسنی، به دلیل رطوبت بالا و کربوهیدرات غیرالیافی پایین خصوصیات مناسب سیلو شدن را ندارند، از این رو بهتر است در هنگام سیلو کردن آنها از مواد افزودنی مناسب استفاده نمود.

    هدف

     در این پژوهش اثر سطوح مختلف دانه جو بر ترکیب شیمیایی و کینیتیک هضم سیلاژ تفاله نعناع و سیلاژ تفاله کاسنی در شرایط آزمایشگاهی مطالعه شد.

    روش کار

     پس از خرد کردن تفاله تازه کاسنی و تفاله تازه نعناع، پودر جو در سطوح 10، 20، 30 درصد به تفاله کاسنی و در سطوح 10 و 20 درصد (وزن سیلاژ) به تفاله نعناع اضافه و به مدت 30 روز سیلو شد. ترکیب شیمیایی، فراسنجه های تولیدگاز، جمعیت پروتوزوآ، غلظت نیتروژن آمونیاکی، pH و ظرفیت بافری سیلاژها اندازه گیری شد. میزان انرژی  قابل متابولیسم، کل اسیدهای چرب فرار و گوارش پذیری ماده آلی برآورد شد. کیفیت سیلاژها با استفاده از شاخص فلیگ مورد ارزیابی قرار گرفت.

    نتایج

    با افزایش سطح جو میزان الیاف غیرقابل حل در شوینده اسیدی سیلاژهای تفاله کاسنی و سیلاژهای تفاله نعناع کاهش یافت و سیلاژ تفاله کاسنی حاوی 10 درصد جو بیشترین میزان الیاف غیرقابل حل در شوینده اسیدی داشت. سیلاژ تفاله نعناع حاوی 20 درصد جو بیشترین میزان سرعت تولید گاز، انرژی  قابل متابولیسم، کل اسیدهای چرب فرار و گوارش پذیری ماده آلی را در مقایسه با سایر سیلاژها داشت (01/0P <). غلظت نیتروژن آمونیاکی و جمعیت پروتوزوآ سیلاژهای آزمایشی باهم تفاوتی نداشتند.

    نتیجه گیری نهایی

    این نتایج نشان داد که در بین سیلاژهای آزمایشی، سیلاژ تفاله نعناع حاوی 20 درصد جو ویژگی های یک سیلاژ مطلوب را دارد.

    کلیدواژگان: تخمیر برون تنی، جو، سیلاژ تفاله کاسنی، سیلاژ تفاله نعناع
  • مهری منتظر هرزند، حمید پایا*، اکبر تقی زاده، علی حسینخانی صفحات 43-55
    زمینه مطالعاتی

     آفلاتوکسین ها گروهی از مایکوتوکسین های تحت عنوان متابولیت های ثانویه سمی هستند که باعث آلودگی خوراک می شوند.

    هدف

    پژوهش حاضر به منظور شناسایی میزان آلودگی آفلاتوکسین M1</sub> شیر، آفلاتوکسین B1</sub> خوراک و متعاقبا جداسازی و شناسایی مولکولی گونه قارچی آسپرژیلوس فلاووس طراحی گردید.

    روش کار

     بدین منظور از 10 گاوداری سطح استان آذربایجان شرقی به طور تصادفی نمونه های خوراک و شیر در ماه های اسفند و فرودین جمع آوری گردید و متعاقبا تعیین میزان آفلاتوکسین ها، به روش الایزا انجام گرفت. همچنین جداسازی و شناسایی قارچ آسپرژیلوس فلاووس نمونه هایی با حداکثر آلودگی (2 نمونه) و سویه های خالص آسپرژیلوس فلاووس با استفاده از محیط کشت پوتیتو دکستروز آگار، پرایمر اختصاصی و واکنش PCR انجام پذیرفت. یافته های به دست آمده از آنالیز آفلاتوکسین M1</sub> و B1</sub> توسط آزمون آماری T و با نرم افزار SAS مورد تجزیه و تحلیل قرار گرفت و اعداد به دست آمده با اعداد استاندارد جهانی و ملی مقایسه شد.

    نتایج

    نتایج به دست آمده نشان داد که تمامی نمونه های شیر و خوراک آلوده به آفلاتوکسین بودند ولی میزان آلودگی نمونه های شیر کمتر از مقادیر مجاز استاندارد ایران، آمریکا و اتحادیه اروپا (به ترتیب 1/0، 5/0 و 05/0 میکروگرم در کیلوگرم) بود و از بین 10 نمونه تنها دو نمونه خوراکی میزان آلودگی آفلاتوکسین B1</sub> بالاتر از حد مجاز استانداردهای ایران و اتحادیه اروپا (5 میکروگرم در کیلوگرم) بود. محدوده آلودگی نمونه های شیر و خوراک به ترتیب در دامنه های 021/0 الی 05/0 و 1/1 الی 9/6 میکروگرم در کیلوگرم مشاهده شد. از لحاظ آماری نیز آلودگی آفلاتوکسین M1</sub> و B1</sub> سطح منطقه از استانداردهای ملی و بین المللی پایینتر بود. تفاوت معنی داری بین میانگین وجود داشت و به طور معنی داری میانگین آلودگی ها پایین تر از این استانداردها بود (به ترتیب 0001/0>p و 01/0>p برای شیر و خوراک). بر اساس نتایج به دست آمده در خصوص شناسایی گونه قارچی نیز با توجه به عدم تشکیل باند در محدوه bp413، می توان نتیجه گرفت که گونه غالب و عامل اصلی آلودگی خوراک های نمونه برداری شده، گونه فلاووس نبوده است.

    نتیجه گیری نهایی

    تفاوت معنی داری بین میانگین آلودگی آفلاتوکسین M1 و B1 سطح منطقه با استانداردهای ملی و بین المللی وجود داشت و میانگین آلودگی ها پایین تر از این استانداردهای مزبور بود.

  • رسول کچویی، حسین عبدی بنمار، *یعقوب منصوری، جمال سیف دواتی صفحات 57-71
    زمینه مطالعاتی

    در سال های اخیر تحقیقات بر روی بهترین منابع مکمل سلنیوم جهت به حداکثر رساندن عملکرد بیولوژیک متمرکز شده است.

    هدف

    این مطالعه به منظور تعیین اثر منابع مختلف سلنیوم بر غلظت سلنیوم خون و سرم بز های خلخالی در اواخر آبستنی و همچنین اثر این منابع بر غلظت سلنیوم خون و سرم بزغاله های آنها، غلظت ایمنوگلوبولین جی (IgG) سرم و آغوز مادران و بزغاله ها (بلافاصله بعد از تولد) و شیر تولیدی انجام شد.

    روش کار

     آزمایش با استفاده از 40 راس بز خلخالی در قالب یک طرح کاملا تصادفی در 4 گروه 10 راسی اجرا شد. گروه شاهد هیچ گونه مکملی دریافت نکردند و تنها با جیره پایه حاویmg Se kg-1</sup> DM 1/0 تغذیه شدند. تیمار های آزمایشی شامل 6/0 میلی گرم سلنیوم به ازای هر راس در روز به شکل سلنو متیونین، نانو ذرات سلنیوم و سدیم سلنیت بود.

    نتایج

     در بین گروه ها تفاوت معنی داری در غلظت IgG سرم بز ها، غلظت IgG آغوز و همچنین غلظت IgG سرم بزغاله ها وجود داشت (05/0>P). به طوری که سلنومتیونین کارایی بهتری داشت. غلظت سلنیوم سرم و خون بز ها قبل از زایش تقریبا مشابه بود، اما در روز زایش، غلظت سلنیوم در سرم و خون بز هایی که مکمل دریافت کرده بودند بالاتر بود (05/0>P). غلظت سلنیوم سرم و خون در بز های دریافت کننده مکمل نانو سلنیوم در مقایسه با سایر گروه ها بالاتر بود (05/0>P). همچنین غلظت سلنیوم سرم و خون بزغاله ها در هنگام تولد و غلظت سلنیوم آغوز گروه های آزمایشی در مقایسه با گروه شاهد افزایش معنی داری داشت (05/0>P)، به جز گروه دریافت کننده نانو ذرات سلنیوم که کاهش معنی داری در مقایسه با گروه شاهد نشان داد. غلظت خونی سلنیوم در هفته اول زندگی بزغاله ها تنها در تیمار دریافت کننده مکمل آلی به طور معنی داری افزایش نشان داد (05/0>P).

    نتیجه گیری نهایی

    مکمل آلی سلنیوم در اواخر آبستنی در انتقال ایمنی خونی از بز ها به بزغاله ها موثر بوده و سبب تغییر در غلظت IgG خون، سرم و آغوز بز ها شد. همچنین مکمل سلنیوم سبب افزایش غلظت سلنیوم خون و سرم مادران شد و مکمل سلنیوم آلی انتقال مادری بهتری نسبت به سایر مکمل های سلنیوم نشان داد.

    کلیدواژگان: تولید شیر، بز خلخالی، سدیم سلنیت، سلنومتیونین، نانو ذرات سلنیوم، غلظت ایمنوگلوبولین
  • کتایون نفوذی*، علی حسن زاده تروجنی، منیره خردادمهر، محمدصادق مددی، وحیدرضا رنجبر، گراهام مک اینتایر صفحات 73-89
    زمینه مطالعاتی

    فزودن اکتینومیست ها به جیره غذایی باعث ارتقاء سطح ایمنی حیوانات مختلف می شود.

    هدف

    این مطالعه به منظور ارزیابی اثرات تقویت سیستم ایمنی با استفاده از باکتری کشته شده تسوکامورلا اینکونینسیس</em>افزوده شده بر جیره به عنوان جایگزینی بر عملکرد رشد، تغییرات عیار آنتی بادی علیه واکسن نیوکاسل، عیار ایمنوگلوبولین A، میزان برخی سایتوکاین ها و مورفولوژی روده در بلدرچین ژاپنی می باشد.

    روش کار

    در این تحقیق 153 قطعه جوجه بلدرچین ژاپنی به طور تصادفی در سه تیمار و سه تکرار و در هر تکرار 17 قطعه جوجه قرار داده شدند. گروه های باکتریایی شامل (1) گروه کنترل یا بدون باکتری، (2) گروه با دوز پایین، و (3) گروه با دوز بالا بود.

    نتایج

    گروه های دریافت کننده باکتری، از نظر عملکرد رشد با گروه کنترل، تفاوت معنی داری در سه دوره زمانی 1-14، 1-28 و 1-42 روز نداشتند هرچند در کل در مقایسه با گروه کنترل افزایش وزن به ویژه در گروه دریافت کننده دوز بالا دیده می شد. در ارزیابی  IL-4 و INF-αدر سرم گروه های مختلف آزمایشی، در روزهای 7 و 42، تفاوت معنا دار دیده شد (05/0P<</>). در اندازه گیریIgA   گروه دریافت کننده دوز بالا، در روز 42  تفاوت معنی داری نسبت به دو گروه دیگر داشت. باکتری تسوکامورلا اینکوننسیس</em> باعث به وجود آمدن اختلاف آماری معنی داری در عیار آنتی بادی علیه نیوکاسل در سن 42 روزگی بین گروه کنترل با گروه های دریافت کننده دوز پایین شده است. همچنین گروه های دریافت کننده باکتری کشته شده در نمونه های بافتی گرفته شده از قسمت های مختلف روده با یکدیگر و با گروه کنترل در شاخص های طول پرز، ضخامت پرز، عمق کریپت، تعداد کریپت و تعداد سلول های جامی تفاوت معنی داری داشتند (05/0P<</>).

    نتیجه گیری نهایی

    با توجه به یافته های ماکروسکوپی و ایمنولوژیک، می توان نتیجه گرفت که باکتری کشته شده تسوکامورلا اینکوننسیس</em>، بدون به وجود آوردن ضایعات پاتولوژیک خاص، باعث ارتقا سطح ایمنی و مورفولوژی روده در بلدرچین ژاپنی شده است.

    کلیدواژگان: بلدرچین ژاپنی، پاسخ ایمنی، تسوکامورلا اینکونینسیس، مورفولوژی روده، نیوکاسل
  • داود کیانی فرد*، سید میثم موسوی شعار، مهدی بساکی صفحات 91-102
    زمینه مطالعاتی

     متیل فنیدات از مشتقات آمفتامین بوده و مصرف آن با بروز تغییراتی در بافت بیضه و اسپرم زایی همراه است. نیکوتین یک آلکالوئید سمی است که با اشکال مختلف در دسترس افراد قرار دارد. اثرات منفی نیکوتین بر اسپرماتوژنز گزارش شده است.

    هدف

     استفاده از ترکیبات محرک نظیر متیل فنیدات گرایش به مصرف فرآورده های حاوی نیکوتین را افزایش می دهد. در این مطالعه اثر مصرف همزمان متیل فنیدات و نیکوتین بر ساختار و عملکرد بافت بیضه بررسی گردید.

    روش کار

    متیل فنیدات (10میلی گرم/کیلوگرم) و نیکوتین (4 میلی گرم/کیلوگرم) به مدت هشت هفته به صورت داخل صفاقی بطور جداگانه یا همزمان در 40 سر موش صحرایی بالغ استفاده شد. حیوانات به چهار گروه (10 حیوان در هر گروه) شامل گروه کنترل، متیل فنیدات، نیکوتین و متیل فنیدات + نیکوتین تقسیم شدند. در انتهای مطالعه، خونگیری از حیوانات جهت آنالیز هورمونی و سنجش استرس اکسیداتیو به عمل آمده سپس موش ها آسان کشی شده و وزن بدن و بیضه ها ثبت گردید. نمونه های بافت بیضه جهت مطالعات هیستومورفومتری و نمونه های اپی دیدیم جهت آنالیز اسپرم آماده سازی شد.

    نتایج

     استفاده از متیل فنیدات و نیکوتین موجب ایجاد تغییرات ساختاری و عملکردی در بافت بیضه در مقایسه با گروه کنترل گردید. کاهش وزن نسبی بیضه ها در گروه های تحت درمان مشاهده شد. استفاده از متیل فنیدات و نیکوتین بطور مجزا موجب افزایش سطح سرمی هورمون FSH و کاهش هورمون LH گردید. در گروه های مذکور سطح خونی تستوسترون در مقایسه با گروه کنترل و گروه دریافت کننده همزمان این ترکیبات افزایش یافت. شاخص استرس اکسیداتیو در سرم موش های تحت درمان افزایش یافت. در مطالعات بافت شناسی تغییرات ساختاری نظیر افزایش ضخامت کپسول همبندی، کاهش قطر لوله های اسپرم ساز، کاهش ارتفاع اپی تلیوم زایگر و کاهش شاخص های میکروسکوپی اسپرماتوژنز در گروه های دریافت کننده متیل فنیدات و نیکوتین مشاهده شد. شاخص های آنالیز اسپرم در گروه های تحت درمان کاهش یافت. بیشترین میزان کاهش جمعیت اسپرم و درصد تحرک و زنده مانی به ترتیب در گروه دریافت کننده نیکوتین و گروه دریافت کننده همزمان متیل فیندات و نیکوتین ثبت گردید.

    نتیجه گیری نهایی

    نتایج این مطالعه نشان داد در موارد مصرف همزمان متیل فنیدات و نیکوتین، اثرات منفی نیکوتین نقش بیشتری در بروز تغییرات ساختاری و عملکردی بافت بیضه داشته باشد.

    کلیدواژگان: بیضه، متیل فنیدات، موش صحرایی، نیکوتین
  • حسین اصغر حسین زاده، فریبا فریور*، جواد بیات کوهسار، فرزاد قنبری صفحات 103-115
    زمینه مطالعاتی

    عمل آوری به روش های مختلف می تواند بر فراسنجه های تولید گاز و قابلیت هضم برون تنی تخمیری دانه ذرت تاثیر بگذارد.

    هدف

    این پژوهش به منظور بررسی تاثیر روش های عمل آوری فیزیکی و بیولوژیکی بر فراسنجه های تولید گاز و قابلیت هضم برون تنی تخمیری دانه ذرت در قالب طرح کاملا تصادفی با 6 تیمار شامل: 1) دانه ذرت بدون عمل آوری (شاهد)، 2) دانه ذرت فلیک شده با بخار (به مدت 3 تا 5 دقیقه)، 3) دانه ذرت فلیک شده+ مخمر (ساکارومایسس سرویزیه) (4 درصد به نسبت 1:2)، 4) دانه ذرت مایکروویو شده (باقدرت850 وات و به مدت 3 دقیقه)، 5) دانه ذرت فلیک شده با مایکروویو و 6) دانه ذرت فلیک شده+ مخمر + مایکروویو انجام شد.

    روش کار

    مایع شکمبه از سه راس گوسفند نژاد دالاق با میانگین وزنی 5/2 ± 45 کیلوگرم قبل از وعده خوراک دهی، صبحگاهی جمع آوری و پس از صاف کردن با بزاق مصنوعی با نسبت 1:2 مخلوط و در داخل ویال ها ریخته و به مدت 96 ساعت در داخل بن باری قرار داده شد. میزان تولید گاز نمونه ها در ساعات مختلف ثبت و نتایج توسط نرم افزار SAS پردازش گردید.

    نتایج

    نتایج نشان داد که روش های عمل آوری تاثیر معنی داری بر پتانسیل تولید گاز داشتند. در بین عمل آوری ها، روش ترکیبی بیشترین تاثیر را بر قابلیت هضم ماده آلی (10/88 گرم بر کیلوگرم) داشت. تیمار های عمل آوری شده با مایکروویو در مقایسه با تیمار شاهد به طور معنی داری قابلیت هضم برون تنی ماده خشک و ماده آلی را کاهش دادند. بالاترین مقدار تولید پروتئین میکروبی در تیما ر های عمل آوری شده به ترتیب مربوط به تیمار فلیک+مخمر، فلیک و مایکروویو بود (به ترتیب: 73/171، 23/170 و 11/170 میلی گرم بر گرم ماده خشک) .

    نتیجه گیری نهایی

     به نظر می رسد بر اساس داده های حاصل از فراسنجه های تولید گاز تخمینی و قابلیت هضم، عمل آوری با مایکروویو تجزیه شکمبه ای دانه ذرت را کاهش داده است.

    کلیدواژگان: تولید گاز، دانه ذرت، عمل آوری، قابلیت هضم برون تنی، مایکروویو، مخمر ساکارومایسس سرویزیه
  • احمد علی ثابتان شیرازی، احمد حسن آبادی* صفحات 117-129
    زمینه مطالعاتی

    افزایش توده بدن حیوان در واحد زمان به عنوان شاخص رشد می باشد. چنانچه نرخ رشد را بتوان در مراحل مختلف پرورش پیش بینی نمود، تعیین مقدار مواد مغذی مورد نیاز و ارائه اقتصادی ترین برنامه مدیریت تغذیه ممکن خواهد شد.

    هدف

    این پژوهش با هدف تخمین فراسنجه های رشد جوجه های گوشتی تغذیه شده با جیره غذایی حاوی پودر برگ زیتون و آلفا-توکوفریل استات با استفاده از مدل گومپرتز انجام گردید.

    روش کار

    داده های مربوط به وزن تعداد 300 قطعه جوجه گوشتی یک روزه سویه کاب500 در قالب طرح کاملا تصادفی با پنج تیمار، سه تکرار و 20 قطعه جوجه در هر تکرار به مدت 42 روز مورد استفاده قرار گرفته و منحنی رشد با استفاده از مدل گومپرتز برای آنها برازش گردید. جیره های آزمایشی شامل: جیره ذرت-سویا(شاهد منفی)، جیره پایه به همراه 250 میلی گرم درکیلوگرم آلفا-توکوفریل استات (شاهد مثبت) و سه جیره به صورت جیره پایه با 2، 5/2 و 3 درصد پودر برگ زیتون بودند.

    نتایج

     بیشترین مقدار میانگین وزن پیش بینی شده در هفته اول و دوم مربوط به تیمار شاهد منفی بود. پیش بینی زمان تغییر نرخ رشد برای تیمارهای پودر برگ زیتون نسبت به شاهد مثبت با تفاوت های اندک همراه بود. نرخ رشد در گروه های تغذیه شده با پودر برگ زیتون تا هفته سوم به یکدیگر نزدیک بود. تفاوت در مقدار عددی نرخ رشد پس از پشت سرگذاشتن هفته سوم در گروه 5/2 درصد پودر برگ زیتون و گروه شاهد مثبت افزایش یافت.

    نتیجه گیری نهایی

     تاثیر تیمارهای 5/2 درصد پودر برگ زیتون و شاهد مثبت بر میانگین وزن پیش بینی شده، بهبود فراسنجه های نرخ رشد، زمان رسیدن به نقطه عطف منحنی رشد و افزایش وزن نهایی در مقایسه با سایر تیمارهای آزمایشی موثرتر بودند.

    کلیدواژگان: پودر برگ زیتون، مدل گومپرتز، منحنی رشد، نرخ رشد
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  • MA Abbasi * Pages 1-13
    Introduction

     According to the FAO in 2017, Iran, with 40 milion head of sheep and 291200 ton sheep meat, is the eighth country in the world of sheep production(http://www.fao.org/faostat/en/#data). One of the most important factors influencing accuracy of the estimated breeding value is complete sire pedigree information. Registration of father's number in sheep flocks of Iran is a big problem, through not having  any program for the control of matting program and artificial insemination. Therefore, the information of sire pedigree is not complete in sheep flocks. Incomplete pedigree causes incorrect relationship matrix and reduces accuracy of the selection and estimation of the genetic parameters of the traits and increases errors in the estimates(Clement et al., 2001). So, the existence of false and missing father’s information reduces genetic gain that this decrease in traits with low heritability have steeper slope. Imperfect sires pedigree data increase standard deviation between different repetitions of estimating variance components and cause bias estimation of genetic and phenotypic parameters(Sanders et al., 2006). Therefore, increase of unknown father's will be decreased direct and maternal heritability and breeding value, but the phenotypic variance will not be affected(Senneke et al., 2004).The estimation of heritability in complete and unbiased pedigree is similar to its actual value. But, random excluding of  50% of father’s ID led to bias estimation of heritability. If 50% of parent’s ID removed  from pedigree, the estiomation of heritability will be incorrect(Cantet et al.,2000). Generally, incomplete pedigree increases the standard error of estimations(Dong et al., 1988). Comparing random and consecutive exclusion pedigree methods (consecutive From zero to the last generation) for a trait with heritability of 0.15 showed random exclusion method leaded to a slight reduction in genetic variation, which consequently declined estimation of heritability. But for other trait with heritability of 0.30 different estimation of variance components leaded to significant decrease in estimation of heritability. In the consecutive exclusion method, the reduction of heritability was not significant with an increase  missing in pedigree of sires(Abbasi et al., 2011). Our objective in this study was investigation of influence of incomplete sire's pedigree on estimation of (co) variance components, genetic parameters and accuracy.

    Material and methods

    In this study we simulated a population with weaning weight (WW) and average daily gain(ADG) records. Heritability for weaning weight (WW) and average daily gain(ADG) were 0.15 and 0.30 respectively and genetic, environmental and phenotypic correlation for two traits were 0.5. Average of weaning weight was 22.29 kg, genetic variance was 1.7525, environmental variance was 9.759, phenotypic variance was 11.5, and heritability was 0.15. The average amount of  genetic variance,  environmental variance, and  phenotypic variance for daily weight gain were 190 g, 1078.2 , 2515.8, 3594, respectively and heritability was 0.3. The pedigree file and performance data were included of animal ID, father and mother ID, phenotypic variance, breeding value, and environmental effects for two traits. Visual Basic 6 program was used for simulation. Mating was random in both populations and the maximum maintenance age of sire and dam was 3 and 6 years, respectively. The ratio of female to male was15:1. In the generated data file, the sire numbers were eliminated asrandom and sequential with proportions 0 to 100 perecnt.The resulted data file were analyzed based on  two traits animal model. The accuracy of selection calculated from correlation between actual and predicted breeding values.

    Results and discussio

    The simulation of data file consist of 20625 head of sheep and base population was 2075 head in this study. Data file included animal ID, sire ID, dam ID, phenotypic value for weaning weight and daily weight gain. Random 10% deletion  of father’s ID increaed unknown fathers from 2750 to 4490 ,while unknown fathers for random 80% deletion  was  equal to 16973. In random and consecutive deletion method, phenotypic variances for two traits were slightly constant. The variance of daily weight gain for random deletion in diferent levels was stable. But the genetic variances were decreased and the environmental variances were slightly increased. The heritabilities of two traits were significantly (P<0.05) reduced in random deletion method.  These results were almost contrary to the results of the randomization method in analysis of a trait with heritability of 0.15, in which the reduction of heritability was not significant(Abbasi et al., 2011). Standard error of heritability in final removal percentage with increase in defect of father's ID slightly increased. In randomization method, variation of variance components led to decrease estimated heritability in 0-80% exclusion of father's ID. In exclusion of father's ID estimated heritability slightly increased by 90 and 100 percent,  which were significant compared with base population (P<0.05). The reduction of genetic variances and heritabilities with increasing in deletion proportion of sire pedigree were only significant(P<0.05) for 50 to 90 percent of sire pedigree sequential deletion. The accuracy of selection were reduced from 0.767 to 0.493 and 0.933 to 0.614 for WW and ADG, respectively. Genetic correlations were reduced with increasing in missing proportion of sire number in random deletion method. But in sequential deletion method, the reductions of genetic correlations were only significant for the proportions of 60 and 80 percent in deletion of sire ID.

    Conclusion

     Incomplete pedigree generates incorrect relationship matrix and bias in the estimation of variance components, genetic parameters of traits and the accuracy of selection. so that , the percentage of  father's ID deletion had a slight influence on phenotypic variance, phenotypic, and environmental correlation. The effect of random deletion of father’s ID on pedigree information had more influence than consecutive deletion method; then, this effect depends on the actual heritability, kind of traits, and the structure of simulated data. Generally, genetic variances, heritabilities, the accuracy of selection and genetic correlation between two traits were reduced with inceasing the proportional deletion  of sire number. The reduction of accuracy associated with genetic progress of traits; then, it is necessary to develop artificial insemination and others control mating method in order to record father's ID.

    Keywords: Computer simulation, Genetic parameters, Missed sire pedigree
  • A Shahbazi, O Javannbakht* Pages 15-29
    Introduction

    The poultry industry supplying the main part of country's food and protein needs, is considered as an important subsector of agricultural sector. Therefore, in order to increase the production efficiency of this sub-sector and accordingly the efficiency of agricultural sector, it is necessary to determine the affecting factors of its production and defining the optimum combination of inputs and scale economies in this industry. Considerable distribution of poultry units in terms of capacity and size in different parts of the country raises the question whether technically the scale of production does not affect the cost of producing per unit of product? In other words, is the structure of production in the poultry subsector constant return to scale or it is ignored, and the expansion of production units is based on the other factors? Answering these questions will lead to produce in optimum scale and reduce the costs of production by using the optimum amount of inputs. Reviewing the literature shows that studying the production structure of firms has attracted the attention of researchers all over the world, like Ansari and Salami (2007), Ghaderzadeh et al (2012), Dashti et al (2018), Taru (2010) and Gezahegn et al (2016). It is osbvious that reducing production costs, the price of product will also decline. According to the law of demand, by decreasing the price of the product, its demand increases and leads to the growth of production in the enterprises. It is clear that with the growth of production and consequently the growth of demand for inputs in an economic sub-sector such as poultry, agricultural growth and ultimately economic growth of the whole country will also be provided. So, in this study, the structure of production and the optimum size of broiler chickens breeding units in Masjed Soleyman town were investigated

    Material and methods

     In this study the production structure of poultry units in Masjed Soleyman town was investigated by estimating the translog cost function using seemingly unrelated regression estimator method. According to statistics provided by the Agricultural Jihad Management of Masjed Soleyman, the number of broiler breeding units in Masjed Soleiman town was 55 units, of which 45 were active and 10 were inactive. So, required data were gathered by setting up a questionnaire and personally interviewing with the managers of all active poultry units. The return to scale and therefore, the economics of a particular industry is shown in the form of its long-run average cost curve. By examining the cost structure of production in an industry, one can see how returns are scaled. If an industry of a given size or level of production had the lowest cost per unit of production and firms smaller or larger than the first group would incur higher production costs per unit of product, the industry would have an average cost curve. The long run will be U-shaped. The existence of a curve in this form means that firms of the second tier can reduce the cost of production per unit of product and increase their competitive ability in the market by changing the size or scale of production and bringing the size of the unit to the size of the first tier. Since in the present study, the estimation of the translog cost function is based on SURE, in which the cost function and the share function of the inputs were estimated as a system of equations, must have cost share functions. According to Sheffard's principle, by deriving the translog cost function from the input price, the cost share functions were obtained. Finally, the parameter of estimated translog cost function were used to obtain scale elasticity, inputs substitution and price elasticities to define the poultry units’ production structure.

    Results and discussion

     The results showed that the own price elasticities of demand for all inputs are negative and their small amount implies that the demand for inputs is less elastic and more demand changes for price changes is not possible. Among the inputs, feed input demand has the least sensitivity to price changes. Cross price elasticities revealed substitution relationship between most production inputs except between the input of feed with chicken and labor force. Regarding the results of this study, the poultry industry in this town is experiencing increasing return to scale, and the optimum size of the units is obtained by maintaining 28,000 pieces of chickens, while the present average capacity is 20,000 pieces. Therefore, these units can benefit from scale economies by proportionate increasing of production inputs and production scale to increase their production at lower costs. In other words, studied units would experience the minimum average costs by 28000 pieces of chickens. This results are consistent with the results of Ansari and Salami (2007), Eshraghi et al (2015).

    Conclusion

     Since most poultry farms produce below optimal capacity; so, one way in reducing costs is to increase poultry units production capacity and to approach the optimum production rate. As such, it is recommended to adopt measures that will increase the capacity of the production units and help to make the production process more economical. As observed, there is a weak substitution relationship between some inputs. On this basis, it can be concluded that if the price of some inputs is increased, the producer will have to accept this price increase and the possibility of substituting these inputs for each other and the reaction of the poultry owners to this price increase is limited. Therefore, it is suggested that, in order to encourage the producer to increase production, by applying appropriate policies prevent the price fluctuations, especially the increase of input prices, and find technically solutions to allow substitution between inputs in the poultry feeding sector. So that, by increasing the prices of some inputs, due to the impossibility of substitution between inputs, production would not be limited. Since poultry industry inputs such as medicines, vaccines and so on are affected by price fluctuations, this causes instability in the market price of poultry and the poultry operates under uncertainty and with high financial risk. So, determining guaranteed price by the government as a financial technique can be fruitful in optimal allocation, stable planning for more poultry production, and increased productivity.

    Keywords: Masjed Soleyman, Optimum size, Poultry units, Production structure, SURE
  • N Biabani, F Fatahnia, G Taasoli*, M Bahrami Yekdangi, H Mirzaie Alamouti Pages 31-42
    Introduction

     Production of animal’s food is constrained by the climate changes.  Severe drought periods cause low availability of feed from natural pastures. Consequently, sheep and goats fed low quality forages. The unavailability of feed was worsened by the continuously increase of imported feed prices. The scarce availability of forage and fluctuant of concentrate prices encouraged the researchers to find new alternatives that have high energy and low cost (Yagoubi et al 2018). During the last decades, to overcome this problem in many countries, many nonconventional feeds such as shrubs and agro-industrial by-products were used. However, the distillation by-products of medicinal plants are used in animal nutrition. Optimum use of agro-industrial co-products in animal nutrition needs some special processing. Silage is an important way for preserving the nutrient of forage, which is a lactic fermentation process driven by epiphytic lactic acid bacteria. Once lactic acid bacteria ferments water-soluble carbohydrates into sufficient lactic acid in an anaerobic silo, low pH is achieved, the activity of undesired microbes is restrained, and the nutrients are well preserved (McDonald et al 1991). Cichorium intybus</em> commonly known as chicory, is fairly woody perennial herb, around 1 m in height with a fleshy taproot of up to 75 cm in length and large basal leaves. Chicory is cultivated for numerous applications such as “forage” chicory, to intensify herbage obtainability in perennial pastures for livestock (Street et al 2013). Mint, (genus Mentha</em>), genus of 25 species of fragrant herbs of the mint family (Lamiaceae) and are widely distributed throughout the temperate areas of the world and have naturalized in many places. Some species are commonly used in herbal medicine. Both of chicory and mint are used for distillation and their residues (pulp) could be used as animal feed. Mint pulp and chicory pulp have high moisture and low non fibrous carbohydrates contents, hence they are not suitable for ensiling. Therefore, it is better to use appropriate additives for ensiling these agro-industrial co-products. This experiment was aimed to study the effect of adding different levels of barley powder to mint pulp silage and chicory pulp silage on chemical compositions, silage quality traits, in vitro</em> gas production parameters, N-ammonia concentration, and protozoa population.

    Material and methods

     Fresh mint pulp and chicory pulp were collected from an agro industry processing factory. Chemical compositions of mint pulp and chicory pulp were measured. Before ensiling, each pulp was chopped to particles with 3-4 cm length. Powdered barley grain was added to chicory pulp at three levels (10, 20, and 30 % (w/w)) and it was added to mint pulp at two levels (10 and 20 % (w/w)) and ensiled for 30 days. Chemical compositions (dry matter, neutral detergent fiber, acid detergent fiber, crude protein, and ash), gas production parameters, total protozoa population and N-ammonia concentration of experimental silages were measured. Silage quality traits including pH and buffering capacity (Jasaitis et al, 1987) were measured and fleig point of each silage was calculated (Kilic 1986). For in vitro</em> gas production tests, the rumen fluid was taken from two rumen fistulated Kordish rams. For measuring kinetic parameters of gas production, 200 mg of samples were incubated with 40 ml buffered-rumen fluid for 120 hours. The cumulative produced gas was recorded at different times of incubation and gas production parameters were fitted to an exponential equation (France et al 1993). For estimating metabolizable energy, organic matter digestibility and total volatile fatty acids, 40 ml buffered rumen fluid was added to 200 mg of silage samples and incubated at 39 °C for 24 hours. After 24 hours of incubation, gas production recorded and metabolizable energy, organic matter digestibility (Menke and Steingass 1988) and total volatile fatty acids (Makkar 2010) were estimated. N-ammonia concentration was measured based on Broderick and Kang (1980). Rumen protozoa were identified according to the method of Dehority (2003).  After 24 h incubation, 5 ml of buffered rumen fluid was pipetted into a screw-capped test tube containing 5 ml of formalin. Thereafter, two drops of brilliant green dye (2 g brilliant green and 2 ml glacial acetic diluted to 100 ml with distilled water) were added to the test tube, mixed thoroughly, and allowed to stand overnight at room temperature. Total and differential counts of protozoa were made with five replications.  All in vitro</em> gas production trials were carried out in three runs. Data were analyzed based on a completely randomized design using Proc GLM of SAS software. The differences among treatments were evaluated using Tukey adjustment, when the overall F-test was ≤ 0.05. Trends were declared when 0.05 < P≤ 0.10. In addition, independent comparisons were done for mint pulp silage vs. chicory pulp silages.

    Results and discussion

     The results showed that with increasing the barely level, dry matter increased and acid detergent fiber decreased in experimental silages and chicory pulp containing 10% of barley grain had the lowest acid detergent fiber content. Similar to the current results, adding different levels of wasted date to Mentha pulegium</em> pulp silage increased dry matter and decreased neutral detergent fiber (Eshaghi Maskoni and Dayani 2016). Average pH, buffering capacity, and fleig point of mint pulp silages and chicory pulp silages were 4.15, 41.62 Meq.1-1</sup>, 87.5 and 5.26, 46.52 Meq.1-1</sup> and 59, respectively. Gas production, constant rate of gas production when half the potential of gas is produced, lag time, and N-ammonia concentration did not differ among all experimental silages. Mint pulp silage with 20% of barley grain had the greatest gas production rate, estimated metabolizable energy content, total volatile fatty acids concentrations, and organic matter digestibility (P < 0.05) and total protozoa population (P = 0.06). Similar to the present experiment, adding wheat bran to citrus pulp silage increased gas production rate and organic matter digestibility (Kordi et al 2014).

    Conclusion

     Considering the obtained data regarding the chemical compositions and in vitro</em> gas production parameters, it is concluded that among all experimental silages, mint pulp silage containing 20% of barley grain could be used as a good silage in ruminant nutrition. Furthermore, these co-product silages could be used as a part of forage portion in ruminant diets. More experiments are needed to study the inclusion of mint pulp silage and chicory pulp silage in diets of productive ruminants.

    Keywords: Barley, Chicory pulp silage, In vitrofermentation, Mint pulp silage
  • M Montazami, H Paya*, A Taghizadeh, A HosseinKhan Pages 43-55
    Introduction

    Aflatoxins are a large group of mycotoxins that are produced through Polyketide pathway by specific species of Aspergillus flavus</em>, Aspergillus parasiticus,</em> and  Aspergillus nomius</em>. These pesticides are known to be the most dangerous mycotoxins affecting human and livestock health (Pleadin et al. 2014). Several hundred mycotoxins have been identified, and more than 25% of the world annual grain production is contaminated with mycotoxin (Smith et al. 2016). Among the 400 known mycotoxins, Aflatoxin B1, B2, G1, and G2 are the most important food and feed mycotoxins (Costanzo et al. 2015). Aflatoxin M1 and M2 are the hydroxyl metabolite of aflatoxin B1 and B2 that can be found in milk or other animal products (Hussein and Brasel. 2001). At the first level, the main manifestations of mycotoxins exposure in animals are reductions in feed intake and weight gain. At the second level, mycotoxins affect the quantity of animal products. The third level of influence is the safety and quality of the products from exposed animals (Wang et al. 2019). The present study was designed to detect contamination of aflatoxin M1 in milkand, aflatoxin B1 in feed and subsequent molecular isolation and identification of Aspergillus flavus</em> species.

    Material and methods

    In this study, 10 milk samples from milk reservoirs and 10 feed samples from a total mixed ration of livestock from dairy farms of East Azarbaijan province (Tabriz and Marand) were collected. After preparation of samples, the experiment was conducted using competitive ELISA method. The principles were as follows: after adding standard solutions or samples to the wells, aflatoxin M1 was bonded from specimens or standards to specific antibody binding sites. After 30 minutes of  incubation step, unbound reagents were removed during a single wash step. Horseradish peroxidase (HRP) aflatoxin M1 was added to the wells and after one 15 minutes of incubation, the unlinked conjugate was removed during the washing step. Then, some aflatoxin M1-HRP was coherent by adding a substrate/chromogen (H2</sub>O2</sub>/TMB) solution. In the presence of colorless chromogen, mixed conjugated aflatoxin and M1-HRP agent was converted to colored product. The addition of sulfuric acid caused the suspension of the substrate reaction and finally, the light intensity was measured by a photometric method at 450 nm. Optical density had an inverse relationship with the concentration of aflatoxin in the sample. To isolate the fungus, first 2 g of the standardized feed  were weighed and milled  in  a falcon containing 18 ml of physiological serum and then, mixed well with a vortex for five minutes. A portion of the diluted feed was removed and cultured on plots containing a Potato Dextrose Agar medium at several locations. Plates were incubated for 7 days at 25 ℃. DNA was extracted from Potato Dextrose Broth (PDB) medium. The resulting mycelium mass was frozen and converted to a uniform powder by liquid nitrogen. DNA extraction was carried out by placing the samples in a buffer and purification with organic solvents such as chloroform/isoamyl alcohol and finally, curing with cold isopropanol. The resulting DNA was stored at -20 ° C. In order to evaluate the actuary of identification for Aspergillus flavus, </em>the primer sequence of AFLA-F and AFLA-R gene was aligned using the BLAST software (GenBank) to find similarity rate within resisted reference sequences. Each PCR reaction consists of: 6 μl of PCR Master Mix, 2 μl extracted DNA, 0.2 μl of each recipe primer, 1.6 μl of distilled water. Then, 10 μl of the final volume of reaction was placed on thermosecler device. A PCR program for amplification of the targeted PCR fragment was fixed based on following temperature: Initial denaturant at 95℃ for 10 min, {denaturant at 95℃ for 1 min, annealing at 66℃ for 2 min, extension at 72℃ for 2 min (total 34 cycle)} and the final amplification at 72℃ for 5 minutes (Zachová et al. </em>2003). Isolated strains of Aspergillus</em> strains were verified using the PCR method; its reaction products were detected in 1% agarose gel by electrophoresis.

    Results and discussion

    The results showed that all milk and feed samples were contaminated with aflatoxin, but the contamination rate of milk samples was lower than the standard values of Iran, America, and the European Union (0.1, 0.5 and 0.05 μg / Kg). Among the 10 collected samples, only two edible samples with aflatoxin B1 contamination were higher than the Iranian and European standards (5 μg / kg). The contamination level of milk and feed samples were observed in the range of 0.021-0.05 and 1.1-6.9 μg / kg, respectively. Statistically, there was a significant difference between the mean of contamination of aflatoxin M1  in milk and B1 in feed in the region with national and international standards and the mean of M1 and B1 contamination was lower than these standards. The level of aflatoxin M1 in milk was detected by HPLC method, indicating that the infection rate of 10 samples was 0.02-0.31 μg / l (Besufekad et al. 2018). In another study, 178 wheat samples were collected in China and reported 18.8% of the samples contaminated with aflatoxin B1 (Liu et al. 2016). The results of the fungal species also showed that the analyzed samples did not show any bands in the 413bp range. As a result, it can be said that the dominant species and the main cause of contamination were not Flavus</em> species. Wang et al. (2016) reported that aflatoxins are mainly produced by the genus Aspergillus</em>, and are commonly found in food and feed in humid and warm environments. Research results in India show that among the 15 collected samples, only 9 samples (60%) were infected with Aspergillus</em>. Seven samples were detected as  Aspergillus flavus</em> and two samples as  Aspergillus niger</em> (Khare et al. 2018).

    Conclusion

     Milk composition, body mass gain, immunity, and reproductive performance are affected in dairy ruminants by feeds contaminated with aflatoxins. It is expected that by controlling animal feed agaisnt aflatoxin and reducing its levels in feed by improving production and storage conditions, a suitable method for preventing contamination of milk and its products will be adopted to help improve the health of the community.

    Keywords: Aflatoxin B1, Aflatoxin M1, Animal feed, Aspergillus, Milk, Polymerase chain reaction
  • R Kachuee, H Abdi, Benemar*, Y Mansoori, J Seifdavati Pages 57-71
    Introduction

     Selenium (Se), as an antioxidant element, is a neutralizing mineral for oxidative stress and urging apoptosis in stressed biological systems. Selenium is a necessary trace element for ruminants that participates in varied biological processes like antioxidant defense, production of thyroid hormone, and response of immune system. In recent years, researches have focused on the best supplementary sources of selenium to maximize biological performance. The studies about reproductive performance, such as that of Gabryszuk and Klewiec (2002), showed that injecting ewes with Se four weeks before breeding and again during the last four weeks of gestation caused a 32% increase in lambing percentage compared with Se-deficient ewes. Furthermore, adequate Se status of the newborn lambs not only ensures prevention of nutritional myopathy, but also decreases losses in lamb productivity. Lambs from Se-supplemented ewes showed faster progression to stand and nurse compared with lambs from unsupplemented ewes and leading to an overall decrease in lamb mortality (Muñoz et al. 2009). It has been observed that selenium mineral supplements, such as sodium selenite and sodium selenate, have the same bioavailability. However, organic selenium supplements such as yeast selenium more effectively increase the concentration of selenium in blood and milk and may have a better bioavailability. However, the recently developed red elemental selenium has promising uses in the environmental protection from the pollution of the excessive selenium (Zhang et al. 2007). Zhang et al. (2007) synthesized nano red elemental selenium (nano-Se) with the size of 5 – 100 nm and observed that nano-Se had a similar bioavailability in rat and much less acute toxicity in mice compared with selenite. Recently, Wang et al. (2007) showed that nano-Se (20 – 60 nm) possesses equal efficacy in increasing the activities of GSH-Px in plasma and liver from male Kunming mice compared with selenomethionine. The periparturient period is the foremost necessary stage in farm animals about health standing and production. The objective of this study was to determine the effect of different sources of selenium on blood and serum selenium concentration of Khalkhali goats during late pregnancy, as well as the effect of these sources on the concentration of selenium in their kids up to four weeks and serum and colostrum immunoglobulin concentration (IgG) of mothers and kids (immediately after birth).

    Material and methods

    The experiment was conducted using 40 Khalkhali goats in a completely randomized design devided into four groups with 10 goats per each group. The goats were randomly allocated to four treatments to receive supplementations of 0 (control), 0.6 mg Se head−1</sup> day−1</sup> of seleno-methionine (SM), 0.6 mg Se head−1</sup> day−1</sup> of nano-selenium (SN), and 0.6 mg Se head−1</sup> day−1</sup> of sodium selenite (SS) from four weeks before the expected day of delivery. Their blood samples were taken at that time and on the kidding day. In addition, colostrums were collected in pre-cleaned polyethylene bottles from the goats as immediately as possible after kidding. Instantly after delivery, newborn kids were taken apart from their dams. The control group did not receive any supplement and received only the basal ration containing 0.1 mg Se kg-1</sup> DM. Blood samples were collected from goats three weeks before the expected kidding. Blood samples of kids were taken from the jugular vein on the day of birth and 7 days after birth. Blood samples were centrifuged at 3000 rpm for 15 minutes to prepare the serum. The ELISA method was used to determine the concentration of IgG and selenium concentration was measured using the ICP-OES device. The weight of kids at the birth and up to four weeks, colostrum production in the first three days and milk production of goats for four weeks were recorded and analyzed.

    Results and discussion

     There were no significant differences in birth weight, weight of kids up to four weeks, colostrum production in the first three days, and milk production until the fourth week in goats. There was a significant difference between the groups in serum IgG concentration, colostrum IgG, and blood IgG concentration of kids (P<0.05). No significant differences were observed between mineral selenium, nano-selenium, and control group. However, seleno-methionine had a significantly better performance than nano-selenium and sodium selenite. Serum and blood selenium concentrations were similar before kiding, but the concentration of selenium in serum and blood of supplemented goats was significantly higher than the control ones (P> 0.05). The results of this experiment showed that serum and blood selenium concentrations in nano-selenium recieved goats were significantly higher compared with other groups (P<0.05). Serum and blood selenium concentrations of kids at birth and colostral selenium concentration in the experimental groups were significantly higher than the control group (P <0.05), except for the goats supplemented with selenium nanoparticles, which significantly decreased compared to the control goats. The serum selenium and blood levels of selenomethionine recieved group showed the highest selenium levels in comparison with other groups. Selenium blood levels increased significantly in the first week of life of the kids only in the organic supplementation treatment (P <0.05).

    Conclusion

    Organic selenium supplementation in late pregnancy was effective in transferring blood immunity from the goats to the kids and led to changes in serum and colostrum IgG levels of goats. The supplementation of different Se forms (sodium selenite, selenomethionine and elemental nano-Se) into pregnant goats’ diet increased Se status in the whole blood and serum compared with controls. Among Se sources, nano-selenium exhibited an excellent increasing Se status in pregnant goats. Current results showed differences in the transplacental Se transfer capacities of sodium selenite, selenium nanoparticles, and selenomethionine. When comparing these three Se sources, the results of the study clearly demonstrated that kids from goats receiving selenomethionine had higher whole-blood and serum-Se concentrations compared with kids from goats receiving sodium selenite and selenium nanoparticles. There was a failure of nano-selenium to increase newborn Se concentrations as compared with control. Seleno-methionine had higher transplacental transfer of Se and also resulted in higher Se concentrations in colostrum. Goats supplemented with seleno-methionine had greater colostral Se concentrations than goats supplemented with sodium selenite and selenium nanoparticles.

    Keywords: Milkproduction, Khalkhaligoat, Sodium selenite, Seleno-methionine, Selenium nanoparticles, Immunoglobulin Gconcentration
  • K Nofouzi*, AHassanzadeh Teroujeni, MKhordadmehr, MSMadadi, VR Ranjbar, G McIntyre Pages 73-89
    Introduction

     Irrational use of antibiotics as growth promoter and as therapeutic agents in livestock and poultry is a major issue under discussion. Inappropriate use of antibiotics is not only responsible for an increase in microbial resistance to antibiotics but also the presence of antibiotic residues in animal products is a topic of public health importance. The International Study Group on Antimicrobial Strategies (ISGNAS) has also mentioned the increased microbial resistance to antibiotic as a serious problem. Newcastle Disease (ND) is one of the most devastating diseases of the domestic fowl, which can cause high level mortality of these animals. ND is caused by Newcastle Diseases Virus (NDV), an avian Paramyxovirus type 1 (APMV-1) that belongs to the genus Avulavirus</em>, family Paramyxoviridae</em> (Silva et al., 2010). Chickens are the natural host of the virus, but it can infect a variety of avian species causing severe disease (Carrasco et al., 2016). The commercial production of Japanese quails (Coturnix coturnix japonica</em>) is extensively distributed in several countries around the world and many studies showed that this species can easily adapt to commercial management conditions, with good performance in terms of meat and egg production (Lima et al., 2004). The purpose of this study was to evaluate the effects of heat-killed Tsukamurella inchonensis</em> (T.inchonensis</em>) in diet as an alternative on growth performance, intestinal morphology and immune responses of Japanese quail.

     Material and methods

     Animal care and experimental designUnsexed Japanese quail (C. cotumix japonica</em>) were obtained at one day of age acclimated to laboratory surroundings for one week before immunizations and measurements were begun. Quail were housed nine cages measuring 61 × 56 × 81 cm. Temperature in the animal room was maintained at 23˚C. Food and water were available ad libitum</em>. Quail were fed bird food containing approximately 20% crude protein that contained no coccidiostat or other medications. Fluoresent lights provided a photoperiod of12 h light and 12 h dark. The University of Tabriz Animal care and Use Committee approved all protocols. Seventeen Japanese quail were assigned randomly to each of nine groups in a 3 × 3 factorial design with three bacterial treatments. The quails were randomly assigned to each treatment, because sexing could not be done until later development. Quail were sometimes moved between cages if pecking started to occur. The bacterial treatments consisted of (1) a control or no bacteria group, (2) a low dose group, and (3) a high dose group. The low- and high dose groups received 105</sup> or 106</sup> CFU per bird per day in food, respectively from the first day of age.Growth performance and sample collection Body weight gain (BWG) and feed consumtionwas recorded during grower period and finisher period. On d 14, 28 and 42, two birds closet to the median weight from each pen (6 per treatment) were randomly selected, weighed, stunned and slaughtered by exsanguination.  The parameters of investigation included hemagglutination inhibition and ELISA titer of antibodies against NDV, intestinal morphology development and IgA and cytokines titer. Feed intake were recorded daily on cage basis. Body weight was determined every week. At days 1, 7, 14, 21, 28, 35 and 42 of the experiment (42 days), antibodies against Newcastle disease were measured. At the end of days 14, 28 and 42, two quails from each cage were randomly selected and killed by cervical dislocation for histopathological and histomorphometrical studies.

    Results and discussion

     In the present study, we determined whether an Actinomycetales species which had previously been shown to enhance treatment of asthma and sweet-itch (Stanford and Stanford, 2012), could affect the development of antibodies in sera of chickens.  </em>FI and FCR were not affected by different doses of T.inchonensis</em> supplementation. The high dose in feed tended to give higher BWG than the control group (Table 2). Interferones were so named due to their anti-viral properties. They consist of two classes: Type I interferons (IFN-α and IFN-β) that have well-defined anti-viral activity, and type II interferon or IFN-γ which plays a vital role in macrophage activation and modulation of the immune system, in addition to its anti-viral activity (Wigley and Kaiser, 2003).There was a significant difference in the measurement of IL-4 and INF-α in the serum of different experimental groups on days 7 and 42. In the measurement of IgA, the high dose recipient group, had significant differences in day 42 concerning other two groups. T.inchonensis</em> caused a statistically significant difference in antibody titer against Newcastle disease at 42 days of age in low dose group. At microscopically examination, there was no hepatotoxicity, nephrotoxicity, cardiac toxicity and neurotoxicity or other side effects in liver, kidney, heart and brain, respectively (Fig 4-5).  The histomorphometrical measurement results of different parts of small intestine and lymphoid tissue of caecal tonsil are shown in Tables 6-8 and figure 6. T.inchonensis</em> treatments, affected (p< 0.05) lengh and thickness of villi, crypt depth, crypt number and number of goblet cells.

    Conclusion

     According to macroscopic and immunological findings, it can be concluded that supplementation of T.inchonensis</em> can improve intestinal morphology and immune responses in Japanese quail.

    Keywords: Immune response, Intestinal morphology, Japanese quail, Newcastle disease, Tsukamurella inchonensis
  • D Kianifard*, SM Mousavi Shoar, M Basaki Pages 91-102
    Introduction

     Exposure to different xenobiotics can affect the male reproductive system by making structural and functional changes in testicular tissue (Aitken and Roman 2008). The changes in the cellular structure of testicular tissue are associated with varying degrees of infertility (Aitken and Roman 2008). Methylphenidate is an amphetamine derivative which used for treatment of ADHD syndrome (Kraus and Burch 1992 and Levin and Kleber 1995 and Doskoch 2002 and Cansu et al 2010). Long-term administration of methylphenidate has been associated with changes in testicular tissue and sperm population. Nicotine is a toxic alkaloid that available in a wide range of population through different forms (Miranda-Spooner et al 2016). The negative effects of nicotine on spermatogenesis and decreased sperm quality have been reported (Mosadegh et al 2017). Experimental studies in humans and laboratory animals have shown that the use of stimulant compounds such as methylphenidate and amphetamine derivatives increases the tendency to consume nicotine-containing products (Wooters et al 2008). Given the importance of above mentioned subject and the negative effects of nicotine (as a gonadotoxic composition) and methylphenidate on the reproductive system, in this study the effects and the complications of the long-term exposure to methylphenidate and nicotine in the form of simultaneous administration were evaluated on the structure and the function of testicular tissue in animal model of adult rats.

    Material and methods

     Methylphenidate (10 mg/kg b.w.) (Geha et al 2000) and Nicotine (4 mg/kg b.w.) (Nesseim et al 2010) were administrated intraperitoneally once a day for eight weeks in adult rats. The animals were divided into control and three treatment groups: 1) methylphenidate administrated group; 2) nicotine administrated group and 3) methylphenidate+nicotine administrated group. At the end of the eight weeks, the blood sampling was performed for measurement of the blood levels of pituitary gonadotropins (follicle stimulating hormone and luteinizing hormone) and testosterone. Plasma lipid peroxidation (malondialdehyde) assay was performed on the blood samples Briefly, testicular tissues were homogenized in KCl. Measurement of tissue and plasma malondialdehyde (MDA) levels were quantitatively carried out base on the MDA-TBA (thiobarbituric acid) complex formation (Katoh et al 2002). The animals were euthanized and the body and testicular weight were recorded. Testicular tissue samples were fixed in 10% formaldehyde solution and paraffin embedded tissue were prepared for histomorphometrical study and evaluation of microscopic indices of spermatogenesis. For morphometric assessment of seminiferous tubules, the slides were studied at 200× magnification. To get extra precise results, only the seminiferous tubules (STs) that sectioned transversely were studied and the shortest diameter of seminiferous tubules was considered for measurement. For every one animal, three microscopic slides from different parts of testicular tissue were prepared and 200 tubules were studied. For estimation of spermatogenesis in testicular tissue, three different indices were used. Tubular differentiation index (TDI), repopulation index (RI) and spermiogenesis index (SPI). To determine the tubular differentiation index, the number of seminiferous tubules with more than three layers of germinal cells derived from type A of spermatogonia was calculated. To find out the repopulation index, the ratio of active spermatogonia (with euchromatic nucleus) to inactive ones (with dense heterochromatic nucleus) was evaluated. The ratio of the number of seminiferous tubules with spermatozoids to the empty tubules, were calculated for spermiogenesis index (Miskowiak et al 1998 and Shetty et al 2000). The sperm analysis was performed on the epididymal tissue. For analyses of sperm, the cauda epididymis was separated from testis and cut into small pieces into one milliliter of Ham’s F10 culture medium. The epididymal sperm count was evaluated by hemocytometer with light microscope at ×400 magnification. Sperm motility was assessed with a phase contrast microscope at ×400 magnification. In average 10 microscopic fields were observed and the mean of counted sperms was considered as sperm motility for each rat (Wyrobek et al 1983). The results were analyzed using the GraphPad PRISM®</sup> software version 5.04 (GraphPad Software, Inc. USA). All data were reported as mean (SD). The comparison of the means between experimental groups was evaluated by one way-ANOVA method followed by Tukey’s multiple comparison tests. Differences were considered to be statistically significant if P< 0.05.

    Results and discussion

     The results showed that, the administration of methylphenidate and nicotine separately or simultaneously induce various structural and functional changes in testicular tissue compared to control group. There was no significant difference in body weight between experimental groups (P<0.05). The mean of testicular weight was reduced in all treated groups in comparison to control group. The ratio of testicular/body weight was decreased in treated groups compared to control group. The separate administration of methylphenidate and nicotine was led to elevation of the blood FSH levels (P=0.002) and decrement of the blood LH levels (P=0.008). Whereas, the coadministration of these compounds led to increase of the blood LH levels. The mean of the blood testosterone levels was increased in all treated groups in comparison to control group (P=0.0002). This elevation of the blood testosterone levels was observed in separately treated groups. The mean of the serum malondialdehyde was increased in treated groups compared to control group (P=0.25). The most elevation of serum malondialdehyde levels was observed in nicotine treated animals.  Histomorphometrical studies indicate various structural changes in testicular tissue such as increasing of the capsule thickness, reduction of tubular diameter, decrease of the height of germinal epithelium. All microscopic indices of spermatogenesis were reduced in treated groups in comparison to control group (P<0.0001). Accordingly, the lowest indices of spermatogenesis were observed in nicotine administrated group. All sperm analysis indices were reduced in treated groups in comparison to control group. The lowest mean of epididymal sperm population and sperm motility and viability was observed in nicotine treated group and methylphenidate+nicotine administrated group consequently (P<0.0001).

    Conclusion

     In conclusion, nicotine and methylphenidate induces testicular tissue damage with different mechanisms. However, the results of this study showed that the simultaneous administration of methylphenidate and nicotine could exacerbate the structural and functional alterations of testicular tissue. Moreover, the comparison of the results between treated groups expresses the greater and stronger portion of nicotine in inducing of alterations in testicular tissue structure and function.

    Keywords: Methylphenidate, Nicotine, Rat, Testicular Tissue
  • HA Hosseinzadeh, F Farivar*, J Bayat Koohsar, F Ghanbari Pages 103-115
    Introduction

    Cereal grains are fed to livestock to supply energy, and the major energy source of the most of  cereal grains is starch. Therefore, starch fermentation potential in the rumen is an important indicator of nutritional value of cereal grain in ruminants' nutrition. Due to lower loss of methane and heat, available energy supply for animal is greater for starch digestion in the small intestine than for starch fermented in either the rumen or large intestine. In order to obtain maximum starch digestion, corn and sorghum grain must be processed before using in livestock nutrition. There are several different methods for processing of cereal grain, which in turn have different impacts on the extend and place of digestion and fermentation of starch, based on the shape and structure of starch granules. Briefly, the aim of all processing methods is to optimize  the rumen fermentation, equilibrate degradability and digestion of starch in different parts of the digestive tract, minimize the rumen acidosis risk, and increase the amount of undegraded digestible starch delivery to the lower parts of the digestive tract. Corn grain is one of the most important feedstuffs in nutrition of high producing animals because it can provide high amounts of metabolizable enrgy to support high levels of milk or meat production. Several physical and chemical methods have been used and studied frequently. However, despite their effectiveness, using the chemical methods is doubtful because of their poisonous effects in animals and human. Most recently new biological processing methods have been proposed for optimizing  of corn grain starch degradability in rumen. So, it can affect the rumen environment and synthesis of microbial protein and determine the place and amount of starch digestion in the different parts of the digestive system. Therefore, the aim of this study was to investigate the effects of different physical or biological methods or methods containing combination of two or three methods of processing on chemical composition and rumen degradability of corn grain.

    Materials and methods

    This experiment was conducted in a completely randomized design with six treatments and three replicates. Experimental treatments were including: 1) unprocessing corn grain (control), 2) steam-flaked corn grain (3 to 5 minutes), 3) yeast (Saccharomyces cerevisiae)</em> treated (4% with the ratio of 1:2( and steam-flaked corn grain, 4) microwaved (850 W for 3 minutes) corn grain, 5) steam-flaked (3 to 5 minutes) and microwaved (850 W for 3 minutes) corn grain 6) yeast (Saccharomyces cerevisiae)</em> treated, steam-flaked and microwaved (850 W for 3 minutes) corn grain. In order to treatwith yeast, corn grains were mixed with a solution of 4%fermenter (Saccharomyces cerevisiae</em>) in a 2:1 ratio and then, incubated in 35°C for 24 hours. For gas production determination, the ruminal fluid was collected from rumen of three canolated mature Dalagh sheeps with an average weight of 45±5.2 kg before the morning feeding. Experimental animals were fed based on their maintenance requirements and had a free access to water during experimental period. Rumen fluid was immediately transferred to lab and purified using 4 leyer cotton textures and then mixed with artificial saliva with a 1:2 ratio in an anaerobic condition and finally, poured into glass vials along with 200 mg samples of each treatment. Glass vials incubated for 96 hours inside a benmarie bath with about 39°C. The gas production of samples was recorded at 2, 4, 6, 8, 12, 24, 36, 48, 72 and 96 hours of incubation. Experimental data were processed based on Ørskov and Mc Donalds non-linear equations and analyzed using SAS 9.1 statistical software.

    Results and discussion

    In general, the results of this experiment showed that the different processing methods had a significant effect on the corn grain potential gas production and gas production rate. The lowest gas production potential amounts were related to steam flaked and steam-flaked+ yeast   treated corn grain and the steam-flaked + yeast treated + microwave treatment had the highest amounts of gas production potential (481.5±3.48 and 479.1±3.87 vs. 523.3±6.69 ml/200 mg DM, respectively). Gas production rates of all treatments except for combination of three methods also were significantly higher than control and the highest amount was related with flaked corn grain (0.0771±0.0017 ml/h). Various processing methods had a significant effect on digestibility of organic matter of corn grain, the estimated metabolizable energy content and short chain fatty acids production of different treatments had no significant difference, however, the partitioning factor, final pH and ammonia concentration among different treatments were not significantly different. The digestibility of organic matter of combination method (yeast  treated +steam-flaking+ microwave irradiation) method and steam-flaked + microwave treatment and steam flaked treatments were significantly higher than control, however the organic matter digestibility in rest of treatments were not significantly different comparing with the control. Among the different processing methods, the treatment processed with combination method (yeast  treated +steam-flaking+ microwave irradiation) had the highest amounts of metabolizable energy, digestibility of organic matter and short chain fatty acids production (respectively 13.27 MJ/ Kg DM, 88.10 g/kg DM and 1.81 mmol/200 mg DM). Treatments containing microwave processing significantly reduced in vitro digestibility of dry matter and organic matter in comparison with the control treatment. The highest amount of estimated microbial protein production among the treatments were related to Steam-flaked+ yeast, Steam-flaked and microwave irradiation treatments (respectively 171.73, 170.23 and 170.11 mg/g DM).

    Conclusion

    The results of this study showed a significant difference in gas production parameters and in vitro </em>digestibility of corn grain among processing methods used in this experiment and the best response in influencing the nutritional value of corn grain for improving rumen fermentation and dry matter degradability can be attributed to microwave irradiation as well as the combination method.

    Keywords: Corn grain, Digestibility, Fermentation, Gas production, Microwave, Processingmethod, Saccharomyces cerevisiae
  • AA Sabetan Shirazeand, A Hassanabadi* Pages 117-129
    Introduction

     An increase in body mass per unit time is considered as a growth index (Nikkhah et al., 2010). If the growth rate can be predicted at different stages of development, it will be possible to determine the amount of nutrients needed and provide the most economical nutrition management plan (Naghos et al., 2013). A growth prediction method is based on the use of growth models. These models are mathematical functions and describe the pattern of body weight growth (Goliomytis et al., 2003). Poultry growth models are non-linear regression functions such as Gompertz, Richards, and logistic (Chaji at al., 2015). When the Gompertz model is used for data, it is expected that the chicks with lower initial growth rate, reach to maximum growth age sooner and exhibit greater exponential weight loss than those with higher growth rates (Novak et al., 2004). The point at which the growth rate changes (from increase to decrease) is called the turning point, and the age at which the maximum growth rate is achieved is called the age at the turning point. In fact, it can be said that the turning point divides the growth curve into two phases of increasing growth rate and decreasing growth rate (Marcato et al., 2008). The use of antibiotics in poultry nutrition as an antimicrobial growth promoter is undoubtedly beneficial for improving broilers growth performance and preventing diseases (Barton 2000). Despite the positive effects of antibiotics, researches have shown that the remains of antibiotics in poultry carcasses lead to the development of resistant bacteria strains in the human body and may prevent treatment of many diseases. So, prebiotics, probiotics, organic acids, medicinal herbs, spices, extracts and essential oils have been suggested as antibiotic substitutes in poultry nutrition (Azeke and Ekpo 2009). Antioxidant compounds in olive leaf as bioactive compounds, have high potential for enhancing animal health and performance. Adding natural antioxidants to feed is one of the most effective ways to delay lipid oxidation and improve growth performance parameters (Botsoglou et al., 2010). The aim of this study was to estimate the growth parameters of broiler chickens fed diets containing olive leaf powder and α-tocopheryl acetate using Gompertz model.

    Materials and methods

    A total of 300 one-day-old broiler chicks (mixed sex) of Cobb 500 strain with similar mean body weight were assigned to a completely randomized design with five treatments, three replicates and 20 chicks per replicate. The experiment lasted up to 42 days of age. The dried olive leaves in the shade, were milled using a mechanical mill with a diameter of 0.5 mm and were added to the experimental diets. The experimental diets consisted of: corn-soybean basal diet (negative control), basal diet supplemented with 250 mg/kg of α-tocopheryl acetate (positive control) and basal diet containing three levels of olive powder (2, 2.5 and 3%). All diets were homogenized in terms of metabolizable energy, crude protein, and other nutrients. Feed and water were supplied for ad libitum</em> consumption throughout the experiment. House temperature was initially set at 32. During the experiment, the lighting program consisted of 23L: 1D. At the end of each rearing period (starter, grower and finisher), the weight of all chicks in each unit of experiment was measured by digital scale at an accuracy of one gram. The number of mortality and weight of dead and culled chicks were recorded separately to adjust feed conversion ratio. Four hours prior to weighing, the birds were deprived from the feed for uniformity of digestive tract.Growth curves were plotted and fitted using the Gompertz model.

    Results and discussion

     The highest predicted mean body weight (BW) of the chicks during the first and second weeks of life were observed in negative control followed by 2.5% olive leaf powder treatment. But, this trend was changed from the third week; so that the highest predicted mean weight at this week was related to the positive control treatment and then in the 2.5% olive leaf powder treatment. In the fourth week, the highest predicted BW was related to 2.5 and then 3% of olive leaf powder treatments. In the 5th and 6th weeks of the age, positive control and 2.5% olive leaf powder showed the highest predicted BW in compare with other treatments. These changes in BW at different weeks of age are probably due to various factors such as tolerance of dietary fiber, growth, health and adaptation of the digestive tract with the applied treatments. The time of growth rate change (increase to decrease) for negative control treatment was at 33.9 days of age. At this time, the BW reached to 1432 g which was lower than the positive control and olive leaf powder treatments. This means that chicks need more time to reach their desired weight. Therefore, as the time of growth rate change in the negative control treatment arrived sooner, it had a lower final weight (4251.8 g). On the other hand, the time of growth rate change (increase to decrease) in positive control treatment was at 39.8 days, which was the longest time between the negative control and other treatments. In this case, the highest final BW was predicted in this group (6115.8 g). The time of change of growth rate for olive leaf powder treatments was predicted with slight differences compared to the positive control treatment and thus the differences in final predicted BW of these treatments were negligible. In a study which soybean meal was replaced with 10, 20, and 30% of raw or heated chickpeas, the results showed that the time of change of growth rate (increase to decrease) in the diet containing 30% crude chickpeas was predicted to be in later ages (47 day) than the other treatments and this was probably due to the presence of more anti-nutrients in this treatment (Amirabadi et al., 2011). In another study, levels of 0, 0.75, 1.5, 2.25, 3 and 3.75% sodium bentonite were supplemented to the diet. The time of growth rate change for the sodium bentonite treatments was increased compared to the control and it was concluded that more time is needed to reach the broilers to desired weight (Chaji et al., 2014). As the age of the bird increases, the growth rate increases, but this increase is limited and, after reaching to its maximum value, decreases, causing the growth curve to change. The turning point in the Gompertz equation is constant and is approximately 37% of maturity weight. In the study of Mignon-Grasteau et al. (1999), body weight of male birds at the turning point (1191 g) was estimated to be higher than body weight of female birds at this point (862 g). This trend has been observed in another study (Ricklefs 1985). It seems that, selection for growth performance in broilers has changed their growth curve.

    Conclusion

     The Gompertz growth function can be used as a part of the main statistical models to fit weight trait data in broilers. All olive leaf powder and positive control treatments increased the age to reach the turning point in compare with negative control. The effect of 2.5% olive leaf powder and positive control treatments on predicted mean body weight and improvement of growth rate parameters were more effective than other treatments. Also, 2.5 and 3% olive leaf powder and positive control treatments were more effective at reaching the turning point of growth curve and final body weight compared to other treatments. Due to the improvement or increase of more broilers traits by 2.5% olive leaf powder and positive control treatments, application of these two treatments is recommended.

    Keywords: Gompertz model, Growth model, Growthrate, Olive leaf powder