بررسی تاثیر جایگزینی بوته سیب‌زمینی بر عملکرد، قابلیت هضم، رفتار نشخوار، فراسنجه‌های خونی و شکمبه‌ای در میش‌های نژاد دالاق

زمینه مطالعاتی: یکی از راهکارهای موجود برای کاهش هزینه خوراک و در نتیجه هزینه تولید و قیمت محصول، استفاده از پسماندها و ضایعات کشاورزی قابل مصرف در جیره دام می‌باشد. هدف: این آزمایش به منظور بررسی اثرات سطوح مختلف بوته سیب زمینی بر عملکرد، قابلیت هضم، رفتار نشخوار، فراسنجه‌های خونی و شکمبه‌ای در میش‌های دالاق انجام شد. روش کار: بدین منظور از 18 راس میش نژاد دالاق با وزن 2.8±29 کیلوگرم استفاده شد. این آزمایش در قالب طرح کاملا تصادفی با 3 تیمار با درصدهای به‌ترتیب صفر، 20 و 40 درصد، جایگزینی ضایعات زراعی گیاه سیب‌زمینی به‌جای کاه و 6 تکرار بود. طول دوره 35 روز که 7 روز عادت‌پذیری و 28 روز دوره آزمایشی بود. جیره‌ها هر روز در دو نوبت، ساعت 8 صبح و ساعت 4 عصر خوراک پس از توزین در اختیار میش‌ها قرار می‌گرفت. هم‌چنین دام‎ها به‌صورت انفرادی در قفس‎های نگهداری دام قرار داشته و دسترسی آزاد به آب داشتند. اندازه‌گیری قابلیت هضم جیره به روش نشانگر داخلی خاکستر نامحلول در اسید در 3 روز آخر آزمایش و نمونه‌گیری از خون و مایع شکمبه در روز آخر آزمایش صورت پذیرفت. نتایج: با توجه به نتایج در بین تیمارهای آزمایشی از نظر افزایش وزن روزانه، وزن انتهای دوره و ضریب تبدیل اختلاف معنی‌داری مشاهده نشد. ولی در میزان مصرف خوراک بین تیمارهای آزمایشی اختلاف معنی‌داری مشاهده شد(0.05>p). هم‌چنین با اینکه در بین تیمارهای آزمایشی از نظر قابلیت‌هضم ماده خشک و الیاف نامحلول در شوینده خنثی اختلاف معنی‌داری مشاهده نشد، ولی بیشترین میزان قابلیت هضم متعلق به تیمار 40درصد بوته سیب زمینی بود. قابلیت هضم ماده آلی تحت تاثیر تیمارهای آزمایشی قرار گرفت(0.05>p). بین تیمارهای آزمایشی اختلاف معنی‌داری در رفتار خوردن، نشخوار و جویدن و استراحت وجود داشت(0.05>p)، به‌طوری‌که با افزایش مقدار بوته سیب‌زمینی، رفتار جویدن و نشخوار افزایش و میزان استراحت کاهش یافت. همچنین سطوح مختلف بوته سیب‌زمینی تاثیر معنی‌داری بر روی فراسنجه‌های خونی و شکمبه‌ای نداشت. نتیجه‌گیری نهایی: بر اساس نتایج حاصل از این آزمایش، می‌توان از بوته سیب‌زمینی تا 40درصد در تغذیه میش‌ها استفاده کرد.

evaluation of the effect of potato plant replacement on performance, digestibility, rumination behavior, blood and rumen parameters in dalagh ewes

introduction:increasing feed costs and the need for rations based on locally available feedstuffs has shifted nutritionists studies to unconventional feedstuffs for ruminants (lashkari et al. 2014). considerable quantities of crop residues by uncommon agro-industrial are generated every year in most de‌veloping countries in the tropics and subtropics. most of the mentioned crop residues are suitable for feeding livestock; however, because of lack of technical-know-how they are considered as waste and are disposed (salehi et al. 2014). using crops by-products led to some advantages such as participating in solving the problem of feed shortage, decrease the cost of feeding and alleviating the pollution problems (gaafar et al. 2014). by-products from the agro-food industry are of increasing importance, which can alleviate part of feed scarcity and thereby contribute to produce cost-effective animal products(grasser et al. 1995, valizadeh and sobhanirad, 2009). one of such alternative feedstuffs is the sweet potato vines which produced and left over after harvesting and can remain green during a long period and it is also a valuable forage for ruminants and other livestock species (giang et al, 2004). sweet potato is a tropical crop of a relatively short vegetative cycle the tubers of which are usually employed for human and animal consumption (zereu et al, 2014). the vines of potato are one of these promising by-products, which have great potential to replace fodder in ruminant diets. potatoes are one of the world’s most important food crops with an annual yield of 365 million tons worldwide (fao, 2013). nutritionally, sweet potato vines are a rich source of protein, fiber, vitamins, also had moderate to good quantities of all the essential amino acids, the dm content of fresh sweet potato vines was 11.9% and crude protein was 19.8% of dm (kebede et al. 2008). etela and kolio(2011) reported that sweet potato vines could be used as an alternative supple‌mentary feed for calves and small ruminants dry season and can be fed to dairy cattle as well (ashiono et al. 2006). correspondingly, there is a large quantity of potato vines produced annually(38–58 tons/ha), which could be used as animal feed (parfitt et al. 1982). however, considered as waste, potato vines are often removed and destroyed some days before tubers are harvested (nicholson et al. 1978). parfitt et al (1982) and dijkstra (1945) reported that potato vine silages can be used safely in the feeding of ruminants. most data in the literature on the using potatoes in animal feed-ing are generally limited to potato tuber or its other by-productsfrom agro-alimentary industry (rooke et al. 1997, eriksson and murphy. 2004, eriksson et al. 2009). this is due mainly to their glycoalkaloid content, which is toxic to mammals (morris and lee. 1984, walker. 1997). from limited data on ruminants, the toxic dose of α-solanine (one of the main components of potato glycoalkaloids) has been reported to be 225 mg/kg body weight for sheep (konig. 1953). although animals are considerably less susceptible to glycoalkaloids than humans (friedman et al. 1997), fresh potato vines with glycoalkaloid content of 60–300 mg/100 g dry matter may be harmful to ruminants when fed in large quantities (nicholson et al. 1978, parfitt et al. 1982, walker. 1997). however, processing such as air-drying or ensiling of potato vines may reduce their glycoalkaloid content (nicholson et al. 1978), potentially making them safe to be used in ruminant nutrition. while the nutritive value of potato tuber or its by-products from the agro-food industry, as animal feeds, has been documented (rooke et al. 1997, eriksson and murphy. 2004, eriksson et al. 2009). this experiment was performed to investigate the effects of different levels of potato plant on performance, digestibility, ruminant behavior, blood and rumen parameters in dalagh ewes.materials and methods: for this purpose, 18 dalagh ewes weighing 29± 2.8 kg were used. this experiment was carried out in a completely randomized design with 3 treatments and 6 replications with percentages of zero, 20 and 40%, respectively, replaced with potato crop waste instead of straw. the animals kept in a separate pen individually in animal research farm of gorgan university of agricultural sciences and natural resources, gorgan, iran. growth performance data were analyzed as a completely randomized design using the general linear model (glm) procedure of sas software (sas. 2003).the duration of the course was 35 days include 7 days adaptation period and 28 days experimental time the ewes were fed twice daily after weighing at 8 am and 4 pm. animals were also held in individual cages and had free access to water. diet digestibility was measured by acid-insoluble ash estimation as internal marker in the last 3 days of the experiment and blood and ruminal fluid samples were taken on the last day of the experiment. results and discussion: according to the results, there was no significant difference between the experimental treatments in terms of daily weight gain, final weight and conversion ratio (p <0.05). however, there was a significant difference in feed intake between experimental treatments. there was no significant difference between the experimental treatments in terms of dry matter and neutral detergent fiber digestibility (p <0.05). the highest digestibility belonged to treatment of 40% of potato plants. organic matter digestibility was affected by experimental treatments. there was a significant difference between the experimental treatments in eating, ruminating and chewing and resting behavior (p <0.05), so that with increasing the amount of potato plant, chewing and ruminating behavior increased and the resting amount decreased. also, different levels of potato plant had no significant effect on blood and ruminal parameters. experimental treatments could not significantly affect the ph of ruminal fluid.conclusion: considering that the results of this experiment show that the use of different levels of potato plant significantly increases the digestibility of organic matter and also improves the digestibility of dry matter and insoluble fibers in neutral detergent and it also significantly increased the dry matter intake. based on the results of this experiment, up to 40% of the potato plant can be used to feed the ewes.