تاثیر سطوح مختلف عصاره آویشن بر ابقاء نیتروژن، تولید گاز، جمعیت میکروبی، تعداد پروتوزوآ و برخی فراسنجه‌های خون در بره‌ها و بزغاله‌های پرواری

هدف از این پژوهش بررسی اثر سطوح مختلف عصاره آویشن بر ابقاء نیتروژن، تولید گاز، جمعیت میکروبی، تعداد پروتوزوآ و برخی فراسنجه‌های خون در بره‌ها و بزغاله‌های پرواری بود. برای این منظور 15 راس بزغاله سه ماهه نژاد بومی استان گلستان با میانگین وزن اولیه 1.2± 3.17 کیلو‌گرم و 15 راس بره سه ماهه نژاد دالاق با میانگین وزن اولیه 5.1± 4.21 کیلو‌گرم به‌طور تصادفی با یکی از 3 جیره: 1) شاهد؛ بدون عصاره آویشن، 2) مکمل شده با 250 میلی‌لیتر عصاره آویشن، 3) مکمل شده با 500 میلی‌لیتر عصاره آویشن به مدت 84 روز و به‌صورت انفرادی تغذیه شدند. نتایج آزمایش نشان داد اختلاف معنی داری در نیتروژن مصرفی از طریق استفاده از عصاره، در بین تیمار‌های مختلف وجود نداشت. اما نیتروژن دفعی مدفوع و ادرار در تیمارهای دریافت کننده 250 میلی‌لیتر عصاره آویشن کمتر و نیتروژن ابقاء شده و هضم شده بیشتر از تیمار‌های دیگر بود (0.01

effect of different levels of thyme extract on nitrogen retention, gas production, microbial population, protozoa and some blood parameters in fattening lambs and kids

low feed efficiency is one of the problems in the rumen of ruminants, which results in reduced growth and production of livestock and, most importantly, environmental pollution due to the release of methane and nitrogenous compounds . changes in ruminal fermentation can be made to improve fermentation efficiency and substrate utilization and optimize feed nutritional value . antibiotics have been successful in reducing energy loss (from methane) and protein (from ammonia nitrogen) in the rumen . however, today, due to general concerns about the remains of these compounds in milk and meat and thus increasing the bacterial resistance to them has caused the use of materials in feed as additive in some countries . therefore, the tendency to find alternatives with natural origin for antibiotics has increased over recent years .plant secondary metabolites are among the natural alternatives that have been studied in recent years that have antimicrobial properties.essential oils, also known as volatile or ethereal oils, occur in edible, medicinal, andherbal plants. as these aromatic compounds are largely volatile, they are commonly extracted by steam distillation or solvent extraction . essential oils can be extracted from many parts of a plant, including the leaves, flowers, stem, seeds, roots and bark. however, the composition of the eo can vary among different parts of the same plant . for instance, eo obtained from the seeds of coriander (coriandrum sativum l.) have a different composition from the eo of cilantro, which is obtained from the immature leaves of the same plant . chemical differences among eo extracted from individual plants, or different varieties of plants, also exist and are attributed to genetically determined properties, age of the plant, and the environment in which the plant grows . one of the plant essential oils that has a great potential for use in ruminant diets is the essential oil of thyme (thymus vulgaris). thyme extract contains 0.6-8.8% (usually 1%) of essential oil, most of which are phenols (20-20%) and monoterpene hydrocarbons (such as p cymen and γ terpinen) and alcohols (such as linalool and terpinen α). they show that sometimes these compounds make up 80% of the extract compounds. naturally, thymol is also a major phenolic component in thyme and carvacrol is a sub – element (leung and foster., 1996). although goats and sheep have often been fed and managed in a similar manner (goats being browsers and sheep being grazers), they are different, especially in their digestive capability, because of differences in the morphology of digestive system, including the mouth structure and gut, which may influence their ability to ingest and digest feed materials . available information on efficiency of feed utilization between goat and sheep has been inconsistent with several studies reported sheep had higher growth performance than goats . in a recent in vitro study, candyrine et al (2016) reported that goats had better rumen fermentation characteristics, including higher volatile fatty acids (vfas) production and higher population of cellulolytic bacteria compared to sheep, suggesting that goats could be more superior in digesting feed materials.the results of studies performed on lambs and goats ) that have examined the effects of thyme extract or its major compounds (thymol and carvacrol) are very contradictory.