اثر استفاده از منابع اوره آهسته رهش بر قابلیت هضم مواد مغذی و عملکرد رشد بره‌های پرواری تغذیه شده با جیره‌ی حاوی مواد علوفه ای کم کیفیت

نوع مقاله : مقاله پژوهشی

نویسندگان

دانشگاه علوم کشاورزی و منابع طبیعی خوزستان

10.22067/ijasr.2021.67175.0

چکیده

آزمایش حاضر با هدف بررسی اثرات استفاده از دو منبع اوره آهسته رهش و مقایسه‌ی آنها با جیره‌های فاقد اوره یا حاوی اوره معمولی در جیره‌ی برههای پرواری تغذیه شده با مواد علوفه ای کم کیفیت انجام شد. چهار تیمار آزمایشی شامل ۱) تیمار شاهد (فاقد اوره)، تیمار ۲) ۸/۱ درصد اوره آهسته‌رهش با نام تجاری اسلوژن، تیمار ۳) ۶۹/۱ درصد اوره آهسته‌رهش اپتی‌ژن و تیمار ۴) ۶/۱ درصد اوره معمولی بود. از 24 راس بره نر عربی با میانگین وزن 65/۲5 کیلوگرم و سن ۵ ماه استفاده شد. در مقایسه با گروه شاهد، استفاده از منابع اورهی آهسته رهش، تاثیری بر مقدار مصرف خوراک و درصد قابلیت هضم ماده خشک، الیاف نامحلول در شوینده خنثی، الیاف نامحلول در شوینده اسیدی و ماده آلی نداشت. قابلیت هضم پروتئین خام در تیمار شاهد بیشترین و در تیمار حاوی اوره معمولی کمترین مقدار بود (۰۵/۰P<) و شاهد با تیمار اسلوژن تفاوت نداشت. عملکرد رشد و پروار بره‌ها در کل دوره شامل وزن نهایی، میانگین افزایش وزن روزانه، کل افزایش وزن زنده‌، ضریب تبدیل و بازده خوراک تحت تاثیر تیمارهای آزمایشی قرار نگرفت. تیمارهای آزمایشی تاثیر معنی‌داری بر غلظت نیتروژن آمونیاکی، اسیدهای چرب فرار، جمعیت پروتوزوآ، pH شکمبه و فراسنجه‌های خونی نظیر غلظت گلوکز و نیتروژن اوره‌ای نداشت. جیره‌های حاوی اسلوژن و اوره معمولی سود مناسب‌تری نسبت به جیره شاهد داشتند. در کـل یافته‌های آزمـایش نشـان داد کـه در شرایط آزمایش حاضر، نتایج تیمارهای حاوی منابع نیتروژن غیر پروتئینی با منابع پروتئینی (جیره شاهد) قابل رقابت بود. از طرفی تفاوت آشکاری بین دو منبع حاوی اوره آهسته رهش با یکدیگر، با جیره‌ی شاهد و با اوره معمولی مشاهده نشد؛ اما اسلوژن عملکرد مناسب‌تری داشت. بنابراین، می‌توان از منابع نیتروژن غیر‌پروتئینی به عنوان جایگزینی برای بخشی از منابع پروتئین جیره‌‌ی بره‌های پروار استفاده کرد تا در نهایت هزینه تولید کاهش داده شود.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

The effect of slow-release urea sources on digestibility of nutrients and growth performance of fattening lambs fed rations containing low-quality forage

نویسندگان [English]

  • Morteza Chaji
  • Sadat ٍSafavi
Agricultural Sciences and Natural Resources University of Khuzestan
چکیده [English]

Introduction The main factors limiting the consumption of low-quality fodder is their low nitrogen. Therefore, it is often difficult to provide sufficient nutrients, especially energy and protein, to ruminants, which use these resources. The deficiency of nutrients in low-quality forage also affects the supply of nutrients for the growth of ruminal microorganisms and leads to a decrease in the ruminal digestion rate of these forages; this in turn reduces the feed intake and performance of the animal. Providing sufficient nitrogen to ruminal microorganisms is important to increase carbohydrate digestibility and microbial protein production. Therefore, to achieve optimal performance, it is important to provide appropriate nitrogen supplements in areas where a significant portion of the ruminant diet consists of low-quality forage. One of the characteristics of ruminants is the ability to use non-protein nitrogen sources for the synthesis of microbial protein in the rumen. Non-protein nitrogen, mainly urea, has been considered as a substitute for part of true protein due to its low price per unit of nitrogen compared to other true protein sources. The problem with using common urea is its rapid hydrolysis in the rumen and its conversion to ammonia. Most ruminal ammonia enters the bloodstream and causes destructive effects, from reduced feed intake and animal function to death from ammonia poisoning. The various slow-release urea compounds are made with the aim of continuously supplying nitrogen in the rumen. However, parts of the slow-release urea compounds may leave rumen without being converted to ammonia, reducing their performance for microbial protein production. Therefore, different sources of slow-release urea may have different effects. Processed or slow-release urea reduces ammonia poisoning and nitrogen wastage by reducing the rate of nitrogen release and improving feed costs. Therefore, the aim of this study was to investigate the effects of two sources of slow-release urea and compare them with diets without urea or containing common urea in the fattening lambs fed with low-quality forage, to ultimately reduce production costs.

 

Materials and Methods The present experiment was conducted at the Agricultural Sciences and Natural Resources University of Khuzestan. Four experimental treatments were including 1- control treatment (without urea) and three treatments containing three different sources of non-protein nitrogen including 2- 1.8% slow-releasing urea-slowgene 3- 1.69% slow-release urea-optigene 4- 1.6% common urea. Twenty-four Arabi male lambs with an average weight of 25.65 kg and 5 months old were used. Twenty-four male Arabic lambs with (mean weight of 25.65 ± 0.6 kg and 5± 1.0 months old were assigned to four experimental treatments with six replication. The nutrients digestibility was measured for seven days. The feed orts and feces were daily weighted and about 10% of them were kept in the plastic bags at -20˚C. At the end of this short period, the orts and feces samples were mixed and one representative sample obtained. The samples were oven-dried and grounded using a 1 mm mesh screen. The chemical composition of rations feeds orts and feces, including dry matter, neutral detergent fiber, acid detergent fiber, organic matter, and crude protein were measured with standard methods. The dry matter intake, initial weight, every two weeks weight, final weight was recorded, and feed conversion ratio and feed efficiency was calculated. Protozoa population, ammonia nitrogen, and pH of the rumen liquor were measured with standard procedure. The blood glucose, cholesterol, triglyceride, high-density lipoprotein (HDL), low-density lipoprotein (LDL), and BUN, were measured by the spectrophotometric procedure. The data were analyzed using the GLM procedure of SAS (version 9.4). The differences among treatments were evaluated using Duncan’s adjustment (P < 0.05).

 

Results and Discussion Compared to the control group, the use of slow-release urea sources had no effect on feed intake and digestibility of dry matter, NDF, ADF, and organic matter. Crude protein digestibility was highest in the control treatment and lowest in common urea treatment (P <0.05) and the control was not different from the slowgene treatment. Feed intake tended to increase in treatments containing urea (P = 0.07). Due to urea malnutrition, the use of urea sources may reduce feed intake, but in the present experiment this did not occur and even a slight increase was observed. This may be due to the presence of more molasses in urea-containing treatments; because molasses, due to its palatability, can increase the dry matter consumption of livestock. The growth performance of lambs in the whole period including final weight, average daily weight gain, total gain, feed conversion ratio, and feed efficiency were not affected by experimental treatments. The experimental treatments had no significant effect on the concentration of ruminal ammonia nitrogen, volatile fatty acids, protozoa population, pH, and blood parameters such as glucose and urea nitrogen. The diets containing common urea and slowgene had better benefits than control diets. In general, the findings of the present experiment showed that the results of treatments containing non-protein nitrogen sources were competitive with protein sources (control diet). In addition, there was no obvious difference between two sources of slow-release urea with each other, control, and common urea diets; but the slowgene worked better.

 

Conclusion Finally, according to the results of the present experiment, related to the concentration of ruminal parameters in the present experiment, it can be concluded that the use of non-protein nitrogen compounds such as normal urea or slow-release as a substitute for conventional protein sources such as soybean meal did not have negative effects on ruminal fermentation. so, due to the lower price of urea compounds compared to soybean meal and other real nitrogen sources, although no difference was observed between slow-release urea sources and common urea; it can be stated that production productivity has also improved economically, therefore, the use of urea sources for fattening periods is recommended.

کلیدواژه‌ها [English]

  • Economic value of diet
  • Slow-releas urea
  • Common urea
  • Volatile fatty acids

مقالات آماده انتشار، پذیرفته شده
انتشار آنلاین از تاریخ 08 آبان 1400
  • تاریخ دریافت: 17 آبان 1399
  • تاریخ بازنگری: 13 مرداد 1400
  • تاریخ پذیرش: 08 آبان 1400