نوع مقاله : مقاله پژوهشی
نویسندگان
1 گروه علوم دامی، دانشکده کشاورزی، پردیس کشاورزی و منابع طبیعی دانشگاه تهران، کرج، ایران
2 گروه علوم دامی، دانشکده کشاورزی، پردیس کشاورزی و منابع طبیعی دانشگاه تهران، کرج، ایران.
3 گروه علوم دامی، دانشکده کشاورزی، دانشگاه تبریز، تبریز، ایران
چکیده
کلیدواژه‌ها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
The purpose of this experiment was to evaluate the effects of supplementing the diet with different sources of urea on the rate of nitrogen release, fermentation kinetics, gas production parameters and nutrient disappearance rate in vitro. For this purpose, four experimental rations included 1) ration without urea source [control]; 2) diet containing 0.38% of DM of Uncotaed Urea; 3) ration containing 0.43% DM of SRU Lab; 4) The ration containing 0.86% DM of SRU Lab were formulated. Solubility of slow release urea (SRU Lab) in distilled water, phosphate buffer and McDougall buffer-ruminal fluid in 9 time series of 0, 60, 120, 180, 240, 300, 360, 420 and 480 minutes was determined using photometric method. Fermentation kinetics, 96-hour gas production parameters, and nutrient disappearance in the time series of 4, 8, 12, 24, 48 hours were estimated using the modified gas production test. The results showed that the solubility of urea in buffer solutions for SRU Lab was low and with a gentle slope compared to commercial optigen. But the solubility of urea in distilled water for SRU Lab was similar to Optigen. The results of 24-hour gas production for diets containing SRU Lab increased significantly (P≤0.001) compared to diets containing uncotaed urea. The digested organic matter for the control diet and the diet containing SRU Lab was significantly higher than the diet containing uncotaed urea (P≤0.05). The highest amount of PF was for diets containing 0.43% DM of SRU Lab and control diet. More than 50% of dry matter disappearance rate of experimental diets occurred after 12 hours of incubation. The 24-hour dry matter digestibility of diets containing SRU Lab was significantly higher than uncotaed urea (P≤0.01). Changes in CP digestibility in the first hours of incubation were significantly affected by diets containing SRU Lab, but changes in digestibility of NDF were not significant (P≥0.05). Percentage of digestibility of NDF and CP in the diet containing 0.43% of SRU Lab compared to the control diet was not significantly different over the times of incubation, but with the increase in the concentration of SRU Lab (fourth diet) the changes were significant and high (P≤0.001). In general, the SRU Lab product was slower than Optigen in terms of urea release rate in various buffer solutions. The addition of SRU Lab to the experimental diets did not have an adverse effect on the in vitro digestibility of nutrients, gas production trends and other measured parameters compared to uncotaed urea.
کلیدواژه‌ها [English]
Extended Abstract
Introduction
Dietary protein plays an important role in ruminant nutrition for providing amino acids and the nitrogen (N) source for microbial protein production in rumen. However, the dietary protein is an expensive feed ingredient, thus a strategy to reduce feed cost without negative impact on animal production needs to be considered. Using slow-release urea (SRU) as a rapidly digestible N source with fermentable energy to support microbial protein synthesis in rumen is the primary purpose. Therefore, the addition of SRU in the diet of ruminants is important not only for providing N sources, but also for the diversity and ruminal microbial population. Considering the importance of this object, the present study was carried out in order to evaluate the effects of supplementing the diet with different sources of urea on nitrogen release rate, fermentation kinetics, gas production parameters and nutrient disappearance rate in vitro.
Materials and methods
Four experimental rations included 1) ration without urea source [control]; 2) diet containing 0.38% of DM of Uncotaed Urea; 3) ration containing 0.43% DM of SRU Lab; 4) The ration containing 0.86% DM of SRU Lab were formulated. Solubility of slow release urea (SRU Lab) in buffer solutions of distilled water , phosphate buffer and McDougall buffer-ruminal fluid in 9 time series of 0, 60, 120, 180, 240, 300, 360, 420 and 480 minutes was determined using photometric method. Fermentation kinetics, 96-hour gas production parameters, and nutrient disappearance in the time series of 4, 8, 12, 24, 48 hours were estimated using the modified gas production test.
Results and discussion
The results showed that the solubility of urea in buffer solutions for SRU Lab was low, with a gentle slope compared to commercial Optigen. But the solubility of urea in distilled water for SRU Lab was similar to Optigen. The results of 24-hour gas production for diets containing SRU Lab increased significantly (P≤0.001) compared to diets containing uncotaed urea. The digested organic matter for the control diet and the diet containing SRU Lab was significantly higher than the diet containing uncotaed urea (P≤0.05). The highest amount of PF was for diets containing 0.43% DM of SRU Lab and control diet. More than 50% of dry matter disappearance rate of experimental diets occurred after 12 hours of incubation. The 24-hour dry matter digestibility of diets containing SRU Lab was significantly higher than uncotaed urea (P≤0.01). Changes in CP digestibility in the first hours of incubation were significantly affected by diets containing SRU Lab, but changes in digestibility of NDF were not significant (P≥0.05). Percentage of NDF digestibility and CP in the diet containing 0.43% of SRU Lab compared to the control diet was not significantly different, but with the increase in the concentration of SRU Lab (fourth diet) the changes were significant and high (P≤0.001).
Conclusions
In general, the SRU Lab product was slower than Optigen in terms of urea release rate in various buffer solutions. The addition of SRU Lab to the experimental diets did not have an adverse effect on the in vitro digestibility of nutrients, gas production trends and other measured parameters compared to uncotaed urea.
Kian Sadeghi and Mehdi Ganjkhanlou contributed to the project idea, design and execution of the study. Mostafa Sadeghi, Abolfazl Zali and Akbar Taghizadeh were in charge of laboratory analyses. Mehdi Ganjkhanlou and Mehdi Dehghan Bonadaki were responsible for writing the manuscript. Kian Sadeghi and Mehdi Ganjkhanlou was responsible for re-writing, scientific editing and finalizing the manuscript. Mostafa Sadeghi was responsible for Software, Validation the manuscript
The data that support the findings of this study are available from the corresponding authors, upon reasonable request.
The authors would like to thank all participants of the present study.
The study was approved by the Ethics Committee of the University of ABCD (Ethical code: IR.UT.RES.2024.500). The authors avoided data fabrication, falsification, plagiarism, and misconduct.
The author declares no conflict of interest.
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