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1 These meta-analysis results showed that slow-release urea supplementation exhibited a consistent improvement in the live weight gain and feed efficiency of beef cattle under several study factors. + 843 word(s) 843 2020-05-26 08:16:06 |
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Slow-Release Urea
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Slow-release urea (SRU) is a coated non-protein nitrogen (NPN) source for ruminant nutrition. This study applied a meta-analytic technique to quantify the effect of a commercial SRU (Optigen®, Alltech Inc., Nicholasville, KY, USA) on the performance of beef cattle. Data were extracted from 17 experiments and analysed using the random-effects model to estimate the effect size of SRU on dry matter intake (DMI), crude protein intake (CPI), live weight gain (LWG) and feed efficiency (FE) of growing and finishing beef cattle. There was no effect of feeding SRU on the overall DMI and CPI of beef cattle. Dietary inclusion of SRU improved the overall LWG (+92 g/d/head) and FE (+12 g LWG/kg DMI/head) of beef cattle. Notably, SRU supplementation in growing cattle exhibited a better improvement on LWG (130 vs. 60 g/d/head) and FE (18 vs. 8 g LWG/kg DMI/head) compared with finishing cattle. Moreover, SRU showed consistent improvements on the LWG and FE of beef cattle under several study factors. Simulation analysis indicated that positive effects of SRU on LWG and FE improved profitability through reduction in feed cost and reduced the emission intensity of beef production. These results indicate that SRU is a sustainable NPN solution in beef cattle production.

beef cattle rumen degradable protein urea growth performance feed efficiency
Subjects: Zoology
Contributors MDPI registered users' name will be linked to their SciProfiles pages. To register with us, please refer to : , , ,
View Times: 942
Revisions: 3 times (View History)
Update Date: 30 Oct 2020
Table of Contents

    1. Introduction

    The livestock industry is confronted with the challenges of using limited land and water resources to meet the growing demand for animal protein in an environmentally sustainable way. Ruminants are important components of a sustainable livestock sector because of their ability to digest and convert human inedible biomass to high-quality edible protein (meat and milk), primarily due to the intricate consortium of microbes residing in their rumen [1]. Crude protein (CP) in ruminant nutrition comprises of the rumen degradable protein (RDP) and rumen undegradable protein (RUP) fractions. Dietary RDP is degraded in the rumen to produce ammonia, which is synchronised with fermentable energy for rumen microbial growth and protein synthesis [2]. Microbial crude protein (MCP) and RUP reaching the small intestine constitute the metabolizable protein absorbed to meet the protein requirement of ruminants [3]. Microbial protein accounts for 50% to 80% of the total absorbable protein, highlighting its significance as a crucial component of metabolizable protein [2][4].

    2. Specifics

    Dietary RDP is derived from nitrogenous compounds, which comprise of both non-protein nitrogen (NPN) sources and soluble true protein from plant and animal protein sources. The NPN sources are typically less expensive than true protein sources and feed-grade urea is often the most available NPN source used in ruminant diets. However, dietary utilisation of urea is limited due to its rapid hydrolysis to ammonia, exceeding the rate of carbohydrate fermentation in the rumen [2]. The lack of synchronisation between rumen ammonia production and fermentable energy availability negatively affect the efficiency of MCP yield. Consequently, this condition reduces the amount of MCP outflow, which may decrease the availability of metabolizable protein for production purposes in ruminants [5]. The rapid ruminal hydrolysis of urea may elevate blood ammonia concentration and increase the risk of ammonia toxicity and related negative health impacts in ruminants [6]. Furthermore, rapid ruminal hydrolysis of NPN sources, including urea, could reduce nitrogen (N) utilisation efficiency and thus increase N excretion and ammonia volatilisation from manure resulting in negative environmental impacts [5].

    Over the last three decades, coating technology has been utilised to produce slow-release urea (SRU) products that degrade less rapidly in the rumen with potential claims of improved synchronisation of ruminal ammonia with energy digestion for microbial protein synthesis. These products are usually available for feeding to all ruminant species (cattle, buffalo, sheep and goat). Cherdthong and Wanapat [2] provided a narrative review of scientific literature that highlighted the potential efficacy of SRU in enhancing the efficiency of rumen N capture, microbial protein synthesis, fibre digestion and improved ruminant production. Moreover, SRU could be an eco-friendly alternative for replacing a portion of vegetable protein sources and the slow formation of ammonia in the rumen could ensure no negative impacts on N excretion [7][8]. However, narrative reviews lack methodological approach and they are subjective to the author’s interpretation of previous research, which may lead to biased conclusions [9].

    It is often difficult to draw quantitative conclusions from the comparison of different research outcomes due to the diversity in study designs, experimental bias, poor statistical analysis and lack of application to a specific livestock production system [9]. These challenges can be overcome by the use of a meta-analysis, which is a rigorous statistical procedure for analysing a combined dataset obtained from multiple research studies [9][10]. A multitude of studies has utilised meta-analysis to provide quantitative and research-based evidence on the efficacy of nutritional products or interventions in beef cattle production [10][11][12]. To our knowledge, there is no published meta-analysis on the effect of SRU supplementation in beef cattle production. Thus, the objective of this study was to apply a meta-analytic technique to quantify the effects of SRU on the performance of growing and finishing beef cattle. In addition, the meta-analysis results were used to conduct a simulation analysis to evaluate the potential effect of SRU on the economic and environmental impacts of beef production. 


    1. Loor, J.J.; Elolimy, A.A.; McCann, J.C. Dietary impacts on rumen microbiota in beef and dairy production. Anim. Front. 2016, 6, 22–29. [Google Scholar] [CrossRef]
    2. Cherdthong, A.; Wanapat, M. Development of urea products as rumen slow-release feed for ruminant production: A review. Aust. J. Basic Appl. Sci. 2010, 4, 2232–2241. [Google Scholar]
    3. Cutrignelli, M.I.; Infascelli, F.; Tudisco, R.; Calabrò, S.; Piccolo, V. Protein Sources in Ruminant Nutrition; INTECH Open Access Publisher: London, UK, 2011. [Google Scholar]
    4. Lu, Z.; Tian, Y.; Shen, H. Dietary energy level promotes rumen microbial protein synthesis by improving the energy productivity of the ruminal microbiome. Front. Microbiol. 2019, 10, 847. [Google Scholar] [CrossRef] [PubMed]
    5. Calsamiglia, S.; Ferret, A.; Reynolds, C.; Kristensen, N.B.; Van Vuuren, A. Strategies for optimizing nitrogen use by ruminants. Animal 2010, 4, 1184–1196. [Google Scholar] [CrossRef]
    6. Cope, R.B. Nonprotein nitrogen (urea) and hyperammonemia. In Veterinary Toxicology; Elsevier: Cambridge, MA, USA, 2018; pp. 1093–1097. [Google Scholar]
    7. Sinclair, L.; Blake, C.; Griffin, P.; Jones, G. The partial replacement of soybean meal and rapeseed meal with feed grade urea or a slow-release urea and its effect on the performance, metabolism and digestibility in dairy cows. Animal 2012, 6, 920–927. [Google Scholar] [CrossRef]
    8. Reddy, P.R.K.; Kumar, D.S.; Rao, E.R.; Seshiah, C.V.; Sateesh, K.; Reddy, Y.P.K.; Hyder, I. Assessment of eco-sustainability vis-à-vis zoo-technical attributes of soybean meal (SBM) replacement with varying levels of coated urea in Nellore sheep (Ovis aries). PLoS ONE 2019, 14, 1–20. [Google Scholar]
    9. Sauvant, D.; Schmidely, P.; Daudin, J.-J.; St-Pierre, N.R. Meta-analyses of experimental data in animal nutrition. Animal 2008, 2, 1203–1214. [Google Scholar] [CrossRef]
    10. Lean, I.J.; Thompson, J.M.; Dunshea, F.R. A meta-analysis of zilpaterol and ractopamine effects on feedlot performance, carcass traits and shear strength of meat in cattle. PLoS ONE 2014, 9, 1–28. [Google Scholar] [CrossRef]
    11. Wagner, J.; Engle, T.; Belknap, C.; Dorton, K. Meta-analysis examining the effects of Saccharomyces cerevisiae fermentation products on feedlot performance and carcass traits. PAS 2016, 32, 172–182. [Google Scholar]
    12. Duffield, T.; Merrill, J.; Bagg, R. Meta-analysis of the effects of monensin in beef cattle on feed efficiency, body weight gain, and dry matter intake. J. Anim. Sci. 2012, 90, 4583–4592.
    Subjects: Zoology
    Contributors MDPI registered users' name will be linked to their SciProfiles pages. To register with us, please refer to : , , ,
    View Times: 942
    Revisions: 3 times (View History)
    Update Date: 30 Oct 2020
    Table of Contents


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      Salami, S.A.; Moran, C.A.; Warren, H.E.; Taylor-Pickard, J. Slow-Release Urea. Encyclopedia. Available online: (accessed on 01 October 2023).
      Salami SA, Moran CA, Warren HE, Taylor-Pickard J. Slow-Release Urea. Encyclopedia. Available at: Accessed October 01, 2023.
      Salami, Saheed A., Colm A. Moran, Helen E. Warren, Jules Taylor-Pickard. "Slow-Release Urea" Encyclopedia, (accessed October 01, 2023).
      Salami, S.A., Moran, C.A., Warren, H.E., & Taylor-Pickard, J.(2020, June 01). Slow-Release Urea. In Encyclopedia.
      Salami, Saheed A., et al. "Slow-Release Urea." Encyclopedia. Web. 01 June, 2020.