Urea Inclusion Research Articles

Environmental Benefits of Palm Oil Biodiesel Enhancement: Urea Complexation Optimization via RSM

Indonesian commercial biodiesel products are unstable due to polyunsaturated fatty acids (PUFA). The urea inclusion compound (UIC) method is used during the fractionation process on PUFA to enhance its quality. This study aims to determine the effect of temperature, fatty acid ester metal (FAME)/methanol ratio, and crystallization time on increasing the concentration of PUFA concentrates and to produce high-performance biodiesel products with an iodine indicator <30–40 g I2/100 g. According to the most recent research, the UCF phase product is obtained at a combination of temperature and crystallization time of 20 °C and 4 h, respectively. It has an iodine number of 44.01 and an oxidation stability of 18.61 h, which is close to the criteria for high-performance biodiesel (<30 –40 g I2/100 g). Meanwhile, the results of this study obtained a UCF phase product that has an iodine number of 34.18 and yields 86.57% is obtained at a combination of temperature and crystallization time of 20 °C and 6 hr and FAME-methanol ratio of 6, respectively, which is close to the criteria for high-performance biodiesel (<30 –40 g I2/100 g). The longer complexation time and temperature significantly affected the FAME fractionation of the UCF phase.

A new integrated strategy for high purity pinolenic acid production from Pinus koraiensis Sieb. et Zucc seed oil and evaluation of its hypolipidemic activity in vivo

Pinolenic acid is a polyunsaturated fatty acid present only in Pinus koraiensis Sieb. et Zucc seed oil. In order to solve the structural instability problem of polyunsaturated fatty acids, pinolenic acid of P. koraiensis seed oil was effectively isolated and purified by the integrated strategy of ethyl esterification followed by urea inclusion for the first time. Under the optimal conditions after the Box-Benhnken Design experimental, ethyl pinolenate with high purity 94.95% could be obtained, and the average content of PNAEE can still reach 86.18%. Then ethyl pinolenate was characterized by Gas chromatography-mass spectrometry, Fourier transform infrared, and Nuclear magnetic resonance spectra, results showed that ethyl pinolenate was successfully prepared. In addition, the hypolipidemic activity of ethyl pinolenate had been tested in vivo and showed that ethyl pinolenate had obvious hypolipidemic activity. The new strategy for high purity ethyl pinolenate production from P. koraiensis seed oil possesses great potential in food healthy field in the future.

Non-protein nitrogen supplementation on in vitro fermentation profile, methane production, and microbial nitrogen synthesis in a corn silage-based substrate.

Non-protein nitrogen (NPN) supplements improve animal performance in backgrounding diets. However, there is scarce information regarding the effect of different NPN sources and combinations on ruminal fermentation profile. The current study aimed to evaluate the effect of different NPN sources and their combinations on in vitro fermentation, microbial N synthesis, and methane (CH4) production in a backgrounding diet. Incubations were conducted on three separate days for 24h using corn silage and cotton gin byproduct (70% and 30% of DM, respectively) as substrate. Treatments were control (without NPN), urea, and five different proportions of urea-biuret and nitrate (100:0, 75:25, 50:50, 25:75, and 0:100). Each treatment, except control, was formulated to be isonitrogenous and equivalent to 1% urea inclusion. Ruminal fluid was collected from two ruminally cannulated Angus crossbred steers fed ad libitum corn silage and cotton gin byproduct plus 100g of a urea-biuret-nitrate mixture. The concentration of volatile fatty acids (VFAs) and ammonia nitrogen (NH3-N) were determined at 12 and 24h of incubation. Final pH, in vitro dry and organic matter digestibility, total gas production, and concentration of CH4 were determined at 24h. The supplementation of NPN increased (P < 0.05) the concentration of NH3-N at 12 and 24h. Although NPN supplementation increased (P < 0.05) the concentration of total VFA and acetate at 12h, treatments did not differ (P > 0.05) at 24h. Supplementation of NPN increased (P < 0.05) the proportion of acetate at 12 and 24h but tended to reduce (P = 0.054) the proportion of propionate only at 12h. Digestibility and pH were not different (P > 0.05) among treatments. Increasing nitrates in the NPN supplement increased (P < 0.05) the proportion of acetate and reduced (P < 0.05) the proportion of butyrate at 12 and 24h. The supplementation of NPN increased (P < 0.05) microbial N synthesis. Furthermore, increasing nitrate proportion in the NPN supplement increased (P < 0.05) the microbial N synthesis and efficiency of N use. Supplementation of NPN did not modify (P > 0.05) total gas or CH4 production. However, increasing nitrate proportion in the NPN supplement linearly reduced (P < 0.05) CH4 production. Supplementation of NPN increased NH3-N concentration and microbial N while increasing the inclusion of nitrate decreased the production of CH4 and increased the microbial N synthesis in a corn silage-based substrate under in vitro conditions.

Front Cover: Determination of the Handedness of Urea Inclusion Compounds (Chem. Eur. J. 59/2023)

Front Cover: Determination of the Handedness of Urea Inclusion Compounds (Chem. Eur. J. 59/2023)

Determination of the Handedness of Urea Inclusion Compounds.

Invited for the cover of this issue is the group of Bo Wang at Biogen. The image depicts the sectored chiral domains of urea inclusion compounds. Read the full text of the article at 10.1002/chem.202302217.

Determination of the handedness of urea inclusion compounds.

Since the discovery of urea inclusion compounds (UICs) in 1940, the handedness of this chiral helical system has not been established experimentally. By studying three UIC systems containing light-atoms only, the optical rotations were first measured, and the absolute structures of the enantiomorphic domains of three UICs were determined via single crystal X-ray diffraction (SCXRD). The correlation between the optical rotation and the absolute configuration of the UICs was finally established, showcasing the power of absolute structure determination via SCXRD, which is essential in structural chemistry and pharmaceutical research.

Dose response to postruminal urea in lactating dairy cattle

Inclusion of urea in dairy cattle diets is often limited by negative effects of high levels of feed urea on dry matter intake (DMI) and efficiency of rumen N utilization. We hypothesized that supplying urea postruminally would mitigate these limitations and allow greater inclusion of urea in dairy cattle diets. Four rumen-fistulated Holstein-Friesian dairy cows (7 ± 2.1 lactations, 110 ± 30.8 d in milk; mean ± standard deviation) were randomly assigned to a 4 × 4 Latin square design to examine DMI, milk production and composition, digestibility, rumen fermentation, N balance, and plasma constituents in response to 4 levels of urea continuously infused into the abomasum (0, 163, 325, and 488 g/d). Urea doses were targeted to linearly increase the crude protein (CP) content of total DMI (diet plus infusion) by 0%, 2%, 4%, and 6% and equated to 0%, 0.7%, 1.4%, and 2.1% of expected DMI, respectively. Each 28-d infusion period consisted of a 7-d dose step-up period, 14 d of adaptation, and a 7-d measurement period. The diet was fed ad libitum as a total mixed ration [10.9% CP, 42.5% corn silage, 3.5% grass hay, 3.5% wheat straw, and 50.5% concentrate (dry matter basis)] and was formulated to meet 100%, 82%, and 53% of net energy, metabolizable protein, and rumen-degradable protein requirements, respectively. Linear, quadratic, and cubic effects of urea dose were assessed using polynomial regression assuming the fixed effect of treatment and random effects of period and cow. Dry matter intake and energy-corrected milk yield responded quadratically to urea dose, and milk urea content increased linearly with increasing urea dose. Apparent total-tract digestibility of CP increased linearly with increasing urea dose and ruminal NH3-N concentration responded quadratically to urea dose. Mean total VFA concentration was not affected by urea dose. The proportion of N intake excreted in feces decreased linearly and that excreted in urine increased linearly in response to increasing urea dose. The proportion of N intake excreted in milk increased linearly with increasing urea dose. Urinary urea excretion increased linearly with increasing urea dose. Microbial N flow responded cubically to urea dose, but the efficiency of microbial protein synthesis was not affected. Plasma urea concentration increased linearly with increasing urea dose. Regression analysis estimated that when supplemented on top of a low-CP diet, 179 g/d of postruminal urea would maximize DMI at 23.4 kg/d, corresponding to a dietary urea inclusion level of 0.8% of DMI, which is in line with the current recommendations for urea inclusion in dairy cattle diets. Overall, these results indicate that postruminal delivery of urea does not mitigate DMI depression as urea dose increases.

Extraction of nervonic acid from Acer truncatum oil by urea inclusion

Extraction of nervonic acid from Acer truncatum oil by urea inclusion

Production of high-performance biodiesel with a high oxidation stability through a fractionation method using urea

The presence of polyunsaturated fatty acids (PUFA) in Indonesian commercial biodiesel products causes instability. The fractionation process is carried out on PUFA by applying the urea inclusion compound (UIC) method to improve its quality. This study aims to determine the effect of temperature and crystallization time on increasing the concentration of PUFA concentrates and to produce high-performance biodiesel products with an iodine indicator <30–40 g I2/100 g. The UCF phase product which has an iodine number of 44.01 and an oxidation stability of 18.61 h is obtained at a combination of temperature and crystallization time of 20 °C and 4 h, respectively, which is close to the criteria for high performance biodiesel (<30 –40 g I2/100 g). The longer complexation time and temperature significantly affected the FAME fractionation of the UCF phase.

Enrichment of high‐purity nervonic acid ethyl ester from Acer truncatumBunge seed oil by combination method of urea inclusion and molecular distillation

AbstractAcer truncatum Bunge is a type of maple that is unique to China. Its fruit setting rate and seed oil content are both high. The oil is mainly composed of C16–C24 fatty acids and contains 5%–7% nervonic acid (NA). NA and its derivatives can delay ageing and prevent and treat disorders such as senile dementia and Alzheimer's disease. The content of NA ethyl ester prepared by the seed oil of A. truncatum Bunge is 5.84%. We report a new process for the enrichment of NA ethyl ester by urea inclusion (UI) and molecular distillation (MD), with the aim of obtaining highly pure NA ethyl ester. First, based on the difference in fatty acid ethyl ester saturation and carbon chain length, unwanted compounds such as oleic acid ethyl ester, linoleic acid ethyl ester, and sterol were removed by one‐stage UI, the content of NA ethyl ester was increased to 18.69%. The oil in the UI compound was used as a feed, and differences in the mean molecular free paths between the components were exploited to separate the C16–C20 fatty acid ethyl esters (FAEEs) by two‐stage MD. The total content of C16–C20 FAEEs decreased to 3.69% and the purity of NA ethyl ester increased to 47.47%. A new purification process of UI‐MD‐UI was established and NA ethyl ester could be purified to 91.8%. The combination of MD and UI has an important reference value for the industrialization of producing high‐purity NA ethyl ester.

Two approaches for bio-lubricant production from soybean oil with organosilicon

With the rapid increasing of environmental pollution concerns and declining petroleum assets, bio-based lubricants industry has aroused increasingly more attention and study. The present paper proposed two methods (a two-step process and a direct hydrosiylation process) for the production of biolubricant from soybean oil with organosilicon. At first, soybean oil was subjected to transesterification with potassium hydroxide under certain conditions. Then, the transesterified soybean oil was undergone urea inclusion for obtaining unsaturated fatty acid methyl esters (UFAMEs). After urea inclusion, the content of UFAMEs was increased to 88.1%. Next, the chemical modification of UFAMEs by the two-step process (epoxidation and ring-opening reaction) and the direct hydrosiylation process (with triethylsilane in present of catalyst) were systematically studied, respectively. With the optimal conditions, the conversions of UFAMEs in the two-step process and direct hydrosiylation process were 86.1% and 82.1%, respectively. In addition, the structure characteristics of material and products were determined by Fourier-transformed infrared (FTIR) spectroscope and 29Si-Nuclear magnetic resonance (29Si-NMR) spectrascopy. The lubrication performances of the two products were proved to be much better than soybean oil according to industry standards. Therefore, both of the two processes appeared to be feasible for bio-lubricant production.

Effects of Post-Ruminal Urea Supplementation during the Seasonal Period on Performance and Rumen Microbiome of Rearing Grazing Nellore Cattle.

The objective was to evaluate the effects of urea with post-ruminal absorption in the supplementation of growing Nellore cattle reared on pasture during a seasonal period. For the study, two experiments were conducted. In experiment 1, rumen and blood parameters were evaluated using eight rumen-cannulated Nellore bulls with initial body weight (BW) of 763 ± 44 kg, distributed in a double Latin square 4 × 4. In experiment 2, 120 Nellore steers with initial BW of 380 ± 35 kg were used for performance evaluation, distributed in a randomized block design (blocking factor or initial BW). The evaluated treatments were 1: (TP-U) (control) = supplement with 24% crude protein (CP) containing urea as a source of non-protein nitrogen (NPN; 3%) and soybean meal, 2: (TP-PRU) = 24% CP supplement containing post-ruminal urea (PRU; 3.6%) and soybean meal; 3: (NPN-U-PRU) = 24% CP supplement containing urea + post-ruminal urea (U = 3% and PRU = 3.9%), without soybean meal; 4: (NPN-PRU) = supplement with 24% CP containing post-ruminal urea (7.5%), without soybean meal. The supplement was offered at 3 g/kg BW per animal, daily, once a day. All animals were kept on Urochloa brizantha cv. Marandu pasture. Statistical analyses were performed using the SAS PROC MIXED, and the data were evaluated by the following contrasts: C1 = TP-U/TP-PRU vs. NPN-U-PRU/NPN-PRU (Soybean meal replacement by NPN); C2 = TP-U vs. TP-PRU (conventional urea vs. post-immune urea); C3 = NPN-U-PRU vs. NPN-PRU (low and high post-ruminal urea-PRU level). The digestibility of dry matter, organic matter, and NDF was lower when soybean meal was replaced by non-protein nitrogen, also being different between the levels of post-ruminal urea used in the supplement. Ruminal pH was different when soybean meal was replaced by NPN (p = 0.003). Total concentration of short-chain fatty acids, concentrations of isobutyrate (p = 0.003), valerate (p = 0.001), and isovalerate (p = 0.001) were different, and blood urea was different when soybean meal was replaced by NPN (p = 0.006). Simpson's diversity index was higher in the rumen of animals supplemented with TP-U than in those supplemented with TP-PRU (p = 0.05). A total of 27 phyla, 234 families, and 488 genera were identified. Nitrospirota and Gemmatimonadota phyla were detected just in the rumen of steers supplemented with TP-PRU. The performance (final BW, weight gain and gain per area) of the animals was different, being higher (p = 0.04) in animals supplemented with soybean meal, compared to NPN. The removal of soybean meal from the supplement and its replacement with either conventional urea plus post-ruminal urea or only post-ruminal urea compromises the performance of the animals. The lower the post-ruminal urea inclusion level, the lower the apparent digestibility of dry matter, organic matter, and NDF, when compared to animals supplemented with higher levels.

Efficient rapid fractionation of fatty acid methyl esters (FAMEs) through evaporative urea inclusion

FAMEs work as an alternative to petroleum-based diesel fuels for its low carbon footprint. However, FAMEs' qualities are constrained by the sources' fatty acid profiles. Fractionation of FAMEs can significantly change biodiesel's qualities. Compared to other fractionation methods, evaporative urea inclusion fractionation can rapidly and effectively separate the saturated FAMEs. In addition, FTIR analysis indicated the possible conjugation of host structures by unstable hydrogen bonding and oxygen bonding. Crystallite sizes and strain of urea inclusion compounds (UICs) were calculated from the XRD spectrum, influenced by FAMEs' structures and operation processes. Only the ratios of urea to FAMEs can significantly affect compositions in evaporative urea inclusion fractionation. However, UICs formation rates were influenced by all operation conditions, such as temperatures, pressures, and ratios of urea to FAMEs to solvent. The products were evaluated by the low-temperature performance, cetane number, oxidation stability, energy density, and emissions. Urea inclusion fractionation can significantly improve the low-temperature performance, the major constraint for enlarging the utilization. However, the decreased cetane number and oxidation stability indicated the possible need for antioxidants and cetane improvers after urea inclusion fractionation. Moreover, the unsaturated enriched products from urea inclusion fractionation can provide the feedstock to synthesize biochemical or biomaterials, such as carboxylic acids, polyesters, and biolubricants.

Enrichment of nervonic acid in Acer truncatum Bunge oil by combination of two-stage molecular distillation, one-stage urea complexation and five-stage solvent crystallization

Nervonic acid is the world's first and only potent substance that can repair damaged nerve fibers and promote nerve cell regeneration with high nutritional value. The wide variety of fatty acids in plant oils and fats with similar structures makes the large-scale separation and purification of high-purity nervonic acid very difficult. A new combined process of molecular distillation, urea inclusion and solvent crystallization was established to prepare high-purity nervonic acid with the mixed fatty acids obtained after saponification and acidification of Acer truncatum Bunge oil as raw materials. First, according to the difference in the mean free path of fatty acids, molecular distillation was used to separate and remove C16 saturated fatty acid of palmitic acid and four C18–C20 fatty acids of stearic, oleic, linoleic, and linolenic acids. The content of C16–C20 fatty acids decreased from 72.92% to 19.22% after two-stage molecular distillation processes, in which the contents of saturated fatty acid of palmitic acid decreased to about 0.5%. Then, according to the difference in carbon chain length and saturation of fatty acid, the contents of C22–C24 saturated fatty acids of tetracosanoic and docosanoic acids decreased to 0.21% and 0.07% by urea inclusion with urea/free fatty acid preparation by saponification (SPOMFs) ratio as 0.6. In addition, all saturated fatty acids were basically separated. Finally, according to the difference in the solubility of fatty acids in solvents, the C18–C20 unsaturated fatty acids of oleic, linoleic, and linolenic acids and C22 unsaturated fatty acid of erucic acid were removed by solvent crystallization. The content of C18–C20 unsaturated fatty acids decreased to less than 5% with pentanol as the solvent after the first stage solvent crystallization. The content of erucic acid decreased to 3.47% with anhydrous ethanol as the solvent after the second to fifth stage solvent crystallization. The combined process of molecular distillation, urea inclusion and low temperature crystallization innovatively adopted an efficient, simple and easy-to-industrial solvent crystallization method to separate erucic and nervonic acids, obtaining nervonic acid with purity of 96.53% and final yield of 47.99%.

Modeling of separation of fatty acid methyl esters derived from fisheries waste by urea complexation method

The aim of the study is to develop a simulation model for the fractionation of fatty acid methyl esters (FAME).by urea complexation. The fatty acids (FAs) were obtained from squid liver and scallop mid-gut, which contain rich in eicosapentaenoic and docosahexaenoic acids well known as health-promoting FAs. FAs can be divided into saturated fatty acid (SFA), monounsaturated fatty acid (MFA), and polyunsaturated fatty acid (PFA) based on the number of double bond in their structure. A fractionation model is proposed and derived from the assumption of the urea-FAMEs complexation reactions, which included equilibrium constants (K) concerned with FAMEs-urea and urea-urea binding. The experiments were conducted at 5 and 28 °C. Different complexation behaviors were observed for SFAME, MFAME, and PFAME. The amount of SFAME captured in the urea inclusion body was larger than MFAME and PFAME. The urea-SFAME and urea-MFAME formation behavior agreed very well with the proposed model, but the urea-PFAME formation behavior showed a large error with the calculation results. The validation experiments showed that the relative error between the experimental data and the model prediction was within 15% for SFAME and MFAME.

Linoleic Acid Isolation from Watermelon Seeds Oil (Citrullus lanatus L) with Urea Inclusion Method

Nutritional problems still become a crucial issue in Indonesian public health. Fulfillment of nutritional balance is expected to improve life quality. In humans, one of the nutrients that play a role in the growth of brain and nervous system functions is PUFA, such as omega-6 and omega-3. Besides, fulfillment of nutritional balance can prevent some diseases; especially linoleic acid used to prevent some diseases. Linoleic acid is an omega-6 and essential fatty acid. Linoleic acid is the main essential fatty acid because it is the precursor for GLA, DGLA, and AA. Omega-6 works with omega-3 and some omega-3 benefits are supported or can arise by omega-6 presence. Studies reveal that watermelon contains high linoleic acid. This study aimed to determine the optimum temperature and ratio of fatty acids: urea for the isolation of linoleic acid from watermelon seed oil. The method used was urea inclusion with a variety of temperatures (-6oC, 6oC, 18oC) and the ratio of fatty acid: urea (1:1; 1:3; 1:5). The results showed the optimum watermelon seed oil linoleic acid isolate at 18oC and the ratio of fatty acids: urea 1:5 with linoleic acid purity (%) of 82.53%.

Fractionation of fatty acid methyl esters via urea inclusion and its application to improve the low-temperature performance of biodiesel

Biodiesel is viewed as the alternative to petroleum diesel, but its poor low-temperature performance constrains its utilization. Cloud point (CP), the onset temperature of thermal crystallization, appropriately shows the low-temperature performance. The effective way to reduce CP is to remove saturated fatty acid methyl esters (FAMEs). Compared to current methods, this work describes an extraordinary approach to fractionating FAMEs by forming solid urea inclusion compounds (UICs). Urea inclusion fractionation reduces the CPs by removing high melting-point linear saturated FAME components. Urea inclusion fractionation in this study was performed under various processing conditions: mass ratios of urea to FAMEs and solvents to FAMEs, various solvents, FAMEs from various feedstocks, and processing temperatures. Supersaturation of urea in the solution is the driving force, and it significantly affects yield, composition, CP, separation efficiency, and selectivity. Through a single urea inclusion fractionation process, FAMEs, except palm oil FAMEs, resulted in CP reduction ranging from 20 to 42 oC with a yield of 77–80% depending on the compositions. CP of palm oil FAMEs could reach as low as -17 oC with a yield of 46% after twice urea inclusion fractionation. According to the model prediction, the cetane number after urea inclusion fractionation decreased about 0.7–2 but was still higher than the minimum biodiesel requirement. Oxidation stability after urea inclusion decreased according to the proposed model, but this can be mitigated by adding antioxidants. Emission evaluation after urea inclusion fractionation indicated decreased hydrocarbons, carbon monoxide, and particulate matter. However, it resulted in the increasing emission of nitrogen oxides.

Scalable production of high-quality carbon nanotube dispersion in aqueous solution using cellulose as dispersant by a freezing/thawing process

Carbon nanotube (CNT) dispersion, which enables scalable fabrication of printed and flexible electronic materials, has brought a revolutionary improvement in CNT-based devices. To progress from the laboratory to commercial applications, it will be necessary to develop simple and scalable methods to produce high-quality CNT dispersions. Here, we propose a freezing/thawing strategy assisted by cellulose to produce high-quality CNT dispersion in an aqueous solution on a large scale. The freezing/thawing process simultaneously serves two purposes: (1) one is to cleave CNTs from their bulk via water-freezing expansion force; (2) the other is to dissolve cellulose in NaOH/urea aqueous solution, facilitating the wrapping of cellulose on the surface of CNTs to improve the stability of the dispersion. The obtained cellulose-dispersed CNT (CDCNT) dispersion is highly homogeneous and stable because of the formation of CNT/cellulose/NaOH/urea inclusion complexes. Importantly, the freezing/thawing strategy using cellulose promises scalable production, including a high CNT concentration of 11.3 mg/mL, high yield of 75%, high production capacity, and unlimited system size, much superior to common ultrasonication. Furthermore, it is demonstrated that the CDCNT dispersion can be used as a precursor solution for fabricating different CNT-based materials via various techniques, such as spinning, dyeing, screen printing, and 3D printing, indicating versatile applications.

195 Interaction of Urea with Frequency and Amount of Distillers Grains Supplementation for Growing Steers on a High Forage Diet

Abstract Two studies determined the interactions of urea inclusion to a dried distillers grains plus solubles (DDGS; 29.4% CP, 5.48% ether extract) supplement fed at 2 amounts and 2 frequencies to steers consuming ad libitum Smooth Bromegrass hay (6.8% CP). In Exp. 1, 120 (247 kg; SD = 20) steers were fed individually for 84 d with treatments arranged in a 2 x 2 x 2 factorial. Supplement was fed every day (D) or 3x/week (ALT), amount of supplement fed was 6.36 kg/week (LO) or 12.73 kg/week (HI) and contained either no urea (-U) or 1.3% urea (+U). In Exp. 2, 8 ruminally cannulated steers (310 kg; SD = 25) were used in an 8 x 6 row-column design with 8 steers and 6, 14-d periods. Treatment design was the same as Exp. 1, except that supplement was fed at a rate of 0.4% (LO) or 0.8% of BW (HI) and supplement was fed either daily (D) or every other day (ALT). In Exp. 1, ADG was 0.30 kg/d greater, and hay DMI was reduced by 0.39 kg/d for HI vs. LO (P &amp;lt; 0.01). Hay DMI was reduced by 0.54 kg/d for ALT vs. D (P &amp;lt; 0.01). In Exp. 2, hay DMI was also reduced HI vs. LO (P &amp;lt; 0.01). Rumen pH was decreased on the day of feeding for steers on ALT (P &amp;lt; 0.01) and was reduced for steers fed HI vs. LO. A reduction in in situ NDF disappearance was observed on the day ALT received supplement between HI and LO (P &amp;lt; 0.01). However, there was no difference between NDF digestibility between D and ALT (P &amp;gt; 0.05). Urea had no effect on digestion or ADG, suggesting RDP was not deficient. Dried distillers grains can be supplemented infrequently without reducing animal performance.

Interaction of urea with frequency and amount of distillers grains supplementation for growing steers on a high forage diet.

Two studies were conducted to determine interactions of urea inclusion to a dried distillers grains plus solubles (DDGS; 29.4% crude protein, 5.48% ether extract) supplement fed at two amounts and two frequencies to steers on a high forage diet. In Exp. 1, 120 (247 kg; SD = 20) steers were fed individually for 84 d. Steers received ad libitum grass hay (6.8% crude protein) and one of eight treatments. Treatment design was a 2 × 2 × 2 factorial. Supplement was fed daily or three times per week, amount of supplement fed was 6.36 kg dry matter (DM)/week [0.37% body weight (BW); LO] or 12.73 kg DM/week (0.74% BW; HI) and contained either no urea or 1.3% urea on a DM basis. Steer BW was measured at the start and end of the trial and hay DM intake (DMI) was measured weekly. In Exp. 2, ruminally cannulated steers (310 kg; SD = 25) were used in a row-column design with eight steers and six 14-d periods. Treatments assigned were the same as Exp. 1, except that supplement was fed at 0.4% of BW (LO) or 0.8% of BW (HI) and supplement was fed either daily (DY) or every other day (ALT). Hay DMI, rumen ammonia-N, rumen pH, in situ neutral detergent fiber (NDF) disappearance, and rumination were measured. In Exp. 1, average daily gain (ADG) was affected by amount of supplement with steers on HI gaining 0.30 kg/d more (P < 0.01) than LO. Hay DMI was reduced by increased amount of supplement (0.39 kg/d; P < 0.01) and by decreased frequency of supplementation (0.54 kg/d; P < 0.01). In Exp. 2, hay DMI was also reduced due to increased amount of supplement and decreased frequency of supplementation (P < 0.01). Rumen pH was decreased on the day of supplement feeding for steers on ALT (P < 0.01) and reduced for steers fed HI vs. LO. There was no difference in NDF digestibility between DY and ALT (P > 0.05). For ALT steers, there was reduction (P < 0.01) in in situ NDF disappearance for the HI compared to LO amount of supplementation on the day of supplementation. Infrequent supplementation of DDGS results in no difference in ADG but decreased hay DMI compared to daily supplementation. Urea had no effect on digestion or ADG, suggesting rumen degradable protein was not deficient when supplementing DDGS. There is little change in rumen fermentation parameters between frequency of supplement feeding, indicating that forage digestion is not impacted by supplementation frequency. Dried distillers grains can be supplemented infrequently without a reduction in animal performance.