Abstract:-The objective of this experiment was to quantify the effects of feeding polymer-coated slow-release urea on nutrient intake and total tract digestion, milk yield and composition, nutrient balances, ruminal fermentation, microbial protein synthesis, and blood parameters in dairy cows. Sixteen Holstein cows (580±20 kg of live weight (mean ± standard deviation); 90 to 180 days in milk (DIM); and 28 kg/d of average milk yield) were used in a replicated 4 × 4 Latin square experimental design. The animals were assi… Show more
“…Miranda et al (2019) reported that there were no differences in most of the blood parameters when cows were fed various urea sources. Similar results were observed by Calomeni et al (2015), who recorded no differences in blood parameters when SBM was replaced partially with protein sources such as yeastderived microbial protein or SRU.…”
The study investigated the effects of replacing soybean meal (SBM) with slow-release urea (SRU) on milk production, milk composition, and rumen fermentation of Holstein dairy cows. Sixteen Holstein cows weighing between 550 and 680 kg in mid lactation were randomly assigned to four dietary treatments in a 12-week study. The treatments consisted of T1: a diet containing 16.7% crude protein (CP), T2: T1 with 0.5% SRU replacing plant protein, T3: T1 with 0.75% SRU replacing plant protein, and T4: T1 with 1.00% SRU replacing plant protein. Animals were fed three times a day with feed being offered ad libitum. Dry matter intake (DMI) and average daily gain (ADG) were not affected by the level of SRU. Feeding SRU did not affect milk production and milk composition significantly, but milk fat and milk urea nitrogen (MUN) levels were increased. Significant differences were observed in ruminal volatile fatty acid (VFA) concentration. Feeding SRU increased butyrate concentration with no significant effects on concentrations of acetate or propionate. Significant differences were observed in cholesterol, triglyceride, high-density lipoprotein (HDL), low-density lipoprotein (LDL), and nonesterified fatty acid (NEFA) concentrations, but glucose, very-low-density lipoprotein (VLDL) and β-hydroxybutyrate (BHB) levels were not affected significantly by the treatments. Thus, feeding SRU altered the release rate of ammonia and provided more ammonia nitrogen (NH3-N) for microbial protein synthesis in the rumen.
“…Miranda et al (2019) reported that there were no differences in most of the blood parameters when cows were fed various urea sources. Similar results were observed by Calomeni et al (2015), who recorded no differences in blood parameters when SBM was replaced partially with protein sources such as yeastderived microbial protein or SRU.…”
The study investigated the effects of replacing soybean meal (SBM) with slow-release urea (SRU) on milk production, milk composition, and rumen fermentation of Holstein dairy cows. Sixteen Holstein cows weighing between 550 and 680 kg in mid lactation were randomly assigned to four dietary treatments in a 12-week study. The treatments consisted of T1: a diet containing 16.7% crude protein (CP), T2: T1 with 0.5% SRU replacing plant protein, T3: T1 with 0.75% SRU replacing plant protein, and T4: T1 with 1.00% SRU replacing plant protein. Animals were fed three times a day with feed being offered ad libitum. Dry matter intake (DMI) and average daily gain (ADG) were not affected by the level of SRU. Feeding SRU did not affect milk production and milk composition significantly, but milk fat and milk urea nitrogen (MUN) levels were increased. Significant differences were observed in ruminal volatile fatty acid (VFA) concentration. Feeding SRU increased butyrate concentration with no significant effects on concentrations of acetate or propionate. Significant differences were observed in cholesterol, triglyceride, high-density lipoprotein (HDL), low-density lipoprotein (LDL), and nonesterified fatty acid (NEFA) concentrations, but glucose, very-low-density lipoprotein (VLDL) and β-hydroxybutyrate (BHB) levels were not affected significantly by the treatments. Thus, feeding SRU altered the release rate of ammonia and provided more ammonia nitrogen (NH3-N) for microbial protein synthesis in the rumen.
“…Nevertheless, we did not detect differences on microbial protein synthesis agreeing with [28] who reported no differences in purine derivatives production of Nellore steers fed the urea sources of the current study. In addition, Calomeni et al [9] found no differences in DM intake, apparent digestibility and microbial protein synthesis of dairy cows fed the same polymer-coated SRA as used in this study or feed grade urea, but the authors added 0.9 g/kg DM of the commercial products.…”
Section: Discussionmentioning
confidence: 66%
“…These effects are related to the fact that several cellulolytic bacteria use N from ammonia to grow in rumen [7]. However, other studies have reported no effects of replacing feed grade urea by SRU on ruminal fermentation [8], nutrient digestibility and N excretion [9]. …”
ObjectiveTwo experiments were performed to evaluate the effects of coated slow-release urea on nutrient digestion, ruminal fermentation, nitrogen utilization, blood glucose and urea concentration (Exp 1), and average daily gain (ADG; Exp 2) of steers.MethodsExp 1: Eight ruminally fistulated steers [503±28.5 kg body weight (BW)] were distributed into a d 4×4 Latin square design and assigned to treatments: control (CON), feed grade urea (U2), polymer-coated slow-release urea A (SRA2), and polymer-coated slow-release urea B (SRB2). Dietary urea sources were set at 20 g/kg DM. Exp 2: 84 steers (350.5±26.5 kg initial BW) were distributed to treatments: CON, FGU at 10 or 20 g/kg diet DM (U1 and U2, respectively), coated SRA2 at 10 or 20 g/kg diet DM (SRA1 and SRA2, respectively), and coated SRB at 10 or 20 g/kg diet DM (SRB1 and SRB2, respectively).ResultsExp 1: Urea treatments (U2+SRA2+SRB2) decreased (7.4%, p = 0.03) the DM intake and increased (11.4%, p<0.01) crude protein digestibility. Coated slow-release urea (SRA2+SRB2) showed similar nutrient digestibility compwared to feed grade urea (FGU). However, steers fed SRB2 had higher (p = 0.02) DM digestibility compared to those fed SRA2. Urea sources did not affect ruminal fermentation when compared to CON. Although, coated slow-release urea showed lower (p = 0.01) concentration of NH3-N (−10.4%) and acetate to propionate ratio than U2. Coated slow-release urea showed lower (p = 0.02) urinary N and blood urea concentration compared to FGU. Exp 2: Urea sources decreased (p = 0.01) the ADG in relation to CON. Animals fed urea sources at 10 g/kg DM showed higher (12.33%, p = 0.01) ADG compared to those fed urea at 20 g/kg DM.ConclusionFeeding urea decreased the nutrient intake without largely affected the nutrient digestibility. In addition, polymer-coated slow-release urea sources decreased ruminal ammonia concentration and increased ruminal propionate production. Urea at 20 g/kg DM, regardless of source, decreased ADG compared both to CON and diets with urea at 10 g/kg DM.
“…Starea, biuret and complexes of urea with formaldehyde or molasses have been used in the rumen to avoid ammonia‐N toxicity; yet slow release rates have failed to improve N utilization in in vitro trials . Other commercial products based on urea used to reduce the degradation of N in the rumen are Rumapro® and Optigen®; the ruminal degradation rate of these products is comparable to vegetable protein concentrates .…”
BACKGROUND: There is a growing interest in the development of novel and innovative vehicles for controlled release of urea into the rumen, aiming to provide ammonia-N for the biosynthesis of proteins of bacterial origin and to prevent urea intoxication by direct feeding to livestock. Urea microencapsulation is a system that can control the release of urea to be slow and steady.
RESULTS:The amount of encapsulated urea was 69% of CSU (calcium silicate + urea + Eudragit RS100 ® + dichloromethane) and 71% of ACU (activated charcoal + urea + Eudragit RS100 ® + dichloromethane) groups (p > 0.05) The buoyancy of the microcapsules was over 50% after 12 h of agitation in both groups (CSU and ACU), producing significant differences in the volume of the organic phase factor, which was 20 mL at the lowest value (p = 0.0005). The morphology of the microcapsules produced with CSU and ACU showed no significant differences in microcapsule morphology (p > 0.05). The lower temperature (35 versus 40 ∘ C, p = 0.035) retained better morphology of the microcapsules. Regarding the in vitro ammonia-N release kinetics, unprotected urea reached a maximal peak after 6 h, while CSU and ACU took more than 24 h to reach ammonia-N released concentration.
CONCLUSIONS:We stabilized the physical factors in the microencapsulation of urea that can allow slow release of rumen fluid.
RESULTS AND DISCUSSIONPhase 1 Urea encapsulation Urea encapsulation was ca 65% for the APV. Urea is hygroscopic and is very soluble. 8 The proportion of encapsulated urea was J Sci Food Agric 2019; 99: 2541-2547
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