Effect of slow-release urea on intake, ingestive behavior, digestibility, nitrogen metabolism, microbial protein production, blood and ruminal parameters of sheep.

We conducted two experiments. The first aimed to obtain and characterize microparticles of slow-release urea (SRU) using calcium alginate as the encapsulating agent. The second experiment evaluated their inclusion in sheep diets. In the first experiment, four treatments from a completely randomized design were employed to develop an SRU through the ionic gelification technique testing two drying methods (oven and lyophilizer) and addition or no of sulfur (S): SRU oven-dried with sulfur (MUSO) and without sulfur (MUO), SRU freeze-dried/lyophilized with (MUSL), and without sulfur (MUL). MUO exhibited better yield and encapsulation efficiency among these formulations than the others. Therefore, the second experiment was conducted to compare free urea (U) as control and three proportions (1%, 1.5%, and 2% of total dry matter) of MUO in the diet of sheep. Twenty-four non-castrated male Santa Ines lambs, with an average body weight of 22 ± 3.0 kg, were used and distributed in a completely randomized design with four treatments and six replications. The inclusion of 1% alginate-encapsulated urea (MUO1%) resulted in higher dry matter (DM) intake than free urea (p ≤ 0.05). MUO2% inclusion promoted higher NDF digestibility than U and MUO1%. MUO1% showed higher DM than MUO2% and higher NFC digestibility than U and MUO2% (p ≤ 0.05). Sheep fed MUO1.5% and MUO2% exhibited similar nutrient intake and digestibility. Sheep receiving MUO1% had higher N-intake, N-urinary, N-excretion total, N-digested, and N-retained compared to U. Sheep fed MUO1% showed greater N-retained (as % ingested and digested), microbial protein production, and efficiency when compared to other treatments (p ≤ 0.05). MUO2% addition (SRU) promoted the lowest microbial protein production and efficiency in sheep. MUO dietary inclusion increased feeding time and reduced idleness time compared to U, regardless of the MUO level (p ≤ 0.05). Adding MUO1% improved the intake efficiency of DM and NDF and resulted in more feed boli than the other MUO levels (p ≤ 0.05). Sheep receiving U had (4 h after fending) higher NH3-N, pH, and blood urea nitrogen (BUN) and lower TGL serum compared to sheep fed MUO (p ≤ 0.05), without significant difference among MUO levels (p > 0.05), except NH3-N was higher in MUO1.5% and MUO2% compared to MUO1.0%. The external ionic gelation technique proved suitable for urea microencapsulation in calcium alginate (3%), demonstrating high quality, efficiency, and yield. MUO represents a promising slow-release urea for ruminants and is recommended for sheep diets at an inclusion level of 1.0%. This inclusion level improves intake efficiency and nutrient digestibility, increases rumen nitrogen retention, and reduces BUN without compromising sheep health.

Effects of extruded urea levels on the productive performance and carcass and meat characteristics of Nellore cattle.

Because the non-protein nitrogen sources can be an option for a ruminant diet to replace true-protein sources, we hypothesized that using extruded urea in increasing levels by reducing soybean meal in the diet can maintain or improve the productive performance of beef cattle in a feedlot. It was aimed to evaluate the effects of extruded urea levels on the productive performance and carcass and meat characteristics of Nellore steers in feedlot. Twenty-four Nellore steers, with an average age of 22 months and an average initial weight of 333.5 kg, were used. A completely randomized design was used with four treatments: 50, 60, 70, and 80 g/100 kg BW of extruded urea. There was no effect of extruded urea levels on nutrient intake. The final weight and average daily gain were adjusted by a quadratic equation, with maximum estimated values of 479.18 kg and 1.02 kg/day with the inclusion of 59.71, 54.14, and 54.16 g/100 kg BW of extruded urea, respectively. There was no effect (P > 0.05) of extruded urea levels on hot carcass weight (233.3 kg), carcass yield (53.2%), ribeye area (72.7 cm2), and subcutaneous fat thickness (5.3 mm). Likewise, there was no effect (P > 0.05) of extruded urea levels on meat chemical composition, shear force (8.9 KgF), cooking losses (28.2%), pH (5.6), and meat color parameters. We recommended the use of 70 g/100 kg BW of extruded urea in the diet for finishing Nellore steers in confinement.

Effect of Post-Ruminal Urea Supply on Growth Performance of Grazing Nellore Young Bulls at Dry Season.

The objective of this study was to evaluate the effect of the use of post-ruminal urea on performance, nitrogen metabolism and the ruminal environment of Nellore cattle reared on pasture during the dry season. In experiment 1 (Exp. 1), nine ruminal-cannulated Nellore steers, 30 ± 2 months old (651 ± 45 kg body weight (BW)), were allotted to a 3 × 3 Latin triple square. In experiment 2 (Exp. 2), 84 Nellore bulls, 18 ± 3 months old (315 ± 84 kg BW), were distributed in complete randomized blocks, by initial BW. Protein supplements were supplied daily, in the amount of 2 g/kg BW, and consisted of either CONT: protein + conventional urea (50% CP), PRU: protein + post ruminal urea (50% CP) and U + PRU: protein + urea conventional + post-ruminal urea (70% CP). The paddocks were composed of Urochloa brizantha cv. Marandu grass. In Exp. 1, there was no treatment effect for DM, OM, NDF, forage intake, and CP, but there was a higher intake for PRU (p < 0.005) and a higher digestibility for U+ PRU (p = 0.001). There was no effect on ruminal pH or NH3-N concentration (p ≥ 0.232), but there was an interaction between treatment and time for them (p < 0.039). Furthermore, there was a treatment effect on the total SCFA concentration, with CONT being higher than the others. A difference in the acetate:propionate ratio was found (p < 0.027), with a greater relationship for PRU and U + PRU. A treatment effect (p = 0.049) was found for the propionate proportion, with a higher proportion in the CONT. Nitrogen intake was consequently lower for the CONT and higher urinary excretion for the U + PRU (p = 0.002). Animals supplemented with CONT showed a tendency to have more Bacteria and fewer Archaea (p = 0.086). In Exp. 2, there was a treatment effect for the disappearance rate of the supplement (p < 0.001). Intake was faster for PRU and CONT, but performance was not affected by PRU (p = 0.311). The use of post-ruminal urea alters the microbial population, but does not affect performance. Therefore, supplementation with post-ruminal urea presented similar results compared to conventional urea. Ruminal and blood parameters and animal performance were not influenced by treatments.

Urea poisoning in cattle: a brief review and diagnostic approach / Intoxicação por ureia em bovinos: breve revisão e abordagem diagnóstica

Urea is an organic compound characterized as a white, solid, and hygroscopic substance. It is recognized as a source of non-protein nitrogen (NPN) and is widely used as a partial replacement for protein in cattle diets due to the ability of the ruminal microbiota to convert it into microbial protein. Despite the advantages of using urea, it also has limitations, particularly the proximity between metabolizable and toxic or fatal doses. Furthermore, for safe use, a period of adaptation is necessary for the animals. Poisoning is characterized by rapid and generally fatal development, which is frequent in non-adapted animals but can also occur in those with previous adaptations. The aim of this study was to characterize the clinical, epidemiological, and pathological aspects of urea poisoning through a brief review and a retrospective study. In addition, interviews were conducted with veterinarians who frequently send diagnostic material to the Laboratory of Anatomic Pathology of the "Faculdade de Medicina Veterinária e Zootecnia" (LAP-FAMEZ) to assess their perception of the outbreaks of urea poisoning. The objective was to obtain a comparative scenario between published cases and those received by the laboratory while considering the real situation of this condition in the field. During this retrospective study, only four outbreaks were investigated; in one, the diagnosis was possible through experimental reproduction. Of 35 interviewees, 88.9% said they had seen more than one case compatible with urea poisoning, but 87.5% did not perform a necropsy and/or send material to confirm the diagnosis. The results show that the reality of urea poisoning may be very distant from that reported in previous studies due to the difficulty often observed in the diagnostic approach, so we developed a flowchart aiming to provide a useful guide for field veterinarians.

A ureia é um composto orgânico, que se apresenta como uma substância branca, sólida e higroscópica, e é reconhecida como fonte de nitrogênio não proteico (NNP), sendo amplamente utilizada como fertilizante e também como substituto parcial de proteína em bovinos devido à capacidade da microbiota ruminal de convertê-la em proteína microbiana. Apesar das vantagens que envolvem o uso da ureia, ela também apresenta limitações, a principal delas é a proximidade entre doses metabolizáveis e tóxicas ou fatais, e para que seja utilizada com segurança é necessário um período de adaptação dos animais. A intoxicação é caracterizada por evolução rápida e geralmente fatal, sendo frequente em animais não adaptados, mas pode ocorrer naqueles com adaptação prévia. O objetivo deste estudo é caracterizar os aspectos clínicos, epidemiológicos e patológicos da intoxicação por ureia por meio de uma breve revisão e um estudo retrospectivo. Adicionalmente foram realizadas entrevistas com médicos veterinários que frequentemente enviam material para diagnóstico no Laboratório de Anatomia Patológica da Faculdade de Medicina Veterinária e Zootecnia (LAP-FAMEZ) com o objetivo de avaliar a percepção dos mesmos em relação aos surtos de intoxicação por ureia, na expectativa de se obter um quadro comparativo entre os casos recebidos pelo laboratório e levantamentos publicados e a real situação desta condição a campo. No período do estudo retrospectivo, foram acompanhados apenas quatro surtos, sendo que em um deles foi possível diagnosticar por reprodução experimental. Dos 35 entrevistados, 88,9% afirmaram ter atendido mais de um caso compatível com intoxicação por ureia, mas 87,5% deles não realizaram necropsia e/ou envio de material para confirmação do diagnóstico. Foi possível observar que a realidade da intoxicação por ureia pode estar muito distante daquela relatada em estudos anteriores, e devido à dificuldade muitas vezes observada na abordagem diagnóstica, desenvolvemos um fluxograma na expectativa de que ele constitua um guia útil para veterinários de campo.

Extruded urea could replace true protein source in supplements for lambs finished in tropical pastures / A ureia extrusada pode substituir a fonte de proteína verdadeira em suplementos para cordeiros terminados em pastagens tropicais

The aim of this study was to evaluate the effects of replacing 50% of the true protein from soybean meal with extruded urea on the performance and carcass characteristics of lambs finished on pasture. Twenty lambs with initial weight of 29.9±6.2kg and 5 months of age, distributed in two treatments in blocks at random, were kept in pastures of Urochloa spp. Supplemented with 2% of body weight (BW). The treatments consisted of supplements containing soybean meal as the only true protein source (control), or extruded urea replacing 50% of soybean meal (NPN treatment). There was no effect of treatment on total supplement intake. There were differences in average daily gain (242.1 vs. 264.6g/day), slaughter weight (41.9 vs. 45.0kg) and carcass weight (18.9 vs. 20.1kg). There was no effect of the treatment on the final body condition score, hot carcass yield, carcass length, breast depth, subcutaneous fat thickness or rib eye area. The group of animals that received extruded urea showed superior carcass finishing characteristics (99.0% vs. 66.0%), maturity (22.0% vs. 0.0%), marbling (55.0% vs. 33.0%), meat texture (44.0% vs. 33.0%) and fat (66.0% vs. 22.0%). There were no significant effects on tenderness (7.5kg/f) or flesh color (L* = 33.2; a* = 16.2; b* = 8.3). There were no significant changes in the biochemical profile of the animals' blood during the experiment for both treatments. The replacement of 50% of protein from soybean meal by the extruded urea as NPN source in the supplement for lambs finished in Urochloa spp pastures provides better animal performance and qualitative characteristics of meat, without altering quantitative carcass characteristics.

Objetivou-se avaliar os efeitos da substituição de 50% da proteína verdadeira do farelo de soja por ureia extrusada sobre o desempenho e as características de carcaça de cordeiros terminados em pasto. Vinte cordeiros de 29,9+6,2kg de peso inicial e com cinco meses de idade, distribuídos em dois tratamentos em blocos ao acaso, foram mantidos em pastagens de Urochloa spp. suplementado com 2% do peso vivo (PV). Os tratamentos consistiram em suplementos contendo farelo de soja como única fonte de proteína verdadeira (controle), ou ureia extrusada em substituição a 50% do farelo de soja (tratamento NPN). Não houve efeito do tratamento na ingestão total de suplemento. Houve diferenças no ganho médio diário (242,1 vs. 264,6 g/dia), no peso ao abate (41,9 vs. 45,0kg) e no peso da carcaça (18,9 vs. 20,1kg). Não houve efeito do tratamento sobre escore de condição corporal final, rendimento de carcaça quente, comprimento de carcaça, profundidade do peito, espessura de gordura subcutânea ou área de olho de lombo. O grupo de animais que recebeu ureia extrusada apresentou características superiores de acabamento de carcaça (99,0% vs. 66,0%), maturidade (22,0% vs. 0,0%), marmoreio (55,0% vs. 33,0%), textura da carne (44,0% vs. 33,0%) e gordura (66,0% vs. 22,0%). Não houve efeitos significativos na maciez (7,5 kg/f) nem na cor da carne (L*= 33,2; a*= 16,2; b * = 8,3). Não houve mudanças significativas no perfil bioquímico do sangue dos animais durante o experimento para ambos os tratamentos. A substituição de 50% da proteína do farelo de soja pela ureia extrusada como fonte de NPN no suplemento para cordeiros terminados em pastagem de Urochloa spp. proporciona melhor desempenho animal e características qualitativas da carne, sem alterar as características quantitativas da carcaça.

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.

Feeding Calcium-Ammonium Nitrate to Lactating Dairy Goats: Milk Quality and Ruminal Fermentation Responses.

We aimed to investigate the effects of calcium-ammonium nitrate (CAN) fed to lactating dairy goats on dry matter (DM) intake, digestibility of nutrients, milk properties (composition, antioxidant capacity, fatty acid profile, and nitrate residues), and ruminal fermentation parameters. Twelve lactating Saanen goats averaging 98.5 ± 13.1 days in milk, 53.5 ± 3.3 kg of body weight, and 2.53 ± 0.34 kg of milk/day were randomly assigned in four 3 × 3 Latin squares to receive the following diets: a control group (without CAN) with 7.3 g/kg DM of urea (URE), 10 g/kg DM of CAN (CAN10), and 20 g/kg DM of CAN (CAN20). Each period lasted 21 days, with 14 days for diet adaptation and seven days for data and sample collection. The DM intake, digestibility of nutrients, yields of milk, 3.5% fat-corrected milk, and energy-corrected milk were not affected by treatments. Similarly, there were no treatment effects on the yields and concentrations of milk fat, true protein, and lactose, along with minor effects on milk fatty acid profile. Total antioxidant capacity in milk was unaffected by treatments; however, concentration of conjugated dienes increased, while thiobarbituric acid reactive substances in milk decreased linearly. Nitrate and nitrite residues in milk were elevated by treatments, while the total of volatile fatty acids and ammonia-N concentration in the rumen were unaffected. Collectively, feeding CAN (up to 20 g/kg of DM) to lactating dairy goats did not affect feed intake, nutrient digestibility, and milk composition; however, it may increase milk lipid oxidation, as evidenced by increased conjugated diene concentration.

Intoxicação por ureia em ruminantes - Revisão de literatura / Urea poisoning in ruminants - Literature review / Envenenamiento por urea en rumiants

A proteína é um dos principais limitantes dentro do planejamento alimentar nos sistemas de criação extensivos, principalmente no período do inverno, as gramíneas de clima tropical e subtropical já possuem baixos teores deste nutriente e no período seco se torna um desafio manter boa ofertae disponibilidade. Com o passar dos anos se intensificou o uso de pastagens, necessitando a utilização de suplementos que permitem suprir as necessidades nutricionais, porém, devido ao alto custo da proteína de origem vegetal, novas formas de suplementação através de fontes de nitrogênio não-proteico foram ganhando espaço, principalmente pelo menor custo, a fonte mais utilizada no brasil é a uréia. Seu uso proporciona diversas vantagens, mas devido a utilização inadequada, tem causado muitos casos de intoxicação, necessitando conhecer a forma como ela é utilizada pelos microrganismos ruminais e pelo ruminante, para entender a forma como a intoxicação ocorre no rebanho e evitar com que ocorra os quadros de intoxicação.(AU)

Protein is one of the main limitations within food planning in extensive creation systems, especially in the winter period, grasses of tropical and subtropical climate already have low levels of this nutriente and in the dry period it becomes a challenge to maintain good supply and availability. Over the years, the use of pastures has intensified, requiring the use of supplements that allow to meet nutritional needs, however, due to the high cost of vegetable protein, new forms of supplementation through sources of non-protein nitrogen have been gaining space, mainly due to its lower cost, the most used source in Brazil is urea. Its use provides several advantages, but due to improper use, it has caused many cases of intoxication, needing to know the way it is used by ruminal microorganisms and by the ruminant, to understand how the intoxication occurs in the herd and to prevent the occurrence of intoxication.(AU)

La proteína es uno de los principales factores limitantes em la planificación alimentaria em los sistema de crianza extensivos, especialmente em el período invernal, las gramíneas em climas tropicales y subtropicales ya presentan bajos niveles de este nutriente um buen suministro y disponibilidade. A lo largo de los años, se há intensificado el uso de los pastos, requiriendo el uso de suplementos que permitam cubrir las necesidades nutricionales, sin embargo, debido al alto costo de la proteína de origen vegetal, han ido ganando nuevas formas de suplementación a través de fuentes nitrogenadas no proteicas espacio, principalmente por el menor costo, la fuente más utilizada em Brasil es la urea. Su uso brinda varias vetajas, pero debido al uso inadequado há causado muchos casos de intoxicación, siendo necessário conocer como es utilizado por los microorganismos ruminales y por el ruminante, para compreender como se produce la intoxicación el rebaño y prevenir la apararición de cuadros de intoxicación.(AU)

Replacement of common urea with protected urea in sheep supplement / Substituição da ureia comum por ureia protegida em suplementos para ovinos

The objective was to evaluate the effect of replacing common urea with protected urea in the supplement on the nutrient intake and digestibility and metabolic profile of sheep. Five adult sheep, with an average age of 4 years and an initial average body weight of 50 ± 4.03 kg, were used. The diet consisted of sorghum silage, supplemented with a multiple mixture of corn bran, soybean meal, white salt, mineral salt, common urea (CU) or protected urea (PU). The experimental design was a 5x5 Latin square. Treatments consisted of: control or 100% CU, 75% CU and 25% PU, 50% CU and 50% PU, 25% CU and 75% PU and 100% PU. Collections and analysis of feed, feces, urine and blood were carried out to assess intake, digestibility and blood metabolites. Analysis of variance and SNK test were applied considering 5% significance. Nonparametric data were analyzed by Kruskal-Wallis at a significance level of 5%. The replacement of common urea with protected urea did not (P> 0.05) alter the intake of dry matter, crude protein and water, and the dry matter digestibility. The production of urine and feces, and the density of urine also did not (P> 0.05) show statistical difference with the replacement of common urea with protected urea. As for protein and energy metabolites, only glycemia showed variation (P <0.05), with the proportion of 75% CU and 25% PU, indicating the highest concentration of glucose in relation to the replacement of 0, 50 and 100% PU in the supplement. There are no benefits from partial or total replacement of common urea with protected urea in sheep supplementation.(AU)

Objetivou-se avaliar o efeito da substituição da ureia comum por ureia protegida no suplemento sob o consumo de nutrientes e digestibilidade da matéria seca e perfil metabólico de ovelhas. Foram utilizadas 5 ovelhas adultas, com idade média de 4 anos e peso corporal médio inicial de 50 ± 4,03 kg. A dieta foi composta por silagem de sorgo, sendo suplementada por mistura múltipla composta de milho moído, farelo de soja, sal branco, sal mineral, ureia comum (UC) ou ureia protegida (UP). O delineamento experimental foi em quadrado latino 5x5. Os tratamentos consistiram em: controle ou 100% UC, 75% UC e 25% UP, 50% UC e 50% UP, 25% UC e 75% UP e 100% UP. Foram realizadas coletas e análise de alimentos, fezes, urina e sangue para avaliação do consumo, digestibilidade e metabolitos sanguíneos. Foi realizado análise de variância e teste SNK considerando 5 % de significância. Os dados não paramétricos foram analisados por Kruskal-Wallis ao nível de significância de 5%. A substituição da ureia comum por ureia protegida não alterou o consumo de matéria seca, de proteína bruta e água e a digestibilidade da matéria seca (P>0,05). A produção de urina e fezes, e a densidade da urina também não apresentaram diferença estatística com a substituição da ureia comum pela protegida (P>0,05). Quanto aos metabólitos proteicos e energéticos somente a glicemia demonstrou variação (P<0,05), sendo que a proporção de 75%UC e 25%UP apresentou a maior concentração de glicose em relação a substituição de 0, 50 e 100% de UP no suplemento. Conclui-se que não há benefícios na substituição parcial ou total da ureia comum pela ureia protegida na suplementação de ovinos.(AU)

Replacement of common urea with protected urea in sheep supplement / Substituição da ureia comum por ureia protegida em suplementos para ovinos

The objective was to evaluate the effect of replacing common urea with protected urea in the supplement on the nutrient intake and digestibility and metabolic profile of sheep. Five adult sheep, with an average age of 4 years and an initial average body weight of 50 ± 4.03 kg, were used. The diet consisted of sorghum silage, supplemented with a multiple mixture of corn bran, soybean meal, white salt, mineral salt, common urea (CU) or protected urea (PU). The experimental design was a 5x5 Latin square. Treatments consisted of: control or 100% CU, 75% CU and 25% PU, 50% CU and 50% PU, 25% CU and 75% PU and 100% PU. Collections and analysis of feed, feces, urine and blood were carried out to assess intake, digestibility and blood metabolites. Analysis of variance and SNK test were applied considering 5% significance. Nonparametric data were analyzed by Kruskal-Wallis at a significance level of 5%. The replacement of common urea with protected urea did not (P> 0.05) alter the intake of dry matter, crude protein and water, and the dry matter digestibility. The production of urine and feces, and the density of urine also did not (P> 0.05) show statistical difference with the replacement of common urea with protected urea. As for protein and energy metabolites, only glycemia showed variation (P <0.05), with the proportion of 75% CU and 25% PU, indicating the highest concentration of glucose in relation to the replacement of 0, 50 and 100% PU in the supplement. There are no benefits from partial or total replacement of common urea with protected urea in sheep supplementation.

Objetivou-se avaliar o efeito da substituição da ureia comum por ureia protegida no suplemento sob o consumo de nutrientes e digestibilidade da matéria seca e perfil metabólico de ovelhas. Foram utilizadas 5 ovelhas adultas, com idade média de 4 anos e peso corporal médio inicial de 50 ± 4,03 kg. A dieta foi composta por silagem de sorgo, sendo suplementada por mistura múltipla composta de milho moído, farelo de soja, sal branco, sal mineral, ureia comum (UC) ou ureia protegida (UP). O delineamento experimental foi em quadrado latino 5x5. Os tratamentos consistiram em: controle ou 100% UC, 75% UC e 25% UP, 50% UC e 50% UP, 25% UC e 75% UP e 100% UP. Foram realizadas coletas e análise de alimentos, fezes, urina e sangue para avaliação do consumo, digestibilidade e metabolitos sanguíneos. Foi realizado análise de variância e teste SNK considerando 5 % de significância. Os dados não paramétricos foram analisados por Kruskal-Wallis ao nível de significância de 5%. A substituição da ureia comum por ureia protegida não alterou o consumo de matéria seca, de proteína bruta e água e a digestibilidade da matéria seca (P>0,05). A produção de urina e fezes, e a densidade da urina também não apresentaram diferença estatística com a substituição da ureia comum pela protegida (P>0,05). Quanto aos metabólitos proteicos e energéticos somente a glicemia demonstrou variação (P<0,05), sendo que a proporção de 75%UC e 25%UP apresentou a maior concentração de glicose em relação a substituição de 0, 50 e 100% de UP no suplemento. Conclui-se que não há benefícios na substituição parcial ou total da ureia comum pela ureia protegida na suplementação de ovinos.

Características produtivas de cabritos Saanen terminados com ureia na ração / Productive traits of young male Saanen goats finished with urea in the diet

Objetivou-se avaliar a inclusão de ureia na dieta de cabritos sobre o desempenho e características de carcaça. Foram utilizados 18 cabritos (150 dias de idade e 21 Kg de peso) distribuídos em dois grupos com dietas isoproteicas. Os animais do grupo controle (GC) foram alimentados com ração sem ureia na sua composição, enquanto os animais do outro grupo (GU) foram alimentados com ração com 1% da MS de ureia na base da matéria seca. Avaliou-se o ganho de peso médio (g/dia), biometrias corporais, assim como o peso e rendimento de carcaça nos animais. Não houve diferenças significativas em nenhuma das variáveis estudadas (p>0,05), como: ganho de peso (g/dia) (GU: 122,1 ± 11,89 vsGC: 132,9 ± 4,97), perímetro torácico (cm) (GU: 73,0 ± 1,2 vsGC: 74,5 ± 0,57), comprimento corporal (cm) (GU: 74,0 ± 1,42 vsGC: 73,67 ± 0,70), peso ao abate (kg) (GU: 34,39 ± 1,76 vsGC: 36,56 ± 0,96), rendimentos de carcaça quente (%) (GU: 47,37 ± 0,82 vsGC: 47,23 ± 0,72) e fria (GU: 45,64 ± 0,60 vsGC: 45,84 ± 0,70). Conclui-se que o uso de 1% de ureia na MS da dieta de caprinos machos jovem não afeta o desempenho dos animais e as características de carcaça.(AU)

The objective of this study was to evaluate the effect of inclusion of urea in the diet of goats on performance and carcass traits. Eighteen kids (150 days old and 21 kg of weight) were divided into two groups receiving isoprotein diets. The animals in the control group (CG) were fed ration without urea, while the animals in the urea group (UG) were fed ration with 1% urea on a dry matter basis. Average weight gain (g/day), body biometrics, and carcass weight and yield were evaluated in the animals. There were no significant differences in any of the variables studied (p>0.05): weight gain (g/day) (UG: 122.1 ± 11.89 vsCG: 132.9 ± 4.97), chest circumference (cm) (UG: 73.0 ± 1.2 vsCG: 74.5 ± 0.57), body length (cm) (UG: 74.0 ± 1.42 vsCG: 73.67 ± 0.70), slaughter weight (kg) (UG: 34.39 ± 1.76 vsCG: 36.56 ± 0.96), hot carcass yield (%) (UG: 47.37 ± 0.82 vsCG: 47.23 ± 0.72), or cold carcass yield (UG: 45.64 ± 0.60 vsCG: 45.84 ± 0.70). In conclusion, the addition of 1% urea in the DM to the diet of young male goats does not affect the performance of the animals or carcass traits.(AU)

Urea supplementation in rumen and post-rumen for cattle fed a low-quality tropical forage.

We evaluated the differences between the supplementation of urea in rumen and/or abomasum on forage digestion, N metabolism and urea kinetics in cattle fed a low-quality tropical forage. Five Nellore heifers were fitted with rumen and abomasum fistulas and assigned to a Latin square design. The treatments were control, continuous infusion of urea in the abomasum (AC), continuous infusion of urea in the rumen, a pulse dose of urea in the rumen every 12 h (PR) and a combination of PR and AC. The control exhibited the lowest (P < 0·10) faecal and urinary N losses, which were, overall, increased by supplementation. The highest urinary N losses (P < 0·10) were observed when urea was either totally or partially supplied as a ruminal pulse dose. The rumen N balance was negative for the control and when urea was totally supplied in the abomasum. The greatest microbial N production (P < 0·10) was obtained when urea was partially or totally supplied in the abomasum. Urea supplementation increased (P < 0·10) the amount of urea recycled to the gastrointestinal tract and the amount of urea-N returned to the ornithine cycle. The greatest (P < 0·10) amounts of urea-N used for anabolism were observed when urea was totally and continuously infused in the abomasum. The continuous abomasal infusion also resulted in the highest (P < 0·10) assimilation of microbial N from recycling. The continuous releasing of urea throughout day either in the rumen or abomasum is able to improve N accretion in the animal body, despite mechanism responsible for that being different.

Características produtivas de cabritos Saanen terminados com ureia na ração / Productive traits of young male Saanen goats finished with urea in the diet

Objetivou-se avaliar a inclusão de ureia na dieta de cabritos sobre o desempenho e características de carcaça. Foram utilizados 18 cabritos (150 dias de idade e 21 Kg de peso) distribuídos em dois grupos com dietas isoproteicas. Os animais do grupo controle (GC) foram alimentados com ração sem ureia na sua composição, enquanto os animais do outro grupo (GU) foram alimentados com ração com 1% da MS de ureia na base da matéria seca. Avaliou-se o ganho de peso médio (g/dia), biometrias corporais, assim como o peso e rendimento de carcaça nos animais. Não houve diferenças significativas em nenhuma das variáveis estudadas (p>0,05), como: ganho de peso (g/dia) (GU: 122,1 ± 11,89 vsGC: 132,9 ± 4,97), perímetro torácico (cm) (GU: 73,0 ± 1,2 vsGC: 74,5 ± 0,57), comprimento corporal (cm) (GU: 74,0 ± 1,42 vsGC: 73,67 ± 0,70), peso ao abate (kg) (GU: 34,39 ± 1,76 vsGC: 36,56 ± 0,96), rendimentos de carcaça quente (%) (GU: 47,37 ± 0,82 vsGC: 47,23 ± 0,72) e fria (GU: 45,64 ± 0,60 vsGC: 45,84 ± 0,70). Conclui-se que o uso de 1% de ureia na MS da dieta de caprinos machos jovem não afeta o desempenho dos animais e as características de carcaça.

The objective of this study was to evaluate the effect of inclusion of urea in the diet of goats on performance and carcass traits. Eighteen kids (150 days old and 21 kg of weight) were divided into two groups receiving isoprotein diets. The animals in the control group (CG) were fed ration without urea, while the animals in the urea group (UG) were fed ration with 1% urea on a dry matter basis. Average weight gain (g/day), body biometrics, and carcass weight and yield were evaluated in the animals. There were no significant differences in any of the variables studied (p>0.05): weight gain (g/day) (UG: 122.1 ± 11.89 vsCG: 132.9 ± 4.97), chest circumference (cm) (UG: 73.0 ± 1.2 vsCG: 74.5 ± 0.57), body length (cm) (UG: 74.0 ± 1.42 vsCG: 73.67 ± 0.70), slaughter weight (kg) (UG: 34.39 ± 1.76 vsCG: 36.56 ± 0.96), hot carcass yield (%) (UG: 47.37 ± 0.82 vsCG: 47.23 ± 0.72), or cold carcass yield (UG: 45.64 ± 0.60 vsCG: 45.84 ± 0.70). In conclusion, the addition of 1% urea in the DM to the diet of young male goats does not affect the performance of the animals or carcass traits.

Analysis of NH3-N Slow Release systems for fiber digestibility of low-quality forage: in vitro approach

Urea is a common non-protein supplement used in ruminant feed; however, excessive consumption may lead to poisoning by NH3. Although the slow release of urea into the rumen has shown to be an essential aspect for ruminant feed, to date only a few studies have addressed this matter. In this study we examined the influence of five different NH3-N slow release systems based on clay-urea nanocomposites on the fiber digestibility of low-quality forage (sugarcane straw) in vitro. Physical properties of nanocomposites were evaluated and their effects on digestibility were tested in vitro using pristine urea as a positive control (level of 1 % of DM of sugarcane straw sample) and sugarcane (with no additives) as a negative control. Ammonia release and digestibility were evaluated at 12, 24, 36, 48, 72 and 96-h. Generally, all nanocomposites increased (p < 0.05) digestibility of fiber over control under all the conditions stipulated, but the samples with hydrogel content were more expressive. We concluded that an ideal release rate and optimum environment for microbial synthesis are necessary to maximize the digestion of sugarcane.

Protein with increasing levels of urea in the diet of dairy cows at pasture / Substituição da proteína bruta por níveis crescentes de ureia na dieta de vacas leiteiras em pastagem

Este estudo teve como objetivo avaliar o efeito da substituição da proteína bruta da dieta por níveis crescentes de ureia nos parâmetros digestivos, produtivos e econômicos de vacas leiteiras mestiças em lactação, em condições de pastejo (Urochloa brizantha cv. Xaraés). Cinco vacas mestiças Holandês x Zebu foram distribuídas em delineamento quadrado latino5 x 5, com cinco períodos experimentais de 21 dias cada. Os níveis de reposição de proteína bruta na dieta por ureia foram de 0, 7%, 14%, 21% e 28%. A ingestão de matéria seca, proteína bruta, fibra em detergente neutro e nutrientes digestíveis totais e o coeficiente de digestibilidade, não foram afetados pelo aumento dos níveis de ureia (p>0,05), exceto pela ingestão de carboidratos não fibrosos que aumentaram linearmente com os níveis suplementares de ureia (p<0,05). A produção de leite, a sua composição química, a eficiência alimentar, o peso corporal e a eficiência no uso de nitrogênio não apresentaram diferença significativa (p>0,05) para vacas alimentadas pelo aumento dos níveis de ureia. Os indicadores financeiros (margem bruta, margem líquida, rentabilidade e taxa de retorno) foram positivos, superando as despesas operacionais e o custo operacional total. A substituição parcial da proteína bruta da dieta pela ureia em vacas leiteiras em lactação sob pastejo não interfere nos parâmetros produtivos. Os resultados deste estudo demonstram que a substituição de 28% da proteína bruta da dieta por ureia pode ser feita para reduzir os custos de alimentação sem impacto negativo no desempenho de vacas em lactação mantidas em pastagens de grama tropical.(AU)

This study aimed to evaluate the effect of replacing dietary crude protein with increasing levels of urea on the digestive, productive and economic parameters of crossbred midlactation dairy cows under grazing conditions (Urochloa brizantha cv. Xaraés). Five crossbred cows (Holstein x Zebu) were distributed in a Latin square design (5 x 5) at five experimental periods of 21 days each. Replacement levels of dietary crude protein by urea were 0%, 7%, 14%, 21% and 28%. The intakes of dry matter, crude protein, neutral detergent fiber, and total digestible nutrients, as well as the coefficient of digestibility, were not affected by increasing levels of urea (p>0.05), except for the intake of non-fibrous carbohydrates that increased linearly with supplemental urea levels (p<0.05). Milk yield and chemical composition, feed efficiency, body weight, and nitrogen use efficiency did not show a significant difference (p>0.05) for cows fed by increasing levels of urea. The financial indicators (gross margin, net margin, profitability, and rate of return) were positive, exceeding operating expenses and the total operating cost. The partial replacement of dietary crude protein by urea in mid-lactation dairy cows under grazing conditions does not interfere with the productive parameters. The results of this study demonstrate that replacing 28% of dietary crude protein by urea could be done in order to reduce feeding costs without negative impact on the performance of lactating cows grazing tropical grass pastures.(AU)

Analysis of NH3-N Slow Release systems for fiber digestibility of low-quality forage: in vitro approach

Urea is a common non-protein supplement used in ruminant feed; however, excessive consumption may lead to poisoning by NH3. Although the slow release of urea into the rumen has shown to be an essential aspect for ruminant feed, to date only a few studies have addressed this matter. In this study we examined the influence of five different NH3-N slow release systems based on clay-urea nanocomposites on the fiber digestibility of low-quality forage (sugarcane straw) in vitro. Physical properties of nanocomposites were evaluated and their effects on digestibility were tested in vitro using pristine urea as a positive control (level of 1 % of DM of sugarcane straw sample) and sugarcane (with no additives) as a negative control. Ammonia release and digestibility were evaluated at 12, 24, 36, 48, 72 and 96-h. Generally, all nanocomposites increased (p < 0.05) digestibility of fiber over control under all the conditions stipulated, but the samples with hydrogel content were more expressive. We concluded that an ideal release rate and optimum environment for microbial synthesis are necessary to maximize the digestion of sugarcane.(AU)

Protein with increasing levels of urea in the diet of dairy cows at pasture / Substituição da proteína bruta por níveis crescentes de ureia na dieta de vacas leiteiras em pastagem

Este estudo teve como objetivo avaliar o efeito da substituição da proteína bruta da dieta por níveis crescentes de ureia nos parâmetros digestivos, produtivos e econômicos de vacas leiteiras mestiças em lactação, em condições de pastejo (Urochloa brizantha cv. Xaraés). Cinco vacas mestiças Holandês x Zebu foram distribuídas em delineamento quadrado latino5 x 5, com cinco períodos experimentais de 21 dias cada. Os níveis de reposição de proteína bruta na dieta por ureia foram de 0, 7%, 14%, 21% e 28%. A ingestão de matéria seca, proteína bruta, fibra em detergente neutro e nutrientes digestíveis totais e o coeficiente de digestibilidade, não foram afetados pelo aumento dos níveis de ureia (p>0,05), exceto pela ingestão de carboidratos não fibrosos que aumentaram linearmente com os níveis suplementares de ureia (p0,05) para vacas alimentadas pelo aumento dos níveis de ureia. Os indicadores financeiros (margem bruta, margem líquida, rentabilidade e taxa de retorno) foram positivos, superando as despesas operacionais e o custo operacional total. A substituição parcial da proteína bruta da dieta pela ureia em vacas leiteiras em lactação sob pastejo não interfere nos parâmetros produtivos. Os resultados deste estudo demonstram que a substituição de 28% da proteína bruta da dieta por ureia pode ser feita para reduzir os custos de alimentação sem impacto negativo no desempenho de vacas em lactação mantidas em pastagens de grama tropical.

This study aimed to evaluate the effect of replacing dietary crude protein with increasing levels of urea on the digestive, productive and economic parameters of crossbred midlactation dairy cows under grazing conditions (Urochloa brizantha cv. Xaraés). Five crossbred cows (Holstein x Zebu) were distributed in a Latin square design (5 x 5) at five experimental periods of 21 days each. Replacement levels of dietary crude protein by urea were 0%, 7%, 14%, 21% and 28%. The intakes of dry matter, crude protein, neutral detergent fiber, and total digestible nutrients, as well as the coefficient of digestibility, were not affected by increasing levels of urea (p>0.05), except for the intake of non-fibrous carbohydrates that increased linearly with supplemental urea levels (p0.05) for cows fed by increasing levels of urea. The financial indicators (gross margin, net margin, profitability, and rate of return) were positive, exceeding operating expenses and the total operating cost. The partial replacement of dietary crude protein by urea in mid-lactation dairy cows under grazing conditions does not interfere with the productive parameters. The results of this study demonstrate that replacing 28% of dietary crude protein by urea could be done in order to reduce feeding costs without negative impact on the performance of lactating cows grazing tropical grass pastures.

Sugarcane and cactus cladodes plus urea: a new option for Girolando dairy heifers

This study was performed to identify the ideal amount of concentrate required for a diet based on cactus cladodes, sugarcane, and urea used to feed heifers. Twenty Girolando heifers (160±8.39 kg) were randomly distributed into four experimental treatments with 0, 0.40, 0.80, or 1.20 kg day−1 of concentrate. The basal diet contained [on dry matter (DM) basis] 38.1% sugarcane, 56.5% cactus cladodes [ Opuntia stricta (Haw). Haw.], 0.5% common salt, 1.1% mineral mixture, and 3.8% urea plus ammonium sulfate. The concentrate contained [on DM basis] 87% corn meal and 13% soybean meal. The basal diet and the concentrate were formulated to provide 13% crude protein (CP). The intake of DM (4.34-4.96 kg day−1), organic matter (3.96-4.98 kg day−1), CP (0.57-0.64 kg day−1), non-fibrous carbohydrates (2.20-2.61 kg day−1), and metabolizable energy (10.3-12.4 Mcal day−1) increased linearly with concentrate amount. Final body weight (196-224 kg), total body weight gain (36.9-61.2 kg), and average daily body weight gain (0.51-0.85 kg day−1) increased linearly with concentrate amount. The nitrogen balance was positive and increased linearly (54.8-62.3 g day−1) with concentrate amount. Based on the data, we recommend supplying six-month-old Girolando heifers (160 kg body weight) 1.20 kg concentrate day−1 added to a diet based on sugarcane and cactus cladodes plus urea for better productive and economic performance.(AU)

Encapsulated nitrate replacing soybean meal changes in vitro ruminal fermentation and methane production in diets differing in concentrate to forage ratio.

The objective of this study was to evaluate the effects of using encapsulated nitrate product (ENP) replacing soybean meal in diets differing in concentrate to forage ratio on ruminal fermentation and methane production in vitro using a semi-automatic gas production technique. Eight treatments were used in a randomized complete design with a 2 × 4 factorial arrangement: two diet (20C:80F and 80C:20F concentrate to forage ratio) and four levels of ENP addition (0%, 1.5%, 3.0%, and 4.5% of DM) replacing soybean meal. There was a diet × ENP interaction (p = 0.02) for methane production. According to ENP addition, diets with 80C:20F showed more intense reduction on methane production that 20C:80F. A negative linear effect was observed for propionate production with ENP addition in diet with 80C:20F and to the relative abundance of methanogens Archaea, in both diet. The replacement of soybean meal by ENP in levels up to 3% of DM inhibited methane production due to a reduction in the methanogens community without affecting the organic matter degradability. However, ENP at 4.5% of DM level affected fiber degradability, abundance of cellulolytic bacteria, and propionic acid production, indicating that this level of inclusion is not recommended for ruminant production.

Cactus cladodes associated with urea and sugarcane bagasse: an alternative to conserved feed in semi-arid regions.

The objective of this study was to evaluate the nutritional value of different roughage sources as an exclusive feed for goats and sheep from the determination of nutrient intake and digestibility. Five goats and five sheep were used and arranged in a double 5 × 5 Latin square design. Treatments consisted of cactus Nopalea cochenillifera (L.) Salm-Dyck cladodes (Nopalea) + urea + sugarcane bagasse (NUB), cactus Opuntia stricta (Haw.) Haw cladodes (Opuntia) + urea + sugarcane bagasse (OUB), Tifton hay (TH), maize silage (MS), and forage sorghum silage (SS). Dry matter (DM) and crude protein (CP) intakes of NUB were greater than SS (0.620 and 0.058 versus 0.416 and 0.040 kg/day). Metabolizable energy (ME) intake was higher for NUB (1.52 Mcal/day). The DM digestibility did not change between the roughages (59%). The NUB, OUB, and MS organic matter digestibility (OMD; 62.4%) were greater than that of SS (57.4%). The roughage consisting of cactus cladodes associated with urea and sugarcane bagasse presented a greater nutritional value, similar to MS and TH, and higher than SS. Cactus cladodes associated with urea and sugarcane bagasse are recommended as an alternative to conserved feed.