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When we refers to animals of production, the considerations that involve knowledge about the behavior of these animals are even more evident, since in addition to impacting their development, it impacts society as a whole and ends up also impacting the economy. of the country, since these animals will provide society with products rich in protein of high biological value, which are essential for the fullness of human beings' quality of life. The proteins of animal origin most commercialized and consumed by human beings come from pigs, poultry, cattle, but as the final product from their creation is directly related to the management during the creation of the animals, and this is related to the behavior of the animals. Animals, which in turn is a decisive variable in the consumption of products by humans, animal husbandry systems must be allied to animal welfare, the latter being closely associated with the understanding of natural habits related to each species and animal category to be produced. However, not all agents of society, whose work culminates in the production of food of animal origin, have the knowledge and know how to proceed to monitor this issue closely. In this sense, the objective was to systematically investigate how production systems interfere with the performance of production animals and how management can affect stress levels and welfare. Cuando el tema se refiere a animales de interés zootécnico, las consideraciones que involucran el conocimiento sobre el comportamiento de estos animales son aún más evidentes, ya que además de impactar en su desarrollo, impacta a la sociedad en su conjunto y termina impactando también en la economía de la misma. país, ya que estos animales proporcionarán a la sociedad productos ricos en proteínas de alto valor biológico, indispensables para la plenitud de la calidad de vida del ser humano. Las proteínas de origen animal más comercializadas y consumidas por el ser humano provienen de cerdos, aves, bovinos, pero como el producto final desde su creación está directamente relacionado con el manejo durante la creación de los animales, y esto está relacionado con el comportamiento de los mismos. animales, que a su vez es una variable determinante en el consumo de productos por parte del ser humano, los sistemas de cría de animales deben estar aliados al bienestar animal, estando este último estrechamente asociado a la comprensión de los hábitos naturales relacionados con cada especie y categoría animal a ser producido. Sin embargo, no todos los agentes de la sociedad, cuya labor culmina en la producción de alimentos de origen animal, tienen los conocimientos y saben cómo proceder para monitorear de cerca este tema. En este sentido, el objetivo fue investigar sistemáticamente cómo los sistemas de producción interfieren en el desempeño de los animales de producción y cómo el manejo puede impactar los niveles de estrés y el bienestar. Quando o assunto se refere a animais de interesse zootécnico, as considerações que envolvem o conhecimento sobre o comportamento desses animais são ainda mais evidentes, uma vez que além de impactar o desenvolvimento destes, impacta a sociedade como um todo e acaba por impactar também a economia do país, visto que estes animais proverão à sociedade produtos ricos em proteína de alto valor biológico, os quais são essenciais para a plenitude da qualidade de vida dos seres humanos. As proteínas de origem animal mais comercializadas e consumidas pelos seres humanos são provenientes de suínos, aves, bovinos, porém como o produto final oriundo da criação destes se relaciona diretamente com o manejo durante a criação dos animais e este, se relaciona com o comportamento dos animais, que por sua vez é variável decisiva no consumo de produtos pelos seres humanos, os sistemas de criação de animais devem ser aliados ao bem-estar animal, sendo este último associado intimamente ao entendimento dos hábitos naturais relacionados à cada espécie e categoria animal a ser produzida. Porém, nem todos os agentes da sociedade, cujo trabalho culmina na produção de alimentos de origem animal, possuem conhecimento e sabemomo proceder para acompanhar esta questão de perto. Neste sentido, o objetivou-se averiguar de maneira sistêmica como os sistemas de produção interferem no desempenho de animais de produção e como o manejo pode impactar nos níveis de estresse e bem-estar.

Aquaponics emerges as an alternative for food production, which is managed by the principle of sustainable production, with a view of respect for the environment and comply with the current demands of a more conscious and demanding consumer market. This production refers to the integration between fish farming and the cultivation of hydroponic vegetables and/or leafy vegetables. The present study aimed to clearly and objectively demonstrate to the population the possibility of producing fish and vegetables in small spaces, especially in urban centers. The model fish species was tambaqui (Colossoma macropomum) and the model leafy vegetables were lettuce (Lactuca sativa), arugula (Eruca vesicaria ssp. Sativa), chicory (Cichorium intybus sub sp. Intybus) and watercress (Nasturtium officinale). The collected data showed good results regarding the growth of fish and leafy vegetables, providing information on the development and cultivation in low-cost urban aquaponic systems. We believe that these results will be of great value to the general population and that they will increase interest in this modality of healthy and low-coast food production. La acuaponía surge como una alternativa para la producción de alimentos, la cual se maneja bajo el principio de producción sustentable, con una visión de respeto al medio ambiente y atendiendo las demandas actuales de un mercado consumidor más consciente y exigente. Esta técnica de producción hace referencia a la integración entre la piscicultura y el cultivo de hortalizas y/o vegetales hidropónicos. El presente estudio tuvo como objetivo demostrar de manera clara y objetiva a la población la posibilidad de producir pescado y hortalizas en espacios reducidos, especialmente en los centros urbanos. La especie de pez modelo fue el tambaqui (Colossoma macropomum) y las hortalizas modelo fueron la lechuga (Lactuca sativa), la rúcula (Eruca vesicaria ssp. Sativa), la achicoria (Cichorium intybus sub sp. Intybus) y el berro (Nasturtium officinale). Los datos recopilados mostraron buenos resultados en cuanto al crecimiento de peces y vegetales, brindando información sobre el desarrollo y cultivo de vegetales y peces en sistemas acuapónicos urbanos de bajo costo. Creemos que estos resultados serán de gran valor para la población en general y aumentarán el interés por esta modalidad de producción de alimentos saludables y bajo costo. A aquaponia surge como uma alternativa para produção de alimento, a qual é gerida pelo princípio da produção sustentável, com uma visão de respeito ao meio ambiente e atendimento as atuais demandas de um mercado consumidor mais consciente e exigente. Essa técnica de produção se refere à integração entre a criação de peixes, e o cultivo de vegetais e/ou hortaliças hidropônicas. O presente estudo teve como objetivo demonstrar de maneira clara e objetiva para a população a possibilidade de produzir peixes e hortaliças em pequenos espaços, principalmente nos centros urbanos. A espécie de peixe modelo foi o tambaqui (Colossoma macropomum) e as hortaliças modelos foram a alface (Lactuca sativa), a rúcula (Eruca vesicaria ssp. Sativa), o almeirão (Cichorium intybus sub sp. Intybus) e o agrião (Nasturtium officinale). Os dados coletados mostraram bons resultados quanto ao crescimento dos peixes e das hortaliças, trazendo informação sobre o desenvolvimento e cultivo em sistemas aquapônicos urbanos de baixo custo. Acreditamos que esses resultados serão de grande valia para a população em geral e que os mesmos possam aumentar o interesse nessa modalidade de produção de alimentos saudáveis e com baixo custo.

Quando o assunto se refere a animais de interesse zootécnico, as considerações que envolvem o conhecimento sobre o comportamento desses animais são ainda mais evidentes, uma vez que além de impactar o desenvolvimento destes, impacta a sociedade como um todo e acaba por impactar também a economia do país, visto que estes animais proverão à sociedade produtos ricos em proteína de alto valor biológico, os quais são essenciais para a plenitude da qualidade de vida dos seres humanos. As proteínas de origem animal mais comercializadas e consumidas pelos seres humanos são provenientes de suínos, aves, bovinos, porém como o produto final oriundo da criação destes se relaciona diretamente com o manejo durante a criação dos animais e este, se relaciona com o comportamento dos animais, que por sua vez é variável decisiva no consumo de produtos pelos seres humanos, os sistemas de criação de animais devem ser aliados ao bem-estar animal, sendo este último associado intimamente ao entendimento dos hábitos naturais relacionados à cada espécie e categoria animal a ser produzida. Porém, nem todos os agentes da sociedade, cujo trabalho culmina na produção de alimentos de origem animal, possuem conhecimento e sabemomo proceder para acompanhar esta questão de perto. Neste sentido, o objetivou-se averiguar de maneira sistêmica como os sistemas de produção interferem no desempenho de animais de produção e como o manejo pode impactar nos níveis de estresse e bem-estar.

A aquaponia surge como uma alternativa para produção de alimento, a qual é gerida pelo princípio da produção sustentável, com uma visão de respeito ao meio ambiente e atendimento as atuais demandas de um mercado consumidor mais consciente e exigente. Essa técnica de produção se refere à integração entre a criação de peixes, e o cultivo de vegetais e/ou hortaliças hidropônicas. O presente estudo teve como objetivo demonstrar de maneira clara e objetiva para a população a possibilidade de produzir peixes e hortaliças em pequenos espaços, principalmente nos centros urbanos. A espécie de peixe modelo foi o tambaqui (Colossoma macropomum) e as hortaliças modelos foram a alface (Lactuca sativa), a rúcula (Eruca vesicaria ssp. Sativa), o almeirão (Cichorium intybus sub sp. Intybus) e o agrião (Nasturtium officinale). Os dados coletados mostraram bons resultados quanto ao crescimento dos peixes e das hortaliças, trazendo informação sobre o desenvolvimento e cultivo em sistemas aquapônicos urbanos de baixo custo. Acreditamos que esses resultados serão de grande valia para a população em geral e que os mesmos possam aumentar o interesse nessa modalidade de produção de alimentos saudáveis e com baixo custo.

The objective of this work was to evaluate the effects of supplementation with nitrogen and starch on the nutritional performance of grazing cattle during the rainy season. Five rumen cannulated Nellore steers, averaging 211 kg of body weight (BW), were used. Animals grazed on five signal grass paddocks. Five treatments were evaluated: control (forage only), ruminal supplementation with nitrogen at 1 g of crude protein (CP)/kg BW, ruminal supplementation with starch at 2.5 g/kg BW, supplementation with nitrogen (1 g CP/kg BW) and starch (2.5 g/kg BW), and supplementation with nitrogen (1 g CP/kg BW) and a mixture of corn starch and nitrogenous compounds (2.5 g/kg BW), thereby resulting in an energy part of the supplement with 150 g CP/kg of dry matter (DM). This last treatment was considered an additional treatment. The experiment was carried out according to a 5 ×5 Latin square design following a 2×2+1 factorial arrangement (with or without nitrogen, with or without starch, and the additional treatment). Nitrogen supplementation did not affect (p>0.10) forage intake. Starch supplementation increased (p0.10), NB obtained with nitrogen plus starch supplementation was greater than NB obtained with either nitrogen or starch exclusive supplementation. Supplementation with starch and nitrogen to beef cattle grazing during the rainy season can possibly improve digestion and nitrogen retention in the animal..

The objective of this work was to evaluate the effects of protein and/or starch supplementation on the nutritional performance of cattle grazing on low-quality tropical forage. Five crossbred steers (Holstein × Gyr) with an average body weight (BW) of 397 kg that were fitted with ruminal and abomasal cannulae were used. The animals were kept in individual signal-grass (Bracharia decumbens) paddocks. Five treatments were evaluated: 1 - control (without supplementation); 2 - supplementation with 1 g of crude protein (CP) per kg of BW; 3 - supplementation with 2.5 g of starch per kg of BW; 4 - supplementation with CP and starch as described for treatments 2 and 3; and 5 - supplementation as described for treatment 4 but replacing the corn starch with a mixture of corn starch and nitrogenous compounds, thereby resulting in an energy supplement of 150 g CP/kg of dry matter. The experiment was performed according to a 5 × 5 Latin square design in a 2 × 2 + 1 factorial arrangement. The forage intake was not affected by any of the factors evaluated in this study. The production of microbial nitrogen in the rumen was not affected by nitrogen or starch supplementation. The apparent nitrogen balance was only increased when both starch and nitrogen were supplied. Supplementation with both starch and nitrogenous compounds for cattle grazing on low-quality tropical forage is characterized by an interactive metabolic effect that increases nitrogen accretion by the animals.

Submitted by Guilherme Lemeszenski (guilherme@nead.unesp.br) on 2013-08-22T19:07:52Z No. of bitstreams: 1 S1516-35982012000200023.pdf: 46654 bytes, checksum: 30965eba025aed84fff84c6dd7ef8ce0 (MD5) Made available in DSpace on 2013-08-22T19:07:53Z (GMT). No. of bitstreams: 1 S1516-35982012000200023.pdf: 46654 bytes, checksum: 30965eba025aed84fff84c6dd7ef8ce0 (MD5) Previous issue date: 2012-02-01 Made available in DSpace on 2013-09-30T20:12:37Z (GMT). No. of bitstreams: 2 S1516-35982012000200023.pdf: 46654 bytes, checksum: 30965eba025aed84fff84c6dd7ef8ce0 (MD5) S1516-35982012000200023.pdf.txt: 26582 bytes, checksum: 58a4225e0eb7844e6898ca66458e29f7 (MD5) Previous issue date: 2012-02-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T15:18:22Z No. of bitstreams: 2 S1516-35982012000200023.pdf: 46654 bytes, checksum: 30965eba025aed84fff84c6dd7ef8ce0 (MD5) S1516-35982012000200023.pdf.txt: 26582 bytes, checksum: 58a4225e0eb7844e6898ca66458e29f7 (MD5) Made available in DSpace on 2014-05-20T15:18:22Z (GMT). No. of bitstreams: 2 S1516-35982012000200023.pdf: 46654 bytes, checksum: 30965eba025aed84fff84c6dd7ef8ce0 (MD5) S1516-35982012000200023.pdf.txt: 26582 bytes, checksum: 58a4225e0eb7844e6898ca66458e29f7 (MD5) Previous issue date: 2012-02-01 The objective of this study was to determine requirements of calcium (Ca), phosphorus (P), magnesium (Mg), potassium (K) and sodium (Na) for grazing zebu bovines. The experiment area was composed of Brachiaria decumbens paddocks. Twenty-seven non-castrated animals, with initial live weight of 311.0 kg and at an average age of 14 months were used. Three animals were slaughtered, after adaptation period, so they were used as control for estimates of empty body weight and initial body composition of animals in the experiment. Out of the 24 remaining animals, four were sent to the maintenance group with restrict grazing time to limit energy intake close to the maintenance level. The other 20 animals were distributed in four treatments: mineral mixture, self-control intake and three-times-a-week-offer frequency (offered on Mondays, Wednesdays and Fridays) and daily. Concentrations of all studied macro elements in empty body and empty body gain decreased as live weight increased. The ratios obtained for g Ca/100 g of retained protein and g P/100 g of retained protein were 9.18 and 4.72, respectively. Total dietary requirement of calcium was lower than the one recommended by NRC (2000), but P requirement was very close to that. UFMT ICAA UFV DZO UNESP UNESP

Objetivou-se avaliar os efeitos da suplementação com compostos nitrogenados sobre o consumo e a digestibilidade em bovinos em pastejo durante o período seco do ano. Foram utilizados cinco novilhos mestiços Holandês × Zebu, com peso vivo (PV) médio inicial de 236 kg, mantidos individualmente em piquetes de Brachiaria decumbens Stapf. (0,34 ha). Utilizou-se delineamento em quadrado latino 5 × 5, com cinco níveis de suplementação (0; 0,35; 0,75; 1,05; e 1,40 g de proteína bruta (PB)/kg PV) e cinco períodos experimentais. Como fonte de compostos nitrogenados empregou-se mistura de ureia, sulfato de amônia e albumina (4,5:0,5:1,0, respectivamente). Os níveis médios de PB nas dietas foram de 7,39; 8,92; 10,98; 12,55 e 13,62%, com base na matéria seca (MS), para os respectivos níveis de suplementação. Verificou-se relação do tipo linear-response-plateau (LRP) entre as estimativas de consumo e os níveis de PB da dieta. O comportamento do tipo LRP permitiu evidenciar aumento no consumo até níveis próximos a 9% de PB, com base na MS, a partir do qual houve estabilidade das estimativas. Os coeficientes de digestibilidade total e ruminal da MS e da fibra em detergente neutro e o nível de nutrientes digestíveis totais na dieta apresentaram relação linear e positiva com os níveis de PB na dieta. A concentração de nitrogênio amoniacal ruminal (NAR) aumentou de forma linear e positiva de acordo com os níveis de PB na dieta, com valor estimado de 8,00 mg NAR/dL, equivalente à otimização do consumo voluntário. A suplementação com compostos nitrogenados em quantidades que permitam elevar o teor de PB da dieta a níveis próximos a 9% proporciona otimização na utilização de forragem de baixa qualidade por bovinos em pastejo. The objective of this work was to evaluate the effects of supplementation with nitrogenous compounds on intake and digestibility in cattle under grazing during dry season. It was used five Holstein × Zebu steers with average initial live weight of 236 kg, kept in five Brachiaria decumbens Stapf. paddocks (0.34 ha). The experiment was carried out according to a 5 × 5 Latin square design, with five supplementation levels and five experimental periods. The supplementation levels were the following: 0; 0.35; 0.70; 1.05, and 1.40 g of crude protein/kg live weight. A mixture of urea, ammonium sulfate and albumin (4.5:0.5:1.0, respectively) was used as nitrogen supplement. The average crude protein levels in the diet were 7.39; 8.92; 10.98; 12.55; and 13.62%, as dry matter basis, for the respective supplementation levels. Linear-response-plateau relationships were observed between intake estimates and diet crude protein levels. The linear-response-plateau pattern showed that intake was increased up to crude protein levels close to 9%, as dry matter basis. The estimates became unchangeable from this level. The total and ruminal digestibility coefficients of dry matter and neutral detergent fiber, and diet level of total digestible nutrients presented a positive linear pattern according to diet crude protein levels. The rumen ammonia nitrogen concentration was linearly increased by diet crude protein levels. This variable assumed the value of 8.00 mg/dL when the intake estimates reached the maximum values. Supplementation with nitrogen compounds in quantities that raise the crude protein content in the diet to levels close to 9% optimizes the use of low-quality forage by cattle under grazing.

The effects of supplementation with nitrogenous compounds on intake, digestibility, and microbial protein synthesis in cattle fed low-quality tropical forage were assessed. Five rumen fistulated crossbred Holstein x Gir heifers were used, with initial average live weight of 180 +/- 21 kg. Signal grass (Brachiaria decumbens) hay (48.6 g kg(-1) of crude protein (CP), on a dry matter (DM) basis) was used as roughage. Five treatments were defined according to nitrogen supplementation level (0, 20, 40, 60, and 80 g of CP kg(-1) above the CP level of the hay). A mixture of urea, ammonium sulfate, and albumin at the ratios of 4.5:0.5:1.0, respectively, was used as nitrogen source. The experiment consisted of five experimental periods, according to a 5 x 5 Latin square design. The average CP contents in the diets were 51.9, 71.1, 86.0, 116.7, and 130.2 g kg(-1), on a DM basis. A quadratic effect was detected (P0.10) of the CP levels in the diets on DM and neutral detergent fiber intake (kg/day), with maximum response at the levels of 102.4 and 100.5 g CP kg(-1) DM, respectively. The average daily concentration of rumen ammonia nitrogen showed increasing linear pattern (P0.01) as function of CP levels in the diet, with estimated value of 9.64 mg dL(-1) equivalent to the maximum DM intake. Microbial nitrogen flow in the intestine was linearly and positively related (P0.01) with the CP levels in the diet.

Avaliaram-se as dinâmicas de trânsito e degradação da fibra em detergente neutro (FDN) em bovinos alimentados com forragem tropical de baixa qualidade e compostos nitrogenados. Foram utilizadas cinco novilhas Holandês x Zebu fistuladas no rúmen. A alimentação volumosa basal dos animais foi constituída por feno de capim-braquiária (Brachiaria decumbens Stapf.), com 5,08% de proteína bruta (PB), com base na matéria seca (MS), fornecido ad libitum. Os cinco tratamentos avaliados foram definidos de acordo com o nível de suplementação proteica (0, 3, 5, 7 e 9 pontos percentuais acima do nível de PB da forragem). Como fonte de compostos nitrogenados, empregou-se mistura de ureia:sulfato de amônia:albumina (4,5:0,5:1,0). O experimento foi estruturado segundo delineamento em quadrado latino 5 x 5. Os níveis médios de PB nas dietas foram de 5,28; 8,08; 9,82; 11,87 e 13,63%, com base na MS. Verificou-se elevação linear (P

The objective of this work was to evaluate the effects of nitrogenous compounds and/or starch supplementation on the intake, digestibility and rumen dynamics of neutral detergent fibre (NDF) in cattle fed low-quality tropical forage. Four crossbred heifers (Holstein × Zebu) with a body weight 231.9 ± 15.5 kg and fitted with ruminal cannulae were used. The forage fed to the animals consisted of low-quality signal grass (Brachiaria decumbens Stapf.) hay, with an average crude protein (CP) level of 51.6 g/kg, on a dry matter (DM) basis. Four treatments were evaluated: control, without supplementation; supplementation with nitrogenous compounds (CP of the roughage was raised to 100 g/kg), on a DM basis; supplementation with starch at a ratio of 200 g/kg DM of roughage; and supplementation with nitrogenous compounds and starch as described above. A mixture of urea, ammonium sulphate and albumin was used as a source of nitrogenous compounds at a ratio of 4.5:0.5:1.0. The experiment was carried out according to a 4 × 4 Latin square design in a 2 × 2 factorial arrangement. There was a positive effect of the nitrogenous compound supplementation on the DM and NDF intake (P < 0.01). In contrast, starch supplementation decreased forage intake (P < 0.10). Nitrogen supplementation increased the digestibility coefficient of DM and NDF (P < 0.05). Supplementation with nitrogen and starch together increased the microbial assimilation of nitrogenous compounds in the rumen (P < 0.05). We observed that nitrogen supplementation increased the estimated weighted degradation rate of NDF by 14.8%, whilst starch supplementation decreased this rate by 32.5%.

This work aimed to parameterize the ruminal degradation of neutral detergent fibre (NDF) from low-quality tropical forage using Michaelis–Menten kinetics. The intake, rumen outflow (L), fractional degradation rate (kd), discrete lag (LAG) and effective degradability (ED) of NDF, and the microbial flow of nitrogenous compounds into the small intestine (Nmic) were assessed in two 5 × 5 Latin square experiments by using five Holstein × Zebu heifers cannulated in the rumen. The experiments were carried out sequentially and the treatments were formed by increasing the level of supplementation with nitrogenous compounds. A low-quality signal grass (Brachiaria decumbens) hay was used as roughage. The nitrogen supplement was a mixture of urea, ammonium sulfate and albumin, at the ratios of 4.5:0.5:1.0, respectively. The crude protein contents in the diets ranged from 51.9 to 136.3 g/kg of dry matter. The rumen ammonia nitrogen (RAN) concentration was used as an independent variable. The NDF intake, L and Nmic showed a quadratic pattern (P < 0.05) as a function of RAN concentration, and the critical points (maximum responses) were observed with 15.17, 16.28, and 14.52 mg of RAN/dL of rumen fluid, respectively. On the other hand, ED and LAG presented a linear-response-plateau (P < 0.05) according to the RAN concentration, with break points close to 8 mg/dL for ED (maximum estimate) and LAG (minimum estimate). The RAN concentrations to optimize NDF degradation and intake were defined as 8 and 15 mg/dL, respectively. This difference between estimates appears to be due to a better adequacy of the metabolizable protein:metabolizable energy ratio in the animal metabolism, which increases the animal intake even after the rumen NDF degradation has been optimized. This observation was supported by Nmic pattern. An adapted Michaelis–Menten model was applied to the data, where RAN was the independent variable and kd the dependent variable. The relationship between these variables was found to be significant by using the Hanes–Woolf plot (P < 0.01). Based on this model, the rate of NDF degradation as a function of RAN concentration indicates that fibre degradation in the rumen could be considered a second order process. In this context, the RAN concentration of 8 mg/dL was assumed as the limit where zero order (below limit) and first order (above limit) reactions become predominant for NDF degradation in the rumen.

Objetivou-se avaliar os efeitos de compostos nitrogenados suplementares sobre o consumo, a digestibilidade e a síntese de proteína microbiana em bovinos alimentados com forragem tropical de baixa qualidade. Foram utilizadas cinco novilhas mestiças Holandês × Zebu, com peso vivo médio de 209 kg, fistuladas no rúmen. O volumoso consistiu de feno de capim-braquiária (Brachiaria decumbens Stapf.) (5,08% de proteína bruta (PB), com base na matéria seca), fornecido à vontade. Os cinco tratamentos avaliados foram definidos de acordo com o nível de suplementação proteica (0, 3, 5, 7 e 9 pontos percentuais acima do nível de PB da forragem). Como fonte de compostos nitrogenados, empregou-se mistura de ureia, sulfato de amônia e albumina, nas proporções de 4,5:0,5:1,0, respectivamente. O experimento constou de cinco períodos experimentais, segundo delineamento em quadrado latino 5 × 5. Os níveis médios de PB observados nas dietas foram de 5,28; 8,08; 9,82; 11,87 e 13,63%, com base na matéria seca (MS). Verificou-se efeito quadrático dos níveis de PB na dieta sobre os consumos de MS, matéria orgânica (MO) e fibra em detergente neutro (FDN) (kg/dia), com respostas máximas nos níveis de 10,83%, 10,78% e 10,37% de PB, respectivamente. Os coeficientes de digestibilidade da MO e FDN apresentaram relação do tipo linear-response-plateau com os níveis de PB na dieta com início de platô (resposta máxima) em 7,93 e 7,55% de PB, respectivamente. A concentração média diária de nitrogênio amoniacal ruminal apresentou comportamento linear crescente em função dos níveis de PB da dieta, com valor estimado de 15,33 mg/dL, equivalente ao máximo consumo de MS. A avaliação da relação entre consumo de nitrogênio e fluxo intestinal de nitrogênio microbiano indica que as estimativas dessas variáveis tornam-se equivalentes no nível de 7,13% de PB na dieta. The objective of this study was to evaluate the effects of supplementation with nitrogenous compounds on intake, digestibility, and rumen microbial synthesis in cattle fed low-quality tropical forage. Five crossbred heifers, averaging 209 kg and fitted with ruminal fistulla, were used. The animals were fed ad libitum with signal grass (Brachiaria decumbens Stapf.) hay, which had crude protein (CP) content of 5.08%, as dry matter (DM) basis. The five treatments were defined according to the increasing level of CP in the diet (0, 3, 5, 7, and 9 percentile points above the forage CP level). The supplement consisted of the following nitrogen sources: urea, ammonium sulfate and albumin (4.5:0.5:1.0, respectively). The experiment was carried out according to a 5 × 5 Latin square design, with five experimental periods. The average CP levels in the diets were: 5.28, 8.08, 9.82, 11.87, and 13.63% on DM basis. The intakes of DM, organic matter (OM), and neutral detergent fiber (NDF) showed a quadratic response according to CP levels in the diet, with maximum responses at 10.83%, 10.78%, and 10.37% CP, respectively. The digestibility coefficients of OM and NDF showed a linear-response-plateau response according to CP levels, with the plateau beginning (maximum response) at 7.93% and 7.55% CP, respectively. The average daily concentration of rumen ammonia nitrogen (RAN) was positively related with CP levels. The RAN estimate associated with the maximum DM intake was 15.33 mg/dL. It was observed that intestinal flow of microbial nitrogenous compounds and nitrogen intake became equivalent to each other at 7.13% of CP.

Objetivou-se avaliar os efeitos da suplementação com compostos nitrogenados sobre a dinâmica ruminal da fibra em detergente neutro (FDN) em bovinos alimentados com forragem tropical de baixa qualidade. Foram utilizadas cinco novilhas mestiças Holandês × Zebu, com peso vivo médio inicial de 180 kg, fistuladas no rúmen. A alimentação volumosa basal dos animais foi constituída por feno de capim-praquiátia (Brachiaria decumbens Stapf) (4,86% de PB, com base na MS), fornecido à vontade. Os cinco tratamentos avaliados foram definidos de acordo com o nível de suplementação protéica (0, 2, 4, 6 e 8 pontos percentuais acima do nível de PB da forragem, utilizando-se como fonte de compostos nitrogenados mistura de uréia, sulfato de amônia e albumina, nas proporções de 4,5:0,5:1,0, respectivamente. O experimento foi constituído de cinco períodos experimentais, segundo delineamento em quadrado latino 5 × 5. Os níveis médios de PB nas dietas foram de 5,19; 7,19; 8,60; 11,67 e 13,02%, com base na MS. Verificou-se elevação linear da fração potencialmente degradável da FDN até o nível de 6,97% de PB, com platô estimado de 47,87% da FDN. A taxa de degradação da fração potencialmente degradável da FDN aumentou linearmente com os níveis de PB da dieta. O fluxo ruminal de partículas fibrosas apresentou relação linear-response-plateau, com estabelecimento do platô (máximo) em 7,24% de PB. O tempo médio de retenção no rúmen-retículo e a repleção ruminal da fração indegradável da FDN apresentaram comportamento semelhante ao fluxo ruminal de partículas fibrosas, com ponto crítico para o início do platô (mínimo) em 6,90 e 6,97% de PB, respectivamente. The aim of this work was to evaluate the effects of supplementation with nitrogenous compounds on rumen dynamics of neutral detergent fiber (NDF) in cattle fed low-quality tropical forage. Five crossbred heifers with average live weight of 180 kg and fitted with rumen cannulae were used. The animals were fed ad libitum with signal grass (Brachiaria decumbens Stapf.) hay, which had crude protein (CP) content of 4.86% of dry matter (DM). The five treatments were proposed in order to raise the CP level of diets to 0, 2, 4, 6, and 8 percentile points above the CP level of the forage. The supplement was a mixture of urea, ammonium sulfate, and albumin (4.5:0.5:1.0, respectively). The experiment was carried out according to a 5 × 5 Latin square design, with five experimental periods. The average CP levels in the diets were: 5.19, 7.11, 8.60, 11.67, and 13.02% on DM basis. The potentially degradable NDF was linearly increased according to the CP levels in diet up to 6.97% of CP. From this point, there was stabilization of estimates (47.87% of NDF). The degradation rate of potentially degradable NDF was linearly increased with the CP levels in diets. The rumen flow of fibrous particles (L) showed a linear-response-plateau pattern according to the CP levels in diets. The plateau (maximum estimate) began on 7.24% of CP. The mean retention time in the rumen and the rumen fill effect of undegradable NDF were affect by the CP levels similarly to L, with plateau (minimum) beginning on 6.90 and 6.97% of CP, respectively.