Luciano da Silva Cabral

Níveis de proteína em suplementos para terminação de bovinos em pastejo durante o período de transição Seca/Águas: digestibilidade aparente e parâmetros do metabolismo ruminal e dos compostos nitrogenados

The objective of this trial was to evaluate ruminal, intestinal, and total tract apparent digestibilities of nutrients as well as metabolism of ruminal and nitrogenous compounds in supplemented finishing cattle during the drought to rainy transition season. Five Holstein x Zebu steers averaging 304 kg of live weight and 24 months of age located in five paddocks (0.34 ha each) of Brachiaria decumbens were used in this trial. The supplements fed (4 kg/animal/day) contained ground corn, whole soybean, urea, ammonium sulfate, and minerals and were formulated to yield, on as fed basis, 12, 16, 20, and 24% of crude protein (CP). Four animals were assigned to a 4 x 4 Latin square with experimental periods lasting 21 days. The remaining animal was not supplemented and was used for comparative purposes (CONT). No significant differences in ruminal, intestinal, and total tract apparent digestibilities of dry matter, organic matter, and neutral detergent fiber were observed by increasing the CP contents of the supplements. Similarly, abomasal flows of total nitrogen, ammonia nitrogen, and microbial nitrogen (MICN) did not differ when the CP contents of the supplements were increased. However, concentration of ruminal ammonia nitrogen increased linearly by incrementing the CP content of the supplement from 12 to 24%. Microbial efficiency averaged 17.5 g of MICN/kg of organic matter fermented in the rumen (OMFR) across supplements and was higher than that of the CONT (10.6 g of MICN/kg of OMFR). In addition, it was observed a significant cubic effect for urinary excretion of urea by increasing the CP contents of the supplements.

Taxas de digestão das frações protéicas e de carboidratos para as silagens de milho e de capim-elefante, o feno de capim-tifton-85 e o farelo de soja

The present work aimed to determine the nitrogen and carbohydrates fractions and to estimate the respective digestion rates for corn silage, Tifton-85 bermudagrass hay, elephantgrass silage and soybean meal. The contents of dry matter (DM), crude protein (CP), ether extract (EE), ash, total carbohydrates (TC), neutral detergent fiber (NDF), NDF corrected for ash and protein (NDFcp), indigestible NDF (INDF), non-protein nitrogen compounds (NPN) and B1+B2, B3 and C nitrogen fractions, nonfiber carbohydrates and B2 and C carbohydrates fractions were determined. TC digestion rates were estimated by in vitro gas production technique, while those of protein fractions were obtained by ruminal proteases utilization. The corn silage and elephantgrass silage showed high NPN proportion, the Tifton-85 bermudagrass hay showed high proportions of B1+B2 and B3 fractions and the soybean meal by high B1+B2 fraction. Corn silage and soybean meal showed high CNF proportion (37.05 and 75.75%) and the Tifton-85 bermudagrass hay and the elephantgrass silage showed high B2 and C fractions (51.20 and 51.70%, 41.77 and 33.56%). The digestion rates of B1+B2 and B3 protein fractions ranged from .0469 to .1512 h-1 for soybean meal and elephantgrass silage and from .0081 to .0757 h-1 for the Tifton-85 bermudagrass hay and elephantgrass silage, respectively. The estimated digestion rates for NFC and B2 fractions ranged from .1294 to .1905 h-1 and from .0254 to .0300 h-1 for Tifton-85 bermudagrass hay and corn silage, respectively.

Consumo de fibra em detergente neutro por bovinos em confinamento

The objective of this work was to evaluate the intake of neutral detergent fiber (NDF) by fedlot cattle, the principal factors that influencing this variable, and to correlate the NDF to total dry matter (DM) intake. The data published at the Brazilian Journal of Animal Science Society and Brazilian Journal of Animal Science among the years of 1991 and 2000, totaling 45 scientific works and 181 averages of treatments, were evaluated. The level of total digestible nutrients was negatively correlated to the level of NDF in diets (r = -0.6006; P .10). The description of the relationship among total DM intake and level of NDF in the diet was accomplished using a biphasic profile, looking for similarity to the curves proposed by the static model of DM intake prediction. The intersection of the curves projected a intake of NDF (NDFI) of 11.93 g/kg LW. However, the evaluation of NDFI estimated during the phase attributed to the physical controllers of intake showed inconstancy, generating divergence among the points of maximum intake of DM and NDF. This profile indicated that the transition among the physical and physiologic mechanisms is, possibly, delimited by an interval with interaction among mechanisms. The evaluation of NDFI according to the level of forage in the diets showed stable profiles in concentrations above to 60%, being of 13.53 g/kg LW in the interval from 80 to 100%. Possible interactions with the indigestible fraction of NDF can dictate the plasticity of the daily limit of NDFI.

Validação de equações preditivas da fração indigestível da fibra em detergente neutro em gramíneas tropicais

The objective of this work was to validate the prediction equations for neutral detergent fiber indigestible fraction (iNDF) employed by the Cornell Net Carbohydrate and Protein System (Sniffen equation) and the National Research Council (Conrads equation). A database with 114 observations taken from tropical grass, with lignin and indigestible neutral detergent fiber (iNDF) contents, was used. Comparison among predicted and observed values was accomplished by adjusting a linear regression model with predicted values as dependent variable and observed values as independent variable. The estimates supplied by Conrads equation were different from observed values, with constant bias of +5.60 percentile points. Alteration of the exponent that composes this equation, from .667 to .85, controlled the bias, guaranteeing the similarity among predicted and observed values. Lack of fitness was observed on the Sniffen equation, which caused under and overestimation of the iNDF contents for lignin concentrations lower and higher than 10.4% of NDF, respectively. This behavior is supported by the absence of non-linear relationships in this equation, constituting its main element of deficiency. The bias free of Conrad equation with empirical correction enlarges the accuracy of estimation process, leading to the lower mean square of the prediction error.

Níveis de Proteína em Suplementos para Terminação de Bovinos em Pastejo Durante o Período de Transição Seca/Águas: Consumo Voluntário e Trânsito de Partículas

Avaliaram-se o consumo e os parâmetros da cinetica de trânsito de particulas em bovinos suplementados durante a fase de transicao entre os periodos seco e chuvoso. Foram utilizados cinco novilhos Holandes x Zebu com idade e peso medios iniciais de 24 meses e 304 kg, respectivamente, manejados em cinco piquetes de Brachiaria decumbens (0,34 ha). Foram fornecidos suplementos (4 kg/animal/dia), constituidos por fuba de milho, grao de soja integral, ureia, sulfato de amonia e mistura mineral, formulados para apresentarem niveis de 12, 16, 20 e 24% de proteina bruta (PB), com base na materia natural. O experimento foi conduzido em quatro periodos experimentais de 21 dias e analisado por delineamento em quadrado latino 4 x 4. O quinto animal, mantido sem suplementacao (controle), foi utilizado como medida de comparacao descritiva. A forragem selecionada pelos animais apresentou teores medios de PB e fibra em detergente neutro (FDN) de 109,9 e 564,4 g/kg de materia seca (MS), respectivamente. A variacao do nivel de PB dos suplementos nao alterou os consumos de MS, de materia orgânica e de FDN. O fornecimento de suplementos reduziu o consumo de pastagem e ampliou o consumo de MS total em relacao ao controle, com coeficiente medio de substituicao de 0,41. O nivel de PB dos suplementos nao afetou a taxa de passagem ruminal das particulas, cujo valor medio (0,034 h-1), foi superior ao observado no controle (0,029 h-1).

Avaliação do vício de "tempo longo" de indicadores internos em ensaio de digestão com ruminantes

Long term bias (LTB) of internal markers indigestible dry matter (iDM), and indigestible neutral (iNDF) and acid (iADF) detergent fiber in a digestion assay with ruminants was evaluated. Twenty castrated male ovines were managed in metabolic crates. A completely randomized block design with five treatments (concentrate rations) and four blocks was used. Diets were isonitrogenous diets (10% of crude protein) were formulated to containing 60% of coastcross hay and 40% of concentrate, in dry matter basis. The concentrates were based on corn grain, soybean meal and coffee hulls, in different levels (0, 6.25, 12.5, 18.75, and 25%), as fed-basis. The markers contents in feeds, orts, and feces were estimated by a 144 hours in situ rumen incubation procedure. The relationship between markers intake and fecal excretion was accomplished by a simple linear regression model adjustment, independently of the effects of block and treatment. The total iDM and iNDF recovery (P>.30), with LTB free, was observed. The iADF had +25.45 g/day LTB (P<.06).

Cinética ruminal das frações de carboidratos, produção de gás, digestibilidade in vitro da matéria seca e NDT estimado da silagem de milho com diferentes proporções de grãos

Foram objetivos do presente trabalho avaliar as alteracoes na composicao bromatologica e nas fracoes nitrogenadas e de carboidratos, estimar a taxa de digestao dos carboidratos fibrosos (CF) e nao-fibrosos (CNF), determinar a digestibilidade in vitro da materia seca (DIVMS) e estimar o teor de nutrientes digestiveis totais (NDT) da silagem de milho com diferentes proporcoes de graos. As silagens foram confeccionadas nas seguintes proporcoes de graos: 0, 15, 30, 45 e 60%. Foram determinados os teores de materia seca (MS), compostos nitrogenados (N), extrato etereo (EE), materia mineral (MM), fibra em detergente neutro (FDN) e fibra em detergente acido (FDA), bem como os compostos nitrogenados nao-proteicos (NNP) e as fracoes nitrogenadas B1+B2, B3 e C. Foram tambem determinados os teores dos carboidratos nao-fibrosos (CNF) e das fracoes potencialmente digestiveis (B2) e indigestiveis da FDN (C). As taxas de digestao dos CNF e da fracao B2 dos carboidratos totais foram estimadas por meio da tecnica de producao de gases. Foram, ainda, realizadas a DIVMS por meio da tecnica de dois estadios e a estimacao do NDT por intermedio da composicao quimica. O acrescimo de graos a silagem aumentou linearmente os teores de MS, N e CNF e reduziu a MM, FDN, FDA e lignina. O NNP e as fracoes B3 e C variaram de 34,04 a 54,62%, 6,63 a 2,61 e 7,83 a 1,32% da PB. Os teores dos CNF e das fracoes B2 e C dos carboidratos totais foram influenciados linearmente pela adicao de graos a silagem, que variaram de 153,55 a 585,10; 489,57 a 203,29; e 233,50 a 85,51 g/kg de MS, respectivamente. As taxas de digestao dos CNF e da fracao B2 apresentaram comportamento quadratico, sendo os valores maximos estimados de 0,2723 e 0,02771 h-1, para as silagens com 40,08 e 14,57% de graos, respectivamente. O volume final de gas, a DIVMS e o NDT estimado, aumentaram linearmente, em funcao da porcentagem de graos, os quais variaram de 20,03 a 28,47 mL, 62,19 a 83,21 e 56,08 a 81,40%, respectivamente.

Níveis de proteína bruta em suplementos múltiplos para terminação de novilhos mestiços em pastejo durante a época seca: desempenho produtivo e características de carcaça

The objective of this study was to evaluate the productive and economical performance of supplemented crossbreed steers during the dry season. Twenty five holstein x zebu steers, with 367.7 kg of live weight and 24 months old, grazing in five paddocks of Brachiaria decumbens (3 ha), were used. The supplements were constituted of grounded corn, whole soybean seeds, urea, ammonium sulfate and mineral salt, and were formulated to contain levels of 12, 16, 20 and 24% crude protein (CP) as fed basis, which constituted the treatments S12, S16, S20 and S24, respectively. The supplements were supplied to the animals in the level of 4 kg/animal/day. A group of animals were allotted to untreated control treatment (SAL) and received exclusively mineral salt. CP levels in the supplements caused quadratic outcome on the variables average daily gain (ADG), final live weight (FLW) and necessary days to reach 450 kg of live weight (D450), which presented critical responses on the CP levels of 19.53% (0.943 kg), 19.38% (465.8 kg) and 19.22% (90.6 days), respectively. The supplementation allowed superior animal performance compared with SAL, which presented averages of daily gain, FLW and D450 of 0.277 kg, 397.4 kg and 312.4 days, respectively. The carcass dressing percentage (CD) and the proportions of muscular, fatty (FT) and bone (BT) tissues in the carcass were not influenced by the composition of supplements. However, supplemented animals presented larger CD and FT and smaller BT compared with SAL. The economical evaluation of the supplements showed larger crude income for S20.

Caracterização das frações que constituem as proteínas e os carboidratos, e respectivas taxas de digestão, do feno de capim-tifton 85 de diferentes idades de rebrota

ABSTRACT - The chemical composition, crude protein fractions (A, B1, B2, B3 and C) and total carbohydrate fractions (A, B1,B2 and C), and respective degradation rate of B1, B2 and B3 protein fractions and A + B1 and B2 carbohydrate fractions of Tifto n 85bermudagrass hay from plants harvested with 28, 35, 42 and 56 days of regrowth, fertilized with 75 kg/ha/cut of N, were evaluat ed. Theprotein content of hays from 28 to 56 days of regrowth ranged from 17.58 to 12.58%. The values of A, B1, B2, B3 and C protein f ractionspresented between 22.1 and 35.53%; 0.24 and 4.55%; 30.37 and 31.34%; 26.55 and 36.62%, and, 5.75 and 6.76%, respectively, as apercentage of the total crude protein, in the hays with ages between 28 and 56 days of regrowth. The degradation rate of B1, B2 andB3 protein fractions presented between 0.319 and 1.324; 0.0724 and 0.0936, and, 0.0077 and 0.012 h -1 , respectively, in the hays withages between 28 and 56 days of regrowth. The total carbohydrates content ranged from 72.98 to 78.77%, for the hays with 28 to 56days of age. The values of A, B1, B2 and C carbohydrate fractions presented between 2.73 and 5.44%; 1.91 and 2.35%; 77.49 and 8 0.59%,and, 13.59 and 17.87%, as a percentage of total carbohydrates, in hays with ages between 28 and 56 days of regrowth. The degrad ationrate of the A + B1 and B2 carbohydrate fractions presented between 0.181 and 0.20, and 0.04 and 0.0466 h

Degradabilidade in situ da matéria seca, da proteína bruta e da fibra de alguns alimentos

O objetivo deste trabalho foi determinar os parâmetros cineticos da degradacao, in situ, da materia seca, da proteina bruta e da fibra em detergente neutro das silagens de milho e de capim-elefante, do feno de capim-Tifton 85 e do farelo de soja. Foram utilizados tres bovinos adultos, fistulados no rumen, com peso vivo medio de 400 kg. Os alimentos foram pesados em sacos de nailon, incubados todos de uma vez e retirados nos tempos 0, 2, 4, 8, 16, 24, 48 e 72 horas, apos a incubacao dos volumosos, e 0, 2, 4, 8, 16, 24 e 48 horas, apos incubacao do farelo de soja. Os residuos dos sacos foram analisados quanto ao conteudo de materia seca, proteina bruta e fibra em detergente neutro. A materia seca e a proteina bruta do farelo de soja apresentaram potencial de degradacao elevado, assim como a proteina bruta da silagem de milho. Destacou-se a elevada fracao nao-degradavel da fibra em detergente neutro do feno de capim-Tifton 85 e, portanto, sua baixa degradabilidade potencial da materia seca. O teor de fibra em detergente neutro e suas caracteristicas cineticas exercem acentuado efeito sobre a digestao dos alimentos.