Fracionamento de carboidratos e proteínas de gramíneas tropicais cortadas em três idades

This study aimed to evaluate urea excretion, nitrogen balance and microbial protein synthesis in lactating goats fed with diets containing different protein sources in the concentrate (soybean meal, cottonseed meal, aerial part of cassava hay and leucaena hay). Four Alpine goats whose mean body weight was 42.6±6.1 kg at the beginning of the experiment, a mean lactation period of 94.0±9.0 days and a production of 1.7±0.4 kg of milk were distributed in a 4×4 Latin square with four periods of 15 days. Diets were formulated to be isonitrogenous, containing 103.0 g/kg of CP, 400 g/kg of Tifton 85 hay and 600 g/kg of concentrate. Diet containing cottonseed meal provided (p<0.05) increased excretion of urea and urea nitrogen in the urine (g/d and mg/kg of BW) when compared with leucaena hay. The diets affected the concentrations of urea nitrogen in plasma (p<0.05) and excretion of urea nitrogen in milk, being that soybean meal and cottonseed meal showed (p<0.05) higher than the average aerial part of the cassava hay. The use of diets with cottonseed meal as protein source in the concentrate in feeding of lactating goats provides greater nitrogen excretion in urine and negative nitrogen balance, while the concentrate with leucaena hay as a source of protein, provides greater ruminal microbial protein synthesis.

Embrapa/CPPSE -São Carlos, SP, Pesquisador do CNPq.RESUMO -O gás metano possui reconhecidamente um importante papel como intensificador do efeito estufa. Pelo seu processo digestivo de fermentação entérica, os ruminantes convertem os carboidratos presentes na dieta em ácidos graxos voláteis, resultando na produção de dióxido de carbono e metano. Dessa forma, os ruminantes são reconhecidos como importantes emissores de metano ruminal para a atmosfera, sendo que a produção deste gás representa ainda perdas energéticas para os animais em relação à energia consumida. Animais consumindo dietas de baixa qualidade podem produzir mais metano por unidade de produto (carne ou leite) em relação aos animais de alta produção consumindo dietas de melhor qualidade em maiores níveis de ingestão. Resultados têm mostrado que a redução da emissão de metano pela pecuária está ligada à melhoria da dieta, à melhoria dos pastos, à suplementação alimentar, à seleção por maior potencial genético de produção e a outras medidas que reflitam na melhor eficiência produtiva, resultando em menores ciclos de produção. Palavras-chave:Fermentação ruminal, metano, produção animal, efeito estufa, ruminantes.ABSTRACT -Methane is well known as a greenhouse effect intensifier. Ruminants, during the ruminal digestive fermentation process, transform carbohydrates available in the diet to volatile fatty acids, with production of carbon dioxide and methane. Therefore, ruminants are known as important methane source to the atmosphere. Methane production also means animal losses of ingested energy. Ruminal fermentation process is driven by dry matter intake, and feed quality. Therefore, consume of low quality diets will produce more methane per product unit (milk or beef) compared to high producing animals ingesting great amounts of high quality diets. The sulphur hex fluoride gas tracer technique did allow good methane emission measurements by grazing or free managed animals. Results show that the reduction of methane emission by cattle is related to better quality diet, to improvement of forage quality of pastures, to grain inclusion in diet, to animal breeds with greater production potential, and other practices that improve production efficiency, and result in shorter production cycles. Key-words:Animal production, greenhouse effect, methane, ruminal fermentation, ruminants. IntroduçãoA interação entre os fatores de produção animal e o impacto ambiental causado pelas diversas atividades tem sido, cada vez mais, o objetivo de pesquisas relacionadas com as mudanças climáticas mundiais. Os ruminantes, devido ao processo digestivo de fermentação entérica, são reconhecidos como importante fonte de emissão de metano (CH 4 ) para a atmosfera. Além disso, a produção desse gás, que pode variar em função do sistema de alimentação, é considerada uma parte perdida da energia do alimento, refletindo em ineficiência na produção animal. Baseado em aspectos de proteção mercadológica, o Brasil, por ser detentor do maior rebanho comercial de bovinos do mundo e por utili...

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ResumoObjetivou-se, com este estudo, avaliar a composição química do pasto de capim marandu consorciado com amendoim forrageiro ou adubado com N e as características das carcaças de bovinos de corte. A pastagem foi manejada sob pastejo rotacionado com lotação contínua, e carga animal variável, utilizando-se 16 novilhos da raça nelore. Na avaliação de produção de matéria seca verde total, foram observadas significâncias estatísticas entre os tratamentos e períodos avaliados, sendo que o tratamento com o consórcio apresentou uma maior média. A variável proteína bruta (PB) apresentou significância entre os tratamentos e períodos avaliados. Os teores de nutrientes digestíveis totais (NDT) e fibras em detergente neutro (FDN) não apresentaram efeito significativo na avaliação da gramínea. Os períodos que apresentaram os menores ganhos médios diários (GMD) foram o quarto e sexto períodos. Para os teores de PB, NDT e FDN da leguminosa, o terceiro período foi o que apresentou as menores médias. Para as variáveis GMD, número de animais por dia (NAD), GPV, a estatística apresentou significância para a interação, sendo que o primeiro período do tratamento com o consórcio apresentou as maiores médias. No tratamento da adubação, as maiores taxas de lotação foram conseguidas nas estações onde ocorreram as adubações químicas. Foi observada significância estatística para a variável conformação na classificação das carcaças. O consórcio do amendoim forrageiro cv. Belmonte pode ser utilizado em substituição à adubação, com 120kg/N/ha, pois garante o mesmo ganho de peso por animal, sem alterar as características comerciais das carcaças.

Cinética e parâmetros de fermentação ruminal in vitro de silagens departe aérea e raízes de mandioca [Kinetic parameters and in

Objectives were to determine the dietary inclusion level of NaOH in a dried distillers grains with solubles (DDGS)-based diet needed to improve growth performance and carcass characteristics of feedlot steers, and to determine the effects of NaOH treatment of DDGS on pattern of feed intake. Based on previous research regarding the acidity of DDGS, we hypothesized that using NaOH in cattle fed 50% DDGS-based diets to neutralize the acidity inherent in DDGS would improve growth performance of cattle but shift intake patterns. Angus-cross steers (120 total) were blocked into 2 BW blocks (light, initial BW = 211 ± 27 kg; and heavy, initial BW = 261 ± 27 kg) and allotted randomly within block to 20 pens (6 steers per pen; = 30). Pens within block were assigned randomly to 1 of 4 dietary treatments: 1) 50% DDGS, untreated; 2) 50% DDGS, treated with 0.5% NaOH (DM basis); 3) 50% DDGS, treated with 1.0% NaOH (DM basis); or 4) 50% DDGS, treated with 1.5% NaOH (DM basis). The remainder of the diets contained 20% dry-rolled corn, 20% corn silage, and 10% mineral and vitamin supplement, on a DM basis. Cattle were fed in a GrowSafe system. There were no effects ( ≥ 0.21) of increasing NaOH inclusion on final BW, ADG, or G:F. Increasing NaOH in the diet increased meal duration (linear; = 0.02) and tended to increase meal size (linear; = 0.06), but did not affect overall number of meals per day (linear; = 0.21) or overall DMI ( ≥ 0.40) for the course of the trial. Relative to cattle fed DDGS treated with 0, 0.5 or 1% NaOH (DM basis), steers fed DDGS treated with 1.5% NaOH consumed a larger proportion of their meals in the afternoon. However, regardless of treatment, all steers consumed 78% or more of their feed in the first 12 h post-feeding. There were no effects ( ≥ 0.19) of increasing NaOH inclusion on HCW, LM area, dressing percentage, KPH, back fat thickness, and marbling. There was a linear ( = 0.02) decrease in USDA Yield Grade (YG) 3 and a tendency ( = 0.09) for a quadratic response in carcasses grading USDA YG 4 as NaOH concentration increased in the diets; however, there were no other YG differences. The quality grade response followed marbling score and was not different ( ≥ 0.11) among treatments. Thus, there were no effects of feeding DDGS treated with NaOH on growing cattle performance or carcass characteristics. However, NaOH inclusion shifted the pattern of intake slightly to the afternoon hours, and increased meal duration without increasing the total number of meals per day.

The objectives were to determine the optimum inclusion of NaOH necessary to buffer the acidity of dried distillers' grains with solubles (DDGS) and its effects on digestibility, ruminal metabolism, and metabolic acidosis in feedlot steers. Rumen cannulated Angus-crossed steers were blocked by BW (small: 555 ± 42 kg initial BW, = 4; large: 703 ± 85 kg initial BW, = 4) over four 21-d periods in a replicated 4 × 4 Latin square design. Steers were assigned to 1 of 4 dietary treatments: 1) 50% untreated DDGS, 2) 50% DDGS treated with 0.5% (DM basis) sodium hydroxide (NaOH), 3) 50% DDGS treated with 1.0% (DM basis) NaOH, and 4) 50% DDGS treated with 1.5% (DM basis) NaOH. The remainder of the diets, on a DM basis, was composed of 20% corn silage, 20% dry-rolled corn, and 10% supplement. Ruminal pH was not affected by treatments ( = 0.56) or by a treatment × time interaction ( = 0.15). In situ NDF and ruminal DM disappearance did not differ ( ≥ 0.49 and ≥ 0.47, respectively) among treatments. Similar to in situ results, apparent total tract DM and NDF digestibility were not affected ( ≥ 0.33 and ≥ 0.21, respectively) by increasing NaOH inclusion in the diets. Urinary pH increased (linear, < 0.01) with increasing NaOH concentration in the diet. Blood pH was not affected ( ≥ 0.20), and blood total CO and partial pressure of CO were similar ( ≥ 0.56 and ≥ 0.17, respectively) as NaOH increased in the diet. Increasing NaOH in the diet did not affect ( ≥ 0.21) ruminal concentrations of total VFA. There were no linear ( = 0.20) or quadratic ( = 0.20) effects of treatment on ruminal acetate concentrations, nor was there a treatment × time interaction ( = 0.22) for acetate. Furthermore, there were no effects ( ≥ 0.90) of NaOH inclusion on ruminal propionate concentration. However, there was a quadratic response ( = 0.01) of ruminal butyrate concentrations as NaOH inclusion increased in the diet; ruminal butyrate concentrations were greatest with the 0.5 and 1.0% NaOH treatments of DDGS. In the current study, feeding DDGS treated with NaOH did not increase fiber digestibility nor was it necessary to alleviate a possible metabolic acidosis. Alkali treatment of DDGS did not increase average ruminal pH or blood pH.