No-till sequential cropping of summer and fall annual forage species compared with grassland

Summer (SAS) and fall annual species (FAS) can supplement animal forage requirements during times of slow growth of cool-season perennials. A 2-yr experiment was conducted in a perennial grassland (G) at the Reedsville Experimental Farm of West Virginia University to determine herbage accumulation (HA) and quality of two summer and two fall crops (in factorial combination) grown on the same land. The summer crops were sudangrass [Sorghum bicolor (L.) Moench] or pearl millet [Pennisetum glaucum (L.) R. Br.], and the fall crops were triticale (xTriticosecale spp.) or a mixture of annual ryegrass (Lolium multiflorum Lam.) and turnip (Brassica rapa L.). Two methods, burning and glyphosate application, were used to control existing vegetation before seeding annual forages. Three levels of N (0, 50, and 100 kg ha–1) were applied to each sequence of crops on two occasions for a total of 0, 100, and 200 kg ha–1 yr–1. On a 12-mo basis, G out-produced (at 0 and 100 kg N ha–1) or equaled (at 200 kg N ha–1) all combinations of SAS and FAS. Sudangrass produced the most herbage mass in summer and was of lower quality than pearl millet and G. Species established after glyphosate and receiving high N application produced more herbage mass than those established after burning or with lower rates of N. Pearl millet seeded after burning failed to establish. Grassland (2543 kg ha–1) and the mixture of annual ryegrass and turnip (2608 kg ha–1) out-produced triticale (1778 kg ha–1) in fall

Juazeiro hay in diets of Morada Nova sheep

This study evaluated intake and apparent digestibility of the nutrients in the diet of Morada Nova sheep that received diets containing increasing levels of juazeiro hay in substitution of Tifton 85 bermudagrass hay (0, 33, 67 and 100%). Sixteen non castrated male sheep, weighing an average of 26.75 kg, were used, placed in individual metabolic cages and distributed in a completely randomized block design with four treatments and four replications. Intakes of dry matter, organic matter, crude protein, ether extract, neutral detergent fiber, total carbohydrates, fibrous carbohydrates and non-fibrous carbohydrates and total digestible nutrients were not influenced by the addition of juazeiro hay to the diets, with mean values of 1,042.78 and 595.59 g/day of dry matter and neutral detergent fiber intake, respectively. Linear reduction was observed for digestibility of the dry matter, organic matter, neutral detergent fiber and fibrous carbohydrates. Quadratic reduction was observed for the acid detergent fiber digestibility coefficient. The digestibility coefficients of the crude protein, ether extract, total carbohydrates and fibrous carbohydrates were not significant. The nitrogen balance was not influenced and was positive for all the treatments. The inclusion of juazeiro hay did not influence nutrient intake or nitrogen balance, but reduced the digestibility coefficient of some diet components

Predição do consumo de pasto de capim-elefante (Pennisetum purpureum, Schumack) por vacas mestiças Holandês x Zebu em lactação Prediction of the voluntary intake of elephantgrass (Pennisetum purpureum, Schumack) grazing by Holstein x Zebu lactating dairy cows

Foram desenvolvidas equações de predição de consumo de pasto de capim-elefante (Pennisetum purpureum, Schumack) por vacas mestiças Holandês x Zebu em lactação, utilizando-se procedimentos de stepwise em regressões múltiplas, aplicados a um banco de dados de experimentos conduzidos ao longo de três anos na Embrapa Gado de Leite (Coronel Pacheco, MG). As variáveis independentes disponíveis foram relacionadas a características inerentes às vacas (dias em lactação; teores de proteína, gordura e extrato seco total e produções destes componentes no leite; produção de leite in natura ou corrigida para 4% de gordura; ordem de lactação; peso vivo atual; peso vivo ao parto e grau de sangue Holandês x Zebu); ao manejo (dias de pastejo; disponibilidade de forragem e período de descanso da pastagem); ao ambiente (estação do ano e precipitação pluviométrica) e à alimentação (digestibilidade in vitro e parâmetros da composição química do pasto de capim-elefante e da cana-de-açúcar - Saccharum officinarum (L.) corrigida com 1% de uréia; consumos de suplemento volumoso (cana corrigida com uréia) e concentrado; concentrações fecais de proteína bruta e de fibras em detergente neutro e ácido). Efeitos linear e quadrático e transformações logarítmicas foram adicionalmente incluídos no banco de dados. Foram obtidas equações de predição de consumo de pasto de capim-elefante (expresso em kg/vaca/dia ou % do peso vivo) com coeficientes de determinação de 65,2 a 67,0%. As principais variáveis independentes incluídas nas equações foram o consumo do suplemento volumoso usado na estação seca do ano (cana corrigida com uréia); a digestibilidade in vitro do pasto de capim-elefante; a precipitação pluviométrica; a produção de leite corrigida para 4% de gordura; o peso vivo atual ou, em alternativa a este, o valor da pesagem realizada após o parto da vaca; além do consumo de suplemento concentrado, que evidenciou um efeito de substituição àquele do pasto de capim-elefante.<br>Equations for predicting elephantgrass (Pennisetum purpureum, Schumack) dry matter intake (DMI) by Holstein x Zebu lactating dairy cows under grazing were developed by stepwise regression analysis. The dataset consisted of results of trials carried out at Embrapa Gado de Leite (Coronel Pacheco, MG, Brazil). The independent variables related to animal factors (days in milk; milk protein, fat and total solids contents and yields; live weight; live weight at calving; milk and fat-corrected milk yield; Holstein x Zebu gene fraction; order of parturition); management factors (occupation day of paddock; forage allowance and availability; resting periods); environmental factors (season of the year; rainfall) and feed factors (in vitro digestibility and parameters of chemical composition of elephantgrass herbage and sugarcane - Saccharum officinarum (L.) plus 1% urea; supplement intake - concentrate and sugarcane plus urea; fecal crude protein, neutral and acid detergent fiber concentration). Logarithmic and quadratic functions for some variables were also considered. The main independent variables selected at the best-fit regressions models (R2 = 65.2-67.0%) for elephantgrass herbage DMI were roughage supplement (sugarcane plus urea) DMI; elephantgrass in vitro digestibility; rainfall; fat-corrected milk yield; live weight (or alternatively live weight at calving) and concentrate intake that showed substitution effect to intake of elephantgrass in supplementing grazing cows

Desenvolvimento e validação de um modelo preditor do desempenho de novilhos de corte sob suplementação em pastagens tropicais Development and validation of a performance predictive model of beef steers supplemented in tropical pastures

Um modelo de simulação foi desenvolvido e validado com o objetivo de conhecer e predizer o desempenho produtivo de bovinos machos castrados com diferentes pesos e idades iniciais mantidos sobre pastagens cultivadas Panicum sp. e Brachiaria sp. em regiões tropicais e subtropicais. O modelo incluiu relações diretas entre os dois componentes principais (animal e forragem) e relações indiretas entre outros dois componentes (clima e solo). O componente animal incluiu: consumo de matéria seca de forragem, consumo de suplemento, carga animal, peso e idade inicial dos animais, biótipo (peso adulto e peso ao nascimento) e exigências de energia para mantença e produção animal (ganho de peso). O componente forragem incluiu: crescimento, senescência, digestibilidade e disponibilidade. Os resultados obtidos com o modelo foram comparados a dados experimentais obtidos da literatura em condições semelhantes e indicaram baixo (35%) erro percentual de estimação. O modelo possibilita avaliar determinadas estratégias nutricionais e, desta forma, auxilia em decisões que dependem do ganho de peso dos animais e das condições da pastagem no decorrer do tempo.<br>A simulation model was developed and validated with the objective of evaluating and predicting the productive performance of steers with different weights and initial ages kept on Panicum sp. or Brachiaria sp. cultivated pastures in tropical and subtropical regions. The model established the direct relationships between two main components (animal and fodder plant) and two indirect components (climate and soil). The animal component included: intake of forage dry matter, supplement intake, stocking rate, initial weight and age of the animals, biotype (adult weight and weight at birth), energy requirement for maintenance and production (live weight gain). The forage components included: growth, senescence, digestibility and availability. The results obtained with the model were compared to those obtained in the literature under similar conditions in Brazil and a low percentage of estimated error was found (35%). The model is an adequate tool to evaluate certain nutritional strategies and thus to assist in decisions that depend on the weight gain of the animals and pasture conditions over time