Leaf tissues degradation of signalgrass hay pretreated with urea and submitted to in vitro digestion

Abstract

-An experiment using signalgrass hay treated with increasing urea levels (0, 20, 40, and 80 g/kg of dry matter), and submitted to in vitro digestion times (0, 6, 12, 24 or 72 hours) was conducted to evaluate the effects of ammoniation rates and digestion times on leaf blade tissue degradation. A completely randomized design with a 4 × 5 factorial treatment arrangement, with three replicates was used. Data were submitted to multivariate analysis. Urea-treated hay presented smaller proportion of remaining tissues measured in leaf blades cross-sections after in vitro digestion. Tissues more affected by urea treatment degradation were parenchyma bundle sheath and sclerenchyma. The hay treated with 80 g urea/kg DM and in vitro digested for 24 or 72 hours showed smallest proportion of tissues with thick and lignified cell walls such as parenchyma bundle sheath and sclerenchyma. The treatment with urea also reduced the time necessary to tissue degradation. The urea-treated hay in vitro digested for 12 hours, showed the same tissue proportion found in untreated hay submitted to 24 or 72 hours of in vitro digestion. The epidermis and lignified vascular tissue showed the smallest degradation following in vitro digestion.Results indicated that treatment of signalgrass hay with urea contributed to cell wall structure disruption, enhancement of tissues microbial degradation and reduction of the time necessary to digestion.

Nutritional value of hay from maize-crop stubble ammoniated with urea

“…This is attributed to the water added during ammoniation, necessary to raise the moisture content to about 30%, which is the ideal for the ammonia to act on the constituents of the cell wall (GOBBI et al, 2008).…”

“…The dry matter content (DM) of the hay was determined following the methodology described by Silva and Queiroz (2002), and based on this DM, the material was then ammoniated with 3% cattle urea, dissolved in enough water to raise the moisture content of the hay to 30% (GOBBI et al, 2008). Samples of 2.0 kg per plot of the DM of the maize stubble were treated.…”

“…Samples of 2.0 kg per plot of the DM of the maize stubble were treated. These were then placed in dark, 0.6 x 0.9 m polyethylene bags, 0.03 mm thick, and sealed with tape to avoid the loss of ammonia by ureolysis, remaining closed for 35 days, as per Gobbi et al (2008). Each bag of treated forage made up one replication, as well as the forage sampled before ammoniation.…”

“…Each bag of treated forage made up one replication, as well as the forage sampled before ammoniation. After opening, the treated forage remained in the bags in a dry, airy place, where it was naturally aerated for 24 h in order to eliminate the excess ammonia (GOBBI et al, 2008).…”

Suplementação da dieta de bovinos de corte como estratégia do manejo das pastagens

“…Tal fato pode ter ocorrido devido à proteção da porção solúvel da célula pela bem desenvolvida e lignificada bainha Tabela 4 -Teores de compostos nitrogenados de forrageiras C4 e C3 Espécie PB% MS Fração (% PB) Fonte Tabela 5 -Taxa de lotação, desempenho animal e produtividade de pastagem de capim-marandu, em função do nível de suplementação da dieta dos animais Variável Nível de suplementação (% do PV/dia) Intercepto* Coef. angular* do feixe vascular, a qual tende a ser menos digerida do que o mesofilo e floema nas espécies C4 (Gobbi, et al, 2008). É evidente que, dependendo do manejo adotado, o teor de PB da planta forrageira apresenta grande variação.…”