Chemical composition and ruminal degradation kinetics of white oat (Avena sativa L.) IPR 126

SUMMARY The present study aiming to determine the nutritional quality of oat (Avena sativa L.) IPR 126 in order to produce forage for ruminants. Four periods between harvests were used: 14, 21, 28 and 35 days, distributed in randomized blocks with four replicates for each treatment. The variables evaluated were: the concentration of dry matter (DM), neutral detergent insoluble fiber (NDF), crude potein (CP), lignin, dry matter (DM), ash, ether extract (EE) and in vitro digestibility of dry matter obtained by measurement of gas production. The profile of gas production was adjusted to the logistic bicompartimental mathematical model. The variables and the parameters of the adjusted gas production curves were analyzed as repeated measurements through the PROC MIXED of SAS (version 9.0) and the restricted maximum likelihood (REML) as the method of estimation of parameters. Regression analysis was performed for the variables: DM, CP, EE, NDF, ash, and for the parameter k2 of the bicompartimental model. DM and NDF concentrations increased linearly, CP, ash, and the estimations of the parameter k2 reduced linearly and the EE concentration showed a cubic behavior in function of the age of harvest. Lignin and other parameters of the Schofield model were not influenced by the age of harvest. The harvest interval influenced some chemical components and degradation rate of fiber carbohydrates, but do not interfere in lignin concentration. The forage with 21 days of cutting interval has the high nutritional value.

本研究旨在测定饲用燕麦（Avena sativa L.）IPR 126的营养品质，以制备反刍动物饲草。试验设置14、21、28、35天共4个收割间隔周期，采用随机区组设计，每个处理设置4次重复。测定指标包括：干物质（dry matter, DM）、中性洗涤不溶性纤维（neutral detergent insoluble fiber, NDF）、粗蛋白（crude protein, CP，原文笔误为potein）、木质素、灰分、乙醚提取物（ether extract, EE）以及通过产气法测定的体外干物质消化率。将产气曲线拟合至逻辑双室数学模型（logistic bicompartimental mathematical model）。采用SAS软件（版本9.0）的PROC MIXED程序，以限制性最大似然法（restricted maximum likelihood, REML）作为参数估计方法，对各测定指标及拟合的产气曲线参数开展重复测量分析。针对干物质、粗蛋白、乙醚提取物、中性洗涤不溶性纤维、灰分以及双室模型的参数k2进行回归分析。结果表明：干物质与中性洗涤不溶性纤维浓度随收割间隔延长呈线性升高趋势；粗蛋白、灰分及参数k2的估计值呈线性降低趋势；乙醚提取物浓度随收割天数呈现三次方变化规律。木质素及斯科菲尔德模型（Schofield model）的其余参数不受收割天数的影响。收割间隔会对部分化学成分及纤维碳水化合物的降解速率产生影响，但对木质素浓度无显著作用。21天收割间隔的饲草具有较高的营养品质。