高油647玉米秸秆营养价值随籽粒成熟期的变化规律

以普通玉米品种CAU80和饲料专用玉米品种FC3为对照，以高油玉米品种HOC647为材料，进行化学成分分析和牛的体外消化试验，研究了HOC647玉米秸秆的主要营养成分含量、干物质和纤维组分消化率随籽粒成熟期的变化规律。结果表明，随籽粒成熟度的提高，HOC647秸秆的水溶性糖、淀粉、粗脂肪含量以及干物质、NDF消化率都呈线性提高（L；P〈0．01）：在1／2乳线期时分别为0．82％、1．68％、1．33％、54．07％和75．79％。3／4乳线期时分别为2．93％、2．12％、1．88％、57．11％和46．36％，4／4乳线期时分别为19．21％、5．53％、2．71％、66．78％和48．38％；而NDF、ADF和木质素含量则呈线性下降（L；P〈0．01）：1／2乳线期时分别为75．79％、50．12％和8．06％，3／4乳线期时分别为74．50％、47．14％和7．7796，4／4乳线期时分别为58．72％、34．60％和4．64％。可见，HOC647秸秆作为粗饲料在4／4乳线期收获，其营养价值高于1／2和3／4乳线期。在4／4乳线期收获的HOC647玉米秸秆，其水溶性糖、淀粉和粗脂肪含量极显著高于普通玉米CAU80秸秆（P〈0．01），也显著高于3／4乳线期收获的饲料专用玉米FC3秸秆（P〈0．05）；相反，其NDF、ADF和木质素等细胞壁成分却明显低于2个对照（P〈0．01）。HOC647秸秆的干物质、NDF消化率以及产气量均极显著高于对照CAU80和FC3秸秆（P〈0．01）。试验结果显示，籽粒成熟后期的HOC647玉米秸秆不仅营养物质含量高，而且消化率高。营养价值优于一般玉米秸秆。

Nutritional values of high oil corn 647 stalks altered with kernel maturity stage

Three types of stalks from high oil corn variety 647 (HOC647), conventional corn (CAU80) and specific fodder corn (FC3) were used to study the change of main chemical contents and digestibility of HOC647 stalks with kernel maturity stage and to compare the difference of HOC stalks with other variety stalks based upon the analysis of chemical components and measurement of digestibility and amount of gas production in vitro. The result showed that as corn kernels matured, HOC647 stalks had linear increases (L; P <0 01) in the contents of water soluble carbohydrate (WSC), starch , ether extract (EE), and the digestibilities of DM (DMD) and NDF (NDFD), which were 0 82%, 1 68%, 1 33%, 54 07% and 75 79% respectively at 1/2 milk line (ML); 2 93%, 2 12%, 1 88%, 57 11% and 46 36% respectively at 3/4 ML; 19 21%, 5 53%, 2 71%, 66 78% and 48 38% respectively at 4/4 ML. In contrast, there were linear decreases (L; P <0 01) in the contents of NDF, ADF and lignin which were 75 79%, 50 12% and 8 06% respectively at 1/2 ML; 74 50%, 47 14% and 7 77% respectively at 3/4 ML; 58 72%, 34 60% and 4 64% respectively at 4/4 ML. The nutritional value of HOC647 stalks harvested at 4/4 ML was, therefore, higher than that at 1/2 ML or 3/4 ML. The content of WSC, starch and EE of HOC647 stalks at 4/4 ML was not only much higher ( P <0 01) than that of CAU80 stalks harvested at 4/4 ML, but also higher ( P <0 05) than that of FC3 stalks harvested at 3/4 ML, whereas the content of cell wall components including NDF, ADF and lignin of HOC647 stalks was significantly lower ( P <0 001) than that of CAU80 and FC3, respectively. The stalks of HOC647 had higher ( P <0 01) in vitro DMD and NDFD, and ruminal gas production than those of CAU80 and FC3 stalks. These results suggested that HOC647 stalks at 4/4 ML of kernels are characterized by their high nutrient contents and being more ruminally digestible, and thus seem to be of highly valuable over other corn stalks.