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首页> 外文期刊>Asian-Australasian Journal of Animal Sciences >Effects of Polyurethane Coated Urea Supplement on In vitro Ruminal Fermentation, Ammonia Release Dynamics and Lactating Performance of Holstein Dairy Cows Fed a Steam-flaked Corn-based Diet
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Effects of Polyurethane Coated Urea Supplement on In vitro Ruminal Fermentation, Ammonia Release Dynamics and Lactating Performance of Holstein Dairy Cows Fed a Steam-flaked Corn-based Diet

机译：聚氨酯包膜尿素补充剂对以玉米片为日粮的荷斯坦奶牛体外瘤胃发酵，氨释放动力学和泌乳性能的影响

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摘要

Three experiments were conducted to investigate the effects of polyurethane coated urea on in vitro ruminal fermentation, ammonia release dynamics and lactating performance of Holstein dairy cows fed a steam-flaked corn-based diet. In Exp. 1, a dual-flow continuous culture was run to investigate the effect of polyurethane coated urea on nutrient digestibility, rumen fermentation parameters and microbial efficiency. Three treatment diets with isonitrogenous contents (13.0% CP) were prepared: i) feed-grade urea (FGU) diet; ii) polyurethane coated urea (PCU) diet; and iii) isolated soy protein (ISP) diet. Each of the diets consisted of 40% steam-flaked corn meal, 58.5% forages and 1.5% different sources of nitrogen. PCU and FGU diets had significantly lower digestibility of NDF and ADF (p<0.01) than the ISP diet. Nitrogen source had no significant effect (p = 0.62) on CP digestibility. The microbial efficiency (expressed as grams of microbial N/kg organic matter truly digested (OMTD)) in vitro of the PCU diet (13.0 g N/kg OMTD) was significantly higher than the FGU diet (11.3 g N/kg OMTD), but comparable with the ISP diet (14.7 g N/kg OMTD). Exp. 2, an in vitro ruminal fermentation experiment, was conducted to determine the ammonia release dynamics during an 8 h ruminal fermentation. Three treatment diets were based on steam-flaked corn diets commonly fed to lactating cows in China, in which FGU, PCU or soybean meal (SBM) was added to provide 10% of total dietary N. In vitro NH3-N concentrations were lower (p<0.05) for the PCU diet than the FGU diet, but similar to that for the SBM diet at all time points. In Exp. 3, a lactation trial was performed using 24 lactating Holstein cows to compare the lactating performance and blood urea nitrogen (BUN) concentrations when cows were fed PCU, FGU and SBM diets. Cows consuming the PCU diet had approximately 12.8% more (p = 0.02) dietary dry matter intake than those consuming the FGU diet. Cows fed the PCU diet had higher milk protein content (3.16% vs. 2.94%) and lower milk urea nitrogen (MUN) concentration (13.0 mg/dl vs. 14.4 mg/dl) than those fed the FGU diet. Blood urea nitrogen (BUN) concentration was significantly lower for cows fed the PCU (16.7 mg/dl) and SBM (16.4 mg/dl) diets than the FGU (18.7 mg/dl) diet. Cows fed the PCU diet had less surplus ruminal N than those fed the FGU diet and produced a comparable lactation performance to the SBM diet, suggesting that polyurethane coated urea can partially substitute soybean meal in the dairy cow diet without impairing lactation performance.
机译：进行了三个实验，研究了聚氨酯包覆尿素对以玉米片为日粮的荷斯坦奶牛体外瘤胃发酵，氨释放动力学和泌乳性能的影响。在实验中参照图1，进行双流连续培养以研究聚氨酯涂覆的尿素对养分消化率，瘤胃发酵参数和微生物效率的影响。制备了三种氮含量相同（CP为13.0％）的处理日粮：i）饲料级尿素（FGU）日粮; ii）聚氨酯涂层尿素（PCU）饮食; iii）分离大豆蛋白（ISP）饮食。每种饮食都由40％的玉米片汽水，58.5％的草料和1.5％的不同氮源组成。 PCU和FGU饮食的NDF和ADF的消化率显着低于ISP饮食（p <0.01）。氮源对CP的消化率没有显着影响（p = 0.62）。 PCU日粮（13.0 g N / kg OMTD）的体外微生物效率（表示为克N / kg真正被消化的微生物有机物的克数（OMTD））显着高于FGU日粮（11.3 g N / kg OMTD），但可与ISP饮食（14.7 g N / kg OMTD）相媲美。经验参照图2，进行了体外瘤胃发酵实验，以确定在8h瘤胃发酵期间氨释放动力学。三种处理日粮是基于在中国通常饲喂泌乳牛的玉米片玉米日粮，其中添加了FGU，PCU或豆粕（SBM），以提供总日粮N的10％。体外NH3-N浓度较低（ PCU饮食比FGU饮食的p <0.05），但在所有时间点都与SBM饮食的相似。在实验中参照图3，使用24头泌乳的荷斯坦奶牛进行了泌乳试验，以比较喂饲PCU，FGU和SBM日粮的母牛的泌乳性能和血尿素氮（BUN）浓度。进食PCU饮食的母牛的饮食干物质摄入量比进食FGU饮食的母牛多约12.8％（p = 0.02）。饲喂PCU日粮的母牛比饲喂FGU日粮的母牛具有更高的牛奶蛋白含量（3.16％比2.94％）和更低的牛奶尿素氮（MUN）浓度（13.0 mg / dl对14.4 mg / dl）。饲喂PCU（16.7 mg / dl）和SBM（16.4 mg / dl）日粮的母牛的血尿素氮（BUN）浓度明显低于FGU（18.7 mg / dl）日粮。饲喂PCU日粮的牛的瘤胃氮比饲喂FGU日粮的牛少，并且泌乳性能与SBM日粮相当，这表明聚氨酯涂层尿素可以部分替代豆粕作为奶牛日粮，而不会损害泌乳性能。

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