牦牛瘤胃代谢与养分利用对日粮氮水平的响应机理研究

发布时间：2018-03-02 17:24

本文选题：牦牛　切入点：瘤胃代谢　出处：《兰州大学》2015年硕士论文　论文类型：学位论文

【摘要】：试验选用四组日粮,包括(干物质基础)低氮(6.45%)、中低氮(12.18%)、中高氮(17.81%)、高氮(23.49%),研究不同氮水平日粮对牦牛瘤胃发酵特征,养分利用状况,尿嘌呤衍生物(purine derivative,PD)排出量的影响以及利用尿PD估测瘤胃微生物蛋白产量。试验采用4×4拉丁方的设计,4头体况体重相近(192±12kg)的3岁去势、健康的公牦牛被随机分为4组。试验分四期进行,每期21天,其中预试期15天,正试期6天,消化代谢部分采用全收粪尿法。日粮包括精料和粗料,其中精料中性洗涤纤维(neutral detergent fibre,NDF)和代谢能(metabolizable energy,ME)相同而氮水平不一致；粗料为青稞秸秆。试验结论如下：1、瘤胃液pH值受饲喂后时间的影响显著(P0.05),饲喂后呈“,饲型先降后升趋势,但不受日粮的氮水平影响(P0.05)；瘤胃挥发性脂肪酸(volatile fatty acids,VFA)中,异丁酸、异戊酸比例及总酸浓度均随着氮水平的升高而增加(P0.05),其余VFA各酸比例以及乙丙比则不受氮水平影响(P0.05)。随着氮水平的升高,瘤胃微生物氮产量显著增加(P0.01)。在中高氮水平日粮组,牦牛微生物蛋白产量最大,为267.81g/d。本试验的创新点是,优化了微生物蛋白氮(MN,g/d)与嘌呤摄入量(X,mmol/d)的关系式：MN=70X/(0.12×0.83×1000)=0.703X(低氮水平饲喂组)MN=70X/(0.12×0.83×1000)=0.703X(中低氮水平饲喂组)MN=70X/(0.15×0.83×1000)=0.562X(中高氮水平饲喂组)MN=70X/(0.19 x 0.83×1000)=0.444X(高氮水平饲喂组)其中,70：单位毫摩尔嘌呤的氮量；0.83：嘌呤消化率；0.12和0.19：嘌呤氮/总氮。2、采食总氮量、可消化氮量、瘤胃微生物合成氮量、尿氮和尿中尿素氮排出量以及氮存留量均随着氮水平升高而显著增加P0.01),而粪氮排出量,氮沉积率不受氮水平影响(P0.05)。3、粗蛋白(crude protein,CP)消化率随氮水平的升高而呈显著增加(P0.01),而有机质(organic matter,OM).干物质(dry matter,DM).酸性洗涤纤维(acid detergent fibre, ADF)和中性洗涤纤维(neutral detergent fibre, NDF)的消化率则不受氮水平影响(P0.05)。4、牦牛尿中PD主要为尿酸和尿囊素两种物质。尿囊素和尿酸排量随氮水平的升高而显著升高(P0.05)。通过氮存留量与PD建立的模型：PD排出量(mmol/d)=106.34 x氮存留量(g/KgBW0.75/d)+22.104 (n=16; R2=0.9754),估测出内源PD为0.41 mmol/(Kg BW0.75·d)。
[Abstract]:Four groups of diets were used in the experiment, including (dry matter basis) low nitrogen 6.45m, low and low nitrogen 12.18, medium and high nitrogen 17.81, high nitrogen 23.490.To study the characteristics of rumen fermentation and nutrient utilization in yak with different nitrogen levels. The effect of purine derivative PDD on excretion and the estimation of rumen microbial protein production by urine PD were used in this study. A 4 脳 4 Latin square design was used for 3 year old castration with similar body weight of 192 卤12 kg. Healthy male yaks were randomly divided into 4 groups. The trial was conducted in four phases, 21 days each, including 15 days in advance and 6 days in positive trials. Among them, neutral detergent fiber (neutral) and metabolic energy (MEM) were the same and nitrogen levels were different. The results showed that the pH value of rumen fluid was significantly affected by the time after feeding (P0.05), and the feeding type decreased first and then increased. However, it was not affected by the nitrogen level in the diet, and isobutyric acid was found in volatile fatty acidsof rumen volatile fatty acids. The ratio of isovaleric acid and total acid concentration increased with the increase of nitrogen level, while the ratios of other VFA acids and ethylc were not affected by nitrogen level. With the increase of nitrogen level, microbial nitrogen production in rumen increased significantly. The production of microbial protein in yak was the highest, at 267.81 g / d. The innovation of this experiment was:. The relationship between microbial protein nitrogen (MNN) and purine intake was optimized by using the formula of: MNN 70XP 0.12 脳 0.83 脳 10000.703X (low nitrogen level feeding group) 0.12 脳 0.83 脳 10000.703X. (MNN 70X70 X / r / r = 0.15 脳 0.83 脳 1000kW 0.562X (medium and high nitrogen level feed group) 0.19 x 0.83 脳 1000x 0.444X (high level feed group)) of which 70 N: a unit of millipurine. Purine digestibility 0.12 and 0.19: purine nitrogen / total nitrogen. 2, total nitrogen intake, The amount of digestible nitrogen, the amount of nitrogen produced by rumen microorganisms, the excretion of urine nitrogen and urea nitrogen in urine, and the amount of nitrogen retention increased significantly with the increase of nitrogen level, while the excretion of fecal nitrogen increased significantly with the increase of nitrogen level. The digestibility of crude crude protein (CPF) was significantly increased with the increase of nitrogen level, while the digestibility of organic matter was increased with the increase of nitrogen level. The digestibility of acid detergent fiber (ADFF) and neutral detergent fiber (Ndfs) was determined by dry matter dry matter.Acid detergent fiber (ADFF) and neutral detergent fiber (NDF). PD in yak urine was mainly allantoic acid and allantoin. The excretion of allantoin and allantoin increased significantly with the increase of nitrogen level. The endogenous PD was estimated to be 0.41 mmol/(Kg BW0.75 路d0.
【学位授予单位】：兰州大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S823.85

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