【作者】 杨维仁；

【导师】 贾志海；

【作者基本信息】 中国农业大学 ， 动物营养与饲料科学， 2004， 博士

【摘要】 本研究选用安装瘤胃、十二指肠前端和回肠末端三段瘘管、体况良好的利木赞×鲁西黄牛杂交一代肉牛，采用拉丁方试验设计，探讨了十二指肠梯度灌注蛋氨酸对肉牛消化代谢的影响及最佳灌注量，不同形式的保护性蛋氨酸的瘤胃稳定性及瘤胃后可利用性，瘤胃投饲不同形式的蛋氨酸对肉牛消化代谢的影响以及瘤胃保护性赖氨酸的最佳投饲量。 结果表明，十二指肠灌注蛋氨酸显著提高试牛小肠氮的表观消化率、氮的沉积效率和日增重（P＜0.05），显著降低试牛血浆氨氮含量（P＜0.05），对血浆尿素氮含量影响不显著（P＞0.05）。十二指肠灌注不同数量蛋氨酸对血浆游离Ser、Met、Ile、Leu、Lys和Cys的含量有显著影响（P＜0.05）。十二指肠灌注13g蛋氨酸显著增加试牛十二指肠Met、Cys、Pro、Lys、EAA和TAA的流通量（P＜0.05），提高Asp、Thr、Ser、Glu、phe、His、Arg在小肠的表观消化率（P＜0.05），而Pro在小肠的表观消化率反而显著降低（P＜0.05）。Lys、Met、Leu、Ile、His、Val、Arg、Thr等必需氨基酸在小肠的表观消化率高于非必需氨基酸。十二指肠灌注蛋氨酸改善了小肠的氨基酸平衡，提高了氨基酸的利用率，增加氮沉积。本试验条件下蛋氨酸为限制性氨基酸，十二指肠蛋氨酸最佳灌注量为13g／d。 采用小尼龙袋法，研究DL-Met、吸附MHA、动物油包被Met和硬脂酸包被Met在瘤胃的稳定性和瘤胃后的可利用性。结果表明，DL-Met不宜直接饲喂反刍动物；吸附MHA和动物油包被Met稳定性最好，硬脂酸包被Met次之；各种瘤胃保护性蛋氨酸不存在过保护。 瘤胃投饲不同形式的蛋氨酸对瘤胃液pH、NH₃-N和VFA无显著影响（P＞0.05）。瘤胃投饲动物油包被蛋氨酸显著提高试牛ADG、DN和RN量（P＜0.05），提高Thr、Ile、Tyr、phe、Pro、Cys在小肠的表观消化率（P＜0.05），而Ala反而显著降低（P＜0.05）；瘤胃投饲动物油包被蛋氨酸显著降低试牛血浆尿素氮和血浆TAA、EAA、BCAA、Ser和Met（P＜0.05）含量。投饲动物油包被蛋氨酸和吸附MHA显著提高瘤胃液微生物phe、Met的含量（P＜0.05）和瘤胃食糜附着微生物Leu、Ile的含量（P＜0.05）。瘤胃投饲保护性蛋氨酸能够改善小肠的氨基酸平衡，提高了氨基酸的利用率，提高瘤胃液微生物蛋白中部分必需氨基酸的含量。最佳瘤胃保护性蛋氨酸为动物油包被蛋氨酸。 在试牛蛋氨酸满足的条件下，瘤胃投饲15 g／d瘤胃保护性赖氨酸，显著提高试牛ADG、DN、RN和部分氨基酸的十二指肠流通量（P＜0.05），而UUN显著降低（P＜0.05）；赖氨酸为限制性氨基酸，瘤胃保护性赖氨酸的适宜投饲量为15g／d。更多还原

【Abstract】 The study were conducted to investigate the effects of duodenal DL-Met gradient infusion on the digestion and metabolism of steers and optimal dosage of Met, the stability and metabolism of DL-Met, MHA, adsorptive-MHA (A-MHA), grease-embedded-Met (G-Met) and fatty-acid-embedded-Met (FA-Met) in the rumen and post rumen, the effect of Met administration in the rumen on the digestion and metabolism of steers and optimal administration dosage of RP-Lys. Crossbred (LimousinxLuxi) steers, fitted with fistula in the rumen, the proximal duodenum and dismal ileum, were used in the study. The experiments were performed in Latin square design.The results showed that the apparent digestibility of nitrogen in the small intestine.the retainded efficiency of nitrogen and ADG were significantly increased while plasma urea-N contents were significantly decreased (P < .05) by duodenal DL-Met gradient infusion. When different quantity Met were infused into the duodenum the contents of plasma free Ser Met Ile Leu Lys and Cys would be effected significantly(P < .05). When the dosage of Met that infused into the duodenum in a gradient manner was 13 g/d, there were obvious increase(P < .05) in Met, Cys, Pro, Lys, EAA and TAA flows in the duodenum, the apparent digestilities of Asp, Thr, Ser, Glu, phe. His, Arg in the small intestine could also be increased(P < .05), while the apparent digestility of Pro in the small intestine should be decreasd(P< .05). The apparent digestibilities of EAA such as Lys, Met, Leu, Ile, His, Val, Arg, Thr were greater than NEAA. So we can see that duodenal DL-Met gradient infusion can improve the balance of amino acid and the utilization of amino acid. At the same time, it led to higher RN. As limited amino acid the optimal accession quantity of DL-Met under present experiment was 13g/d.Small-nylon-bag method was used to study the stability and metabolism of DL-Met, MHA, adsorptive-MHA (A-MHA), grease-embedded-Met (G-Met), and fatty-acid-embedded-Met (FA-Met) in the rumen and post rumen. The results indicated that DL-Met was not suit for feeding ruminant animals directly; the stability of FA-Met was better than that of DL-Met. A-MHA and G-Met were better than FA-Met. The disappearance rates of different RP-Met in post rumen, small intestine, large intestine, whole gastrointestinal tract were similar, and so were the utilization rates of different G-Met in the gastrointestinal tract.The steers were administrated with DL-Met( II), G-Met(III) and A-MHA(IV) in the rumen respectively. The results showed that ADG, DN, RN and RN/DN of group III were greater (P < .05) than those of groups. The apparent digestibilities of Thr, Ile, Tyr, Phe, Pro, Cys in group III were greater (P < .05) than those of group I , while Ala was lower (P < .05) than those of group I ;the contents of plasma urea-N, plasma TAA, EAA, BCAA, Ser, and Met were lower (P < .05) than those of group I .The Phe and Met in rumen liquid microorganism and the Leu and Ile in rumen chyme microorganism of group III and group IV were greater (P < .05) than those of group I . From the above it revealed that the balance of amino acid in the small intestine and the utilization of amino acid and the contents of part EAA in rumen liquid MCP were improved by rumen RP-Met administration. The optimal RP-Met under present experiment was the G-Met.Under the condition of the requirement of Met being contented, the steers administrated with 15 g/d RPLys in the rumen had the highest (P < .05) ADG, RN, DN, RN/NI, and RN/DN and urine urea nitrogen vice versa; As limited amino acid the optimal dosage of RP-Lys may be 15 g/d.更多还原