相比于反芻動物日糧蛋白質(zhì)含量,蛋白質(zhì)的品質(zhì)在生長、生產(chǎn)和繁殖中起著更重要的作用。提高高產(chǎn)奶牛的日糧蛋白含量并不意味著可提高動物生產(chǎn)性能和十二指腸限制氨基酸(AA)的平衡,反而會提高動物尿液和糞便的氮(N)排泄。到達后腸的蛋白質(zhì)主要以胱氨酸的形式,蛋氨酸的形式非常缺乏,被稱為第一限制性AA。日糧中添加過瘤胃形式的限制性AA被認為有利于動物的生理功能:生產(chǎn)性能,生理和繁殖性能等。為此,我們提出研究假設:到達小腸的第一限制性AA為蛋氨酸。這些蛋氨酸來自瘤胃未降解的蛋白,微生物蛋白(MCP)和補充的過瘤胃蛋白(RPMet)。低蛋白日糧添加RPMet不僅降低了飼料成本,而且可改善營養(yǎng)代謝,提高N和能量利用。試驗分為4組:(1)高蛋白組(HP,163.39 g/kg),(2)低蛋白組(LP,146.33 g/kg);(3)低蛋白+低濃度RPMet組(LPLMet,141.80 g CP+0.11 g RPMet/kg DM);(4)低蛋白質(zhì)+高濃度RPMet(LPHMet;143.30 g+0.81g RPMet/kg DM)。其中HP日糧作為陽性對照,低LP組作為陰性對照。依次采用人工瘤胃(Rusitec,15 d適應和7d采樣)、皺胃和回腸體外消化(8 d)技術評定消化率。試驗結(jié)果表明,LPLMet和LPHMet組的Rusitec和后腸道CP體外消化率顯著上升。然而,飼料NDF和GE在Rusitec的消化率中無變化,但LPHMet組的后腸道NDF消化率顯著高于HP組。此外,RPMet提高了16S r RNA基因的豐度,但對種類無影響。對纖維降解菌R.flavefaciens和F.succinogenes相對豐度無影響,但改變了R.albus。然而,MCP產(chǎn)量、總短鏈脂肪酸濃度和R.albus相對豐度在LPHMet與HP組無顯著差異。HP組的總氣體和甲烷產(chǎn)量以及NH3-N濃度顯著高于LP、LPLMet和LPHMet組。Rusitec發(fā)酵罐在進食前后的p H沒有顯著變化。與其他組相比,LPHMet組回腸(小腸)液體部分的總AA流量無差異,但蛋氨酸流量顯著增加。HP組固體殘留物中的總AA和一些必需和非必需的AA明顯高于其他組。綜上,在低蛋白日糧中補充RPMet(0.11 g/kg DM)對后腸道的大多研究指標無影響。低蛋白日糧中補充高水平RPMet(0.81 g/kg DM),可顯著提高MCP、短鏈脂肪酸濃度、NDF和GE體外消化率、人工瘤胃R.albus豐度。HP組的總氣體和甲烷產(chǎn)量顯著高于其他組。LPHMet組的后腸道NDF消化率顯著高于其他組。HP組固體殘留物中的總AA和一些必需和非必需的AA明顯高于其他組。從目前的研究可得出結(jié)論:低蛋白日糧添加過瘤胃蛋氨酸可顯著提高回腸中總氨基酸,必需氨基酸和蛋氨酸的流量,此日糧可替代中產(chǎn)奶牛的高蛋白質(zhì)日糧。
【學位單位】：西北農(nóng)林科技大學
【學位級別】：博士
【學位年份】：2018
【中圖分類】：S816
【文章目錄】：
ABSTRACT
摘要
CHAPTER 1: INTRODUCTION
    1.1 Problems due to feeding excessive protein ration in dairy ruminants
    1.2 Crude protein, rumen degradable, undegradable and metabolizable protein
    1.3 Studies of rumen-protected methionine supplementation and crude protein
    1.4 Problems statements, methionine role and hypothesis of the proposed research
    1.5 Hypothesis and objectives of the proposed research
CHAPTER 2: REVIEW OF THE LITERATURE
    2.1 Introduction of the methionine and biosynthesis process
    2.2 The impacts of methionine supplementation on dairy ruminants
    2.3 Description of current experimental product
    2.4 Characteristics of Rusitec technique and structure of apparatus
    2.5 Operation and preparation for running the Rusitec apparatus
    2.6 Inoculation of ruminal microbes, incubation process and adaptation period
    2.7 Fermenters volume, dilution rate, ration amount and feedbags size
    2.8 Parameters reported in the literature during operation of the Rusitec
CHAPTER 3: LOW DIETARY PROTEIN DIET WITH SUPPLEMENTATION OF RUMEN PROTECTED METHIONINE: THEIR EFFECTS ON APPARENT NUTRIENTSDISAPPEARANCE
    3.1 Abstract
    3.2 Introduction
    3.3 Hypothesis and objective
    3.4 Material and methods
        3.4.1 Animal care
        3.4.2 Experimental strategy
        3.4.3 Test product description
        3.4.4 Experimental diets and inoculum donors
        3.4.5 Rumen simulation technique and sampling
        3.4.6 In vitro abomasum digestibility, collection of small intestinal fluid of goatsand lyophilization technique
        3.4.7 In vitro ileum digestibility technique, and laboratory analyses of feed andsamples
    3.5 Statistical analyses
    3.6 Results
        3.6.1 Effects of supplementation of rumen-protected methionine on disappearanceat Rusitec
        3.6.2 Rumen-protected methionine supplements their post-ruminal effects on thedisappearance
    3.7 Discussion
    3.8 Conclusion
CHAPTER 4: TOTAL POPULATION AND THREE CELLULOLYTIC SPECIFIC SPECIES RESPONSES TO RUMEN PROTECTED METHIONINE WITH LOW DIETARYPROTEIN DIET USING RUSITEC FERMENTERS
    4.1 Abstract
    4.2 Introduction
    4.3 Hypothesis and objective
    4.4 Material and methods
        4.4.1 Experimental treatments and methodology
        4.4.2 Sterilization preparation
        4.4.3 The reagents preparation
        4.4.4 DNA extraction protocol for rumen microbes
        4.4.5 Agar gel electrophoresis
        4.4.6 Spectrophotometry test
        4.4.7 Quantitative real-time PCR （qrt PCR）
        4.4.8 qrt PCR and determination of the bacterial copy number
    4.5 Statistical analyses
    4.6 Results
        4.6.1 Effects of supplements on total and cellulolytic species gene copy of liquidfraction
        4.6.2 Effects of supplements on total and cellulolytic species gene copy of solidfraction
    4.7 Discussion
    4.8 Conclusion
CHAPTER 5: ADDITION OF DIFFERENT LEVELS OF RUMEN PROTECTED METHIONINE WITH LOW PROTEIN DIET: THEIR EFFECTS ON RUMEN ANDPOST- RUMEN FERMENTATION CHARACTERISTICS
    5.1 Abstract
    5.2 Introduction
    5.3 Hypothesis and objective
    5.4 Material and methods
    5.5 Statistical analyses
    5.6 Results
        5.6.1 Effects of supplements with low CP on total and individual volatile fattyacids at Rusitec
        5.6.2 Post-ruminal effects of supplements with low CP on total and individualvolatile fatty acids
        5.6.3 Effects of supplements on total and greenhouse gases production
        5.6.4 Rumen p H, microbial protein synthesis, and NH3-N production ruminal andpost-ruminal
    5.7 Discussion
    5.8 Conclusion
CHAPTER 6: ADDITION OF DIFFERENT LEVELS OF RUMEN PROTECTED METHIONINE AS A CONCEIVABLE APPROACH TO DEPLOYING MAXIMUMTOTAL AND METHIONINE AMINO ACID FLOW AT THE SMALL INTESTINE
    6.1 Abstract
    6.2 Introduction
    6.3 Hypothesis and objective
    6.4 Material and Methods
        6.4.1 Experimental methodology and treatments
        6.4.2 Laboratory analyses of experimental feed and collected samples
        6.4.3 The methodology of preparation of Rusitec and in vitro fluid samples foramino acids analyses
        6.4.4 The methodology of preparation of Rusitec and in vitro residue samples foramino acids analyses
        6.4.5 Sample filtration and constant volume preparation for the amino acidanalyzer
    6.5 Statistical analyses
    6.6 Results
        6.6.1 Low protein with RPMet supplementation their effects on EAA, NEAA andMet flow from the rumen to ileum residue
        6.6.2 Low protein with RPMet supplementation their effects on EAA, NEAA andMet flow from rumen to ileum fluid
    6.7 Discussion
    6.8 Conclusion
CHAPTER 7: Conclusion and Recommendations
    7.1 Conclusion
    7.2 Recommendations
PUBLICATIONS
ACKNOWLEDGEMENTS
REFERENCES
APPENDIXA
ABBREVIATIONS
BIOGRAPHICAL SKETCH


本文編號：2881447