2010 Lecture Protein Metabolism by liwenting

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									  Protein Metabolism III

Protein requirements and B agonists
            Metabolizable Protein Model

                                        Tissue proteins

      NH3     Blood urea     Urine        Amino acid
                                            pools
                    Energy
  A         NH3                         Metabolizable
                    Microbial             protein
  B
                    protein   Protein
  C
Protein
from diet
              Rumen              Intestine       Feces
Protein Requirements of Growing Cattle
             Changes with Increase in Weight

                              Gain       Maintenance        Total

                      900
  Protein Required,




                      800
    Metabolizable




                      700
                      600
                      500
         g/d




                      400
                      300
                      200
                      100
                        0
                            600   700   800    900 1000 1100 1200 1300
                                              Weight, lbs
Protein Requirements of Growing Cattle
                                Relation to Rate of Gain

                          740
 Metabolizable protein,




                          720
                          700
                          680
          g/d




                          660
                          640
                          620
                          600
                                 1.75    1.87         1.97    2.07
                                         Rate of gain, kg/d
     Increased Protein Requirements
                  Ruminants
      Situation                 Consequences
1. Young animals            Leaner gain
    Fast rate of gain        More total protein
    Leaner gain               in tissues
2. Compensatory gain        Greater muscle growth
3. High levels of lactation More milk protein
4. Hormone implants and bGH More protein synthesis
5. Low feed intakes         Less MP from diet
                            and microbes
     Need to feed higher concentrations of
     protein or less degradable protein
  What is The Requirement for DIP?
                  Finishing Cattle
Cooper et al. JAS 2002
Fed different concentrations of urea to finishing steers
Diets: Dry rolled, high moisture and steam flaked corn
Measured feed intake and gain
Estimated requirement for DIP (DIP as % of diet DM)
    Dry rolled – 6.3
    High moisture – 10.0
    Steam flaked – 9.5
High moisture and steam flaked corns more digestible
in the rumen – Increased microbial protein production

Limitations:
Protein requirements change during the experiment
            Bacterial Protein
          Synthesis in the Rumen

 Microbial protein synthesis related to:
    1. Available NH3 and amino acids (DIP)
    2. Fermentation of CHOH - Energy


NH3         Amino acids & Peptides

VFA               Amino acids         Microbial
       Fermentation                   proteins

CHOH                VFA
                                BCP
Microbial protein synthesis
• BCP (gm) = .13 TDN (gm)
   – Assumes
       • TDN is corrected for fat
       • RDP is adequate
RDP requirement
• RDP = 1.18 BCP (gm) - .2 diet CP (gm)
• If RDP < 1.18 BCP – .2 diet CP, then
   – actual BCP (gm) = .85 (RDP+.2(CP)) (gm)
• BCP is assumed to be 80% protein which has a
  digestibility of 80% in the small intestine
     Supplementation of Diets with Urea

If inadequate DIP is available for synthesis
of BCP, need to add degradable N
Can add urea
   Urea Fermentation Potential (g urea/kg diet DM)
      UFP = (BCP, g/kg - DIP, g/kg)/2.8
         kg = kg diet DM
         2.8 = Urea is 280% crude protein
+ UFP: Inadequate DIP, urea will benefit
- UFP: There is surplus DIP, urea of no benefit
         Feed Values Beef NRC

                 % DIP   % TDN   % CP
Soybean meal      65       87     49
Dry corn          45       90     9.8
Corn silage       75       75     8.0
Alfalfa hay       82       60     17
Fescue hay        67       56     9.1
Corn stalks       68       55     6.3
 DDG             40        85       30
 Brome pasture   80        74       21
      Protein Values for Feeds
                DIP,    BCP,     UFP,
                 g/kg    g/kg     g/kg
Soybean meal    318.5   113.1    -73.4
Corn            44.1    117.0     26.0
Corn silage     60.0     97.5     13.4
Alfalfa hay     139.4    78.0    -21.9
Fescue hay      61.0     72.8     4.2
Corn stalks     42.8     71.5     10.2
DDG             120      110       -5
Brome pasture   161      91        -25
Programmed Feeding of Supplemental Protein
                   Feedlot Steers - ISU

    Program                     Crude protein, % DM
                          (MP – DIP, Percent of requirement)
 Source within period    1 to 42 d     43 to 84 d    85 to 135 d
Program I                   12.4          12.4          12.4
SBM-SBM-SBM              (104 -101)    (127 – 101)   (151 – 101)
Program II                  11.7          11.7          11.7
Urea-Urea-Urea           (96 – 101)    (117 – 101)   (138 – 101)
Program III                 12.4          11.7          11.7
SBM-Urea-Urea            (104 – 101)   (119 – 101)   (140 – 101)
Program IV                  12.4          11.7          10.0
SBM-Urea-Lo Urea         (104 – 101)   (119 – 101)   (123 – 80)
Programmed Feeding of Supplemental Protein
                  740 lb Feedlot Steers
                         I        II       III    IV
0 – 42 d, ADG          3.95     3.56      4.13   4.03
        Feed/d         15.7     15.6      15.7   15.6
43 – 84 d, ADG         4.32     4.38      4.16   4.44
        Feed/d         21.6     21.3      21.1   21.3
85 – 135 d, ADG        3.21     3.14      2.99   3.17
        Feed/d         22.5     22.2      22.3   22.8
0 – 135 d, ADG         3.79     3.66      3.71   3.85
        Feed/d         20.1     20.0      19.9   20.1
     What is The Requirement for DIP?
                   Conclusions
All of calculated DIP does not have to be satisfied
when MP is being fed in excess
    • Enough nitrogen is recycling
    • Reduces quantity of nitrogen fed
            Metabolizable Protein Model

                                        Tissue proteins

      NH3     Blood urea     Urine        Amino acid
                                            pools
                    Energy
  A         NH3                         Metabolizable
                    Microbial             protein
  B
                    protein   Protein
  C
Protein
from diet
              Rumen              Intestine       Feces
    If Diet Needs More Metabolizable Protein

First consideration
   Can microbial protein be increased?
       If short of ruminal available N
           Add urea
           Provide ammonia to microorganisms
       If surplus of rumen available N
           Add fermentable feed (TDN)
           Provide energy to microorganisms
Second consideration
  Supplement diet with less degradable protein
Protein Requirements of Dairy Cows

      Body weight
         Maintenance
         Body weight change
      Pregnancy
      Milk yield
         Composition of milk
                             Protein Requirements of Lactating Cows

                             3000
Metabolizable protein, g/d




                             2500

                             2000

                             1500                             Maintenance
                                                              Lactation
                             1000
                                                              Total
                              500

                                0
                                    20        30        40
                                           Milk, kg/d
Meeting Dairy Cow’s Protein Requirement

 • Feed intake
    Nature of feed ingredients
       Fermentable energy
          Microbial protein synthesis in the rumen
       Proportion of feed protein(s) degraded
 • Digestibility of proteins in the intestine
 • Amino acids available for absorption
    Amino acid balance
                 Amino Acid Composition
                % Crude Protein or G/100g CP

                Tissue Milk     ----------Bact ----------    Corn   Soy
                              Cell wall Non wall Mean
Methionine      1.97   2.71    2.40        2.68       2.60   2.28   1.46
Lysine          6.37   7.62    5.60        8.20       7.90   3.03   6.32
Histidine       2.47   2.74    1.74        2.69       2.00   3.16   2.72
Phenylalanine   3.53   4.75    4.20        5.16       5.10   5.32   5.65
Tryptophan      0.49   1.51     NA         1.63         -    0.89   1.46
Threonine       3.90   3.72    3.30        5.59       5.80   3.67   4.18
Leucine         6.70   9.18    5.90        7.51       8.10   12.66 7.95
Isoleucine      2.84   5.79    4.00        5.88       5.70   3.67   5.44
Valine          4.03   5.89    4.70        6.16       6.20   5.32   5.65
Arginine        3.30   3.40    3.82        6.96       5.10   5.06   7.53
     Recommendations for Feeding High RUP
          Byproducts to Dairy Cows
                      CP   RUP   Recom ByProd      ByProd
                                 intake CP intake CP intake
                      %    %       lb/d   lb/d     % total
Blood meal            87   82    .75-1.0     .87         9.7
Feather meal          92   71     .5-1.0     .92         10.2
Meat & bone           54   70    2.0-2.5     1.35        15.0
Fishmeal              67   60    1.0-2.0     1.34        14.9
Corn gluten meal      67   55    2.0-3.0     2.01        22.3
Corn distill. grain   30   47    4.0-6.0     1.80        20.0
Soybean meal          52   33
Extruded SBM          49   61         Feed as needed
Extruded soybeans     43   54        Oil intake might limit
Roasted soybeans      43   62
              Digestibility of RUP
                        Dairy NRC
                              CP, %   RUP, % dig
Grass/legume hay               19.1      70
Corn silage                     8.8      70
Soy hulls                      13.9      70
Corn, dry cracked               9.4      90
Soybean meal                   53.8      93
Dry distillers grains          29.7      80
Corn gluten meal               65.0      92
Fish meal                      68.5      88
Hydrolyzed feathers            92.0      65
      Why Limit High RUP Proteins?
             Lactating Cows
• Animal byproducts tend to reduce feed intake
    Palatability
    Fat content (Fish meal decreases milk fat)
       Decreased feed intake reduces
       microbial protein synthesis
• Plant byproducts may have poor amino acid
  balance
    Corn proteins deficient in lysine and tryptophan
    Digestibility of RUP (UIP)
• Might create a deficiency of RDP (DIP)
• Quality of RUP proteins can be variable
    Why a Variable Response to RUP?
                Lactating Cows
• Protein requirements may have been met
   Protein might not be first limiting
   Cows mobilizing body proteins
• First limiting amino acid might not be increased
   Amino acid ratios of metabolizable protein
   Digestibility of RUP
• Use of RUP might cause a shortage of RDP
• Overestimation of degradation of other
  supplemental proteins
  Limiting AA for Dairy Cattle
• Lysine and methionine
• Based on corn silage or alfalfa based diets
• NRC (2001) suggests 7.3% of metabolizable
  protein as Lys, 2.5% as Met
• Amino acid composition varies by protein
  source
• Rumen protected (bypass) lysine and/or
  methionine can be supplemented
Vyas and Erdman, 2009

								
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