OHIO AGRICULTURAL RESEARCH AND DEVELOPMENT CENTER ...tortuga.com.br/isvit2016/doc/24.02/24.02...
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OHIO AGRICULTURAL RESEARCH AND DEVELOPMENT CENTER
Bill Weiss
Department of Animal Sciences
Wooster, 44691
Importance of Starch to the Energy Supply of Dairy Cows
Starch: do cows need it?
1. Most forages (‘the natural food’ for ruminants) have <5% starch
2. Of the 68 major feeds listed in NRC, only 13 have > 20% starch
3. Many beef cows live to a ripe old age and never eat a gram of starch
Energy Sources (% of DE) Typical US Dairy Diet
20%
7%
24%
34%
4%
11%
Protein Fat Fiber Starch Sugar Other
*Starch rarely <25%
If you are going to formulate for starch you must get feeds assayed
Owens, 2009 Tri-State Dairy Nutr. Conf. Proc.
Starch
Cheap Energy More Bacterial Protein
Less Manure
It is a good thing
Starch increases bacterial protein
synthesis (usually)
0
50
100
150
200
250
g M
icro
bia
l p
rote
in
Glucose Starch NDF
0
50
100
150
200
250
300
350
400
450
31% Starch 21% Starch
Hristov et al., 2005 Oba and Allen, 2003
GE
DE
ME
NEL
Fecal Energy
Heat increment
Urine/methane
Energy
Retained + work
+ maintenance
Energy Flow
Average Energy Values (Beltsville Energy Lab)
4,60 3.06 2,64 1,63
0,0
0,5
1,0
1,5
2,0
2,5
3,0
3,5
4,0
4,5
5,0
Mc
al/
kg
DM
67% 57% 35%
87% 53%
62%
N = 301 GE DE ME NEL
8% M
5%U
Energy from Carbohydrates Diet DMI = 23 kg lbs 25% starch 5.8 kg 5.3 kg dStarch 32% NDF 7.4 kg 3.5 kg dNDF
Starch 22 Mcal DE 12.8 Mcal NEL NDF 15 Mcal DE 7.4 Mcal NEL
0.78 X
1.5 X 1.7 X
On average 1 kg of starch = 2.3X
more NEL than 1 kg NDF
1.5 X
Starch and Energy Supply
Function of:
1. Starch digestibility
2. Starch concentration
NEL
Su
pp
ly, M
cal/
day
Digestibility or Concentration
Non-linear relationship
Optimal Dietary Starch %
Usually 20 to 30%
Too Low
Low intake Inadequate energy
Too High
Low intake Low fiber digest Acidosis
1. Economics (feed costs)
2. Cow requirements
3. Available feeds
Starch (corn) Digestibility in Lactating Dairy Cows
13 experiments 58 diets 287 observations Avg = 92.1%
16 experiments 65 diets 356 observations Avg = 48.5%
Grass-based
NDF (corn silage, alfalfa, NFFS) digestibility by lactating dairy cows
What affects starch digestibility?
1. Plant species •Wheat = barley = oats > corn > sorghum
2. Plant (seed) maturity •Immature > mature
3. Maize hybrid (type) •Dent > flint
4. Processing •Fine > coarse •Steam-flake > dry roll
Grain Processing and Starch Digestibility
30
40
50
60
70
80
90
100
Corn Sorghum Barley
Sta
rch
Dig
es
tib
ilit
y,
%
Cracked
Ground
Fine grind
Steam flaked
HM, rolled
HM, ground
Literature review, Firkins et al., 2001
Particle size of dry corn
50
60
70
80
90
100
Sta
rch
dig
esti
bil
ity, %
<1 1 to 1.5 1.5 to 2
3 to 3.5 3.5 to 4
1,3
1,32
1,34
1,36
1,38
1,4
1,42
1,44
1,46
0 1 2 3 4F
CM
/DM
I
Mean Particle Size, mm
TMR: 2.8%/mm
Ferraretto et al., 2013
Grind corn to <1000 μm
Vitreous or flinty
Pictures courtesy of Mike Allen, MSU
Floury
Hybrid Effects: Vitreousness
Dent
Vitreousness of DRY Corn
• Diets balanced for starch and starch source
• ~53% of starch from corn grain
• Hybrid 1: 3% Vitr
• Hybrid 2: 67% Vitr 20
30
40
50
60
70
80
90
100
Total Ruminal
'Soft'
'Hard'
~5%
Taylor and Allen, 2005
Kernel Texture
Very soft Very hard
Floury Flinty Dent
Real world range in hardness will be less
and
so will range in starch digestibility
Be patient: Starch digestibility of HM corn and corn silage
increases over time
0
10
20
30
40
50
60
70
3 h
Sta
rch
Dig
est,
%
2 month
4 mo
6 mo
8 mo
10 mo
DM ~36%
Newbold et al., 2006
Reduce diet % starch as corn silage and HM
corn ages
Young vs old corn silage
1 to 1.5 % units of starch
Is variation in starch digestibility important?
2,5
2,6
2,7
2,8
2,9
3
3,1
3,2
3,3
3,4
3,5
20% Diet Starch 30% Diet Starch
DE,
Mca
l/kg
0.88 Digest
0.98 Digest
+3% +4%
~ 3 kg milk ~2 kg milk
Maximize Starch Digestibility
0
5
10
15
20
25
30
24%Starch
26%Starch
28%Starch
% D
igesti
ble
Sta
rch
88% 96%
Starch digestibility Starch Digestibility
(dairy)
80 – 99% (88-96%)
8% Digest =
2% Concentration
Cost to digest vs cost of starch
Fecal starch % predicts starch digestibility (Fecal starch also predicted by NIRS)
Fredin et al. (2014; JDS 97:1862)
Wisconsin Dairy Survey (30 farms) (Huibregtse et al., 2012)
75% had <5% starch
Why does this occur?
Starch and Energy Supply N
EL S
up
ply
, Mca
l/d
ay
Digestibility or Concentration
1. Negative effects on intake
2. Negative effect on fiber digestibility
• Wheat vs. corn
– 19% fNDF
– 36% Starch (Lechartier and Peyraud, 2010)
• Dry vs. High
moisture corn
– 16 or 25% fNDF
– 31 or 21% starch (Oba and Allen, 2003)
14
16
18
20
22
24
DM
I, k
g/d
Wheat Dry corn HM corn
Diets with excess FERMENTABLE starch can reduce DMI
Grain
Source
Corn grain
storage
High Low
starch
On average, a 5%unit increase in starch = ~2.5%unit decrease in NDF digestibility
(Meta-analysis; Ferraretto et al., 2013)
Y = 58.3 – 0.48X
320 Trt means
Associative Effects: Steam-flaked corn density
0
10
20
30
40
50
60
70
80
90
100
R. Starch TT Starch TT ADF TT OM
0.39
0.32
0.26 kg/L
Firkins et al., 2001 from Plascencia and Zinn, 1996
Alfalfa hay + ~24% Starch
% of NDF from Wheat
0 13% % of ADF from Wheat
0 6%
Leddin et al., 2009
52 32% NDF
29 17% ADF
Confounding is Inevitable
2 20% Starch
Changing starch% while maintaining ‘inherent’ NDF digestibility
NDF:Starch
0.75 1.0 1.25
Corn silage 42 42 42
Corn grain 34.8 29.0 23.3
SH + CSH 0 5.6 11.3
NDF 24.7 28.6 32.2
Starch 33.3 30.1 25.4
IS NDF digest, % 43 43 43
NDF digest, % 45.3 46.4 46.4
Beckman and Weiss, 2005
Starch Depression of NDF Digestibility: Mechanisms
1. rumen pH alters bacterial population
2. pH-(in)dependent slowing of bacterial attachment
3. pH-(in)dependent inhibition of cellulolytic enzymes
4. rumen pH reduces bacterial population
Fermentable Starch Rate of NDF Digest
0,0
0,5
1,0
1,5
2,0
2,5
3,0
3,5
4,0
21% Starch 31% Starch
%/h
r (p
dN
DF)
Dry Corn HM Corn
Oba and Allen, 2003
- In vivo (lact cows)
- Corn replaced corn and alfalfa silage
- Diets had ~5% DDG
- DMI: High>Low
Starch and Depressed Fiber Digestion: More than just pH
10
20
30
40
50
60
70
5,5 6,2 6,8
ND
F, IV
PED
,%
Media pH
None-Alf Corn-Alf
Grant 1994
1. Diets: 0 or 29% starch
2. pH was fixed
3. Low pH, starch was –
4. High pH, starch was +
Amylase may stimulate NDF digestion
20
30
40
50
60
70
80
90
100
Starch NDF . Starch NDF
-Amylase +Amylase
1. Amylase often does not increase starch digest
2. Amylase often increases NDF digest
Rumen Total
Noziere et al., 2014 Weiss et al., 2011
Cow Energetics:
or
How much should nutritional models discount NEL as starch
increases ?
Is the decrease in NDF digestibility important?
Assumptions:
▪ DE from NDF and starch = 4.2 Mcal/kg (from NRC)
▪ Starch digest: 92% (from Weiss dataset)
▪ NDF digest: 48%
▪ Effect of starch on NDF digest = -0.48/% (from Ferraretto et al., 2013)
5% Substitution of Starch for NDF: Effects on DE
DE increases 3.11 to 3.20 Mcal/kg +2.9%
5% Substitution of Starch for NDF: Effects on ME
Assumptions:
▪ Methane from digestible starch and NDF (modified from Jentsch et al., 2007)
▪ NDF digestion assumed to decrease
▪ No effect on urinary N
Basal CH4 from CHO: 0.16 Mcal/kg +5% starch, -5%NDF: 0.155 Mcal/kg
-3.1%
%5 Substitution of Starch for NDF: Effects on ME to NE
Assumptions:
▪ Propionate 2 units, acetate 2 units (Weiss et al., 1991)
▪ Propionate to glucose k = 0.59 Acetate to fat k = 0.29 (from Hanigan, 2012 and Baldwin, 1995)
Basal k = 0.275 +5% starch, -5%NDF k = 0.282
+2.5%
5% Substitution of Starch with NDF: Effect on NEL
Assumed decrease of 0.025 in NDF digestibility
Basal +5%Starch
DE, Mcal/kg 3.11 3.20
ME, Mcal/kg 2.69 2.79
NEL, Mcal/kg 1.70 1.79
+2.9%
+3.7%
+5.3%
+6.5% No Effect on NDF
Potential Factors Affecting Starch Affect on NDF Digestibility
1. Starch fermentability
2. Source of NDF
- Species (corn silage, alfalfa, grass, NFFS)
- ‘Inherent’ NDF digestibility (forage maturity, soyhulls vs wheat bran, etc)
3. DMI interactions
Starch Fermentability and NDF Digest
10
15
20
25
30
35
40
45
50
55Less More
Forage based diets, mostly alfalfa+corn silage
Treatments were:
Wheat or barley vs corn
HM vs dry corn
SF-corn vs dry corn
Degree of vitreous
Fine vs coarse ground corn
For modeling: How do you measure fermentability?
Type of forage and Starch Effect
0
10
20
30
40
50
60
70
80
0 5 10 15 20 25 30 35
ND
F D
ige
stib
ility
Estimated Starch, %
Alf OG
40
44
48
52
56
60
20 25 30 35
ND
F D
ige
stib
ility
, %
Diet Starch, %
75:25 AS:CS
25:75 AS:CS
Weiss and Shockey, 1991
No interaction No interaction
Weiss et al., 2009
Starch and Byproduct NDF
Decrease starch by increasing nfNDF NDF digestibility ◦nfNDF can be highly digestible ◦ reduces (-)associative effect
Decrease starch by reducing fNDF NDF digestibility ◦does faster ROP counter reduced negative associative effect
Highly dependent on byproduct
Conclusions
1. On average, starch NDF digestibility
2. On average, starch NEL
3. Usually, starch ferment NDF digest
4. Source of fiber affects response
5. DMI affects response
6. Energy modeling must include more than just starch%
http://dairy.osu.edu