Download - Carbohydrates in Dairy Nutrition
Carbohydrates in Dairy Nutrition
L.E. Chase and T.R. OvertonDept. of Animal Science
Cornell University
Used with permission from Dairy Herd Management magazine
ForagesPhysical Fiber
Rumen DegradableProtein
NFC feedsGrains Byproducts
Minerals and Vitamins
“Bypass”Protein
FatSuppl.
FeedAdditives
The Feed Pyramid (Rick Lundquist, 1995)
Use the Feed Pyramid to think about how rations should be formulated and cows fed. A basic ration with high quality forages (bottom three sections of pyramid) should support up to 75 lbs (or more) of milk per day. Fats, bypass proteins and feed additives are needed by higher producing cows and should top off the base ration
Carbohydrates
Comprise 65 - 75% of the total dry matter consumed by the cow
Most important source of energy for rumen bugs
Carbohydrates are essential in maximizing microbial protein
Provide the major component of NE-l
Maximum Microbial CP Yield(MCP per gram of OM)
47
86 88100
0102030405060708090
100
% o
f sta
rch
NDF Sucrose Pectin Starch
(Hall and Herejk, 2001)
What Does Your Forage Customer Want?
What Does Your Forage Customer Want? A consistent supply of
- High quality- High digestibility- “Effective” physical fiber- Palatable- Well-fermented silage
How Important is Forage Quality? Kawas et. al., Univ. of Wisconsin Used alfalfa hay 4 stages of maturity 4 levels of grain feeding Short-term trial
Milk Production as Affected by Hay Quality
50.0
55.0
60.0
65.0
70.0
75.0
80.0
85.0
90.0
95.0
100.0
20 30 40 50 60 70 80 90
% Hay
Milk
, lbs
/day
Pre BloomEarlyBloomMidBloomFullBloom
JDS: 66, Suppl. 1, 181
Alfalfa Maturity - Conclusions Feeding increased grain could not
overcome the effects of lower forage quality
Milk decreased about 1 lb./day for each day increase in maturity after prebloom
Milk decreased by 1 lb./day for each 1% increase in alfalfa NDF content
How Important is Forage Digestibility?
Data from 23 research trials Alfalfa hay, alfalfa silage, corn silage,
timothy silage, wheat silage Reported NDF dig. (in situ or in vitro) High NDF dig. = 62.9% Low NDF dig. = 54.5%
Oba & Allen – Michigan State - 1999
DMI & Milk Production
40
45
50
55
60
65
70
75
DMI Milk 4% FCM
lbsHigh dNDFLow dNDF
Summary - 1 unit of increased NDF digestibility ( i.e. 45
to 46%)= + 0.37 lbs. DMI + 0.51 lbs. milk + 0.55 lbs. 4% FCM This may not be a linear response across all
levels of NDF digestibility
Using NDF to Determine Forage in the Ration NDF is currently the best method to use to
set the quantity of forage to be fed. Guideline is between 0.85 and 1.1% of
body weight as forage NDF (F-NDF)
Example
1400 lb. cow 0.85% BW = 11.9 lbs. of F-NDF 1.1% BW = 15.4 lbs. of F-NDF
Typically, I use about 1% of BW as a starting point
How Many lbs. of Forage DM to Feed?
05
10152025303540
lbs DM
0.85 0.95 1.05F-NDF Intake, % of BW
405060
What About NDF Digestibility?
Oba & Allen - 1999
Data from 23 research trials Alfalfa hay, alfalfa silage, corn silage, timothy
silage, wheat silage Reported NDF dig. (in situ or in vitro) High NDF dig. = 62.9% Low NDF dig. = 54.5%
DMI & Milk Production
40
45
50
55
60
65
70
75
DMI Milk 4% FCM
lbs High dNDFLow dNDF
Summary -
1 unit of increased NDF digestibility ( I.e. 45 to 46%)=
+ 0.37 lbs. DMI + 0.51 lbs. milk + 0.55 lbs. 4% FCM This may not be a linear response across all
levels of NDF digestibility
The relationship between corn silage NDF and digestible NDF
20
30
40
50
60
70
80
90
25 30 35 40 45 50 55 60NDF, %
Dig
estib
le N
DF,
%
50 60 70
NDF30 Chem
DistributionsNDF30 Distribution in Corn Silage by Chemistry, CVAS 2008
Mean = 60.0SD = 6.9N = 3830
Physically effective NDF
peNDF Related to physical properties of NDF that
stimulate chewing and establish rumen digesta mat Animal response = chewing activity
peNDF and Chewing Activity (cont.) Cows only chew ~10-11 h/d (Welch, 1982) 88 min to chew 1 lb of NDF from oat straw
Or, 1.5 h Only takes 6.8 lb straw NDF to reach cow’s
capacity (or, 8 lb of straw DM)! Explains response to 1 lb supplementation (or to
bedding)
Importance of NDF and Chewing Activity Chewing data set (Mertens, 1997)
Equivalent particle length Alfalfa, coarse 60 min/lb of NDF Bermudagrass 68 min/lb Ryegrass 63 min/lb Oat straw 88 min/lb Corn silage 44 min/lb
Two Basic Methods for Measuring Physical Fiber (Particle Size)
Penn State ParticleSeparator(moist, as-fed samples)19, 8, 1.18 mm, pan; 40 horizontal shakesOn-Farm evaluation
Dry sieving Ro-Tap(dried sample, standardprocedure for peNDF)19, 13, 9.5, 6.7, 4.75, 3.35, 2.36, 1.18, 0.6 mm; shakes for 10 minLaboratory procedure
peNDF (dry sieving) and cow response: chewing activity
(Mertens, 1997)
r2=0.47
peNDF and Ruminal pH
Positive Impacts of Digestible NDF Increased DMI Increased Energy Intake Higher ruminal pH Increased A:P No lactic acid Greater MCP production Less need for RUP supplements More constant supply of absorbed nutrients
NFC (Non-Fiber Carbohydrates) 4 basic categories Organic acids (no energy for bugs) Sugars Starch Neutral-detergent soluble fiber (pectin's,
beta-glucans, fructans, etc.) Is a calculated value
Nonfiber Carbohydrates
All NFC are NOT created equal! Chemically & nutritionally diverse Different effects on cow health and performance
NFC = 100 – (NDF+CP+EE+Ash) NFC = 100 – ((NDF-NDICP)
+CP+EE+Ash) NSC = sugars + starch
directly measured
General recommendation for NFC 37 to 42% of DM
Rumen Degradability of CHO Sources
Source FormFastest Wheat Steam flaked
Barley High moistureOats Dry groundCorn Dry rolled
Slowest Sorghum Dry whole
Ruminal Feed Carbohydrate Fermentation Profile
EAT 1 3 5 7 9 11 13 15 17 19 21 23Time after Feeding (h)
Rat
e of
Fer
men
tatio
n
sugars
Starches and pectin
starchescelluloses
• oat> wheat>barley> corn>milo• grinding, ensiling, steam• how fast and how much
Rate of ruminal starch digestion of corn
fine ground corn
cracked corn
hours after feeding2 12 24
%
dige
sted
90
80
60
40
20
0
rumen pH fiber digestion
AcidosisLow milk fatoff-feed Healthy rumen
performance
If there is too much nonfiber carbohydrates or if it breaks down
too fast:
Summary
Carbohydrates are the key to providing energy for both microbial bug growth and energy for the cow
Structural (fiber) carbohydrates stimulate chewing and rumination
Non-structural (sugars, starch) provide rapidly available energy in the rumen but can also lower rumen pH