TTNDFD: A new (and better) tool to evaluate forages and monitor dairy

rations

Dr. David Combs

Dept. of Dairy Science

University of Wisconsin-Madison

Better Understanding Forage Fiber

and Digestibility

Carbohydrate Digestibility

Affects Health & Production

Properly balancing NFC and NDF is critical for

health and production in high producing dairy cows.

Variations in fiber digestibility affect production

more than variations in starch digestibility

Starch digestibility => 1.5-2.5 L milk /day

Fiber digestibility => 2.5-3 L milk /day

Assessing fiber digestion is not easy

Poor digestion < 40% Excellent digestion > 50%

A 2-3 unit change in fiber digestibility corresponds to a 0.5 liter change in milk yield.

How is TTNDFD determined?

How to use TTNDFD information

TTNDFD Total Tract NDF Digestibility

Licensed procedure through the University of WI >15 years of research, > $500,000 invested in development A more appropriate measure of forage digestibility in dairy cattle NDFD30 or uNDF

Energy from forage is affected by:

• The amount of fiber (NDF)

• The digestibility of fiber (NDFD)

– Potentially digestible fiber (pdNDF)

– Rate of fiber digestion (kd)

Plant characteristics

Animal and diet

• Intake affects rate of fiber passage (kp)

• Hindgut digestion of fiber is significant

TTNDFD combines feed and cow factors to measure energy from fiber

Feed fiber Potentially digestible NDF Rate of fiber digestion

Fiber digestion Rate of passage

TTNDFD

A 2-3 unit change in ration TTNDFD corresponds to a 0.5 l change in milk yield.

How is TTNDFD determined?

Rate of fiber digestion (kd)

Potentially digestible NDF (pdNDF)

Rate of fiber passage, (kp)

TTNDFD (total tract NDF

Digestibility)

Standardized iv NDFD (24, 30, 48h) and iNDF

Forage sample

PD NDF * kd/(kd +kp)

Rumen and

hindgut digestion

Think of TTNDFD as how far you

can travel on a tank of gas:

How far you go depends on:

The size of the tank (pdNDF)

AND

The kilometers traveled per liter

(kd)

HOW much milk your forage will make

depends on the amount of potentially

digestible fiber AND the rate of fiber

digestion!

42.34 TTNDFD 47.98

TTNDFD is a prediction of NDF digestibility for a feed (or diet) in a 630 kg cow consuming 24 kg DM of a 28-30% NDF diet.

Feed Analysis Lab Report

Typical NDF and TTNDFD values of forages

NDF TTNDFD Average Good

Alfalfa < 40% 42% > 48% Corn Silage < 40% 42% > 48% Temperate Grasses < 45% 44% > 50%

Dairy quality alfalfa and corn silages will be < 40% NDF with a TTNDFD value of at least 42%

Item USA* Brazil**

NDF 42.7 47.8

TTNDFD 40.3 33.8

Starch 31 24.6

Starch

digestibility 92 ?

Crude Protein 7.8 7.8

Comparing Corn Silages from

USA and Brazil

*Rock River Labs 4 year average

** 3rlabs average 220 samples

Fiber digestion parameters of forages from Brazil

(Lopes et al. 2013)

106 samples total

Palisade grass

(Brachiaria brizantha)

Mulato grass (Brachiaria

hibrida)

Bermuda grass (Cynodon

dactylon)

Star grass (Cynodon

nlemfuensis)

Guinea grass (Panicum

maximum)

Elephant grass

(Pennisetum purpureum)

N = 22 N = 30

N = 31

N = 04

N = 13 N = 06

NDF and TTNDFD of high quality grasses from Brazil

Forage Specie n CP NDF TTNDFD DOM

Palisade Grass Brachiaria brizantha 22 14.0 60.9 48.1 55.6

Mulato Grass Brachiaria hibrida 6 15.7 59.8 48.2 55.3

Bermuda Grass Cynodon dactylon 13 20.3 62.8 53.3 60.3

Star Grass Cynodon nlemfuensis 5 20.6 61.6 48.5 56.8

Guinea Grass Panicum maximum 31 17.3 62.5 47.8 54.5

Elephant Grass Pennisetum purpureum 30 18.3 60.4 53.0 58.4

Alfalfa Medicago sativa 946 18.0 46.0 46.5 71.0

Corn Silage Zea mays 993 6.8 44.9 40.3 68.8

Lopes, et al., 2013

Validating the TTNDFD model

What do the ‘real experts’ say?

Legume/grass feeding trials Mean 47.3 % of NDF (20 trials, 64 observations Median 47.5 % of NDF In vivo NDF diet digestibility) Range 31.1-66.2 % of NDF St. Dev 8.1 Cows report that TTNDF digestibility of legume/grasses are higher than TTNDF digestibility of corn silage. Corn Silage/Sorghum feeding trials Mean 40.2 % of NDF (25 trials, 81 observations, Median 41.1 % of NDF In Vivo NDF diet digestibility) Range 20.1-58.8 % of NDF St. Dev. 8.8

Validating the TTNDFD approach at UW-Madison

Can we optimize fiber use in dairy diets with TTNDFD?

Grass feeding studies (Verbeten, 2012 UW-Madison)

BMR vs conventional corn silage (Lopes et al, 2013a UW-Madison)

Alfalfa vs corn silage utilization (Lopes et al, 2013b UW-Madison)

Temperate Grasses:

Are higher in NDF than alfalfa or corn silage

Have higher TTNDFD than alfalfa or corn silage

What’s the potential of grass fiber for high NFC, low fiber

diets (ie high corn silage rations)

Cool Season Grass in TMR’s

Control Tall

Fescue Meadow Fescue Straw

-----------------------% of Diet DM------------------------

Corn silage 26 17 17 20

Alfalfa silage 26 17 17 20

Bariane Tall Fescue* 17

Pradel Meadow Fescue* 17

Wheat Straw 8

High Moisture Corn 26 25 26 24

Protein/minerals 22 24 23 28

100 100 100 100

What happens if we add grass fiber (high TTNDFD) or wheat straw fiber (low TTNDFD) to a diet with high quality

alfalfa and corn silage?

(Verbeten et al., 2012)

Control Tall Fescue Meadow Fescue Straw

Diet NDF 24 27 27 28 in Vivo NDFD 25 41 41 29

3.5 % FCM, L 41 42 43 42 Milk Fat, % 2.9a 3.4b 3.4b 3.2ab

DMI, kg 26ab 25a 27b 26ab

Trial 1 results: Adding grass or wheat straw to TMR with high quality corn silage and alfalfa

(Verbeten et al., 2012)

Adding more digestible fiber from grass increased ration fiber

digestibility and increased fat test

Trial 2: Using TTNDFD to Evaluate BMR and Conventional Corn Silage

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65

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Tota

l Tra

ct N

DFD

Pre

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Corn Silage NDF, % of DM

Late 2012 BMR Late 2012 Conventional

TTNDFD: BMR vs Conventional Corn Silage

Feeding TMR with low fiber digestibility corn silage (36 TTNDFD) vs high fiber digestibility

corn silage (45 TTNDFD) Low Fiber

Digestibility Corn Silage

TMR

High Fiber Digestibility Corn Silage

TMR

SE

4% FCM, L/d 34.3 35.0 1.0

Observed rumen NDFD, % of NDF 40.5 41.5 2.5

Predicted rumen NDFD, % of NDF* 38.4b 42.8a 0.9

* In vitro NDFD assay predicted rumen fiber digestibility at ad lib intake

Lopes et al, 2013

Trial 3: Using TTNDFD to Evaluate Fiber Digestion in Alfalfa and Corn Silage Diets

Can the in vitro TTNDFD test detect a difference in fiber digestibility as ratios of corn silage (36% TTNDFD) and

alfalfa(42% TTNDFD) change in the ration?

Corn silage:alfalfa ratio 100CS 0AS 67CS 33AS 33CS 67AS 0CS 100AS

SE

DMI, kg/d 25.2ab 25.3a 24.3b 21.9c 0.8

4% FCM, l/d 36.3 35.4 35.2 36.0 0.9

Observed TTNDFD, in vivo 38.3a 40.9ab 39.4ab 43.8a 1.9 Predicted TTNDFD, in vitro* 38 41 41 45 2.1

*In vitro TTNDFD analysis of feeds matched the observed (in vivo) NDF digestibility values

Lopes et al, 2013

How to use TTNDFD

68

70

72

74

76

78

80Switched from 2009 to 2010 Corn Silage WHAT HAPPENED?

Item 2009 2010 NDF 43% 37% NDFD30 62% 61% TTNDFD 48% 32%

Lb m

ilk

Troubleshooting with TTNDFD

46.0 43.7

46.5 44.1

47.3

39.8

2011 2012 2013

NDF TTNDFD

2011, 2012 and 2013 Corn Silage Quality, Midwest & East

On average, 2013 crop corn silage is nearly 8 units lower in fiber digestibility (TTNDFD) last year’s corn silage

Adapted from Goeser, 2013 Hoard’s Dairyman, Nov. Issue.

Low NDF corn silage (good)

BUT- Lower than average fiber digestibility (bad)

39.7 %

37.1 TTNDFD

aNDF

Feed Analysis Lab Report

Which is the better Haylage?

Feed Analysis Lab Report

aNDF

aNDF

42.6%

42.2%

TTNDFD

TTNDFD

51.4

44.1

1. Fiber digestibility has a big impact on milk yield.

A 2-3 unit change in ration TTNDFD corresponds to a

0.5 liter change in milk yield.

2. The TTNDFD test was developed to predict fiber digestibility in high producing dairy cattle Can be used across forage types and byproduct feeds Can be used in ration balancing and evaluation

TTNDFD: The Take Home Message

TTNDFD Guidelines

• Remember 42% TTNDFD

– Corn silage and haylage average!

• Grasses = 44% TTNDFD

• Goal = 48+%

Thank You!

Visit our Web site:

http://dysci.wisc.edu/

y = 0,0783x + 35,279 R² = 0,0088

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Tota

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In Vitro NDFD30

30 h in vitro NDFD values are poorly correlated with TTNDFD

1000 corn silage samples

Stand-alone in vitro NDFD30 or iNDF values are poor predictors of in vivo fiber digestion

y = -0.864x + 68.3 R² = 0.364

0

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0 10 20 30 40 50 60In v

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ND

F d

ige

stio

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Indigestible NDF, % of NDF

In vivo NDF digestion vs indigestible NDF (240h in vitro or 288h in situ)

y = 0.043x + 42.8 R² = 0.005

0

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40

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0 20 40 60In v

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NDFD 30h in vitro, %

In vivo NDF digestion vs In vitro NDFD30h

Arndt C, Armentano LE, Hall MB. J. Dairy Sci. 2009;92 (E-Suppl. 1):94. Ferraretto L. F., A. C. Fonseca, C. J. Sniffen, A. Formigoni, and R. D. Shaver. 2014. Submitted to ADSA meeting 2014. Fredin SM, Bertics SJ, Shaver RD. 2013 J. Dairy Sci. 2013;96(E-Suppl. 1):149. Fredin SM, Ferraretto LF, Akins MS, Shaver RD. 2013 J. Dairy Sci. 2013;96(E-Suppl. 1):34. Lopes, F., D. E. Cook, R. W. Bender and D. K. Combs. 2013a. J. Dairy Sci. 96( E-Suppl 1): 523.. Lopes. F., D. E. Cook and R. W. Bender and D. K. Combs. 2013b.. J. Dairy Sci. 96( E-Suppl 1): 16.. Verbeten, W. D., D. K. Combs and D. J. Undersander. 2011. J. Dairy Sci. 94 (E-Suppl 1): 556.

TTNDFD combines in vitro rate of NDF digestion with iNDF to improve the prediction of in vivo fiber digestion

y = 1.03x R² = 0.660

25

30

35

40

45

50

55

60

25 30 35 40 45 50 55 60

In v

ivo

ND

F d

ige

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TTNDFD in vitro, %

Fiber digestion is affected by plant and animal factors

Rumen Fiber digestibility = pdNDF x kd

(kd + kp)

+ hindgut fiber digestion

TTNDFD is an indexing tool that predicts how fiber will be utilized in a cow consuming 53 lbs of DMI/d of a typical dairy diet (28-30 % NDF)

In Vitro NDF Digestion: TTNDFD is different from NDFD30 or NDFD48

Reasons why NDFD30 or NDFD48 values are

poor predictors of fiber digestibility:

1. Single time point values do not differentiate between

indigestible and undigested potentially digestible fiber.

2. Single time point in vitro values to not necessarily

reflect rate of fiber digestion.

To evaluate forage fiber utilization you need to know pdNDF, kd

and kp!

Fiber digestibility = pdNDF x kd (kd + kp)

Trial 2: Feeding TMR with Normal corn silage (36 TTNDFD) vs BMR corn silage (45 TTNDFD)

Normal Corn Silage

TMR

BMR Corn Silage

TMR

SE

DMI, lb/d 56.1 56.3 2.9

4% FCM, lb/d 75.5 77.0 2.4

Observed rumen NDFD, % of NDF 40.5 41.5 2.5

Predicted rumen NDFD, % of NDF* 38.4b 42.8a 0.9

* In vitro NDFD assay predicted rumen fiber digestibility at ad lib intake

Lopes et al, 2013

In Vivo Fiber Digestion Kinetics

High Starch High Starch Low Starch Low Starch

HMC Dry Corn HMC Dry Corn SE

Diet Starch, % 31.1 32.2 21 21.3 0.5

Diet NDF, % 23.1 24.2 30.1 30.5 0.2

Rumen digestion rate, %/h

Pot. Dig. NDF 2.25 2.91 3.15 3.44 0.23

Rumen passage rate, %/h

Pot. Dig. NDF 2.59 3.01 2.84 2.67 0.33

Total Tract Digestibility

NDF 37.5 35.2 39.3 38.2 3

Over 50 feeding studies (> 175 treatments) have been

published that have measured kd, kp and pdNDF in lactating

cattle

Oba and Allen 2003

Fiber digestibility = pdNDF x kd + hindgut digestion (kd + kp)

Validation: Do in vitro TTNDFD model inputs and outputs match what was measured in the cow?

Method* P-value

Predicted Invivo SEM Method

Input

pdNDF,%ofNDF 71.5 67.4 1.01 <0.01pdNDFkd,%/h 4.11 4.27 0.46 0.72pdNDFkp,%/h 2.67 2.79 0.35 0.56 Output RumendigestedNDF,kg 2.73 2.63 0.22 0.64HindgutdigestedNDF,kg 0.36 0.64 0.19 0.05TotaltractdigestedNDF,kg 3.09 3.27 0.22 0.42TotaltractNDFdigestibility,%ofNDF 46.4 49.5 2.07 0.13*PredictedbytheinvitroTTNDFDmodel,ormeasuredincattleby‘fillandflux’method.

Lopesetal.,2014.Effectofsourceofcornsilageandlevelofdrymatterintakeonrumendigestionkineticsandtotaltract

digestibilityindairycows.