Better Understanding Forage Fiber and Digestibility

Transcription

1 Better Understanding Forage Fiber and Digestibility TTNDFD: A new (and better) tool to evaluate forages and monitor dairy rations Dr. David Combs Dept. of Dairy Science University of Wisconsin-Madison

2 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 => L milk /day Fiber digestibility => L milk /day

3 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.

4 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 How is TTNDFD determined? How to use TTNDFD information

5 Energy from forage is affected by: Plant characteristics The amount of fiber (NDF) The digestibility of fiber (NDFD) Potentially digestible fiber (pdndf) Rate of fiber digestion (kd) Animal and diet Intake affects rate of fiber passage (kp) Hindgut digestion of fiber is significant

6 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.

7 How is TTNDFD determined? Forage sample Rate of fiber digestion (kd) Potentially digestible NDF (pdndf) Rumen and hindgut digestion Standardized iv NDFD (24, 30, 48h) and indf Rate of fiber passage, (kp) PD NDF * kd/(kd +kp) TTNDFD (total tract NDF Digestibility)

8 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!

9 Feed Analysis Lab Report 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. TTNDFD

10 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%

11 Comparing Corn Silages from USA and Brazil Item USA* Brazil** NDF TTNDFD Starch Starch digestibility 92? Crude Protein *Rock River Labs 4 year average ** 3rlabs average 220 samples

12 Fiber digestion parameters of 106 samples total forages from Brazil (Lopes et al. 2013) N = 22 N = 30 N = 04 Palisade grass (Brachiaria brizantha) N = 31 Elephant grass (Pennisetum purpureum) N = 06 Star grass (Cynodon nlemfuensis) N = 13 Guinea grass (Panicum maximum) Mulato grass (Brachiaria hibrida) Bermuda grass (Cynodon dactylon)

13 NDF and TTNDFD of high quality grasses from Brazil Forage Specie n CP NDF TTNDFD DOM Palisade Grass Brachiaria brizantha Mulato Grass Brachiaria hibrida Bermuda Grass Cynodon dactylon Star Grass Cynodon nlemfuensis Guinea Grass Panicum maximum Elephant Grass Pennisetum purpureum Alfalfa Medicago sativa Corn Silage Zea mays Lopes, et al., 2013

14 Validating the TTNDFD model

15 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 % 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 % of NDF St. Dev. 8.8

16 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)

17 Cool Season Grass in TMR s 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)

18 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? Control Tall Fescue Meadow Fescue Straw % of Diet DM Corn silage Alfalfa silage Bariane Tall Fescue* 17 Pradel Meadow Fescue* 17 Wheat Straw 8 High Moisture Corn Protein/minerals (Verbeten et al., 2012)

19 Trial 1 results: Adding grass or wheat straw to TMR with high quality corn silage and alfalfa Control Tall Fescue Meadow Fescue Straw Diet NDF in Vivo NDFD % FCM, L Milk Fat, % 2.9 a 3.4 b 3.4 b 3.2 ab DMI, kg 26 ab 25 a 27 b 26 ab (Verbeten et al., 2012) Adding more digestible fiber from grass increased ration fiber digestibility and increased fat test

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

21 Total Tract NDFD Prediction, % of NDF TTNDFD: BMR vs Conventional Corn Silage Corn Silage NDF, % of DM Late 2012 BMR Late 2012 Conventional

22 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 Observed rumen NDFD, % of NDF Predicted rumen NDFD, % of NDF* 38.4 b 42.8 a 0.9 * In vitro NDFD assay predicted rumen fiber digestibility at ad lib intake Lopes et al, 2013

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

24 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 DMI, kg/d 25.2 ab 25.3 a 24.3 b 21.9 c 0.8 4% FCM, l/d SE Observed TTNDFD, in vivo 38.3 a 40.9 ab 39.4 ab 43.8 a 1.9 Predicted TTNDFD, in vitro* Lopes et al, 2013 *In vitro TTNDFD analysis of feeds matched the observed (in vivo) NDF digestibility values

25 How to use TTNDFD

26 Lb milk Troubleshooting with TTNDFD Switched from 2009 to 2010 Corn Silage WHAT HAPPENED? Item NDF 43% 37% NDFD30 62% 61% TTNDFD 48% 32%

27 2011, 2012 and 2013 Corn Silage Quality, Midwest & East NDF TTNDFD 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.

28 Feed Analysis Lab Report andf 39.7 % Low NDF corn silage (good) TTNDFD 37.1 BUT- Lower than average fiber digestibility (bad)

29 Feed Analysis Lab Report andf TTNDFD 42.6% 51.4 Which is the better Haylage? andf TTNDFD 42.2% 44.1

30 TTNDFD: The Take Home Message 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

31 TTNDFD Guidelines Remember 42% TTNDFD Corn silage and haylage average! Grasses = 44% TTNDFD Goal = 48+%

32 Thank You! Visit our Web site:

33 Total Tract NDF digestibility h in vitro NDFD values are poorly correlated with TTNDFD y = 0,0783x + 35,279 R² = 0, corn silage samples In Vitro NDFD30

34 In vivo NDF digestion, % In vivo NDF digestion, % Stand-alone in vitro NDFD30 or indf values are poor predictors of in vivo fiber digestion In vivo NDF digestion vs In vitro NDFD30h In vivo NDF digestion vs indigestible NDF (240h in vitro or 288h in situ) y = 0.043x R² = y = x R² = NDFD 30h in vitro, % Indigestible NDF, % of NDF 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 Submitted to ADSA meeting Fredin SM, Bertics SJ, Shaver RD J. Dairy Sci. 2013;96(E-Suppl. 1):149. Fredin SM, Ferraretto LF, Akins MS, Shaver RD 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): 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 J. Dairy Sci. 94 (E-Suppl 1): 556.

35 In vivo NDF digestion, % TTNDFD combines in vitro rate of NDF digestion with indf to improve the prediction of in vivo fiber digestion y = 1.03x R² = TTNDFD in vitro, %

36 Fiber digestion is affected by plant and animal factors Rumen Fiber digestibility = pdndf x kd + hindgut fiber digestion (kd + kp) 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)

37 In Vitro NDF Digestion: TTNDFD is different from NDFD 30 or NDFD 48

38 Reasons why NDFD 30 or NDFD 48 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)

39 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 % FCM, lb/d Observed rumen NDFD, % of NDF Predicted rumen NDFD, % of NDF* 38.4 b 42.8 a 0.9 * In vitro NDFD assay predicted rumen fiber digestibility at ad lib intake Lopes et al, 2013

40 In Vivo Fiber Digestion Kinetics High Starch High Starch Low Starch Low Starch HMC Dry Corn HMC Dry Corn SE Diet Starch, % Diet NDF, % Rumen digestion rate, %/h Pot. Dig. NDF Rumen passage rate, %/h Pot. Dig. NDF Total Tract Digestibility NDF Oba and Allen 2003 Over 50 feeding studies (> 175 treatments) have been published that have measured kd, kp and pdndf in lactating cattle

41 Validation: Do in vitro TTNDFD model inputs and outputs match what was measured in the cow? Fiber digestibility = pdndf x kd + hindgut digestion (kd + kp) Method* P-value Predicted In vivo SEM Method Input pdndf, % of NDF <0.01 pdndf kd, %/h pdndf kp, %/h Output Rumen digested NDF, kg Hindgut digested NDF, kg Total tract digested NDF, kg Total tract NDF digestibility, % of NDF *Predicted by the in vitro TTNDFD model, or measured in cattle by fill and flux method. Lopes et al., Effect of source of corn silage and level of dry matter intake on rumen digestion kinetics and total tract digestibility in dairy cows.