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7. Friday - Ruminant Sessions prof mike allen michigan state university - forage fragility - passage rate and gut fill applications
1. Effect of forage fragility on turnover time of
forage NDF and feed intake
Mike Allen
2. Overview
• Ruminal distention and feed intake
• Diet factors affecting gut fill
• Filling effects of forages on feed intake
• Turnover of forage NDF in the rumen
3. Effect of diet NDF content and inert bulk on rumen
contents volume and DMI of lactating cows
Dado and Allen 1995 J. Dairy Sci. 78:118
RIB: 25% of pretrial rumen contents volume
0
5
10
15
20
25
25 25 + RIB 35 35 + RIB
22.8a
22.7a
18.7a
16.6a
DMI, kg/d Volume, L
0
20
40
60
80
100
120
140
25 25 + RIB 35 35 + RIB
90b
101a
99a 105a
79c 83c
4. Rumen contents: weight vs. volume
0
10
20
30
40
50
60
70
80
90
100
7.25 L
1.1 SG
7.25 L
1.3 SG
14.5 L
1.1 SG
14.5 L
1.3 SG
Dry Matter Intake, % of control
550 kg steers
43% ADF diet
50 or 100 balls
Volume: P < 0.01
Weight: P < 0.05
Schettini et al., 1999 J. Anim. Sci. 77:1896
88% 84%
78%
72%
7. Non-forage fiber sources have relatively little effect on
feed intake when substituted for grain
Allen, 2000, J. Dairy Sci. 83:1598
13
17
21
25
29
0 10 20 30 40 50
NFFS, % of DM
DMI,kg/day
8. Interaction of forage particle length and diet forage %
Alfalfa silage
35% forage, 27.2% NDF
65% forage, 31.2% NDF
Silage: P < 0.01
Length: NS
Interaction: P < 0.01
Forage, % of DM
DMI, kg/d
19
20
21
30 40 50 60 70
22
5 mm TLC
10 mm TLC
Beauchemin et al. 1994 J. Dairy Sci. 77:1326
9. Forage particle size is probably not a major factor
affecting feed intake (for corn silage and alfalfa)
Allen, 2000, J. Dairy Sci. 83:1598
19
20
21
22
23
24
25
26
0 0.2 0.4 0.6 0.8 1.0 1.2
Mean Sieve Aperture Size, cm
DMI,kg/day
10. Variation in in vitro NDF digestibility of forages
0
5
10
15
20
25
30
30 35 40 45 50 55 60
Number of Samples (n = 140)
In Vitro NDF Digestibility, 30 h
0
20
40
60
80
100
120
140
25 30 35 40 45 50 55 60
Number of Samples (n = 640)
In Vitro NDF Digestibility, 30 h
Corn Silage Alfalfa
Allen, 1993 NRAES-67
11. Effects of in vitro NDF digestibility on DMI and milk yield
• In vitro NDFD positively related to DMI
• Alfalfa silage (Dado and Allen, 1996)
• Corn silage (Oba and Allen, 1999a)
• DMI response to increased NDFD is positively related to
milk yield (Oba and Allen, 1999a)
• DMI and FCM positively related to NDFD within family but
negatively related to NDFD across family (Oba and Allen, 1999b)
• 1 unit change in forage NDF digestibility (in vitro or in situ) =
0.17 kg/d change in DMI and 0.25 kg/d change in 4% FCM
(Oba and Allen, 1999b)
13. Diet had no effect on feed intake averaged across cows, but cows with
greater drive to eat responded more positively to alfalfa over grass.
Pretrial DMI, kg/d
-4
-2
0
2
4
6
13 14 15 16 17 18 19 20 21
r = 0.87
P < 0.01
DMIalfalfa-DMIgrass
(kg/d)
Pretrial DMI, kg/d
r = 0.69
P = 0.06
Kpalfalfa-Kpgrass
(hr-1)
Grass vs. legume: response depends on pretrial DMI
INDF passage rate response to
alfalfa over grassDMI response to alfalfa over grass
-0.25
0.00
0.25
0.50
0.75
1.00
13 14 15 16 17 18 19 20 21
Voelker Linton and Allen, 2005, J. Dairy Sci. 88S:252
14. Passage rate is affected by forage characteristics
Comparison of bm3 corn silage to isogenic control in 29% and 38% NDF diets
(Oba and Allen, 2000, J. Dairy Sci. 83:1350
29% NDF 38% NDF Significance, P
bm3 control bm3 control NDF CS NDFxCS
INDF kp, h
-1
3.73 3.13 3.55 3.27 0.81 0.0001 0.09
Comparison of alfalfa silage (43% NDF) to orchardgrass silage (48% NDF)
(Voelker Linton and Allen, 2007 J. Dairy Sci. 90:4770)
alfalfa orchardgrass Significance, P
INDF kp, h-1 2.93 2.52 0.03
16. Buoyancy of particles by size from the dorsal rumen of
sheep fed alfalfa
Percent of dry matter
Sieve
aperture, mm
Floating Suspended Sinking
4 90 2 8
2 85 4 11
1 53 5 42
0.5 20 3 77
0.25 7 2 91
fines 21 10 68
Sutherland, 1988
17. Mean retention time of inert particles in the
reticulorumen of cattle and sheep
Lechner-Doll et al., 1991
Time, h
100
80
60
40
20
0
Particle density, g/ml
0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5
18. Effect of fermentation on particle buoyancy
Gases
Potentially digestible
Indigestible
Float
Sink Fermentation Time
Allen, 1996 J. Anim. Sci. 74:3063
19. Proposed relationship between digestion characteristics
and ruminal retention time
0
20
40
60
80
100
0 10 20 30 40 50 60 70
Rumen retention time, h
Percent
of NDF
Indigestible NDFGrass
Allen, 1996 J. Anim. Sci. 74:3063
Legume
Legume
Grass
NDF digestibility
20. Rate of particle size reduction
Voelker Linton and Allen, 2007 J. Dairy Sci. 90:4770
21. Kinetics of particle size reduction and passage
Size Fraction % /h % of NDF
in rumen
≥ 2.4 mm iNDF 2.10 15.5
≥ 2.4 mm pdNDF 0.59 19.6
< 2.4 mm iNDF 5.67 40.7
< 2.4 mm pdNDF 1.70 24.2
L -> S iNDF 6.92
Voelker Linton and Allen, 2007 J. Dairy Sci. 90:4770
Passage rate:
~2.8x higher for S vs L
~3.5x higher for iNDF vs pdNDF
kr 3.3x higher than kp for iNDF
65% of NDF in rumen below
threshold size for passage
22. Grass vs. legume revisited:
particle size reduction and passage
• Crossover design with preliminary period
• 13 ruminally and duodenally cannulated cows
• Passage measured using the pool and flux method
• Alfalfa silage: 42.3% NDF
• Orchardgrass silage: 58.2% NDF
• Rations: 25% FNDF, 30% NDF, 17.5% CP
• AL: 59.9% forage
• OG: 42.7% forage
• Similar DM and NDF intakes
Kammes and Allen, 2012 J. Dairy Sci. 95:3288
25. Alfalfa NDF was more fragile than orchardgrass NDF
Kammes and Allen, 2012 J. Dairy Sci. 95:3288
0
1
2
3
4
5
Alfalfa Orchardgrass
P < 0.001
iNDF rate of reduction
from L to S, %/h
0
20
40
60
80
100
Alfalfa Orchardgrass
P = 0.02
Ruminating time,
min/kg forage NDF intake
26. Rate of passage for L particles
Treatment P
Alfalfa Grass Trt Trt x pDMI
Rate of passage, %/h
pdNDF L 1.05 0.75 0.07 0.10
iNDF L 1.18 1.01 0.38 0.23
Kammes and Allen, 2012 J. Dairy Sci. 95:3288
27. Interaction of treatment and pDMI for
pdNDF L passage rate
Kammes and Allen, 2012 J. Dairy Sci. 95:3288
P < 0.10
0
0.5
1
1.5
2
18 20 22 24 26 28 30
pdNDFLpassagerate,%/h
Preliminary DMI, kg/d
Alfalfa
Orchardgrass
28. Rate of passage of S particles was greater for alfalfa
than orchardgrass
Treatment P
Alfalfa Grass Trt Trt x pDMI
Rate of passage, %/h
pdNDF S 3.80 2.50 <0.01 0.27
iNDF S 3.85 2.66 <0.001 0.97
Kammes and Allen, 2012 J. Dairy Sci. 95:3288
29. 0
1
2
3
4
5
Alfalfa Orchardgrass
Passage rates for pdNDF S and iNDF S were similar
within forage family
P = 0.81
P = 0.49
Kammes and Allen, 2012 J. Dairy Sci. 95:3288
pdNDF iNDF
Passagerate,%/h
Alfalfa Orchardgrass
pdNDF iNDF
30. Limiting factor for passage from the rumen?
• Critical particle size?
• Proportion of NDF in rumen below the threshold for passage > 55%
• Buoyancy?
• Passage rates for iNDF and pdNDF same for small particles
• Large particle pool?
• Slower passage rate of NDF S for orchardgrass than alfalfa is likely
because of greater entrapment of NDF S within rumen mat by larger
pool of NDF L
• Affected by initial particle size and rate of breakdown (fragility)
31. uNDF240 to predict DMI?
uNDF240 turnover time, h
alfalfa
orchardgrass
orchardgrass
alfalfa
Kammes and Allen, 2012 J. Dairy Sci. 95:3288
uNDF240 is not
limiting DMI:
something else
32. Relationship between DMI and diet factors
Term Estimate P
Intercept 12.0 < 0.0001
fNDF -0.107 <0.001
ADF/NDF 8.17 <0.001
NDFD 0.025 0.1
(ADF/NDF-0.602)*(NDFD-48.3)* -0.328 0.03
MY** 0.225 <0.0001
(NDFD-48.3)*(MY-33.1)*, ** 0.0039 0.06
Sousa et al., Abstract #329, Tues 10:00 am
Mean bias, kg/d -0.09
CCC 0.83
RMSE, kg/d 1.54
33. Implications
Models without diet factors over-predicted DMI at high DMI and under-
predicted DMI at low DMI
Mean bias, kg/d -0.26
CCC 0.78
RMSE, kg/d 1.62
Mean bias, kg/d 0.14
CCC 0.71
RMSE, kg/d 2.31
Mean bias, kg/d -0.03
CCC 0.71
RMSE, kg/d 1.99
Model including diet factors NRC (2001) Souza et al, 2017
Models including animal factors only
34. Summary
• Concentration and digestibility of forage NDF and forage type
(legume, perennial grass, annual grass) are the primary factors
related to the filling effect of diets.
• Forage type affects rate of particle size breakdown and ruminal
retention time.
• In vitro NDF digestibility is highly variable and is useful within, but
not across forage types.
• Benefits of reducing forage NDF concentration and increasing
forage NDF digestibility are greater for high producing cows.
Before looking at the particle size distribution of NDF intake, I’ll explain the layout for column charts used in this presentation which have categories listed on the x-axis and values on the y-axis. The P-value listed above a pair of columns indicates significance between treatments for each category. The alfalfa treatment is represented by the green color and orchardgrass treatment by the blue color.
This chart shows the proportion of NDF L and NDF S as a % of the total NDF intake. Despite the low p-values, particle size distribution of NDF intake was similar for alfalfa and orchardgrass with each treatment consuming approximately 75% of total NDF as L particles and 25% as S particles.
This chart shows rumen pool particle size distribution for NDF L and NDF S in kg. ORCHARDGRASS increased rumen pool size of NDF L compared to ALFALFA, but there was no difference in rumen pool sizes for NDF S. In addition, ORCHARDGRASS also had higher rumen pools of pdNDF and DM as well as rumen digesta wet weight and volume compared to ALFALFA. The larger pool of large particles in the rumen for ORCHARDGRASS may entrap the small particles resulting in the slower passage rate of pdNDF S and iNDF S observed for ORCHARDGRASS. Also, note that over half of the particles in the rumen are less than the threshold for passage.
ALFALFA NDF was more fragile than orchardgrass NDF. The chart on the left shows rate of reduction of iNDF from L to S expressed in %/h, which was 35% faster for ALFALFA than ORCHARDGRASS.
The chart on the right shows ruminating time expressed in min/kg of forage NDF intake, which was 7% greater for ORCHARDGRASS compared to ALFALFA.
Thus, ALFALFA had a faster rate of reduction than ORCHARDGRASS with less rumination.
This table shows the passage rate of large particles expressed in %/h, which are approximately 1% for pdNDF L and iNDF L for both treatments.
There was a treatment by pDMI interaction for the rate of passage of pdNDF L but no treatment effect or interaction for iNDF L.
Taking a look at the interaction…
… of treatment and pDMI for pdNDF L passage rate which is on the y-axis and pDMI in kg/d on the x-axis. The dots are passage rates of individual cows when consuming alfalfa (green dots) or orchardgrass (blue dots). This shows that: as pDMI increased, ALFALFA increased the passage rate of pdNDF L and ORCHARDGRASS decreased it .
This table shows the passage rate of small particles expressed in %/h.
ALFALFA increased the rate of passage of pdNDF S and iNDF S compared to ORCHARDGRASS.
Also, noted was the similar passage rates of pdNDF S and iNDF S within forage family, which was analyzed further.
This chart shows the passage rate in %/h for pdNDF S (in solid colored columns) and iNDF S (in patterned columns) for alfalfa and orchardgrass. There were no differences for the passage rates of pdNDF S and iNDF S within forage family.
Gas from the fermentation of digestible NDF entrapped in fiber particles increases their buoyancy and decreases the likelihood of ruminal escape. Because both indigestible and digestible fractions are contained in the same particle, it is reasoned that the probability of particles to pass from the rumen should increase as the particle increases in indigestible material; therefore, the the passage rate of iNDF should be greater than that of pdNDF.
The similar passage rates shown here for pdNDF and iNDF suggests buoyancy was not a constraint to passage of S particles.
