This document discusses factors that influence the nutritional value of forages used for silage, including forage type and treatments during ensiling like inoculants and acids. It reports on studies that found Lactobacillus plantarum inoculation improved protein preservation over untreated controls, though formic acid preserved more protein. In in vitro ruminal fermentation tests, formic acid and L. plantarum increased microbial biomass over controls. While formic acid had the greatest benefits, L. plantarum provided intermediate improvements to silage quality and ruminal fermentation relative to untreated controls.

1. Basim Refat
Nutritional factors influencing
value of forages used as
substrates for silage

2. Introduction

3. Russell et al 1992
Average distribution of protein and nitrogen
fractions in some feedstuffs
Soybean meal, 44% 49.9 11.0 9.0 75 3.0 2.0

4. Poor N utilization from silages is a product
of two consequences of ensilage
 Solubilization of protein
 Protein solubilization reduces the proportion of undegraded
protein passing from the rumen to the small intestine.
 Fermentation of soluble sugars to VFA
and lactic acid
 Energy yield and utilization from VFA and lactic acid is
considerably less than from non-fermented carbohydrate
(ARC1984)
Efficiency of utilization of fermented organic matter for microbial protein synthesis is only approximately
60 to 70% of that for energy from non-fermented feeds
Thomas and Thomas1985

6. Relationship between non-protein N intake, rumen
ammonia and voluntary intake of silage
Concentration of Ammonia :
threshold level for microbes requirements (50 mg/L; Satter and Slyter, 1974)

7.  Forage type –Red clover and timothy seem to have lower NPN levels than
alfalfa
 Select carbohydrate sources that break down rapidly in the rumen (Barley,
Molasses)
 Processing: Increasing crop DM or by reducing crop pH / combination of both
 Acid-type additives: formic acid
 Polyphenolic compounds (Tannins) (tannins protein complex;= pH3.5- 8.0)
 Inoculant(LAB)
Charmley et al. (1994)
Tabacco et al 2006
Inhibiting Proteolysis

8. Fate of dietary protein in dairy cows fed
combinations of alfalfa and corn silages

9. LAB
 Increase the silage shelf-life by
 inhibiting deleterious epiphytic microbial populations
 Antibacterial activity
 Produce ferulate esterase enzymes during fermentation
 increase neutral detergent fiber degradation of the inoculated crop during ensiling.
 Enhance animal performance when treated silage is fed to
ruminants

10. Lactobacillus plantarum
 Positive effects on milk production : + 4.6% above
untreated silage
(summarize of 9 published studies; Kung et al. 2003)
 Improve protein preservation during ensiling
 Soluble nonprotein N (NPN) fractions in silage
 Produce greater microbial biomass
Contreras-Govea et al. (2011)

11. Silage fermentation characteristics (pH and g/kg DM) of
four combined experiments with no inoculant (Control), L.
plantarum (LP) or formic acid (FA).
Treatment P>F
Control LP FA
pH 4.38a 4.28b 4.25c <0.001
Lactic acid 61.0b 66.3a 12.1c <0.001
Acetic acid 20.5a 17.1b 5.7c <0.001
L:A ratio 3.1b 4.1a 1.8c <0.001
Ethanol 5.1a 4.5a 2.1b <0.001
Formic acid 0.0
b
0.2
b
19.5
a
<0.001
Contreras-Govea et al. (2013)

12. Silage nutritive characteristics (g/kg DM) of four
combined experiments
Treatment P>F
Control LP FA
DM 339.1b 336.4b 350.0a 0.002
CP 189.7b 190.2b 193.7a 0.05
aNDF 327.7 317.0 323.2 0.127
ADF 227.7 218.5 222.4 0.090
WSC 11.1b 10.1b 63.0a <0.001
Contreras-Govea et al. (2013)

13. Silage soluble N fractions (g/kg total N) of four
combined experiments
Characteristic Treatment
Control LP FA P>F
NH3-N 34.0a 27.7b 12.4c <0.001
FAA-N 286.6a 262.1b 187.9c <0.001
Peptide-N 151.8b 162.6b 190.1a <0.001
NPN (total) 472.5a 440.7a 390.4b <0.001
Contreras-Govea et al. (2013)

14. LP vs. FA
 Formic acid preserved the most protein and peptides during ensiling
 Lactobacillus plantarum provided an intermediate level of
preservation relative to the untreated control.
 Plant protease activity is highest on the first day of very high
after ensiling
 FA treatment, which immediately drops pH, preserve more
protein than LAB.
 lower pH and greater lactic acid concentration, lower acetic
acid and ethanol concentrations, homolactic fermentation in
LP than in the control
Contreras-Govea et al. (2013)

15. In vitro ruminal fermentation characteristics of
four combined experiments
Characteristic Treatment P>F
Control LP FA
Acetate (mM) 27.3 28.2 29.5 0.638
Propionate (mM) 10.6 10.7 10.0 0.687
Butyrate (mM) 4.7 4.7 4.4 0.659
A:P ratio 2.7b 2.7b 3.1a <0.001
Total VFA (mM) 42.6 43.5 43.9 0.936
Gas (mL/g DM) 155.5 152.3 155.2 0.402
Contreras-Govea et al. (2013)

16. In vitro ruminal fermentation characteristics of
four combined experiments
Characteristic Treatment P>F
Control LP FA
MNAN (mg/g DM) 10.3b 12.4ab 14.4a 0.002
MDM (mg/g DM) 343.5 356.4 361.1 0.376
MBY
(mg MDM/100 mg TDM)
43.7b 47.3a 47.5a 0.012
MNAN = microbial non-ammonia N
MDM = microbial DM
MBY = microbial biomass yield
TDM = truly digested DM Contreras-Govea et al. (2013)

17. LP vs. FA
 Ruminal microbial biomass production as measured by two methods
was highest on formic acid, intermediate on L. plantarum, and lowest
on untreated control.
 Increased ruminal microbial biomass production on L. plantarum-
treated silage
 related to its effects on protein preservation in the silo, which may
explain its positive effects on milk production in other studies.