Comment Log Display

March 31, 2009

To:	Mary D. Nichols, Chairwoman
	c/o Clerk of the Board
	Air Resources Board
	1001 I Street
	Sacramento, CA
	95814

From:	Monty Kerley, PhD	
	Professor
	University of Missouri						 
Re:	Review of appended report to the Proposed Regulation to
Implement the Low Carbon Fuel Standard (Vol II) by the California
EPA Air Resource Board

I have read the appended report and provided my comments below.  I
have limited my comments to the review of animal nutrition
literature provided in the report and to the storage of wet
distillers grain.  Globally this is the worst representation of
scientific literature review that I have read to date.  It appears
that this appendix was written with a severe bias against ethanol. 
I have no interest in the debate on the merits of ethanol use as a
fuel, thus a bias in favor of ethanol is not the motivation of my
response.  What I believe is relevant is that truth regarding the
nutritional value of distillers grains be recorded and evaluated if
it is to be used in policy decision.  As the appended report now
exists such would be impossible.

Authors state that “staff conducted an extensive review of the
literature”.  The literature review conducted resulted in only
eleven referenced articles, of which it appeared that only six were
peer-reviewed.  A search command of distillers grain in the Journal
of Animal Science, Journal of Dairy Science and Poultry Science
returned 88 scientific peer-reviewed articles.  The review of the
literature conducted for this appended report was not extensive,
nor was it thorough.

Nutrient content variability has been extensively published for
all feed ingredients and commodities.  As an example corn can
routinely vary in protein content from 8 to 10%.  This range
represents a 25% variation in the crude protein content of corn
grain, which was used as the standard in the report to judge
distillers grain.  The range in nutrient content of commodities,
such as distillers grain, is dealt with on a commercial basis by
guaranteeing minimum nutrient specifications.  This prevents
negative consequences on animal performance form occurring and this
procedure has been in place for years.  The minimums guaranteed are
actually regulated/tested by the Department of Agriculture of most
states.  I would expect this to be the case for the state of
California.  Further the range in nutrient composition of
distillers grain has been researched and findings published and
presented at national meetings in the US.  This topic is well
understood by livestock feed companies and livestock producers. 
Handling and storage of distillers grain has been well established.
 Many livestock producers prefer the wet form of distillers grains
because it can often be purchased at a reduced cost per nutrient
basis compared to dry distillers grain.  The University of Nebraska
Extension Program has extensively researched procedures for storing
wet material for prolonged periods.  These procedures consist of
storage in air-limited environments such as silage bags or silos. 
We have wet distillers grains that was delivered in September, 2008
that we are just now beginning to feed.  No apparent loss in
nutrient quality or spoilage is detectable.  The use of distillers
grains by livestock producers has been extensive.  It is widely
used in beef, dairy and swine diets.  Beef feedlots have routinely
used distillers grains in diets at levels of 30 to 40% of the diet
when corn prices were elevated.  The issues of nutrient
concentration variability, handling and storage, and education of
livestock producers limiting use of distillers grains as written in
the report is baseless.  
If this were the case, why are there not mountains of distillers
grains around the country now.  Some locations of ethanol
generation the demand for distillers grains by livestock producers
has been greater than supply.

The Maillard reaction (browning reaction) occurs between an
available carbonyl present on a carbohydrate and a terminal amino
group on an amino acid.  When involved in peptide linkages as would
be the case in protein, only two amino acids will quantitatively
compete in Maillard reations, lysine and arginine.  For most animal
feeding applications lysine is typically the first-limiting amino
acid, and its indigestibility when tied up in a Maillard reaction
would be the most problematic.  Thong et al (1978, Journal of
Animal Science 46:674) reported that nitrogen retention in a
gestating sow model was the same between distillers grains and
soybean meal.  This work showed that protein in distillers grains
is not less nutritionally available than the standard protein
(soybean meal) widely used in animal diets.  Stein et al (2006,
Journal of Animal Science 84:853) reported amino acid
digestibilities from ten different distillers grains sources
compared to corn.  Some amino acids in distillers grains were more
digestible than in the corn.  The range in digestibility of lysine,
methionine, threonine, tryptophan and isoleucine was 44 to 63%, 74
to 85%, 64 to 71%, 74 to 80% and 67 to 75%, respectively.  These
values are substantially greater than the digestibility values
suggested in the appended report.  There is little in the
scientific literature that substantiates the protein digestion
estimates presented in the appended report.  A cursory review of
the relevant literature leads to the conclusion that protein in
distillers grain is extensively digested by small intestinal and
pancreatic proteases.  It is true that overheating can render the
protein indigestible similar to what can occur for any by-product
overheated during processing or drying or a stored grain commodity.
 However such is visibly apparent and can be easily tested as acid
detergent fiber-nitrogen.

Discussion of antinutritional factors associated with distillers
grain demonstrates a lack of understanding of diet formulations. 
Distillers grain does typically have high sulfur levels similar to
corn gluten feed.  This is routinely remedied by adding a copper
salt or thiamine to the diet to ameliorate the potential effects of
sulfur.  Because this is an issue that has already been established
from feeding corn gluten feed no new interventions are needed.  The
high phosphorus issue is similar to sulfur in that any grain-based
diet results in high dietary phosphorus and low dietary calcium. 
Therefore lime (calcium carbonate) is added to grain-based diets as
standard diet formulation protocol to adjust the calcium to
phosphorus ratio.  What is interesting is that feeding distillers
grains has actually benefited livestock producers as providing an
expensive source of phosphorus in the diet (the cost of feed grade
phosphorus increased dramatically this past year) and increased the
value of the manure used as fertilizer due to its higher phosphorus
content (phosphorus fertilizer prices increased dramatically as
well).  The high fiber content for pigs is a concern as noted in
the report, but the higher fat content of distillers grain results
in the energy density of the distillers grain being equal to corn. 
Stein and Shurson (2006, Journal of Animal Science 87:1292) in a
review of the literature reported that distillers grains can
replace up to 30% of the corn in the diet of growing swine without
any impact on growth performance.  Diets of dairy cattle exceeding
6 to 7 % lipid (fat) can depress diet digestibility in the rumen. 
One of the factors limiting the inclusion of distillers grains to
less than 40% of the diet is its lipid content.  However, the lipid
content of distillers grain does not create an issue for dairy
application but rather a potential benefit.  Dairy diets typically
will have fat added to increase the energy density of the diet
which subsequently will increase milk production.  Distillers grain
is an inexpensive source of dietary lipid.  The statement in the
appended report that diets high in fats can lead to milk with
unacceptably high fat content is erroneous.  In many markets milk
value is increased as fat content increases.  An ability to
increase the fat content of the milk would be a trait sought after
by dairy producers.  Finally the comment that the small particle
size of distillers grain predisposes swine to ulcers is also
erroneous.  The diets fed to swine in commercial production are
finely ground to increase nutrient digestibility by the animal. 
The particle size of distillers grain is not finer than the total
diet fed to swine.  Links between gastric ulcer and particle size
can be made, but it is not causative due to distillers grains. 
Such would be the case if distillers grain were not placed in the
diet.

The reported conclusion that “distillers grain at 25% of the diet
reduced pH which in turn suppressed growth of ruminal bacteria
responsible for fermentation” defies logic.  The reduction in pH in
the rumen must occur via an increased growth of ruminal microflora
responsible for acid production, not a suppression of microflora
growth.  The literature does not support the conclusion that
dietary inclusion of distillers grain suppresses animal performance
via ruminal pH reduction.  Depenbusch et al (2008, Journal of
Animal Science 86:2338) 

measured the same dry matter intake, average daily gain and feed
efficiency in cattle fed diets with 13% distillers grain compared
to control diets without distillers grain.  Al-Suwaiegh et al
(2002, Journal of Animal Science 80:1105) reported the same
performance in beef cattle fed diets with 30% distillers grain or
without distillers grain inclusion and the same level of milk
production in dairy cows fed diets with or without 15% distillers
grain.  The abundance of data does not support grave consequences
in level of growth performance by ruminants fed distillers grain
compared to diets without distillers grain.  Rather the abundance
of data reports that distillers grain can be successfully used in
ruminant feeding applications, and the industry is widely using
this commodity.

I agree with the conclusion of the report that wet distillers
grain stored open to the air in warm environments is prone to
spoil.  This would be similar to almost any feed ingredient fed to
animals; all feed ingredients are either protected from rainfall or
stored in a manner that retards spoilage, such as silage.  Several
approaches have been tested and are now routinely used by livestock
producers to store wet distillers grains for prolonged periods of
time (several months).  As stated earlier, many producers prefer
the wet form due to an often advantaged price for the distillers
grain.  

I do not mean this comment to be derogatory, but I am curious if
the authors of this report have ever viewed an agriculture
enterprise.  Distillers grains is widely used by several domestic
farm species and feed companies.  I am dumbfounded how the
statement “livestock managers generally lack the information they
need on the potential advantages of distillers grain…” can be
regarded as credible.

My assessment of the appended report is that it is almost
inaccurate from beginning to end.  It does not adequately assess
the nutritional value of distillers grain and is erroneous in its
conclusion on use potential of this feed ingredient.  The report
reads as fiction supportive of a desired outcome but not as factual
information useful for establishment of policy.