SAN JOAQUIN VALLEY UNIFIED AIR POLLUTION CONTROL DISTRICT 

Appendix I: Supporting Documents October 21, 2010 

 I-1 Final Draft Staff Report with Appendices For 

Revised Proposed Amendments to Rule 4570 

APPENDIX I 

SUPPORTING DOCUMENTS FOR 

REVISED PROPOSED RULE 4570 (CONFINED ANIMAL FACILITIES) 

October 21, 2010 
SAN JOAQUIN VALLEY UNIFIED AIR POLLUTION CONTROL DISTRICT 

Appendix I: Supporting Documents October 21, 2010 

 I-2 Final Draft Staff Report with Appendices For 

Revised Proposed Amendments to Rule 4570 

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August 25, 2010

Ramon Norman

San Joaquin Air Pollution Control District

Dear Ramon,

You recently requested information to identify the cost and/or feasibility of eliminating silage from diets fed to

dairy animals in the Central Valley.  A brief overview of dairy cattle nutrition was provided at the meeting 8 July

2010 with US EPA held in Modesto.   

In brief, diets are formulated to provide various classes of dairy cattle with specific quantities of energy,

protein, fiber, vitamins and minerals.  Forage (herbaceous plants or plant parts consumed by animals such as

pasture, hay, silage, dehydrated plants, and fresh green chop) is essential in the diet of ruminants and is a key

contributor to dietary fiber quality and quantity.  Preservation of herbaceous plants fed to dairy animals in

California is primarily done through field drying (hay) or ensiling (silage).  Feeding of ensiled forages in California

began in the 1940’s and numerous research and demonstration projects were underway by the 1970’s.  The

improved feeding of animals resulted from introduction of ensiling technologies which in turn led to the

introduction of totally mixed rations (which were not practical prior to the introduction of silage) and led to more

efficient production of milk and the raising of replacement heifers.   

Ensiling is a technology that was introduced to preserve nutrients in the plant material that would

subsequently be fed to cattle.  For example, sugars in fresh cut plant material laid down to field dry will largely be

consumed by continuing plant respiration (the plant continues to ‘live’ after cutting until it dries out) and respired

as CO2.  Sugars in fresh cut plant material preserved during the ensiling process will predominantly be converted to

acetic, propionic and butyric acids.  Although small amounts of these volatile fatty acids may volatilize, much of the

carbon content will be consumed by the cattle and be be used as nutrients, primarily as a source of energy.  It is

‘common knowledge’ that properly ensiled feeds have higher nutrient value than their dried counterparts.  

Removing silage from diets of cattle would return California to less efficient production practices and turn the

clocks of dairy management back more than 50 years.  

Removing silage from dairy feed will have widespread impacts.   

 Dairy operators would have an unfair disadvantage to their counterparts out of state if feeding of

silage was banned.  Meeting dietary nutrient requirements of cattle will become difficult and will

result in decreased milk yield and less efficient production.  Reduced efficiency will increase

environmental impacts.

 Dairy producers developed nutrient management plans with CVRWQCB to utilize manure

generated nutrients in cropping systems.  Utilization of a double crop system (corn and cereal

grains) tends to recycle the largest quantity of nitrogen (N).  Modifications to the nutrient

management plan would require implementation of alternative cropping patterns and ultimately

require more land for the same amount of N produced (since any other practical cropping pattern

would use less N per acre).  Few cropping patterns fit with dairy production to both utilize manure

nutrients and generate feed for animal consumption.  The latter is important to control costs of

production.  If additional land is not available to utilize manure N then manure will need to be

UNIVERSITY OF CALIFORNIA, DAVIS

DEPARTMENT OF ANIMAL SCIENCE 

ONE SHIELDS AVENUE 

DAVIS, CALIFORNIA 95616.8521 

TELEPHONE: (530) 752.1250 

FAX: (530) 752-0175 

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manifested off site.  This may or may not be viable (location specific) and will most likely increase

costs associated with manure management.

 Use of silage in diets provides highly digestible nutrients for the animal.  There is no direct

substitute for silage.  It is often included in diets in relatively large amounts to provide animal

nutritional needs and maintain rumen health.

 Substitution of alfalfa for part or all on the dietary silage would result in overfeeding N, increase N

excretion and increase N volatilization as ammonia.  Again, more land would be needed to manage

manure N.  Additionally, growing of alfalfa increases N fixation (imported into the watershed).  

Production of hay requires cutting, turning, baling and collecting bales.  Volatiles will be emitted

during the curing process.

 Replacing silage with feed by‐products and/or combinations of by‐products and grains will result in

greater transportation needs.  At some point, each California by‐product will be consumed leaving

the need to import these feeds from out of state.  This will increase costs of all feeds nationwide.  

It is unclear how much capacity is available for additional feeds to be imported.  A finite number of

loads of feed can be brought in to California via rail, especially in the winter when rail links can be

weather impacted.  Alfalfa is already purchased from out of state (i.e., NV, AZ, ID, UT).  Importing

nutrients and increased transportation should be considered before additional imports are

required.

 Imported feeds bring in N and salts which will increase salt loading in the Central Valley, which is

not desired by CVRWQCB.

 Costs of all feeds will go up because costs of hay and currently available commodities are

interlinked.  Removing existing feeds will impact the cost of all remaining feedstuffs.

No doubt, the question which may be asked is: ‘Why don’t farmers simply field dry the corn and cereal

plants and then feed them to cattle?’   Let’s consider what feeding dried corn or cereal plants instead of

ensiled materials might look like under San Joaquin Valley conditions.

Planting

Most probably a different configuration to planting rows of corn seeds will be needed in order to support

the material at harvest (i.e., so that it does not rest directly on the soil which increases drying time).  

Current planting configurations of rows will be less desirable as some corn stalks would fall between the

rows.  The last possible planting date will need to be identified in order to allow growth, harvest and drying

before temperatures change sufficiently to prevent field drying.  Shortening the planting window will

reduce cropping options from a manure nutrient recycling perspective, and reduce the ability of operators

to control feed costs.   

Harvest

The crop would dry out in the field and it is likely that some or even a lot (depending on wind speed) of the

leaves (the readily fermentable fiber) of the corn would blow away.  This would not likely be an issue with

the cereal.  Once dry, which would be a prolonged period of time for corn due to the thick and heavily cutin

protected stem, the windrows would need to be picked up and chopped into trucks, more or less as is done

now, except that this process would create a great deal of dust as small particles of the crop lifted into the

air during chopping and blowing.  Due to the light nature of the chopped material, some of it would blow

away as well.   

Water Loss

Water incorporated into plant material and included in animal diets contributes to animal daily water

needs.  Loss of this water (through drying) would require use of replacement water to meet animal

drinking needs.  In many locations within the San Joaquin Valley, irrigation water sources are from surface

water supplies whereas cow drinking water is from groundwater supplies.  Removing the incorporation of

surface water (in silage) from animal consumption will require additional drafts of groundwater.

Transport and Storage to Storage Piles

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As the chopped crop material would now be dry and light, the weight loads of the transport trucks would

be much reduced, and uncompacted, leading to more truck traffic to transport the material to the storage

areas, where it would need to be unloaded and packed into large piles (more or less as is done now) except

that the light material would be impossible to pack effectively and the piles would have to be much, much

larger (width not height, as the material would not pack enough to allow equipment to work on it very high

in the air) to accommodate the fluffy crop.  This would lead to a sharp increase in the need for pad surface

area, and a sharp increase in the amount of plastic used to cover the stored crop to prevent spoilage from

wind, rain, etc.  Additionally, this dry, porous material would be a rodent haven which could lead to feed

contamination and compromised milk quality.

Storage Pile Unloading

This is difficult to envision since the piles would be very fluffy (not dense) and any semblance of a 'smooth

face' or indeed a face of any kind would be eliminated.  Unloading would create a very wide and

deep unloading area that would blow badly in the wind leading to loss of material.  The actual unloading at

the face with the unloaders would create clouds of dust as the small particulates lifted into the air.  The

weight of dry matter carried by the unloader buckets would be less, leading to more unloaded loads to fill

TMR mixers.  The crop material would blow and fall off the unloader buckets both during transport to the

TMR mixers and while being dropped into the TMR mixers.   

TMR Mixing and Loadout to the Bunklines

The amount of dry feed weight that could be accommodated by the TMR mixers would go down as the

density of the TMR's would go down.  This would lead to more mixing time and more loads delivered to the

bunklines. Again, this would add up to more vehicular trips to accomplish feeding cattle.   As it has been

shown numerous times that intake of TMR are maximized in the 40 to 50% moisture range and, in an effort

to reduce dust and create some semblance of a homogeneous diet mixture, water would need to be added

to the TMR's from sprayheads fitted over the TMR mixers, probably continuously to create even mixing

(without added water to the TMR, it would be virtually impossible to mix and feed using current

equipment, or really any equipment for that matter, as the rations would be very light and would blow

badly in the wind as well as needing to be delivered numerous times per day).  This would create a large

new need for water on dairy farms (noted above).  The loadout process to the bunklines would work more

or less as it does now but, due to the less dense nature of the TMR, more loads per day would need to be

delivered.

Animal Response

The ability of cows to sort and select within the TMR's would be sharply increased and this would lead to

an increase in animal health problems, particularly acidosis and displaced abomasums, as cows sorted

away from the coarse fibers (such as stems) that provide the structural fiber that stimulates rumination

and saliva production.  This new TMR would also lead to a sharp increase in the amount of feed that would

not be consumed by the cattle, thus leading to an increased need to transport it back to the feed area for

re‐mixing into other diets.  Feed intake would decrease as the fermentability of the structural fiber, which

is an important contributor to the net energy density of the TMR and a driver of voluntary feed intake,

decreased. As the energy density of the corn and cereal crops would be lower, both due to the lower

fermentability of the structural fiber and due to losses of sugars during the field dry down process to

aerobic epiphytic bacterial and cellular respiration, attempts would be made by farmers to increase the

energy density of the TMR's by adding more high energy feeds, such as grains, which would need to be

imported by rail from the MidWest.  However this would exacerbate the issue of sorting and acidosis noted

earlier.  Finally, due to the genetic drive of modern dairy cows to produce milk, even at the expense of

their own bodies, the lactating cows would get thinner faster during lactation leading to poorer

reproductive performance, lower milk yield, emaciation and higher death loss.  In short, more cows would

be required to meet current milk production levels, which would require yet more, and/or larger, dairy

farms, and a higher proportion of the dietary net energy consumed by the cows being used to maintain the

cows' bodies, and less used to produce milk.  In short, nutrient efficiencies would decline on a larger total

herd (if current milk production was to be sustained).

Without silage as an option for San Joaquin Valley dairy farms, you can reasonably expect:

1) More dust

2) More vehicular emissions

3) More traffic on county roads

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4) More concrete pads on farms and less arable land

5) Higher local feed needs due to reduced feed quantity and quality

6) Higher imported feed needs due to less local feeds

6) Reduced animal health and impaired animal welfare

7) Higher costs of all feeds nationwide

8) Higher costs of dairy products nationwide  

7) Lower dairy farm profitability

Feel free to follow‐up with additional questions.

Sincerely,

Dr. Deanne Meyer, Livestock Waste Management Specialist

Dr. Peter Robinson, Dairy Cattle Nutritionist

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