A longitudinal study of milk nutrient levels among varied farm management systems

Final Report for FNE05-541

Project Type: Farmer
Funds awarded in 2005: $9,964.00
Projected End Date: 12/31/2007
Region: Northeast
State: New York
Project Leader:
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Project Information

Summary:

The purpose of this SARE grant was to synergize research efforts. It expanded an already funded
OFRF study led by Dr. Linda Tikofsky of Quality Milk Production Services at Cornell
University to include testing for Vitamins A and E, along with a full range of fatty acid levels, in
the milk of farms under three different management systems: organic, conventional grazing, and
conventional confinement.
Bulk milk samples and farm data were collected from 17 farms in Central New York from
November 2005 through October 2006. The samples were sent to the Diagnostic Center for
Population and Animal Health at Michigan State University for nutrient testing.
Dr. Tikofsky analyzed the data and concluded that "A multitude of factors influence the fatty
acid and vitamin content of bovine milk, including farm management, season, geography, diet
and breed. Many of these aspects are not easily quantifiable. This study did not elucidate
statistically significant differences in milk from three management styles. However, milk from
cows with a high percentage of dry matter intake coming from lush pasture did tend to have
higher levels of some nutrients beneficial to human health. A larger study, limited to the grazing
season and including more frequent sampling would be necessary to confirm the trends seen
here."

Introduction:

We have approximately 130 lactating age organic dairy cows and around 120 young stock on our
farm. We have over 700 acres in certified organic production as pasture, hay crop, small grains,
corn, and soybeans. In the past year we began selecting and using only sires for breeding our
lactating herd that are A2A2 for beta casein and also endeavoring to find sires that carry the
polled gene.
We recently installed a 27.6 kW solar system consisting of four 30 panel arrays on two axes solar
trackers. The grid tied system is sized to meet the annual electrical needs of our main farmstead.
We received a raw milk permit from NYS Department of Ag & Markets early in 2009 and began
offering farm fresh milk to customers at the farm.
We are currently in the midst of an addition/restoration project surrounding our milk house. One
side of the addition provides a safer, more attractive entrance for our fresh milk customers as
well as offers us needed storage room for barn supplies and equipment. The addition on the other
side of the milk house will house a bathroom, a washing machine so we can switch from paper
towels to cloth towels for cow prep, and an office/break room. In doing the project, we also took
off the existing milk house roof and replaced it with a new roof over the milk house and additions,
found rotting beams that have been replaced, and replaced an existing problematic stairway to
the haymow with a much safer design.

Project Objectives:

The purpose of this SARE grant was to synergize research efforts and fund further nutrient
testing of milk samples that were collected for an Organic Farming and Research Foundation
(OFRF) study lead by Linda Tikofsky, DVM at Cornell University’s Quality Milk Production
Services (QMPS).

Research

Materials and methods:

All farms were visited monthly by QMPS staff on two consecutive days each month from
November 2005 to October 2006. At each farm visit, a bulk milk sample was collected into a
236 ml sterile container after five minutes of agitation and was placed on ice in a cooler for
transport back to the laboratory. At the laboratory, a 30 ml aliquot of milk was removed from
each sample and submitted for somatic cell counting. All remaining milk samples were stored at
-80 DC until submitted for analysis. Milk production, herd numbers, and diet information was
collected at each farm visit.
I helped develop the feed data worksheet and assisted in identifying organic dairy farm
participants for the study. Dr. Tikofsky lined up all the farms, set up the sample collection
procedures, and interfaced with the lab at the Nutrition Section of the Diagnostic Center for
Population and Animal Health at Michigan State University (Lansing, MI) which tested all 198
samples for 36 essential fatty acids, Vitamin A, and Vitamin E.

Research results and discussion:

Part A
Dr. Linda Tikofsky wrote the following study results in her report to OFRF. Rather than
paraphrase, I am copying her complete text and tables to include the full data in this SARE
report, but all the credit for this Part A section goes to Dr. Tikofsky.
2
Descriptive statistics for farms
Summary statistics for farms participating in the study are included in Table 1 and
include herd size, average annual production per cow and average percent of dry matter
intake (DMI) from pasture during the grazing season. For Central New York in 2006, the
grazing season extended from May until October. Fourteen farms were predominantly
Holstein-Friesian; two farms (one organic and one grazing conventional) were mixed
breeds.
Vitamin A levels did not differ significantly among farm type (Figure 1). Levels for all
farms increased from April through October. There was a trend (though not significant)
for organic and grazing herds to have higher vitamin A levels than conventional non grazing
April through July, but this tendency was reversed August through October
Vitamin E
Vitamin E levels ranged between 1 and 3 f1,g/ml from January through July and then
increased sharply for August and then began decreasing (Figure 2). Overall there were
no significant differences among farm types. However, GC herds has significantly higher
levels of vitamin E in August than either NC or 0 herds (p=O.02); 0 herds had
significantly higher vitamin E content than GC or NC herds in November (p=0.00l).
Fatty acid content
The mean percentage, standard deviation, maximum and minimum levels of each of the
fatty acid groups and individual fatty acids in organic, conventional grazing and
conventional non-grazing milk averaged over the twelve months of the study are
presented in Appendix A. Conventional grazing, conventional non-grazing and organic
did not differ across the year with respect to any fatty acid group or individual fatty acid.
Saturated fatty acids (SF A)
Only one SF A showed differences across the year, C 18:0. Levels for CG were higher in
the spring and levels for 0 were higher in the fall. For the remaining SF A, overall there
were no significant differences among the three groups across the year, although for
occasional months there were significant differences. Milk from organic herds tended to
be higher in butyric acid (C4:0) in March (p=O.08), in palmitic acid (C16:0) in October
5
(p=0.03) and in arachidic acid (C20:0) in July (p=0.02). For CNG herds, myristic acid
levels (CI4:0), level in milk were lower in July (p=0.02).
Mono-unsaturated fatty acids (MFA), cis
There were no significant differences among the three groups across the year, nor were
there any significant monthly differences.
Poly-unsaturated fatty acids (PFA), cis
There were no significant differences among the three groups across the year, but there
were some significant monthly differences. 0 and CNG herds had higher levels of
linoleic acid (CI8:2) than CG herds in June (p=0.043) and 0 herds had significantly
higher levels of this same fatty acid in October (p=0.OI7). There was also a tendency
(though not significant) for levels ofy-linoleic acid to be higher in milk from 0 herds in
June (p=0.094). CNG had higher levels of arachadonic acid (C20:4) than 0 herds in
February (p=0.004), September (p=0.068) and November (p=0.08) while CG herd
exhibited significantly lower levels of this fatty acid in December (p=0.002). Levels of
C22:2 were higher for 0 herds in June (p=0.006) while level of C22:3 were lower for
CNG herds than the other two groups in May (p=0.006).
Trans Fatty Acids (TFA)
Overall there were no significant differences among the three herd categories for any
trans fatty acid. Levels of C 16: It were higher for 0 herds in October (p=O. 047) and
levels of trans vaccenic acid were highest for 0 herds in June (p=0.05) and July (p=0.08).
Conjugated Linoleic Acid (CLA)
No significant differences were detected among the groups overall for either of the
CLA’s, but there were some significant monthly differences. Levels of cis-9, trans-II
CLA tended to be higher for 0 herds in May (p=0.07) and for CNG herds in August
(p=0.06). For trans-IO, cis-I2 CLA, 0 herds had significantly higher levels in milk
(p=0.OI7).
Part B
Our farm was one of the participating certified organic herds in this study with 11 samples (Dec.
’05 through Oct. ’06). In looking at our individual farm test results for Vitamin E and the 2 CLA’s
(cis-9, trans-II CLA and trans-IO, cis-I2 CLA), there is no discernible trend over the months;
the numbers varied all over the place. For example, the rank of values for Vitamin E by
consecutive month, starting with December ’05, are as follows: 8,2, 7, 5, 4, 10, 1,9, 11,6,3. The
Vitamin E values ranged from a low of .92 ug/mL in August to a high of 5.71 in June, the June
level being 6.2 times higher than the August level. There was not quite such a dramatic variation
during the non-grazing season, although there still was quite a range: from 1.78 ug/ml in
December to 4.84 in January-an increase of2.7 times. There did not appear to be a correlation
with amount of pasture intake.
Vitamin A, however, did show a significant difference as the five highest values were during the
grazing season-May through October. The average value for Vitamin A from May through
October was 405 ng/mL versus an average of 268 for December through April-a 51 % increase
during the grazing season, although a spike in August brought the average up considerably.
However, as noted by Dr. Tikofsky in her report, all the farm management types saw an increase
in Vitamin A from April through October and not just the grazing farms.
A few other observations on our data: in August when we had the highest Vitamin A value, we
had our lowest Vitamin E reading; May did show some of the highest levels of CLA. Looking at
the averages of CLA values for months with grazing and months without, the average of
C18:2tl0c12 levels for the 5 main months of grazing was .0214 versus .0204 for the 5 months
with no grazing. For C18:2c9tll the averages were reversed with the non-grazing months
average being a tad higher at .684 versus .671 for the 5 main grazing months. I don’t know
statistics well enough to verify if these difference are statistically significant, but I would expect
that they are not.
Overall, I could reach no conclusions as to what factors may be influencing differences in these
nutrient levels.

Research conclusions:

The study results, showing little to no significant differences in the nutrient levels trending over
time in the three management systems, was unexpected, given much research in recent years
showing increased levels of favorable essential fatty acids when cows have higher levels of
pasture in their diet. Other studies have also shown higher vitamin values for organic milk. This
study did not corroborate similar findings, although Dr. Tikofsky did note that "milk from cows
with a high percentage of dry matter intake coming from lush pasture did tend to have higher
levels of some nutrients beneficial to human health."

Participation Summary

Education & Outreach Activities and Participation Summary

Participation Summary

Education/outreach description:

I attended the March 3-6,2009 Northeast Pasture Consortium Meeting in Morgantown, WV,
and presented a poster report of this study. Dr. Tikofsky designed the laminated poster showing
the data charts. Dr. Tikofsky submitted her written report to OFRF and the study results will be
available on the Quality Milk Production Services website (www.qmps.vet.cornell.edu). Participating farmers will receive their own farm’s results along with the findings from the study.
Because of minimal results, greater outreach efforts are not merited.

Project Outcomes

Assessment of Project Approach and Areas of Further Study:

Potential Contributions

Linda Tikofsky, Senior Extension Veterinarian at Cornell University’s Quality Milk Production
Services (QMPS), took the lead role in this study by organizing and orchestrating the collection
and storage of all milk samples and farm data and sending the samples to the Michigan State
University Laboratory for testing. QMPS staff collected the samples and data at the farms. Dr
Tikofsky analyzed the resulting data and submitted a written report to OFRF (report is attached).
Eight certified organic (0), five conventional grazing (G) and four conventional non-grazing
(NG) herds located in Central New York state participated in the study. 20 farms had been
initially been planned, but varying circumstances dropped the final number of participating
farms to 17. Bulk milk samples, production data, diet information (including pound of dry matter
from pasture) and number of animals milking on these farms was collected monthly from
November 2005 to October 2006. One organic herd and one grazing herd dried all cows off
from January until March; data for these herds is limited to eight months.

Future Recommendations

A multitude of factors influence the fatty acid and vitamin content of bovine milk,
including farm management, season, geography, diet and breed. Many of these aspects
are not easily quantifiable. This study did not elucidate statistically significant
differences in milk from three management styles. However, milk from cows with a high
percentage of dry matter intake coming from lush pasture did tend to have higher levels
of some nutrients beneficial to human health. A larger study, limited to the grazing
season and including more frequent sampling would be necessary to confirm the trends
seen here.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.