Integrating grazing research with surveys to assess and advance the current knowledge about kelp meal supplementation for organic dairy farms in the northeast

Final Report for GNE12-031

Project Type: Graduate Student
Funds awarded in 2012: $14,963.00
Projected End Date: 12/31/2013
Grant Recipient: University of New Hampshire
Region: Northeast
State: New Hampshire
Graduate Student:
Faculty Advisor:
Dr. Andre Brito
University of New Hampshire
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Project Information


The purpose of this project was to examine the impact of kelp meal (KM) supplementation on several parameters including animal performance (milk yield, milk quality, metabolic markers, and markers of heat stress), environmental impact (methane emissions) and farm economics. The current project utilized 20 organically managed lactating Jersey cows and took place at the University of New Hampshire (UNH) Burley Demeritt Organic Dairy Research Farm in Lee, New Hampshire. The study lasted 114 days during the summer of 2012, between the months of June and October. While on study cows were allowed access to pasture for approximately 16 hours daily and were additionally supplemented with 6.8 kg of total mixed ration (TMR) twice daily. Cows were placed on one of two treatments (0 g KM or 114 g KM) and remained on the same treatment for the duration of the study. During each of the one-month long periods, a week long sampling period was used to collect data on several variables including: milk, blood, urine, feces, indicators of heat stress (rectal temperature, respiration rate, skin surface temperature and activity level), grazing behavior, and methane output. Following the on-farm portion of the study, laboratory analyses were done and data analyzed statistically using SAS.

Feeding KM had no impact on milk yield, components or heat stress indicators. Cows fed KM had higher milk iodine which may be explained by the high concentration of iodine (820 mg/kg DM basis) found in KM. No significant results were found for plasma cortisol, non-esterified fatty acids, and thyroxine (T4); a statistical trend was observed for lower plasma triiodothyronine (T3) in cows fed KM possibly due to higher iodine intake. There was no numerical difference in the measured methane emissions between treatments. The economic impact of feeding KM was calculated using income over feed cost (IOFC) for each treatment group. Because KM feeding had no improvement on milk or component yields there was no added income to offset the cost of feeding KM. In conclusion, KM did not improve milk yield or mitigate heat stress but increased milk iodine, which may be of concern to human health. In this study adding KM to the diet of lactating cows resulted in decreased IOFC, negatively impacting overall farm profitability.


Organic dairy farming is a rapidly growing segment of the US agricultural industry with an estimated increase of 25% between the years 2000 and 2005. Within the organic dairy farming segment of New England agriculture there is a high demand for research on a variety of aspects including animal health and nutrition as well as environmental impact and impact of dairy products on human health. This project involved many of these aspects by studying the impacts of KM, an organic approved and widely used mineral supplement for animals (nutrient analysis Table 1 below). KM is made from the brown algae species Ascophyllum nodosum, common name Rockweed. Rockweed grows in the intertidal zone of the North Atlantic and is harvested for use in KM for livestock and as fertilizer. A previously conducted study at UNH feeding KM to organic dairy cows during the winter season showed a significant increase in milk iodine. This previous study also indicated that KM may be effective at reducing cortisol and non-esterified fatty acids levels in the plasma of lactating dairy cattle during the winter months while cattle were consuming TMR. According to National Organic Program’s access to pasture rule, organic systems must provide cattle with access to the outdoors year round and during the grazing season pasture must contribute 30% of the total dry matter intake. Consuming fresh forages (pasture) versus stored forages (baleage) dramatically changes the dairy cows’ diet; therefore it is important that research is conducted on both diet types to evaluate if there are difference in how cows utilize KM and how milk quality may be effected. The results of the previous winter KM feeding trial raised some concerns about the high iodine content of milk when cows were supplement with KM. One goal of the pasture trial was to determine if high concentrations of milk iodine would continue when cows were grazing. Results of the winter trial also showed a reduction in plasma cortisol concentrations. Cortisol is often referred to as the stress hormone and levels are higher in animals under stressful conditions. Grazing animals during the summer months often suffers increased stress as a results of heat and humidity and flies. Another goal of this study was to determine if KM may help mitigate some of the stress response by the dairy cow.

Project Objectives:

Objective 1: Evaluate the impact of kelp meal supplementation on animal (e.g., performance, milk quality, behavior, health, and heat stress), environmental (e.g. methane emissions), and economic responses (e.g., income over feed costs) during the grazing season.

This objective was broken down into three segments: animal impact, environmental impact and economic impact. Data collection for all three segments took place while cows were on-study from June 2012 to October 2012. Majority of the laboratory analysis on samples and statistical analysis of data took place from October 2012 to October 2013. Challenges to completing this objective were greatest in the animal impact segment and included those to be expected in a study involving a large number of animals, modern technology and complex laboratory analyses. This animal impact segment of objective 1, is completed with the exception of ongoing grazing behavior and milk fatty acid profile results; due to extensive amount of time needed to complete milk fatty acid laboratory analysis and to read the grazing data from a large number of animals. Despite some complications including issues with data loggers, grazing monitors and low pasture availability towards the end of the study, enough data was collected to successfully run statistical analysis on all of the completed parameters. An additional challenge was found in the environmental impact segment of objective 1, where data was only collected consistently from 10 of the 20 cows (6 on KM and 4 on control treatments). Cows were hesitant to use the GreenFeed® which resulted in a lack of data for statistical analysis. The lack of cow visitation to the GreenFeed® was thought to be due to the long narrow entry gate, which could be unwelcoming to cows and a lack of palatability in the feedstuff (pelleted barley based concentrate) offered to the cows while they used the GreenFeed®. All aspects of the economic analysis portion of the objective have been completed.

Objective 2: Survey organic dairy farmers across the Northeast to collect detailed information about the feeding practices, potential animal health benefits, and regional distribution of kelp meal supplementation.

 This objective was successfully completed by surveying about 1,200 organic dairy farmers in the Northeast.

 Challenges to completing this objective included gathering a comprehensive list of organic dairy farmers to participate in the survey. This challenge was overcome by working with the Northeast organic Dairy Producers Alliance (NODPA). An article was published through NODPA before mailing the surveys explaining the importance of KM research and need for farmers feedback. NODPA was then able to aid in the distribution of surveys via their mailing list.


Click linked name(s) to expand
  • Andre Brito
  • Adam Crowther
  • Andre Pereira
  • Melissa Rubano
  • Kathy Soder
  • Gina Soule
  • Nancy Whitehouse


Materials and methods:

Twenty organically managed lactating Jersey cows were housed at the UNH Burley Demeritt Organic Dairy, Lee, N.H. Cows were grazed for approximately 16 hrs/day on mixed mostly grass pasture. Pastures were managed using the strip grazing technique where the front fence was moved approximately every 12 hours. Twice a day at 4:00 AM and 2:30 PM cows are brought in from pasture and individually supplemented with treatments: 226.8 g concentrate and 0 g KM (control) or 226.8 g concentrate and 113 g KM (KM treatment). After milking cows had access to a bedded pack barn, free choice water and TMR fed using Calan doors (American Calan). The TMR consisted of 51% mixed mostly grass baleage, 47% concentrate blend (a cornmeal, barley based grist), 1.8% molasses. An average of 8.1 kg of TMR was consumed by each cows daily provided per cow per day, with the remainder of the diet coming from pasture which intake was estimated at 9.2 kg/d.

Four-week long sampling periods were conducted, one during each month of study. During this time samples of milk, blood, urine and feces were collected for laboratory analysis. Most of the blood and urine lab work were conducted at UNH using commercially available assay kits. Milk and fecal samples were analyzed at DairyOne and Agri-King Laboratories. Pasture intake was estimated using chromium oxide as a marker; chromium was fed for 13 consecutive days with fecal collection occurring on days 7 through 13. In addition, measures of heat stress were taken, including twice daily rectal temperatures and respiration rate. Cows also wore temperature loggers and pedometers which every 15 minutes measured skin surface temperature, time spent lying, standing and the number of steps taken. A portable, automated system [i.e., The GreenFeed® system; C-Lock Inc., Rapid City, SD] consisting of air sampling and gas quantification modules powered by solar energy was mounted on a trailer for assessing breath carbon fluxes from grazing cows (See Figure 2 below). In addition to direct animal sampling, samples of feeds including pasture, TMR, baleage, concentrate, and KM were collected and analyzed for nutritional content at DairyOne, Agri-King Laboratories and University of Missouri, Experiment Station Chemical Laboratory.

Research results and discussion:

All results are reported below in Table 2. No significant results were observed for milk yield or milk components, although there was a significant difference in milk iodine concentration between treatments. Although stats have not been run on intake data as of this report, the numerical difference between treatments is small and not likely to be found significant. No difference was observed for plasma cortisol, non-esterified fatty acids or T4. To evaluate the potential for KM to alleviate heat stress, twice daily rectal temperature and respiration rate were recorded, no difference was seen for these factors. A trend was seen for a significant decrease in T3 with KM supplementation. No numerical difference was found for methane emissions.

The survey design was completed in January 2013 and distributed in February 2013. Survey results were are listed below in Table 3. Approximately 1,200 surveys were distributed to organic farmers throughout the Northeast with an approximate 21% response rate. A total of 245 surveys were returned completed, farms milking less than 10 cows were eliminated from the final results leaving the data from 227 farms to be analyzed. From these 227 farms we were able to determine that 64% (145 farms) were feeding KM in some manner on their farm.

Research conclusions:

The only significant results were found in the animal impact segment of objective 1, where higher milk iodine was found for cows supplemented with KM. These results are particularly important and concerning because they directly impact milk quality and human health. These results coincide with previous results from the winter KM supplementation study where a significant positive linear response was found for milk iodine when KM supplementation was increased. Milk and other dairy products are an important source of iodine for the human population. Mammals including cows readily secrete iodine in milk to provide for their growing young, as iodine is of added importance for those that are still developing due to its role in neurological development. Throughout recent years human nutrition has focused more on the impacts of iodine deficiency rather than iodine excess. Iodine deficiency is the leading cause of mental retardation worldwide which provides much of the motivation for iodine supplementation to the human population via iodized salt. Iodine excess however has received less publicity and majority of the population has been found to be tolerant to high levels of iodine intake. However, iodine excess may be a concern particularly for infants and children as well as those with underlying thyroid conditions.

One of the most surprising results of this study, which perhaps underlines the importance of examining ruminant nutrition both when pasture is available and during winter months when stored forages are fed, was the dramatic increase in milk iodine when pasture availability for cows was decreased. During period four of this study pasture availability was on the decline and cows were allowed to graze only during the day to conserve pasture. During this time milk iodine was found to increase. These results coincided with several other studies which have shown a decrease in milk iodine while cows are consuming pasture. See results in Figure 2 below.

A trend was found for lower plasma T3 levels in cows supplemented with KM, a significant difference which was not found in the winter kelp supplementation study. T3 and T4 make up the thyroid hormones which are necessary for the maintenance of homeostasis or normal body function, including oxygen metabolism, body temperature and heart rate. The thyroid gland is the only gland in the body which uptakes iodine and it uses it to form these two hormones. While previous research where cows were fed high iodine intakes did not show a difference in thyroid hormone concentrations, the form of iodine in KM or how it is metabolized by the animal in the current study, may be impacting T3 production, which could ultimately lead to impaired animal efficiency.

Results of objective 2 indicate as suspected that KM is currently being supplemented on a high percentage of Northeastern organic dairy farms. These results indicate the current and future need for more research to be conducted on the impact of KM supplementation on animal performance, the environment and farm profitability.

Participation Summary

Education & Outreach Activities and Participation Summary

Participation Summary

Education/outreach description:

This research was presented during the poster session at the Joint Annual Meeting in July of 2013 in Phoenix Arizona. Attendance at this event was high and included mostly professionals in the field of animal science.

An article was published in NODPA which included the results of this study as well as the results of the incremental levels of KM supplementation study conducted in the winter of 2011.

Results were presented at Farm and Forest conference in N.H. This conference is open to all members of the community and many dairy producers were in attendance. Project leaders were available to answer questions about KM and the project results.

These results were also made available to producers as well as other researchers at a field day which was conducted at the Burley Demerrit farm at the University of New Hampshire in 2013. Results were presented via a poster with the project leaders present to answer any questions. Much of the attendance at this event was current and prospective graduate students to UNH although some dairy producers and nutritionists were in attendance as well.

Results were also presented at the Undergraduate Research Conference at UNH, by an undergraduate student who helped throughout the project. The student presented the results via a poster and fielded questions from faculty members, graduate students, fellow undergraduates and to members of the community. Results were also presented at the Undergraduate Research Conference at UNH, by an undergraduate student who helped throughout the project. The student presented the results via a poster and fielded questions from faculty members, graduate students, fellow undergraduates and to members of the community.

In May of 2014 this research will be presented as part of a graduate student thesis defense. Shortly after results will be submitted to peer reviewed journals including Journal of Dairy Science.

Project Outcomes

Project outcomes:

The economic analysis conducted with this study was a relatively simple income over feed costs IOFC. With no improvement in milk production or component yields there was no added profit for cattle consuming KM. In addition there was no difference in dry matter intake between control- and KM-supplemented cattle. Therefore, the only difference between treatments groups was the addition of KM to the diet which added approximately $0.25/cow/day. Over the course of the 114 day long study, adding KM at a rate of 113 g/head/day to the diets of 10 cows, cost the farm an additional $28.50.

Farmer Adoption

Based on the KM survey results the current use of KM as a feed additive is widespread throughout much of the Northeast. Despite its high rate of use, 26% of the farmers feeding KM admitted they did not know if it was making a difference on their farm. However, of the 145 farms feeding KM 71% do believe that KM has made a difference on their farm. Surveys allowed farmers to provide feedback as to how they thought KM has benefited their herds. Responses included reduced incidence of pinkeye and ringworm, improved conception rates, improved body condition and coat appearance, decreased flies and decreased somatic cell counts. Overall, farmers were happy with the mineral profile provided by KM. By far the largest concern with KM was cost, while additional concerns included sustainability and environmental impact of KM harvesting, and the potential to overfeed some minerals.

Assessment of Project Approach and Areas of Further Study:

Areas needing additional study

As with many studies which are the first to examine a particular nutrient or product, the results of the study tend to lead to more questions than answers. Several questions that were brought up by the results of this study and others which have examined KM supplementation for cattle include…

How does long term supplementation of KM impact animal performance, milk beneficial fatty acids, the environment and farm profitability?

Two aspects that would greatly improve the current knowledge of KM supplementation would be a long term KM supplementation study and on-farm studies. In previously conducted research on KM it has been suggested that any impacts of KM may not be observed in the short term. In addition, several of the surveyed farmers stated they did not see any changes in their herds until after they had been feeding KM for an extended period of time. As well as conducting a longer term study, conducting on-farm studies would also be beneficial. Many of the benefits of KM listed by farmers included improved mineral profile of the diet and decreased incidence of illness (pink-eye). During this study cows were fed a balanced ration and had no health issues. On-farm studies allows for better examination of real world scenarios.

Does KM supplementation improve dry cow health and performance?

Surveys stated that 82% of farms utilizing KM were feeding it to dry cows (119 farms). Currently no studies have been conducted on feeding KM to dry cows although there may be potential benefits of KM supplementation, including a reduction in fresh cow metabolic problems. In addition to the potential for improved cow performance, dry cows are not lactating, thus the concern for human health about milk iodine excess are avoided. This study found numerically lower non-esterified fatty acid levels in cows supplemented with KM, although not statistically significant. Further research is needed to determine if dry cows supplemented with KM may have reduced non-esterified fatty acids which could help to prevent ketosis in cows at freshening. In addition, nutritional analysis of KM showed it has a negative dietary cation-anion difference (DCAD). Feeding a negative DCAD during the dry period has been found to reduce the incidence of milk fever at freshening. This potential for a reduction in milk fever is of added interest to the many organic farms raising Jersey cattle, a breed notorious for higher rates of milk fever.

In what other ways may KM supplementation contribute to overall farm economics?

In addition to added research on animal performance and human health, the economic impact of feeding KM could be studied in greater detail. This study used only IOFC calculated by using milk price, DMI and feed costs. Farmers have suggested that KM benefits are not seen by improved milk yields or components but by improved animal health. While the current study showed no difference in cortisol levels or animal response to heat stress, a more comprehensive on-farm examination of total farm costs including medication and veterinary costs may provide a more accurate economic analysis of the potential benefits of KM feeding.

Does KM supplementation help to reduce flies and other parasites?

Some responses to the KM surveys included farmers who stated KM supplementation helped with fly and other parasite control. Because they are certified organic these farms have only a limited arsenal of protection against flies and other external or internal parasites. If KM is indeed effective in minimizing flies or other parasites farmers may benefit from the added income seen from a reduction in animal stress due to parasites or a reduction in medication needed to combat fly and parasite induced illness. When asked about areas of future research many farmers who completed the survey suggested there was a need for more research on organic fly and parasite control methods.

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.