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

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

Summary

The purpose of this project is to examine the impact of kelp meal supplementation on performance, milk yield, milk components, and markers of health and heat stress of in organically-managed Jersey cows. The feeding experiment was conducted at the University of New Hampshire Burley Demeritt Organic Dairy Research Farm in Lee, New Hampshire. Twenty lactating Jersey cows were randomly assigned to one of two treatments, 0 or 4 oz of kelp meal daily from June to October during this past grazing season. Kelp meal was mixed with 1.5 lbs of a concentrate blend carrier and supplemented to cows before milking twice daily. After each milking cows were supplemented with a total mixed ration (TMR) prior to be moved to pasture. Each month a week long sampling period was used to collect pasture, TMR, feed refusals, milk, blood, urine, and fecal samples. During the sampling period measurements were taken twice daily for four days to record rectal temperature and respiration rate to investigate the impact of kelp meal on mitigating heat stress. In addition to monthly sampling, weekly samples of pasture, TMR, refusals, and feed ingredients were collected. Methane measurements were collected daily using a gas sampling and quantification system that allows automated measurements of enteric methane and carbon dioxide emissions (The Green Feed System).

Objectives/Performance Targets

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.

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.

Accomplishments/Milestones

The field portion of the feeding trial was completed this past October and laboratory and statistical and statistical are being currently processed (Objective 1). Plasma samples were analyzed for nonesterified fatty acids (NEFA), urea N, cortisol, thyroid hormones (T3 and T4), glucose, and total antioxidant activity using commercially available kits. Milk samples were analyzed for components (e.g., fat, protein, lactose, solids nonfat, and total solids), milk urea N (MUN), and iodine. Some of these results were statistically analyzed and are presented in the table 1.

The results presented in the table show that kelp meal had no significant effects in the yields of milk, milk components and MUN in organic cows during the grazing season. Likewise, there was no significant difference between treatments (0 vs. 4 oz of kelp meal) on plasma cortisol, NEFA, and thyroid hormones (T3 and T4). However, concentration of iodine in milk was significantly higher in cows supplemented with 4 oz of kelp meal compared to those fed no kelp meal. The iodine concentration of kelp meal is very high averaging 820 ppm (dry matter basis) and as a result possibly explains the differences in milk iodine between supplemented and non-supplemented cows. It is important to note that most of the current results are consistent with those from a previous study conducted from November 2011 to February 2012, where cows were supplemented with incremental dietary levels of kelp meal (0, 2, 4, or 6 oz). In this earlier study we observed that milk from organic Jersey cows supplemented with 4 oz of kelp meal averaged 1,014 microg/L of iodine while the same level of supplementation resulted in 592 microg/L of iodine in the current study. Thus, further analysis is required to determine what caused this discrepancy in milk iodine concentration between identically supplemented cows in our two studies. Access to pasture was a major difference between our two studies; therefore, pasture samples will be analyzed for nutritional content, specifically minerals to determine if there is an interaction between pasture nutrients and iodine in kelp meal. Environmental temperature could also be involved in the discrepancy in milk iodine concentration between studies. Higher environmental temperatures during the grazing compared with the winter season could lead to increased water intake, which may have impacted the rate of passage through the digestive tract limiting time for iodine absorption.

Samples of pasture, TMR, refusals and feed ingredients are prepared to be shipped to commercial laboratories for analysis of nutritional content at the start of the next calendar year. Measures of heat stress including rectal temperature and respiratory rate are currently being prepared for statistical analyses. Statistical analyses will be also conducted on the remaining blood, urine, and fecal samples. In addition, results on the impact of kelp meal on methane and carbon dioxide emissions are being compiled. The gas emissions data was gathered using the GreenFeed system, a gas sampling and quantification system that allows automated measurements of enteric methane and carbon dioxide emissions. An economic analysis (e.g., income over feed costs) will also be conducted to determine if feeding kelp meal results in an overall increase in farm income and profitability.

The only change to the timetable of this project so far has been the distribution of surveys to farmers (Objective 2). Originally the surveys were to be sent in the fall of 2012 but this date has been postponed to February of 2013. The decision was made in order to increase time to gather a more comprehensive list of farmers and to use some preliminary results of our feeding trials to help formulate relevant questions for the survey. Surveys are currently under construction and a mailing list is being organized using a database of organic dairy farmers in the Northeast with the assistance of Northeast Organic Dairy Producers Alliance (NODPA).

• Table 1: Effects of kelp meal on performance and milk production of Jersey cows supplemented with kelp meal during the grazing season.

Impacts and Contributions/Outcomes

Feed costs are the major expense on a dairy farm and at $67 for a 50 lb bag (www.noamkelp.com) the cost of kelp meal supplementation can quickly add up over time. The cost of kelp meal could be balanced out by two possible mechanisms. One would be by increasing overall milk production or milk quality leading to increased profit through milk sales. Another would be through a reduction in animal stress leading to a decrease in animal illness which could lower veterinary and medical costs helping to improve overall farm profitability. Both of these possibilities will be examined further over the next several months although our preliminary results did not show an increase in milk production, milk components or a decrease in stress in animals supplemented with kelp meal. Results of the economic analysis will be used to advise farmers if the potential benefits of feeding kelp meal outweigh the costs.

Iodine has been added to salt to supplement the human population in order to lower the incidence of iodine deficiencies. More recently, however, concern has shifted to the opposite end of the spectrum with an increased incidence of iodine toxicity particularly in children. Although humans are generally tolerant of high iodine concentrations, these levels can be concerning particularly in children where iodine toxicity can lead to goiter (Borucki Castro et al., 2010). The results of this study can be used to develop guidelines for feeding kelp meal to prevent iodine concentrations in milk from reaching levels which could lead to iodine toxicity.

Previous research has indicated that kelp contains high levels of phlorotannins which may impair ruminal methaogensis resulting in decreased methane emissions from cows supplemented with kelp meal. (Wang et al., 2008). Methane is a potent greenhouse gas, therefore reducing methane emissions from dairy cattle could help to limit the impact of the dairy industry on overall greenhouse gas production and climate change.

As of December of 2012 study results are still under analysis and have not yet been published or distributed to any farmers in the area. Once the final laboratory analyses have been completed and statistics have been conducted on all variables, results will be made available to farmers through several publications, scientific and farmer meetings and conferences. Results of this study are to be included in a master’s thesis and will be presented at national conferences in the summer of 2013. In addition, scientific articles will be prepared and submitted to peer-reviewed journals. Along with these scientific publications, the results will also be presented in trade publications including GRAZE, NODPA, and Foraging Around. Along with these publications, meetings and conferences will be held to share results with farmers. Webinars may also be arranged to reach a wider audience of farmers as well as to answer any questions farmers may have.

Despite the widespread use of kelp meal in the Northeast minimal research has been done on the impact of kelp meal on animal health and performance as well as the potential impact on methane emissions and overall farm profitability. The ultimate goal of the project is to determine the effectiveness of kelp meal on improving health and performance of lactating dairy cattle in order to advise farmers if kelp meal supplementation leads to an increase in herd health, profitability or environmental sustainability. Our preliminary results have shown a minimal impact of kelp meal on animal performance or stress levels. Over the next several months the significant difference in milk iodine will be examined to better determine its potential impact on human consumption of organic milk products. The decrease in milk iodine seen in kelp-supplemented cows during the grazing vs. winter season will also be examined further. Additional analyses from heat stress indicators, methane output, urine, fecal and feed samples will aid in the development of a recommendation which will be distributed to farmers through a series of scientific and farmer orientated articles and conferences.

Borucki Castro S.I., R. Berthiaume, P. Laffey, et al. 2010. Iodine Concentration in Milk Sampled from Canadian Farms. J. Food Protection. 73:1658-1663.

Wang, Y., Z. Xua, and T.A. McAllister. 2008. Effects of phlorotannins from Ascophyllum nodosum (brown seaweed) on in vitro ruminal digestion of mixed forage or barley grain. Anim. Feed Sci. Tech. 145:275-395.

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