Results from Short-Term Studies Using Kelp Meal as a
Supplement to Dairy Animals at the University of New Hampshire
By Nicole Antaya and André F. Brito
For the past three years several studies were done at the University of New Hampshire (UNH) investigating the effectiveness of kelp meal supplementation to dairy animals (i.e., calves and lactating cows). Most of this research was conducted at the UNH Burley Demeritt Organic Dairy Research Farm, a working dairy farm currently milking 40 registered Jerseys in Lee, New Hampshire. It is important to note that all studies conducted at UNH were focused on the potential effects of kelp meal on improving animal performance (i.e., milk production, intake, weight gain, etc.) while changing milk composition or reducing animal stress. In addition, these studies were short-term ranging from 56 days (heifer calves/winter and summer) to 84 days (lactating cows/winter) to 114 days (lactating cows/summer). However, based on anecdotal observations from dairy farmers, enhanced immune function and animal heath are only seen after long-term use of kelp meal as indicated by minimal lice infestation and pink eye occurrences in the herd.
We are not aware of any long-term research, in which kelp meal made from the brown algae Ascophyllum nodosum also known as rockweed - the most common source of kelp meal in the Northeast - was supplemented long-term to dairy animals. The only long-term scientific study we are aware of was done in the mid 40’s (Berry and Turk 1944) using a different species (Marcocystis pyrifera) of seaweed commonly known as giant kelp. In this 1944 study, kelp meal was fed to 78 heifers (24 Holsteins, 24 Ayrshires, 18 Guernseys, and 12 Jerseys) prior to their first calving with 50 of these animals (18 Holsteins, 18 Ayrshires, 8 Guernseys, and 6 Jerseys) maintained in the study through their second gestation period resulting in 30 months or 900 days of continuous kelp meal supplementation at the rate of 0.16 lb or 2.6 oz per head per day. Berry and Turk results showed no effects of kelp meal on animal health (e.g., retained placenta), reproductive performance (e.g., number of services per conception, abortions, and length of gestation), milk production, and percentage and production of milk fat and protein. Quoting Berry and Turk paper conclusions:
1) “Under the conditions of dairy heifers showed no particular benefits for growth, breeding efficiency, general health, physical condition, appetite, and size and condition of calves at birth; and 2) “Continued feeding of kelp meal through a second gestation showed no favorable effects on breeding efficiency, feed consumption, and milk production”.
Kelp meal made from Ascophyllum nodosum is commercialized throughout the Northeast primarily as a supplement rich in minerals, particularly iodine (see Table 1), and kelp meal feeding has been associated with improved feed efficiency, reproduction, milk production, and animal health. These improvements are believed to be a result of kelp’s high nutrient density combined with its antioxidant and antimicrobial properties, which boost the animals’ immune system helping them to fight bacterial infections and even heat stress. For instance, feeding a kelp extract made from Ascophyllum nodosum to grazing beef cattle reduced body temperature and increased cell mediated immune function in hot weather (Allen et al. 2001). In a subsequent study, Bach et al. (2007) demonstrated that supplementing beef cattle with ground, sun-dried kelp made from Ascophyllum nodosum at either 2% or 1% of diet dry matter for seven and 14 days, respectively, reduced fecal shedding of E. coli compared to the non-supplemented diet. Although these researchers (Allen et al. 2001; Bach et al. 2007) targeted issues pertinent to the beef cattle industry, decreasing fecal E. coli shedding may help controlling environmental mastitis in dairy cows. Despite these earlier observations, there is limited research data to help northeastern farmers to make informed decisions about the use f kelp meal in their family farms.
The first study conducted at UNH lasted 84 days and extended from November 2011 to January 2012. Sixteen early lactation (average = 49 days in milk) Jersey cows (four first lactation and 12 second lactation or older) were fed a TMR diet containing (dry matter basis) 64% alfalfa/grass baleage and 36% of a cornmeal/barley/soybean meal-based concentrate supplemented with 0 oz, 2 oz, 4 oz or 6 oz of kelp meal made from Ascophyllum nodosum. For this study a replicated 4 × 4 Latin square design was used, which means that each cow received one of the four doses of kelp meal at a given 21-day period (total of four periods).By the end of the study, all 16 cows received the four doses of kelp meal. Latin square is possibly the most used experimental design in dairy cattle research because it provides strong statistical power to detect differences among diets or doses.
To ensure complete consumption, kelp meal doses were mixed with half a pound of concentrate and fed after the a.m. milking while cows assigned to the control dose (0 oz of kelp meal) received concentrate only. Over the course of the study, milk production and dry matter intake were recorded daily. Milk samples were analyzed for fat, protein, milk urea nitrogen (i.e., MUN), and iodine concentration. The results (see Table 2) showed no statistical effects of kelp meal on milk production or dry matter intake. There was also no effect of increasing levels of kelp meal on percentage and production of milk fat and protein. However, milk iodine content increased substantially as a result of kelp meal supplementation, thus indicating a high transfer of iodine from kelp to milk.
To examine the potential benefits of feeding kelp meal to lactating dairy cows year-round, a second kelp meal supplementation study was conducted in the summer of 2012. Twenty mid lactation (average = 135 days in milk) Jersey cows (12 first lactation and 8 second lactation or older) were assigned to one of two doses (0 oz or 4 oz) of the same kelp meal used in the winter study. In our summer study, a completely randomized design was used, which means that half the cows were fed 0 oz of kelp meal whereas the other half received 4 oz of kelp meal during the entire study (mid-June to early-October). Cows had access to paddocks containing grass-legume pasture mix (predominantly grass) for approximately 16 hours daily in a rotational strip grazing management system (i.e., a new piece of fresh pasture was provided twice daily after each milking). In addition to pasture, cows were supplemented twice daily with a TMR composed (dry matter basis) of mixed mostly grass balage (50%), a cornmeal/ barley/soybean meal-based concentrate (47%), liquid molasses (2%), and a vitamin plus mineral mix (about 1%). TMR intake and milk production were recorded daily throughout the study. Total dry matter intake was estimated using a dairy nutritional model (NRC, 2001). Pasture dry matter intake was calculated by subtracting total dry matter intake from TMR intake.
Milk samples were collected and analyzed as done for the winter study. In addition to plasma concentration of the hormone cortisol, which increases with heat stress, other indicators of heat stress such as rectal temperature and respiration rate were measured twice daily during four consecutive days each month. Results of our summer study (see Table 3) showed no statistical effects of kelp meal on percentage and production of milk fat and protein. Despite the 1.4 lb/day increase in milk production comparing cows supplemented with 4 oz of kelp meal with those receiving no kelp meal, this difference was not statistically significant. Kelp meal also did not change the indicators of heat stress even during the hottest summer months (July and August). Similar to results obtained during the winter study, feeding kelp meal substantially increased the content of milk iodine showing that iodine from kelp is effectively transferred to milk during both winter and summer seasons.
In general, results from our winter (84 days duration) and summer (114 days duration) short-term studies appear to indicate that kelp meal did not improve milk production or indicators of heat stress. However, we recognize that short-term studies may not capture the potential long-term benefits of kelp meal supplementation including reduction of infections such as pink eye. Nevertheless, the value of short-term research cannot be neglected. For instance, short-term studies using beef cattle fed kelp or kelp extracts (Allen et al. 2001; Bach et al. 2007) demonstrated the beneficial antimicrobial and anti-stress properties of kelp. In addition to beef research, a short-term study conducted at UNH showed improved weight gain in organic Jersey calves supplemented with 2 oz of kelp meal (Soule et al. 2012). A six-week study conducted at Kansas State University showed significant improvements in milk production (+3.8 lb/day) and production of milk protein (+0.19 lb/day) but no statistical effects on indicators of heat stress (rectal temperature and respiration rate) in confined Holstein cows fed 2 oz of kelp meal during summer heat stress (Cvetkovic et al. 2004).
We are also interested in the impact of kelp meal on milk fatty acids profile (particularly CLAs and omega-3 fatty acids) due to the potential beneficial effects of these bioactive compounds on improving human and cow health. Research conducted at South Dakota State University found significant increases in the concentration of milk CLA and omega-3 fatty acids in Holstein cows fed marine microalgae (Schizochytrium sp.) supplemented diets (Franklin et al. 1999). Overall, future research by UNH and fellow Universities in the region is necessary to provide a better understanding about the short- and long-term effects of kelp meal supplementation on immune status and animal health as well as on animal performance and milk composition. A comprehensive economic analysis is also needed to assess the cost effectiveness of kelp meal supplementation in northeastern organic dairy farms.
The goal of the research presented here is to provide farmers with rigorous scientific information about the short-term effects of kelp meal on animal performance and milk composition. Our kelp meal projects were funded by Northeast SARE and the NH Agricultural Experiment Station. The kelp meal used in both studies was kindly donated by Thorvin. In order to continue serving the organic dairy community in the Northeast, we are asking you to complete a short survey that will be mailed via NODPA in the next few weeks. This survey contains a brief questionnaire about the use (if any) of kelp meal at your farm. Please take the time to read and complete this upcoming survey, which will provide UNH with essential feedback to better understand the use of kelp meal across the region. This brief survey also provides a unique opportunity to you share questions or comments about kelp meal supplementation as well as other aspects of organic dairy farming that you would like to see research projects in the near future. With your valuable input we will tailor our research program to match your needs.
If you have further questions or concerns please don’t hesitate to contact André F. Brito [Assistant Professor of Organic Dairy Management; firstname.lastname@example.org; (603) 862-1341] or Nicole Antaya (UNH Graduate Student; email@example.com).