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By Dr. Andre Brito
Added December 2, 2010. We have been very busy at the University of New Hampshire (UNH) this whole year. Two research studies were completed, and we are presently conducting a feeding experiment investigating the effects of kelp meal on growth and body weight gain of organic and conventional calves. Preliminary results of these studies are shown below:
This study was conducted during this last winter at the UNH-Organic Dairy Research Farm. Dr. André Brito and his graduate student Shara Ross used 16 lactating organic Jersey cows in this experiment. Dr. Helene Petit from the Dairy and Swine Research and Development Centre, Sherbrooke, Quebec is collaborating with UNH on this project.
A component present in flaxseed meal known as lignans has been associated with prevention of menopausal symptoms, breast and prostate cancers, cardiovascular diseases, and, possibly, osteoporosis. We believe that cows fed flaxseed meal will produce milk rich in lignans, which can potentially improve human health. Metabolites resulting from the rumen degradation of lignans have been also associated to stimulate the activity of antioxidant enzymes resulting in improved immune system helping cows fight diseases including mastitis. It is well known that sugarcane molasses is a rich source of sugars, particularly sucrose, and may be a viable energy supplement to organic dairy cows. Compared to starch from corn meal, sucrose from molasses has a faster rumen degradation rate, which may increase nitrogen utilization in lactating dairy cows. We hypothesize that feeding energy sources with different carbohydrate profiles and rate of rumen degradation (molasses vs. corn meal) would affect microbial utilization of flaxseed meal-lignans resulting in different output of lignans metabolites in milk and blood of cows. To test our hypothesis, 16 cows were randomly assigned to four different diets all containing (% of total diet dry matter) 70% grass baleage plus 2% minerals and vitamins supplemented with: 1) 12% liquid molasses and 16% flaxseed meal; 2) 12% liquid molasses, 11% soybean meal, and 5% sunflower meal; 3) 12% corn meal and 16% flaxseed meal; or 4) 12% corn meal, 11% soybean meal, and 5% sunflower meal. Each cow was assigned a different diet at each period of 21 days, and each cow was on each of the four diets by the end of the study. We collected several samples including feedstuffs, milk, urine, feces, and blood. Our preliminary data showed no statistical difference in milk production comparing diets containing molasses vs. diets containing corn meal, which averaged 29.2 and 29.8 lb/day, respectively. Although milk components were also not affected by these two different energy supplements, milk urea nitrogen (MUN) was significantly lower in cows fed molasses suggesting improvement in nitrogen utilization. We also observed that milk production was 3-lb higher in cows fed diets containing the mixture of soybean meal plus sunflower meal (mean = 31 lb) compared to those containing flaxseed meal (mean = 28 lb), showing that flaxseed meal impaired milk production under the conditions of our study.
In this past summer Dr. Brito and his students Shara Ross and Kristen Greene in collaboration with Dr. Kathy Soder from the USDA-ARS conducted at the UNH-Organic Dairy Research Farm a grazing study to investigate the effects of feeding molasses vs. corn meal on milk production and nitrogen utilization of organic dairy cows, and profitability of these two supplemental sources. According to Karen Hoffman (USDA-NRCS), the amount of molasses typically fed on organic dairies ranges from 3 to 7 lb per cow daily depending on milk production. However, on-farm data collected during 2009 grazing season by Hoffman and Soder showed mixed results with molasses supplementation with some organic farmers using it successfully while others reporting major milk production or body condition losses. We fed in our summer study either liquid molasses or corn meal as the sole energy supplements (12% of total dry matter intake) to 20 lactating organic Jersey cows (10 cows in each diet). Cows had free access to pasture and were also supplemented with grass-silage baleage. Our preliminary results showed that cows fed molasses produced 1.8 lb more milk (mean = 28.9 lb/day) than those fed corn meal (mean = 27.1 lb/day), suggesting that molasses can replace corn meal when cheaper to feed. Feeding molasses rather than corn meal also resulted in reduced MUN (13.4 vs. 15.1 mg/dL) indicating improvement in nitrogen utilization.
Dried seaweed (kelp meal) is widely used in the organic dairy industry as a source of minerals to animals. However, no scientific research is available to help dairy farmers make informed decisions regarding kelp supplementation to calves. Dr Brito and his undergraduate students Lindsay Chase and Ashley Miranda have been investigating the use of kelp meal for organic Jersey calves at the UNH-Organic Dairy Research Farm and for conventional Holstein calves at the UNH Fairchild Dairy Farm. So far a total of 12 dairy heifer calves, 6 organic Jerseys, and 6 conventional Holsteins, were used to study the effects of kelp meal (SeaLifeTM) on performance and growth measurements (body weight, wither and hip height, and body length). Calves were randomly assigned to one of two diets: 1) Control (calf starter grain plus 3% hay); or 2) Kelp (calf starter grain, 3% hay, plus 1 ounce of kelp meal). No statistical differences were observed between diets for feed intake and daily body weight gain, which averaged, respectively, 1.61 and 1.42 lb/day for Jerseys, and 1.85 and 1.81 lb/day for Holsteins. Similarly, growth measurements were not affected by feeding Control vs. Kelp.
In general, it is important to note that conclusive answers cannot be obtained from our preliminary results because we are still conducting laboratory and data analyses, and collecting data in the case of the kelp study. Therefore, all these preliminary results should be interpreted carefully. Look out for future NODPA News issues.
Dr. André Brito is an assistant professor of organic dairy management at the UNH. He has 15 years of research experience focused on enhancing nitrogen utilization in dairy cattle to minimize environmental impact of dairy farming. Since August 2009, he has been actively conducting research on different supplementation strategies for organic dairy cows.
Posted: to Organic Production on Thu, Dec 2, 2010
Updated: Thu, Dec 2, 2010