Forage & Grains
Kathy Soder, USDA-ARS, University Park, PA; André F. Brito, University of New Hampshire; and Karen Hoffman, NRCS, Norwich, NY
As organic grain prices have increased and organic milk prices have decreased, dairy farmers are seeking lowercost supplementation strategies. Sugarcane molasses, a rich source of sucrose, seems to be a viable option as a source of energy. Molasses frequently costs less per pound of dry matter (DM) than organic corn, is energy-dense, has high palatability, and is available in organic form.
Some organic dairy farmers have experimented with molasses supplementation with mixed results- some farmers reported benefits, while others experienced major losses in milk production or body condition. While the impact of using molasses as the only supplemental source of feed to grazing dairy cows. Therefore, a group of experiments, combining on-farm, laboratory, and research farm projects, is in progress to evaluate the value of molasses as the sole supplemental feed for organic dairy cows. The goal of this work is to develop feeding guidelines for molasses supplementation that are backed by science. A brief summary of each project is presented below.
Karen Hoffman is evaluating how pasture quality and molasses feeding worked on an organic dairy farm in central New York over the last two grazing seasons. Feed data was collected and summarized with milk production, components, milk urea nitrogen (MUN), and body condition score of the cows. Taking the project one step further, she also evaluated the diets with the Cornell Net Carbohydrate and Protein System model (CNCPS). To date, only the data from 2008 has been summarized. The farm used was a 56 cow, seasonally calving, crossbred herd. They fed a combination of 3 pounds of molasses and 1 pound of a corn/barley mix, with kelp and minerals offered free choice. Pasture samples and body condition scores were collected monthly. At the end of the grazing season, the farm provided copies of all milk weight tank sheets and milk plant reports.
The results showed that the cows had a greater than normal drop in persistency for the first month after they reached their peak of 52 pounds per day. This coincided with the pastures becoming over mature in June, resulting in a drop in forage quality and possibly decreased total intake due to palatability. Thus, it is unclear whether the drop in persistency was due to the molasses feeding, the pasture quality, or both. Body condition dropped to a low of 2.1 in mid-summer, but recovered through September and October to over 2.5 by the end of the grazing season. The MUN levels were consistently greater than 14 mg/dl, suggesting that there was not enough energy in the rumen to recapture the excess ruminal ammonia as microbial protein- rather, it was excreted as urea. The recommended level for MUN is between 8 and 12 mg/dl.
When the diets were evaluated using CNCPS, energy was the most limiting factor for milk production. The recommended level of non-fiber carbohydrates is between 38 and 42%; these diets were only 24 to 33%. Starch levels were between 0.75 and 4.86%, whereas the recommended level is 25%. The sugar levels were at times higher than the recommended 4 to 7%, coming in between 3 and 15%. It will be interesting to evaluate the data from 2009 and compare the results.
André Brito is presently conducting a winter-feeding study using sixteen lactating organic Jersey cows supplemented one of four ways: 1) corn meal; 2) molasses; 3) corn meal plus flaxseed meal; or 4) molasses plus flaxseed meal. The objective is to evaluate the effect of these supplements (particularly flaxseed) on milk production, nitrogen utilization, nutrient digestibility, and milk composition (especially fatty acid profiles). André and colleagues [Kathy Soder, Karen Hoffman, Rick Kersbergen (University of Maine), and Pete Erickson (UNH)], with funds partially provided by the Organic Farming Research Foundation, will study the effects of molasses vs. corn meal on milk production, milk composition, body condition, nutrient digestibility, and income over feed costs of grazing organic Jersey cows beginning in May 2010. Research tailored to farmers’ needs is the ultimate goal of the University of New Hampshire Organic Dairy Research Farm.
Kathy Soder evaluated the effects of supplementing a pasture diet with molasses (5% of total DM), corn meal (7% of total DM), or a combination of molasses (5%) and corn meal (7%), on ruminal fermentation using continuous culture fermenters. The fermenters are ‘artificial rumens’ that are inoculated with rumen fluid, fed various diets, and can be used to evaluate ruminal fermentation patterns, including pH, volatile fatty acid and ammonia concentrations, and nutrient digestibility. This is a screening tool that can be used to evaluate diets before conducting a large-scale animal research trial. The supplementation levels were selected based on what is currently being fed to organic dairy herds. The results from this study showed that molasses responded similarly to corn meal, with all treatments showing only marginal benefits (at this low inclusion level) over a pasture-only diet.
Previous research results (often with beef cows fed low-quality forages) indicate that forage quality may have an impact on ruminal response to molasses supplementation. Kathy is currently conducting another fermenter study evaluating the effects of forage quality (high and low quality) and level of molasses supplementation (5 and 10% of total DM) on ruminal fermentation. Results from this study will be available later this year.
While this work will by no means answer every question related to molasses supplementation, this research was developed in response to questions from organic dairy farmers who are either
currently using, or who may be interested in trying, alternative supplementation strategies to decrease feed costs while maintaining or improving productivity, and ultimately profitability,
of organic dairies. Further, the strategy of conducting a combination of on-farm, laboratory, and research farm projects to examine a single management strategy is somewhat unique, and will hopefully result in better answers to many of the questions being raised.
Posted: to Organic Production on Thu, Oct 18, 2018
Updated: Thu, Oct 18, 2018
