Molasses as the primary energy supplement on an organic grazing dairy farm

Authors: HOFFMAN, KAREN - Natural Resources Conservation Service (NRCS, USDA); CHASE, LARRY - Cornell University; Soder, Kathy

Submitted to: Third Grazing Livestock Nutrition Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 5/12/2010
Publication Date: 7/8/2010
Citation: Hoffman, K., Chase, L., Soder, K.J. 2010. Mollasses as the primary energy supplement on an organic grazing dairy farm. In: Proceeding 4th Grazing Livestock Nutrition Conference. Estes Park, CO. p. 203.

Interpretive Summary: An interpretive summary is not required.

Technical Abstract: Due to increasing organic grain costs, organic dairy farmers are looking for less expensive ingredients that can be reasonably fed to lactating dairy cows. Molasses seems to be a less expensive source of supplemental energy and vitamins. Organic dairy farmers inquire about molasses as an alternative based on testimonials from other farmers. Research has been conducted on molasses as feed for many decades, much of it published in the 1950’s-1970’s. Today’s knowledge of dairy nutrition is much greater, so results of that research may not be directly applicable. Also, little research was conducted with dairy cows fed a high rate of molasses as the sole energy supplement, or with dairy cows grazing cool-season pastures in the northeastern USA. Anecdotal results have been mixed, with some farms reporting success, while others reporting failure. This could be due to a variety of management or feed quality factors, but it is not currently known which factors have the greatest influence. This research project quantified (on a monthly basis) milk production and other animal performance measures on an organic dairy farm in central New York that is currently feeding molasses successfully. Forage quality, nutritional data, economics, and other management techniques (i.e. pasture management) were assessed. Body condition score (BCS) averaged slightly over 2.5 in early May, which was approximately 40-60 days in milk for most of the cows. At the lowest point in August, BCS averaged 2.1 and increased through the remaining months to 2.71 by November. Milk production followed a typical lactation curve for a seasonal-calving management system. Peak production occurred in the middle of May at 24 kg per cow, and then gradually declined through the rest of the study period. Production in November was 11 kg per cow, which is a persistency rate decline over the 6 month period of 12% per month. However, the rate of decrease in persistency from late May to early July was greater at 25% per month, likely due to the lower pasture quality during this time. Also, breeding began in early June, which may have increased their energy requirements slightly. The pregnancy rate was 95% using natural service, indicating that the cows were in an adequate energy status during this time period and were able to cycle and conceive. Milk components were very consistent throughout the grazing season, ranging from a low of 4.01% milk fat to a high of 5.53% milk fat at the end of the study. Milk protein and other solids were also consistent, with milk protein averaging 3.4% and trending up towards the end of the study as milk production declined. These increases in components are typical in seasonal-calving herds. Further, by November the cows were being fed a fair amount of dry hay and baleage, which would help to increase the milk fat percentage. The milk urea nitrogen levels were relatively high (16.15 mg/dl average) throughout the grazing season, as would be expected on a high protein pasture diet with low levels of non-fiber carbohydrates. Compared with simulated results from the Cornell Net Carbohydrate and Protein System, the cows were not as efficient at utilizing the pasture protein as the model expected. This raises the question of whether or not molasses actually provides a higher level of energy compared to corn, as purported by some farmers who have used it. It also calls into question the values the model uses for molasses to predict rumen dynamics. The cost of organic starch sources in comparison to the cost of organic molasses would need to be evaluated both individually and in combinations of various feeding rates, as interest in the use of molasses is motivated by higher organic grain costs. This study was continued through the 2009 grazing season, as the farm decided to feed a slightly higher grain rate due to some cows beginning their lactation in low bod