Effects of Corn Meal or Molasses on Milk Production of Grazing Organic Dairy Cows
Dr. Andre Brito, assistant professor of dairy nutrition, University of New Hampshire
This experiment compared the effects of molasses or corn meal on milk production, milk composition, and nitrogen metabolism. Twenty organic lactating Jersey cows were randomly assigned to 2 treatments, either corn meal or molasses. The cows had free access to pasture from June to mid-September in a management intensive grazing (MIG) system. Animals were individually fed twice a day about 2.0 kg (4.4 lbs.) of molasses or corn meal plus 3 kg (6.6 lbs.) of a grass-legume balage with refusals recorded daily before each feeding. Milk production was recorded throughout the study. Body weight and BCS was recorded monthly.
The data and samples collected were:
- Feed samples: DM, OM, CP, NDF, ADF, AIA, starch, and sucrose
- Blood samples: PUN and NEFA
- Urine samples: total N, urea N, creatinine, and PD
- Milk samples: fat, true protein, lactose, MUN, and fatty acids
- Data analyzed using the MIXED procedure of SAS with repeated measures over time.
The cows supplemented with 2 kilograms of molasses daily produced about a kilogram more milk per day than did the cows supplemented with 2 kilograms of corn meal. However, milk production was not particularly high for either set, daily average production was 12 to 13 kilograms (26.4-28.6 lbs.). Feed intake was higher with cows fed a molasses supplement, 12.6 kg/day, versus 11.2 kg/day for cows fed a corn meal supplement. Thus, the primary reason for the slightly higher milk production observed in the molasses supplemented cows. There was no significant difference in any of the values found in milk components measured between molasses supplemented cows and corn meal supplemented cows. MUN and PUN values fell with cows fed molasses compared to the cows fed corn meal, but these values were still above the recommended range for a cow being fed a well-balanced diet. (Ed. note: The corn meal ration is quite low owing to the cost of organic grain. More corn meal would be required to get adequate starch in the diet to better utilized the protein in the pasture forage.)
In general, the two experiments revealed:
- Flaxseed meal negatively impacted milk production.
- Molasses reduced MUN and PUN.
- Molasses can replace corn meal without negatively impact milk production, at least at the level of supplemented here, 2.0 kg/day (4.4 lbs/day).
- Feed cost will determine the use of molasses on organic dairy farms.