Recommendations for use of a feed additive for dairy cows have been made by a University of Illinois Extension dairy specialist. Mike Hutjens said proper use of the additive, monensin (commercially known as rumensin), should increase feed efficiency, improve protein status, and reduce bloat risk.
"With the FDA clearance to feed monensin to dry and lactating cows, dairy managers have a new tool to improve feed efficiency and herd health," said Hutjens. "However, dairy managers should carefully monitor milk fat and milk protein test. Under certain rations--high starch, low effective fiber, and/or unsaturated oils--the level of monensin may need to be reduced. In the field, several herd owners have reported drops of 0.3 percentage unit. Herds with higher than breed average milk fat test can be candidate herds to be fed higher levels of monensin."
Hutjens said dairy managers, nutritionists and veterinarians might want to note these points:
--Efficiency of milk production increased 2 to 4 percent with the recommended level of 11 grams to 22 grams of monensinper ton of total ration dry matter on a dry matter basis;
--The suggested level of monensin for the milk cow ration is 240 to 275 milligrams per day, initially to allow the rumen microbes to adjust to the additive and adjust the level (up or down) based on milk component changes;
--With higher milk yield and lower components at higher level of monensin, the amount of solids-corrected milk did not change;
--Dry matter intake did not change in early lactation and dropped in the later stages of lactation. Body weight was not different between controls and supplemented cows;
--The benefit to cost ratio for monensin for lactating cows was five to one.
"Based on Canadian research results, monensin should be fed to dry cows at 200 to 250 mg per day, reducing displaced abomasums, increasing glucose precursors, lowering ketosis risk, and allowing smoother transition of dry cows to the lactating cow ration," said Hutjens.
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