The condensed tannins in birdsfoot trefoil improve rumen fermentation, resulting in higher milk production when the crop is grazed or fed as dry hay, say Utah State University researchers.

The legume was compared to cool-season grasses in a 10-week grazing trial on a commercial organic dairy farm using mid-lactation cows. Both groups also received 5 lbs/cow of a barley grain, vitamin and mineral concentrate twice a day after milking.

Milk production averaged 58 lbs/day and was similar between treatments. The milk of trefoil-grazed cows tested 3.86% fat vs. 3.44% for cows on grass, resulting in 8 lbs/cow/day more 3.5% fat-corrected milk.

In a second trial, Holsteins were fed a TMR that was 42% birdsfoot trefoil hay, alfalfa hay or a combination of the two types. All diets had the same energy and protein levels.

Cows fed trefoil hay had higher dry matter intakes than cows fed alfalfa hay (58 vs. 56 lbs/day), produced more milk (88 vs. 84 lbs/day) and had slightly higher protein levels.

The results of both trials were attributed to higher volatile-fatty-acid levels in the rumens of cows fed birdsfoot trefoil.

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