Alfalfa in dairy rations increases production, nitrogen excretion

SOUTH DAKOTA - Optimizing dietary nitrogen utilization by dairy cows is important to both a producer's bottom line and the environment.
calendar icon 4 October 2006
clock icon 2 minute read

South Dakota State University Extension dairy specialist Alvaro Garcia says research has shown that diets containing high concentrations of alfalfa silage result in higher production, but also increase nitrogen excretion.

That's why it's important to find a compromise between production optimization and nitrogen excretion to the environment.South Dakota State University Extension dairy specialist Alvaro Garcia says research has shown that diets containing high concentrations of alfalfa silage result in higher production, but also increase nitrogen excretion.

That's why it's important to find a compromise between production optimization and nitrogen excretion to the environment.

A recent trial conducted by researchers from the University of Wisconsin and the U.S. Dairy Forage Research Center addressed this issue by comparing different ratios of alfalfa silage to corn silage. Dry matter intake, milk yield, 3.5 percent fat-corrected milk and fat, milk fat content, and digestibility of neutral detergent fiber and acid detergent fiber all decreased when corn silage replaced alfalfa silage.

As corn silage increased in the diets, nitrogen was utilized more efficiently by the cows which resulted in less nitrogen being excreted in urine and feces. No diet minimized nitrogen excretion without negatively affecting production, Garcia noted.

Urinary urea and total nitrogen excretion decreased when dietary alfalfa silage plus high moisture shelled corn were replaced with corn silage plus soybean meal. The diet that least affected production was one that used a ratio of alfalfa silage to corn silage of 24:27. Although the energy content and crude protein in silages can vary, Garcia said, it is safe to assume that the best compromise between production and nitrogen efficiency is obtained when corn silage and alfalfa silage are included in the diet at similar proportions.

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