Using Bluegrass Straw to Modulate the Elevated Dietary Crude Protein and Phosphorus Caused by Including Distillers Grains and Solubles in Dairy Diets

View the project final report

• 2008 annual report
• 2009 annual report

Commodities

• Animals: bovine
• Animal Products: dairy

Practices

• Animal Production: feed/forage, feed formulation, winter forage
• Crop Production: continuous cropping
• Education and Training: demonstration, extension
• Farm Business Management: budgets/cost and returns, whole farm planning
• Production Systems: holistic management

The greatly accelerated production of ethanol in the U.S. has increased prices of feed grains but also has increased the availability of distillers grains and solubles (DGS) for livestock feeding. Because DGS contains comparatively high fiber content, most DGS will be fed to cattle. The high phosphorus (P) and crude protein (CP) content of DGS challenges existing nutrient management plans for dairy farms, most of which already have excess phosphorus imports and face increased scrutiny concerning ammonia emissions. Feed ingredients containing low concentrations of P and nitrogen (N) need to be included in rations to offset the high P and N in the DGS. Recently, bluegrass straw (BGS) has been added to diets of cows entering their final 100 days of lactation without affecting milk yield or composition. In addition, incorporating BGS into diets instead of field burning the bluegrass seed residues reduces particulate emissions, which can reach 159 kg PM2.5 per acre. This proposal seeks to extend previous work of feeding BGS to late lactation cows and proposes to use BGS to reduce N and P excretion of cows in mid-lactation fed diets containing DGS. The proposed study also will consider income over feed costs with BGS. Thus, the hypothesis is that BGS in diets not only will reduce N and P excretion in cows fed DGS, but also will improve net income of dairies.

To encourage greater use of BGS in dairy diets, data on milk yield, composition, and income over feed costs are needed when BGS is included in diets of cows in mid-lactation. These data are urgently needed because many dairies already are incorporating DGS into lactation rations to compensate for the relatively high cost of feed grains and soybean meal. Accordingly, the objectives are to determine: If bluegrass straw can be used in diets to offset the increased excretion of nitrogen and phosphorus of cattle fed distillers grains and solubles; If bluegrass straw can be fed to cows in mid-lactation without affecting milk yield and composition; Income over feed costs when bluegrass is incorporated into lactation diets.