Bluegrass Straw in Dairy Diets to Enhance Environmental Quality

View the project final report

Commodities

• Animal Products: dairy

Practices

• Animal Production: feed/forage, feed formulation, feed rations, stockpiled forages
• Education and Training: demonstration
• Farm Business Management: budgets/cost and returns, value added
• Production Systems: agroecosystems, holistic management

The benefits of feeding some bluegrass straw to late lactation dairy cows included a slight reduction in daily feed costs (using actual feed intakes and current ingredient costs): 10% bluegrass straw reduced feed costs by 5 cents/day/cow whereas 15% bluegrass straw reduced feed costs by 20 cents/day/cow. The reduction in feed costs was less than expected because cows fed bluegrass straw tended to eat more feed, presumably to compensate for the lower net energy of the TMR. Another benefit to feeding bluegrass straw is reduced crude protein intake of cows and, therefore, lowered nitrogen excretion. The predicted nitrogen excretion was reduced 46 g/day for cows fed 10% bluegrass straw and 69 g/day for cows fed 15% bluegrass straw. Because much of the excreted nitrogen eventually is released into the air as ammonia, reducing nitrogen intakes without affecting milk yield provides an environmental benefit.

Introduction

Incorporation of bluegrass straw in dairy total mixed rations could be an important new market for bluegrass seed producers. In the Pacific Northwest region of Washington, Oregon, and Idaho, there are approximately 781,000 dairy cows and an approximately equal number of growing replacement heifers. If bluegrass straw was included at the rate of 4 lb/head/day for mature cows and 2 lb/head/day for growing heifers, the annual potential use of bluegrass straw would be 855,195 tons. At $55/ton, this equals about $47 million. Although universal acceptance of bluegrass straw in dairy rations is not expected, bluegrass straw may be widely used as an ingredient in diets of dairy cattle because it is a much lower price roughage source, and it contains much lower concentrations of nitrogen and phosphorus which complements high-phosphorus byproducts in diets.

The objectives were to determine the level at which bluegrass straw can be added to diets of lactating cows without adversely affecting milk production and composition, calculate a phosphorus balance with cows fed bluegrass straw and determine the reduction in phosphorus excretion that results, determine the level at which bluegrass straw can be included in diets of growing dairy heifers, and estimate the impact on feed costs and phosphorus balance when bluegrass straw is incorporated into dairy diets.