Enhancing the Nutritive Value of Grass Seed Straw for Beef Cattle Carl Hunt Department of Animal and Veterinary Science University of Idaho Kristen Johnson Department of Animal Sciences Washington State University

“I am almost 11 years old, and I was born with cystic fibrosis and asthma. Because of the grass burning, there are many things I can't do…I can't go outside during recess…I can't be a kid.” —Letter from Derek published in the Spokesman Review (October 5, 1997)

Standardized Performance Analysis (SPA) for the Western States What characterizes a profitable cow/calf producer? High weaning weight? High calving percentage? Low cost of production; low unit cost of production ($/cwt)? YES!! Feed cost represent the largest cost of production Winter feed cost is the major feed cost

Can grass seed straw help reduce wintering cost?  Low quality roughages, have same potential energy as contained in grains  Need to make that energy available to the animal – bioavailable  We believe grass seed straw is prime for enhancing energy value

Nutritive value of bluegrass straw needs to be enhanced to support a productive beef cow Nutrient Bluegrass straw Cow requirement* ME, Mcal/lb Protein, % * NRC (1996) requirements for a late pregnancy, 1000 lb beef cow

Need a Way to Improve Straw!  Ammoniation increases the nutritive value of straw  Increased DM digestion by 8-15 % units  Increased DMI % units  Increased CP 5 – 6 % units Momont et al, 1992 and Sundstol et al., 1984

Research on Ammoniation % DM Digested

Principles of Ammoniation Swells “cracks” fiber to provide better ruminal microbial attack Provides a source of nitrogen for microbes to convert to protein Agents for ammoniation: *** Anhydrous ammonia Aqueous ammonia Urea

Tested Methods of Ammoniation

Past Success Ammoniating Cereal Straw Treated barley straw with 1, 2, or 3% ammonia

Grass Seed Straw Ammoniation 18 bales (400 lbs) of bluegrass straw Treatments: Control 3% Ammoniation 5% Ammoniation Core sampled before and after treatment to measure composition and laboratory digestibility

Composition of grass seed straw treatments ItemControl3% Straw5% Straw Crude protein NDF ADF Lignin

Ruminally Fistulated Cow Ruminally Fistulated Cow

Removing bags

In situ (laboratory) Digestibility of Grass Seed Straw

 Dietary treatments: Control = Untreated straw Positive Control = Untreated straw + CP A3 = 3% ammoniated straw A5 = 5% ammoniated straw Cattle digestion trial

Effect of Ammoniation on Dry Matter Intake kg/d

Effect of Ammoniation on In Situ DM Degradation SE < Hours of Ruminal Incubation % Disappearance *A5 and A0+DIP were > A0 † † A5 was > others * * *

Effect of Ammoniation on Total Tract DM Digestibility % Digested a,b,c Means lacking a common letter differ aa a,b b* *A5 differed from A0+DIP at the P = 0.06 level

Effect of Ammoniation on Total Tract Fiber Digestibility % Digested a,b,c Means lacking a common letter differ aaaa b a a b

Implications  Digestibility of bluegrass straw was substantially enhanced by ammoniation; however, intake was still low (1.3% of BW) for winter feeding of beef cows  Ammoniation ($18/ton) was cost beneficial when compared against the cost of barley ($105/ton) and alfalfa hay ($85/ton) that would be required to supplement untreated straw

Daily feed cost for 1000 lb, late gestation cow  Untreated bluegrass straw  Straw = 15.4 lb  Barley = 7.5 lb  Alfalfa hay = 5.1 lb  $/day = $.89  Ammoniated bluegrass straw  Straw = 8.6 kg  Barley = 1.2 kg  $/day = $.61, or  Instead of $18, could afford $47/ton) treatment cost Rations formulated using “Balancer”

Any Questions?