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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
NutrientBluegrass
straw
Cow requirement
*
ME, Mcal/lb .77 .91
Protein, % 3.6 9.0
* 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 15-20 % units
Increased CP 5 – 6 % units Momont et al, 1992 and Sundstol et al., 1984
Research on Ammoniation
202530354045505560
Barley Wheat Oats Rice Corn
stoverStraw Type
Ammoniated
Non-ammoniated%
DM
D
igeste
d
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 with1, 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
Item Control 3% Straw 5% Straw
Crude protein
3.6 11.6 13.9
NDF 74.7 75.4 74.2
ADF 41.1 42.8 43.0
Lignin 5.8 5.8 5.0
RuminallyFistulated
Cow
RuminallyFistulated
Cow
Removing bags
Removing bags
In situ (laboratory) Digestibility of Grass Seed Straw
40.641.7
46.2
31
36.3
41
25
30
35
40
45
50
DM NDF
Control
3% Ammonia
5% Ammonia
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
6.2
6.7
7.2
7.7
Con + Con A3 A5
DMI
kg
/d
Effect of Ammoniation on In Situ DM Degradation
0
10
20
30
40
50
60
70
Con+ ConA3A5
SE < 3.61
8 16 24 36 48 96 Hours of Ruminal Incubation
%
Dis
ap
pe
ara
nc
e
*A5 and A0+DIP were > A0
†
†A5 was > others
*
*
*
Effect of Ammoniation on Total Tract
DM Digestibility
65
67.5
70
72.5
75
DM
Con+ ConA3A5
%
Di g
este
d
a,b,cMeans lacking a common letter differ
a a
a,b
b*
*A5 differed from A0+DIP at the P = 0.06 level
Effect of Ammoniation on Total
Tract Fiber Digestibility
65
70
75
80
85
NDF ADF
Con+ ConA3A5
%
Dig
este
d
a,b,cMeans lacking a common letter differ
a aa a
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 costRations formulated
using “Balancer”
Any Questions?
