Forage Quality And Utilization Of Kentucky Bluegrass Residue

John HolmanPlant, Soil and Entomological Sciences

Carl HuntAnimal and Veterinary Science

Larry Van TassellAgricultural Economics and Rural Sociology

Kentucky Bluegrass Forage Quality

• Post-seed harvest forage valueBaleGrazeBale and graze

• Pre-seed harvest forage value (during fallowyear)

•Bale•Graze•Graze and bale

Bluegrass Forage Quality - Analogy

• I need to come to this meeting in Spokane but my department head only gave me funds for gas (energy) to make 85% of the trip. Does that mean his offer is of no value to me?

• Of course not, it just means that I have to find funds for gas (energy) for the rest of the trip

Nutritive value of bluegrass straw needs to be enhanced to support a productive beef

cow

Nutrient Bluegrass straw

Cow requirement*

ME, Mcal/lb .77 .91

Protein, % ~4.0 9.0

* NRC (1996) requirements for a late pregnancy, 1200 lb beef cow

Methods to Enhance Straw Quality

Energy and protein supplementation

Chemical modification: Ammoniation

Physical modification Grinding Pelleting

Energy and protein supplementation

1200 lb cow, late gestationConventional program

19.3 lbs grass hay ($75/ton)7.5 lbs alfalfa ($96/ton)$1.08/cow/day

Grass straw program

14.0 lbs grass straw ($40/ton)9.5 lbs alfalfa ($96/ton)3.4 lbs barley ($102/ton)$0.91/cow/day

Energy and protein supplementation

What happens with a 10% improvement in straw quality? Grass straw program

14.0 lbs grass straw ($40/ton) 9.5 lbs alfalfa ($96/ton) 3.4 lbs barley ($102/ton) $0.91/cow/day

Improved straw program 14.0 lbs grass straw ($40/ton) 8.1 lbs alfalfa ($96/ton) 3.2 lbs barley ($102/ton) $0.83/cow/day

Or, straw is worth $51.50!

Ammoniation!!

How does ammoniation work in the “real world” – Study with WSU beef herd

Lbs of ration intake per cow per day

No difference in performance: cow weight, body condition, calf weight (45 day), rebreeding

Ration ingredient

Ammoniated Non-ammoniated

Alfalfa hay 10.1 13.6

Bluegrass straw

20.8 19.6

Rumen digestibility: 36-h ISDMD

Same as Control (P > 0.10)

Pre-seed harvest forage value:

We don’t know yet

Seasonal quality and quantity of grazable forage

Kentucky Bluegrass (KBG) Forage Study Background

• Baling is an integral component of many reduced and non-thermal KBG residue management alternatives-Baling removes 75-80% of the post-harvest residue

▪ Proprietary types produce ~ 1 ton/ac

▪ Common types produce ~ 2 ton/ac

• Baled residue needs to be utilized for alternative methods of residue removal to be economically viable

Kentucky Bluegrass Forage Study Objectives

• Determine if KBG can be hayed or grazed in an alternate year production system while maintaining system profitability and sustainability • Quantify the decline of KBG quality post combine• Determine if variety impacts forage quality

- Quantify stem/leaf ratio, C/N ratio, and elemental nutrient content

• Quantify the amount and type of nutrients removed with the baled residue

Kentucky Bluegrass Forage Study Methods

• RCB design with 3 replications-For 2 years under non-irrigated conditions at the WSU

Turfgrass Research Site- Varieties: Kenblue, Touchdown, Ascot, and Limousine

• Collect KBG forage samples at boot, flowering, swathing, combining, and 0-21 days post combining• Measure the collected samples for fiber (ADF & NDF),

crude protein, in-vitro digestibility, lignin content, C/N ratio, and elemental nutrient content

Kentucky Bluegrass Forage Study Outcomes

• Identify the optimum time to bale post-harvest residue

• Identify the type and amount of nutrients removed with the baled residue

• Calculate the optimum time of grazing or baling KBG in the fallow year of the alternate year cropping system to maximize profitability

• Determine KBG forage quality and energy value

• Determine if KBG variety impacts forage quality

• Disseminate information to KBG growers and public