Logicistics and economics of blending condensed distillers solubles with stover on small to mid-size cattle farms

Katharine Helen Bartlett, Purdue University

Abstract

Condensed Distillers Solubles (CDS) and corn stover mixed at a 3:1 or 2:1 ratio has shown to be of potential value for beef and dairy cattle producers. Through lab scale silo tests, the aerobic stability, pH, mold and nutrient values suggest that these blends can partially replace corn silage. Crude protein for the 3:1 and 2:1 blends ranged from 13 to 18% on a DM basis. The NEL was 1.41 Mcal/kg DM and NDF averaged at 55%. The pH was under 5.0 for blends that were mixed, but above 5.0 for those that demonstrated a layering process in a bunker. Cost projections were modeled for 8 processes of mixing the CDS and stover for storage in bag silos. They were based on published custom rates, machinery prices, fuel price, machinery capacity, power requirements, transportation, and material costs. Stover nutrient removal cost was also included. The processes focused on strategies of baling or chopping the stover, while shredding and processing were additional options. Five of the processes used a vertical mixer, while the last three left the mixing cost out so we could determine the value of a (not yet developed) device that would meter and dribble the CDS over the stover as it entered a bagger. The least expensive methods were Chop/Dribble/Bag and Shred/Chop/Dribble/Bag, but since they did not include mixing cost, the Chop/Mix/Bag model was considered best with currently available technology, costing $63.6/Mg. CDS was priced as a function of corn. The base corn price was $194/Mg ($6/bu) and three addition scenarios were made for corn priced at $130/Mg ($4/bu), $259/Mg ($8/bu), and $324/Mg ($10/bu). All changes were made ceteris paribus for each scenario to determine the effect on cost of the 3:1 blend. Decreasing the price of CDS saved the user $11.1/Mg, while increasing the price of CDS cost $11.3/Mg to $22.5/Mg more. The initial cost projections also included a travel distance to haul CDS of 80.5 km (50 mi) per round trip. Cutting this round trip in half saved the user $2.5/Mg and increasing the haul distance to 161 km (100 mi) increased the total CDS blend cost by $3.5/Mg. A sensitivity analysis to mixer performance was determined by adding 6 minutes onto each scenario's original 4 minutes of mixing time. This additional time cost the user $2.1/Mg. The savings of replacing mixing with the yet developed dribble approach amounts to $5.34/Mg of blended material. The cost from the Chop/Mix/Bag process was used in a least cost ration balancer as to determine the value of this substitute feedstuff in a typical dairy ration. With 5% of intake as an upper bound, fat was the greatest limitation to use of the CDS blend in the dairy ration: 6.55 kg DM of the CDS blend was the limit; in this case, 23% of the TMR was CDS. The overall cost for the ration using the CDS and stover blend was $0.64/cow/day less than a similar ration of corn silage. Use of a 2:1 ratio shifted the active constraint from fat to physiological fill. Overall, it seems that the use of CDS and stover blend can be appropriate for some cattle farmers in close vicinity to ethanol plants that sell CDS. Corn silage may be preferred, however, due to its close proximity to the farm, relatively easy handling and lower fat content compared to the CDS and stover blend.

Degree

M.S.

Advisors

Buckmaster, Purdue University.

Subject Area

Agriculture|Agricultural economics

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