J.A. Lory 1, R.E. Massey 2 and M.C. Shannon 3 1

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1 J.A. Lory 1, R.E. Massey 2 and M.C. Shannon 3 1 Plant Sciences, 2 Agricultural and Applied Economics, 3 Animal Science University of Missouri, Columbia MO 65211

2 Software is commonly used to optimize diets based on nutritional needs of the animal while identifying low-cost formulation of available ingredients. Feed optimization programs only consider input costs for evaluating low-cost rations. National Swine Nutrition Guide (NSNG) Diet Formulation and Evaluation Software (NSNG, 2010) estimates manure fertilizer value of different diets Does not include manure value as part of the optimization routine. Diet recommendations Available P was reduced in 2007 for lb pigs; constant, otherwise. Ca was reduced in 2007 for all diets affects Ca:P ratios that can affect P in the manure. Amino Acid changed (some increased, some decreased) in 2007 can affect N in manure by affecting crude protein in diet.

3 Regulatory and voluntary strategy to minimize impact of manure management on water quality is to fully utilize manure nutrients as fertilizer for crop production(usepa, 2008). Fertilizer nutrients can be a significant component of net income on swine operations (e.g. Lory et al., 2004). Fertilizer value of nutrients excreted by pigs can vary widely due to many factors including: diet, manure handling system, method of application and soil nutrient status.

4 Cost ($/ton) 600 Corn Soybean Meal (47.5%) DDG

5 Cost ($/ton) $1, MonoCal (21%P) DiCal (18.5%P) Anhy Ammon DAP Potash $1, $ $ $ $ $

6 Assess the impact of incorporating manure into feed management decisions. How have changes in low-cost diets over the period from 2002 to 2011 affected estimated fertilizer value of manure? Period covers the widespread adoption of incorporating corn dried distillers grains with solubles (DDG) into swine diets. Determine how low-cost diets would have changed if fertilizer value of excreted was integrated as a c0-product into linear programming feed optimization routines. The goal is no longer least cost ration formulation but jointly considering ration cost and manure value.

7 Evaluated four diets: grower-1 (23-35 kg pigs) and finish-2 ( kg pigs) diets, with or without DDG as a feed component option. Diet composition constraints based on Kansas State University Swine Nutrition Guide (1998; 2007). In DDG diets maximum constraint was 40% inclusion for grower-1 and 30% for finish-2. Feed component composition based on NSNG (2010). Feed costs for corn, soybean meal (SBM) and distillers grains with solubles (DDG) based on USDA Annual Prices Summary ( ). Prices for minerals and phytase based on production records from the Missouri Swine Feed Group (personal communication). Fertilizer value of N, P and K based on USDA Annual Prices Summary ( ). Nutrient retention (N, P, K) of pigs based on equations in NSNG (2010). Nutrient availability for crop production of excreted nutrients based on slurry tank manure injected into soil. Excreted N, P and K were assumed to be 70%, 100% and100% available, respectively. Phytase effectiveness based on Naturophos option in NSNG (2010). Linear programming optimization routines executed in Microsoft Excel Solver.

8 Key assumptions: Excreted nutrients are the difference between fed nutrient and retained nutrients. Over feeding nutrients in swine diets does not further increase nutrient retention of pigs(e.g. Henley et al., 2012;McDonnell et al., 2011). Curvilinear relationship between phytase units (FTU kg -1 ) and P availability (%) linearized for optimization routine by transforming relationships into six linear segments with decreasing effectiveness. Farmers received full fertilizer value for plant-available manure N, P and K.

9 Results

10 Cost ($/ton) lb phase lb phase $ No DDG 40% DDG $ No DDG 30% DDG $ $ $ $ $ $ $ $ $ $ $50.00 $50.00 $0.00 $0.00

11 lb. N/ton feed) lb phase lb phase 45 No DDG 40% DDG 45 No DDG 30% DDG Constraints 2007 Constraints Constraints 2007 Constraints

12 lb. P2O5/ton feed) lb phase lb phase 25 No DDG 40% DDG 25 No DDG 30% DDG Constraints 2007 Constraints Constraints 2007 Constraints

13 lb. K2O/ton feed) lb phase lb phase 25 No DDG 40% DDG 25 No DDG 30% DDG Constraints 2007 Constraints Constraints 2007 Constraints

14 lb. P/ton feed) No DDG in diet 40% DDG in diet 14 Corn P SBM P DDG P Mineral P 14 Corn P SBM P DDG P Mineral P Constraints 2007 Constraints Constraints 2007 Constraints

15 Value ($/ton of feed) lb No DDG lb 40% DDG lb No DDG lb 30% DDG

16 Percent lb No DDG lb 40% DDG lb No DDG lb 30% DDG 25% 20% 15% 10% 5% 0%

17 Costs: $ /hog (58% feed) Loss: $ /hog Manure 1 : $ 8.41 /hog Feed, $ Variable Costs, $22.19 Operating Interest, $3.32 Fixed Costs, $8.45 Feeder Pig, $ ISU analysis did not include manure value.

18 Profit/Loss ($/pig) Includes Full Manure Value No Manure Value

19 DDG always the low-cost diet. DDG always increased diet CP and excreted N. In Grower diets, DDG diet is the low-p diet. In Finish diets, Corn-SBM diets is the low-p diet. Differences are small. There are fewer manure nutrients due to diet changes over time; but increasing fertilizer costs have made manure nutrients more valuable.

20 Results

21 lb. P/ton feed) 12 Manure value not in optimization Corn P SBM P DDG P MonoCal P DiCal P Manure value in optimization Corn P SBM P DDG P MonoCal P Dical P Constraints 2007 Constraints Constraints 2007 Constraints

22 Change ($ Mg -1 ) Year Diet Cost Manure Value Net Value

23 lb. P/ton feed) Corn P SBM P DDG P MonoCal P DiCal P Manure value not in optimization Manure value in optimization Corn P SBM P DDG P MonoCal P Dical P Constraints 2007 Constraints Constraints 2007 Constraints

24 Change ($ ton feed) Year Diet Cost Manure Value Net Value

25 Mean Benefit Max Benefit $ Mg Grower-1 w/o DDG Grower-1 w/ddg Finish-1 w/o DDG Finish-2 w/ddg

26 Net Feed Cost Difference between Manure included and Manure not included in optimization Net Feed Cost = Feed Cost Manure Value DDG No DDG $0.00 $0.20 $0.40 $0.60 $0.80 $1.00

27 1. Had no effect on diet composition Small benefits but worth evaluating in Eliminated phytase from diets containing DDG. 4. Reduced or eliminated phytase in C-SBM diets. Controlled by energy in diet and P- density of P sources.

28 Manure is a significant source of value to livestock producers. Opportunities exist to integrate the value of manure into the least cost diet decision so that net income is optimized. Impact is currently small. Caveat: cost of diets are certain expense; value of manure is uncertain revenue. Minimizing P Excretion in C-SBM diets still limited by P availability of corn.