9/25/2015 Department of Large Animal Sciences Introduction Global - PDF document

9/25/2015 Department of Large Animal Sciences Introduction Global food demands increase -> more animal products will be produced A linear programming model to optimize diets in environmental policy scenarios Carbohydrate fermentation (from forage) in dairy cattle Moraes, L.E. et al. (2012) produces CH 4 Protein, starch and minerals in feed can lead to excretion of N Katarina Nielsen Dominiak and minerals if fed at higher levels than animal requirements Department of Large Animal Sciences 72% of total emitted CH 4 in Brazil was from enteric fermentation (1994) K.N. Dominiak, AQMHM 2015 Department of Large Animal Sciences Department of Large Animal Sciences Introduction Problem Greenhouse gas (GHG), NO 3 -, and minerals contaminate Mandatory carbon (CH 4 ) emission policies might be the the environment future Policies and legislations formulated to limit Two policies are discussed: environmental impacts of livestock production - Limit the quantity of CH 4 emitted - Require emission taxes - Clean Water Act (US EPA 2003) - Manure applied to crops and pastures at levels the A precise diet formulation and balance will meet BOTH plants can extract (Nitrate,Phosporous) animal nutritient requirements AND decrease - Kyoto Protocol reduces GHG to level of 1990 environmental impacts of animal agriculture - Carbon markets in Europe (and the States) K.N. Dominiak, AQMHM 2015 K.N. Dominiak, AQMHM 2015 Department of Large Animal Sciences Department of Large Animal Sciences Aim Three scenarios – three models BASEM: Cheapest possible feed – No GHG policies (baseline) Reduce CH 4 emission and excretion of N and minerals Decision variables: Constraints: Available feed Nutrient requirements Optimal diet cost and feed selection and their costs Defined feed limits Fibre proportions Joint optimization of costs and emisions+excretions TAXM: Effect of tax on diet costs and composition, emission and excresion Computes optimal feed input mix that balances off tax savings for Linear programming: lower emissions A method to achieve best outcome given certain constraints Constraints are represented by linear relationships REDM: Feed costs vs emission and excresion if forced to reduce CH 4 emission Decision variables like BASM but with the extra constraint K.N. Dominiak, AQMHM 2015 K.N. Dominiak, AQMHM 2015 1

9/25/2015 Department of Large Animal Sciences Department of Large Animal Sciences Assumptions Assumptions � � � � � kg/kg DM � � � � �� $/kg DM � � � � �� � � � � �� Locally collected K.N. Dominiak, AQMHM 2015 K.N. Dominiak, AQMHM 2015 Department of Large Animal Sciences Department of Large Animal Sciences Prediction of emission and manure production Objective functions How much CH � is emitted? ~55 MJ/kg BASEM and REDM j = feed x = amount of feed (kg of DM) c = cost of feed Feed composition – absorbstion � Excrete composition K.N. Dominiak, AQMHM 2015 K.N. Dominiak, AQMHM 2015 Department of Large Animal Sciences Objective functions Constraints Other Limits, 1 TAXM Diet. Feet Limits Nutrient req . DMI Diet. Barley Limits Other Limits, 2 j = feed x = amount of feed (kg of DM) Diet. Forage Proportions c = cost of feed Methane Restrictions CH � e = expected emission (tonnes) p = tax price per tonne K.N. Dominiak, AQMHM 2015 Dias 12 2

9/25/2015 Department of Large Animal Sciences Department of Large Animal Sciences Nutrient requirement constraints Dietary feed limits constraints Amount Requirement �� 7 x 14 = 98 equations = � �� � � �� ∙ � � �� ��� Nutrient content 7 x 10 = 70 equations j = feed j = feed a = cow category (7 kinds) a = cow category (7 kinds) l = limit (for 10 kinds of j ) i = nutrient (14 kinds) K.N. Dominiak, AQMHM 2015 K.N. Dominiak, AQMHM 2015 Department of Large Animal Sciences Methane Restriction constraints (REDM) Results TAXM Total feed Max. (all cows, all feed) Emission Cost of reducing CH � emission through the diet > tax costs Therefore: CH � No differences in emission between BASEM and TAXM Methane 1 - CH � reduction (%) BASEM emission emission predictions Dias 15 K.N. Dominiak, AQMHM 2015 Department of Large Animal Sciences Department of Large Animal Sciences Shadow prices Results REDM Sensitivity analysis ‘What is the cost of reducing 1 tonne of CH 4 emission?’ Extremely sensitive to feed prices – further analysis required 5% 19,1% 48,5% CH � emission reduced but diet costs increased K.N. Dominiak, AQMHM 2015 K.N. Dominiak, AQMHM 2015 3

9/25/2015 Department of Large Animal Sciences Department of Large Animal Sciences Results – trade offs in diet formulas Results – trade offs in diet formulas Consequences of CH 4 reduction Because forage = NDF (lignin, cellulose, hemicellulose) Feed ME NDF N+min ex And grain/soy = ME (protein, starch, minerals) Corn silage Low High Low Soy silage High Low High Grain High Low High Cereal High Low High Soybean meal High Low High The model results in a trade off between the two types Total reduction in DMI But at what consequences? K.N. Dominiak, AQMHM 2015 K.N. Dominiak, AQMHM 2015 Department of Large Animal Sciences Department of Large Animal Sciences Discussion What about the cow? Consequences of CH 4 reduction Animals vs Human in competition for feed ressources Feed ME NDF N+min ex ‘N + mineral excresions follows same pattern as intake’ Corn Low High Low silage - results in conflicting environmental interests Soy silage High Low High CH 4 vs NO 3 Grain High Low High Should mineral diets be based on excresion levels? Cereal High Low High Soybean High Low High meal Total reduction in DMI K.N. Dominiak, AQMHM 2015 K.N. Dominiak, AQMHM 2015 4