29-09-2014 A linear programming model to optimize diets in environmental policy scenarios Paper by: L.E. Moraes, J.E. Wilen, P.H. Robinson, J.G Fadel (2012) Presented by: Dan Jensen Introduction • Problem: (Dairy)-farming is messy! • Agriculture: 6.3 % total US GHG emissions (2009) • Enteric fermentation ( �� � ): 20 % of US human GHG • Also nitrogen, phosphor, etc. • Goal: Tool for optimizing dairy cattle diet • Effect of emission taxes • Forced (assumed) reduction • Status of this research: Preliminary! • Sensitive to constraints. E.g. feed prices Advanced Quantitative Methods in Herd Management Dias 2 – 29/09 2014 Methods General Background • Linear Programming Model (LPM) • Reminder - an LPM is: • Method to achieve best outcome given certain constraints • Constraints are represented by linear relationships Advanced Quantitative Methods in Herd Management Dias 3 – 29/09 2014 1
29-09-2014 Methods The models • Three scenarios – three models: • BASEM: Cheapest possible feed (baseline) • TAXM: what if there was an emission tax? • … of 5 $ per tonne? • … of 17 $ per tonne? • … of 250 $ per tonne? • REDM: what if you were forced to reduce emissions? Advanced Quantitative Methods in Herd Management Dias 4 – 29/09 2014 Methods The models, Assumptions 1 � � − � � Advanced Quantitative Methods in Herd Management Dias 5 – 29/09 2014 Methods The models, Assumptions 2 � � − � �� � � − � �� � � − � �� kg/kg DM $/kg DM Locally collected Advanced Quantitative Methods in Herd Management Dias 6 – 29/09 2014 2
29-09-2014 Methods The models, Assumptions 2.1 Advanced Quantitative Methods in Herd Management Dias 7 – 29/09 2014 Methods The models, specifics • BASEM/REDM: Remember: j = feed c = cost of feed Advanced Quantitative Methods in Herd Management Dias 8 – 29/09 2014 Methods The models, specifics • TAXM: Remember: j = feed c = cost of feed �� � Notice: e = expected emission (tonnes) �� � p = tax price per tonne Advanced Quantitative Methods in Herd Management Dias 9 – 29/09 2014 3
29-09-2014 Methods The models, Outputs • How big is the mess? 55.65 MJ/kg Feed composition – absorbstion � Excrete composition Advanced Quantitative Methods in Herd Management Dias 10 – 29/09 2014 5 minute break Methods The models, Constraints 1 Other Limits, 1 Diet. Feet Limits Nutrient req . DMI Diet. Barley Limits Other Limits, 2 Diet. Forage Proportions Methane Restrictions Advanced Quantitative Methods in Herd Management Dias 12 – 29/09 2014 4
29-09-2014 Methods The models, Constraints 2 7 x 14 = 98 eq. Nutrient req . Amount Requirement Nutrient content Remember: j = feed a = cow category (7 kinds) i = nutrient (14 kinds) Advanced Quantitative Methods in Herd Management Dias 13 – 29/09 2014 Methods The models, Constraints 3 Diet. Feed Limits 7 x 10 = 70 eq. �� � �� ≤ � �� ∙ � � �� ��� Remember: j = feed a = cow category (7 kinds) l = limit (for 10 kinds of j ) Advanced Quantitative Methods in Herd Management Dias 14 – 29/09 2014 Methods The models, Constraints 4 Methane Restrictions (REDM) Total feed Max. (all cows, all feed) Emission 1-Reduction Methane predictions BASEM emission Advanced Quantitative Methods in Herd Management Dias 15 – 29/09 2014 5
29-09-2014 Results • REDM: ↓ �� � → ↓ ���� ! ∴ ↓ �� � → ↑ $�%�! Advanced Quantitative Methods in Herd Management Dias 16 – 29/09 2014 Results Crude protein consumption • REDM: Metabolisable energy given Methane reduction proportion given Methane For the 7 kinds of cows reduction Advanced Quantitative Methods in Herd Management Dias 17 – 29/09 2014 Results • REDM: Consumption Excretion Advanced Quantitative Methods in Herd Management Dias 18 – 29/09 2014 6
29-09-2014 Results • Shadow prices, Feed stuff: �%&!� �'( )��*!%' )�%�!+: -.)��*!'* /�� �-0� �!(1�*%�'+ Advanced Quantitative Methods in Herd Management Dias 19 – 29/09 2014 Results • Shadow prices, Methane emissions: Advanced Quantitative Methods in Herd Management Dias 20 – 29/09 2014 Conclusions • Cost of low emission diet exceeds cost of taxes � TAXM ~ BASEM • Reduction of �� � emissions yields increase in Nitrogen-excretion • Further studies are needed! Advanced Quantitative Methods in Herd Management Dias 21 – 29/09 2014 7
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