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Milk carbon footprint on grazing dairy farms
8
Milk production systems in Uruguay
Model description
GHG associated with
dairy system
Statistical analysis
Variables with highest correlations with CF were:
milk production per ha ( r = - 0,78)
milk yield per cow ( r = - 0,81)
concentrate fed per cow ( r = - 0,71)
dry matter intake per cow ( r = - 0,69)
Cluster 1: low herd milk production due to a low milk yield per cow as well as a low stocking rate and low herd efficiency. The low milk yield per cow was due to a low dry matter inake per cow. As a result, high milk CF
Cluster 3: high milk prodcution due to a high milk yield per cow and high stocking rate. Herd efficiency was high as well. These farms used feed management practices with a higher forage intake per cow and a high proportion of concentrate in diets, resulting in the lowest milk CF.
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Method
Data:
Data collected from 24 actual dairy farms located in SW Uruguay
Farms were not randomly selected, quality data were a criterion for inclusion
Information was collected through a semi structured questionnaire and interviews with references
Methane: enteric fermentation
Methane: manure
Nitrous oxide: soil
We assumed that 10% of orine and dung was excreted at the milking shed and that all farms had uncovered anaerobic lagoon system,
average daily feed intake expressed as gross enegy intake (pastures + concentrate) multiplied by the methane conversion factor fro IPCC (2006) and Dini(2012): Ym=6.5 %
Other emissions...
We also considered emissions from diesel, electricity,
extraction of raw materials/manufacture/transport
(fertilizers and pesticides)
Milk carbon footprint
La HC se expresa por litro de leche corregido
(grasa y proteína) cuantificando todas las entradas
y salidas de las emisiones de GEI y convirtiendo
las mismas en CO2 equivalente
In fact, most of the farms had that system
Direct emissions of N2O from the soil and stored manure were also estimated following IPCC guidelines (2006b)
synthetic N fertilizer: 0.01 kg N20-N per kg N applied
N excreted: 0.02 kg N20-N per kg N excreted
N excresions = total N feed intake – N in milk and retained in animals
Model used to quantify milk CF
Feed supply
Feed requirements of all animals were
calculated using the AFRC system
(AFRC,1993)
Define a pasture-crop rotation and production
Define concentrate consumption
Estimate pasture production from the difference
of herd requirements and concentrate consumption
Inputs:
milk production
different herd categories
live weight
pregnacy status
Dairy system model
(Comisión InterCREA de Producción Intensiva de Leche, 2004)
The milk CF for each dairy farm was determined using a software tool called CIPIL
The model used an excel spreadsheet format to simulate biological, physical and environmental processes of a dairy farm over a 12 month period.
The model integrates integrates animal and forage production activities linked and bounded by different contrainsts
Statistical analysis
correlation analysis between CF and 10 possible explanatory variables
simple regression analysis
multivariate analysis: principal components analysis (PCA)
and cluster analysis
INFOSTAT software (2012)
Functional unit and system boundaries
System boundaries: cradle to farm-gate
We followed the methodology of the International Dairy Federation (IDF, 2010)
Funcional unit: 1 kg fat (4%) and protein (3,3%) corrected milk
Allocation between milk and meat was done using the biological method
Results and discusion
Objective
Multivariate analysis
Cluster analysis
2 B
Multivariate analysis
Grupo 3
Principal components analysis
Grupo 2
2 A
Grupo 2
Cluster analysis
Grupo 1
A cluster analysis was used to study the distribution of farms when placed into homogenous groups
We used the same 8 variables that we used in the PCA:
milk production per ha
milk production per cow
stocking rate
herd efficiency
concentrate per cow
dry matter intake per cow
N excreted per ha
Milk CF
Relationship between CF and milk production per ha
Some management variables were strongly correlated with one another, which made interpretation of relationships between individual variables and CF difficult.
PCA allowed the transformation of a set of correlated explanatory variables to new variables, the so-called
principal components
Improving milk production decreases CF if this production is associated with high yielding cows with
greater feed efficiency.
8 variables explained 85.6% of the total variance in the data set
1,09
0,96
0,92
Relationship between CF and milk yield per cow
Milk CF for each cluster of farms broken
by source emissions (%)
1,09
0,96
0,92
Results were similiar to studies from Heriksson et al. 2011, Iribarren et al. 2011, Lovett et al. 2006, Casey y Holden 2005
The exponential decline is a result of fewer cows being maintained to produce a given amount of milk, so maintaing more animals per unit of milk produced increases the CF
Enteric fermentation produced the greatest contribution
Soil carbon sequestration
Simulation of the inclusion of C sequestration to the average results from:
Díaz y Durán, 2011
Relationship betweeen CF and milk yield per cow
Correlation analysis
With these variables we did regression analysis
Characteristics of the dairy farms
Internacional studies on pastures systems:
(otro FE y asig.)
New Zealand (Flysjo et al., 2011): 1,0 CO2 eq/ kg LCGP
New Zealand (Basset- Mens et al., 2009): 0,93 kg CO2 eq/ LCGP
Irland (Lovett et al., 2006): 1,0 a 1,2 kg CO2 eq/ kg LCGP
Irland (Casey y Holden, 2005): 0,92 a 1,51 kg CO2 eq/ kg LCGP
Spain (Hospido et al., 2003): 0,84 kg CO2 eq/ kg LCGP
Uruguay sin asig. 1,14
Objective
Estimate the milk carbon footprint produced on 24 uruguayan dairy
farms and to evaluate the impact of management practices on this
footprint using multivariate analysis
Conclusiones
Practices to reduce milk carbon footprint on grazing dairy farms in southern Uruguay: case studies
Introduction
The variation in production data found among the studied dairy farms
suggested that the CF of uruguayan milk production varies by at least
+/- 10%.
Farms with more efficient production in terms of greater milk yield
and a greater ratio of milking cows to total stock provided a low
milk CF.
Lower CF was also associated with higher feed dry matter intake
per cow using and appropiate mixture of pasture and concentrate
feeds
huella de carbono:
Emisiones de GEI que se producen durante toda la vida de un producto o servicio desde la extracción de la materia prima y la manufactura para su uso, utilización final, reciclado o disposición final
Países desarrollados
(Anexo I P. Kyoto)
realizan campañas
conscientizando a sus
consumidores sobre CC
A su vez estos son
los países donde Uruguay
coloca productos como
carne y leche.
The CF from agriculture products
Food miles (´90)
Environmental competitiveness
Livestock's Long Shadow
(Steinfeld et al. 2006)
estimates that livestock are responsible
for 18 percent of greenhouse gas
emissions
A survey done to consumers from TESCO supermarket (2008):
Surge preocupación en consumidores de países
industrializados (firmantes de Anexo I, P. Kyoto)
por conocer las emisiones de GEI producidas por
los alimentos
inicialmente impulsado
en el Reino Unido
sustitución de food miles
por huella de carbono
Huella de carbono
Kyoto Protocol (1997)
places a heavier burden
on developed nations
under the principle of
common but differentiated responsabilities
emisiones de GEI que se producen durante toda la vida de un producto o servicio, desde la extracción de materia bruta, manufactura, utilización, reciclado o disposición final
(Carbon Trust, 2013)
forma parte ACV
antes de esto una introduccion de los factores de variacion en la HC
La HC de la leche según características
de los sistemas productivos
Todos estos trabajos resaltan la
importancia de realizar un análisis de tipo global para poder realizar comparaciones entre sistemas productivos y entre países.
Relación entre productividad por ha
y la huella de carbono para 10 predios lecheros
Casey y Holden, 2005
Relación entre la productividad por vaca y la huella de carbono
para 10 predios lecheros
Casey y Holden, 2005
Estrategias de mitigación de GEI en sistemas pastoriles
a mismo tipo de sistema hay disminución de la HC solo por ajustar la eficiencia biológica del rodeo o la calidad de la comida
Beukes et al. 2010
Estudio comparativo
Rotz et al. 2009
Pastoril vs confinado
Flysjo et al, 2011
En el sistema confinado pesan las emisiones
asociadas al alimento y al manejo del estiércol
Flysjo et al. 2011
Sistema confinado vs pastoril
Pastoril vs Confinado
Los resultados de estos dos trabajos
muestran que la huella de carbono de la
leche a nivel de predio es menor
en países desarrollados en comparación
a países en desarrollo.
Las diferencias se deben en gran medida al nivel de intensificación
( leche por vaca y por ha)
Relación entre la productividad de leche
por ha y la HC para distintos países
Hagemann et al. 2011
Relación entre la producción de leche por
vaca masa y la HC para distintos países
Hagemann et al. 2011
Hagemann et al (2011), para distintos países
alrededor del mundo, muestra variaciones
muy importantes según los sistemas de
producción y los recursos disponibles en
distintas regiones del mundo
El sector global lechero contribuye
un 4% a las emisiones globales totales
de gases efecto invernadero
Variaciones regionales de HC están
explicadas principalmente por las
diferencias en los sistemas productivos
FAO, 2010
¿Distintos sistemas productivos (pastoril vs confinado) presentan HC de la leche contrastantes?
Uruguay situation
Uruguay: is a non- anex I country in the Kyoto Protocol
with no legally binding targets, but....
large amounts of commodities
are exported and there is a
current international concern
of consumers for product´s CF
In Uruguay agriculture contributes about 80% of the total GHG emissions
In the last decade the uruguayan milk production has increased 4 % per year
MGAP,2012
92% of national methane emissions are produced by the agriculture sector, enteric fermentation is responsible for 87% of the emissiones
Diario El País, 17/06/13
METANO
DIEA, 2012
The increase is explained by intensification (milk/cow)
99% of nitrous oxide comes from agriculture sector, 61% of the emissions are from cattle
OXIDO NITROSO
MVOTMA, 2010
Most of dairy farms in Uruguay are located in the SW
Diferencias en metodologías
70% of dairy producs are
exported
DIEA, 2012
En el 2010 se edita una guía de cálculo de la HC, ésta es internacionalmente aceptada (IDF, 2010)
Las publicaciones anteriores al 2010 difieren entre sí en aspectos metodológicos como:
límites del sistemas
unidad funcional
factores de emisión
asignación de co-productos
Por lo cual, los HC de distintos países/publicaciones no son comparables para un mismo producto