Two contrasting dairy systems were implemented and studied over 8 years at an experimental farm in Western France: one based on grazed grass with 0.4 hectares of grazing area per cow, and one based on stored forages like maize silage with 0.15 hectares of grazing area per cow. The grazed grass system produced slightly more milk per cow, had lower feeding costs, and was more profitable, generating over 50,000 euros more profit within 5 years. Both systems were sustainable with lower nitrogen and carbon balances than regional averages, but the grazed grass system had a smaller environmental impact through lower fossil energy use, less pesticide use, and a higher self-sufficiency in feeding.

1. Technical, economical and environmental performances
of 2 contrasted dairy systems
Valérie Brocard & Sylvain Foray, Idele, France
Elodie Tranvoiz, Solenne Dupré, Guylaine Trou,
Morgane Raison, Pascal le Coeur & Denis Follet,
Agricultural Chamber of Brittany, France

2. Two forage pilars for dairy production in
Western France:
• Winter: maize silage with
protein concentrate +…
• 6-9 months per yr: grazed grass
(+ maize)
• Limited difference in yield
between grass and maize:
Usually less than 2 t DM ha-1

3. Which system is the most sustainable?
3
•If you can choose, is is better to produce milk with maize silage or with
grazed grass?
•And if you lack grazeable area for your cows, can you still make a living with
a "maize" based system AND be "environment friendly" ?
• At Trévarez experimental farm
(Western France),
• 8 years with 2 contrasted systems
run in parallel
Implementation

4. Two systems implemented:
0.15 ha grazable per
cow
60 ha / 59 cows
46% maize in FA
5.4 ha cereals
Definitive allocation of paddocks and cows (batches)
Remained in common: heifers rearing, dry cows, buildings
(allocation of slurry), equipments, staff
Holstein herd
2 calving seasons for calv. interval 12 months
Diet with 95 g PDI per UFL
4 kg production concentrate during
first 120 days of lactation
0.40 ha grazable per
cow
65 ha / 64 cows
28% maize in FA
4.2 ha cereals

5. + milk or + self sufficiency
MS Yield t DM ha-1
% EM in monoculture
% permanent grasslands
11.8
67
20
13.5
12
30
Fat / t Proteins (%)
% culling rate
% in calf within 3 months*
Health troubles cow-1 yr-1
Days without soja per year
Days without maize per year
35
0
4.17 / 3.17
26
88
1.17
4.03 / 3.10
28
83
0.95
135
70
Milk
produced
kg cow-1 y-1
Milk sold
l cow-1 y-1
8,162 7,551 7,608 7,167
* within the AI period
Grazed
grass
Stored
forages
concentrates

6. Environment: two virtuous systems but
advantage to
6
Nitrogen balance kg N ha-1
Potential leaching kg N ha-1
NUE (Nitrogen Use Efficiency) %
GHG emission
Net Carbon Footprint
**CarbonDairy Bretagne 2017 (Idele, 2018)
*Dairy cows systems, Western France, Inosys 2009-13 (excl. organic)
Protein feeding self sufficiency %
Total use of energy (*106 MJ)
g plant health molecules ha-1 yr-1
0.96
0.86
0.94
0.81
1.01**
kg eq CO2 l-1 ECMilk
68
1.74
756
81
1.60
470
111
51
37
88
15
40
103*

7. Profit: + 50,000 € within 5 years for
Milk sold (l yr-1)
Milk price
Feeding cost (cows)
Gross Operating Surplus
(excl. labour)
Profit
€
per
1.000
l
447,898
327.0
79
183
86
465,058
326.3
58
211
110
+ 24 € per 1,000 l
+ 48,000 €
in 5 years
+ 56,250 €
in 5 years
60
cows
400,000 L

8. 8 years to conclude that:
With both systems: N & C balances lower than regional references
for dairy farms, and economically profitable
More milk per cow,
milk solids slighly higher
Less feeding costs,
more profit
whatever the economic
background
• N mineral balance lower, more possibility to store Carbon, less
fossile energy used, less pesticides
• A higher feeding self sufficiency

9. And the winner is :….FORAGE! grazed if possible
• 2 systems with good management
sustainable  thanks to the
FORAGES used
• The most grazing system = the
most profitable.
• If lack of grazable area, it is still
possible to optimize a system with
0.15 ha grazing platform per cow.
Weaknesses: look for solutions.
9
Grouping fields to avoid fragmentation and enlarge grazing platforms =
technical, economical and environmental optimizations.
Monoculture
of maize
Sensitivity to
economic
conditions
Nitrogen
inputs

10. Implementation of a Low Carbon Footprint dairy system at
Trévarez conventional farm in 2019.
Targets:
• Decrease by 20% the farm carbon footprint
• Check adequacy between environmental efficiency, profitability
and workload acceptability of the system
• Test levers to decrease carbon footprint with 3 axes: feeding, herd
management and fields management
What’s next?
10

11. Thanks for your attention. Questions ?
valerie.brocard@idele.fr

12. 0
20000
40000
60000
80000
2014 2015 2016 2017
€
Profit per yr
S1 S2
Whatever the economic context, leads to an
equal or higher profit than
The evolution of ratio milk price / input price impacts the
difference between and
But keeps higher margin and profit: more resilient
150
200
250
300
350
2014 2015 2016 2017
€/1000
l
sold
Margin over feeding cost
S1 S2