Florencia Garcia
What is the effect of inhibiting methane production
in the rumen on nitrogen use efficiency?

Purpose of research
C
H
H
H
H
↑ H2
↑ NADH/NAD+ ratio
• Rumen is an anaerobic environment
NADH ↔ NAD+ + H+
• Methane → Main electron sink in rumen
CO2 + 4 [2H] ↔ CH4 + 2 H2O
…What happens with other metabolic pathways when the hydrogen
dynamic has change because of methane inhibition?

Purpose of research
Aim
To understand how inhibiting methane production in the rumen affects
microbial protein production, and its implications to the efficiency of
nitrogen utilization of dairy cows.
Hypothesis
The inhibition of methane production results in a greater abundance of
reducing equivalents that will stimulate an increase in microbial protein
production in the rumen, improving nitrogen use efficiency.
Implication
This research focused on understanding the interface between energy
and N metabolism in the rumen as part of the interaction between
fermentation and anabolism.

Measurement
6 d
Measurement
6 d
Adaptation
Diet + Placebo - 21 d
Research methods
• Place: Unit of Digestion and Metabolism
• 4 Treatments: Methanogenesis inhibition x Protein source
• Animals: 8 rumen cannulated lactating cows in early lactation
• Diet: Grass silage, corn flakes, rapeseed meal (RM), mineral and vitamin
premix and (urea)
• Experimental design:
2º Period
Methanogenesis-inhibition
Adaptation
Inhibitor - 10 d
Yes No Plant Inorganic
1º Period
Control4 cows
RM only
4 Cows
Urea + RM

Research methods
Variables evaluated:
• Microbial nitrogen production: 15N enrichment - Purine
derivatives - In situ incubations
• Methane: SF6 technique
• Rumen environment: VFA, ammonium, pH, Eh, microbial long-
chain fatty acids and microbial community composition
• Animal performance: Production and composition of milk, ∆
weight, ∆ body condition
• Others: DMI, nutrient digestibility, metabolizable energy, nitrogen
balance, blood metabolites

Take-away message
Methane:
• Plays a biological role in the rumen
• Hydrogen dynamic
Long chain
fatty acids
VFA
Microbial
mass
Hydrogen
Methane
… What are the implications of its inhibition?
… What other processes may be affected?

Other metabolic processes that occur
in the rumen…??

Advice to future CLIFF-GRADS students
• It was enriching to have a deep knowledge of the hypothesis and the work
proposal before my arrival →This allowed me to discuss in deep the
conceptual framework of the experiment, the methodology and to take full
advantage of my time
• It was an opportunity to interact with other researchers → Networking
Take time to meet people, places, different costumes
…every moment is a chance of doing something new