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Hassan II Institute of Agronomy and Veterinary Sciences 

Effect of a natural food additive rich in thyme essential oil on methane emissions in dairy cows

Researchers at the Hassan II Institute of Agronomy and Veterinary Sciences (IAV) in Morocco are addressing methane emissions that come from livestock ruminants (cud-chewing animals). To combat methane production from ruminants, IAV researchers conducted a study in animal science to develop mitigation strategies using natural feed additives.

The Study 

A research team evaluated the effect of a natural feed additive rich in thyme essential oil on methane emissions from dairy cows. In order to test the effect of this natural feed additive, researchers provided five Holstein dairy cows with a ration composed of 4 kg of industrial concentrated feed, 2 kg of alfalfa hay, and 2 kg of wheat straw with free access to drinking water. After two weeks of adaptation to the feed without the additive, the team took measurements of the cows’ production of methane. Then, they added 50 g of the thyme essential oil to the cows’ feed. After two weeks of adaptation to the enhanced feed, the team measured the cows’ production of methane. The team then added 100 g of the same product to the cows’ feed and measured the production of methane after two weeks of adaptation.

Table 1: Methane production in the cows during the first period

Cow Weight (Kg) Liter/hour Liter/day Liter/kg DM
A 408.0 8.68 208.3 29.8
B 358.0 8.41 202.0 28.9
C 432.0 8.26 206.8 29.6
D 504.0 7.39 177.4 25.4
E 487.0 7.70 184.8 26.4
Average 437.8 8.16 195.8 28.0
Standard Deviation (SD) 59.4 0.60 13.9 2.0

Table 2: Methane production in the cows during the second period

Cow Weight (Kg) Liter/hour Liter/day Liter/kg DM
A 408.0 6.90 165.6 23.7
B 358.0 7.16 171.9 24.6
C 432.0 6.38 153.2 21.9
D 504.0 6.26 150.3 21.5
E 487.0 5.35 128.3 18.4
Average 437.8 6.41 153.9 22.0
Standard Deviation (SD) 59.0 0.69 16.8 2.4

Table 3: Methane production in the cows during the third period

Cow Weight (Kg) Liter/hour Liter/day Liter/kg DM
A 408.0 5.19 124.8 17.8
B 358.0 6.35 152.2 21.8/td>
C 432.0 6.15 147.7 21.1
D 504.0 4.97 119.3 17.1
E 487.0 5.15 123.6 17.7
Average 437.8 5.56 133.6 19.1
Standard Deviation (SD) 59.3 0.63 15.3 2.2

Results 

Based on the measurements, the researchers estimated that the quantity of methane produced by the five cows on the standard diet was an average of 195.9 liters of methane per day. When 50 g of the additive was incorporated into the feed, the cows produced an estimated average of 21.6 percent less methane emissions than without the additive. When 100 g of the additive was incorporated into the feed, the cows produced an estimated average of 31.8 percent less methane emissions than without the additive.

Download the paper here.

Figure 1. Dairy cows