In his doctoral work, Hendra Nur Cahyo has investigated how biological differences between cows and different feeding strategies affect methane emissions.
When dairy cows digest the feed, they produce methane, a powerful greenhouse gas responsible for around 30 percent of global warming. Livestock production is an important source of greenhouse gas emissions from agriculture.
In his research, Cahyo found that individual differences between cows are of great importance. Cows that emit less methane per unit of feed at the start of lactation were found to have weaker immune systems and lower feed utilisation.
On the other hand, he discovered that cows that produce less methane per litre of milk had better energy use. This suggests that these cows are more efficient in converting energy from their feed into milk.
"This shows the complex relationship between methane emissions and the biology of cows," says Cahyo.
In addition to individual biological differences, diet has a major impact on methane emissions. And feeding strategies appear to be promising for reducing methane emissions.
Hendra discovered in a meta-analysis of literature data that adding fat to the feed can reduce methane emissions. Medium-chain fatty acids in particular had a marked effect, especially when the cows were fed a diet with starch-rich and low-fibre feed.
"Even small amounts of fat in the diet can have a major effect on methane emissions, but the effect decreases when the amount of fat becomes too high," Cahyo explains.
Cahyo also investigated the use of grape marc (a tannin-rich by-product of wine/juice production) as an additive in the feed. This significantly reduced methane emissions without negatively impacting feed intake and milk production. The disadvantage he discovered was that the digestion of nutrients was impaired.
Sustainable development on biology's terms
"Livestock production must become more sustainable, and we must develop solutions that both reduce climate impact and maintain productivity in dairy production. It requires that we understand how the cows' biology and diet affect methane production," says Cahyo.
Hendra Nur Cahyo is 30 years old and from Wonosobo, Central Java, Indonesia. He previously holds a Master's degree in Agricultural Sciences and Resource Management in the Tropics and Subtropics, University of Bonn, Germany.
On 24 November, he defends his doctoral thesis " Enteric methane emission fromdairy cows: Comparison of low and high methane emittersand the effects of dietary manipulation ". The main supervisor has been Prof. Angela Schwarm, PhD. Co-supervisors: Prof. Phillip B. Pope, PhD; Prof. Bjørg Heringstad, PhD; Prof. Ulrike Gimsa, PhD; Velma Tea Essi Aho, PhD.