According to a recent study, “The impact of crossbreeding and feed efficiency on methane emission”, led by SimHerd, crossbred cows can reduce methane gas emissions by up to 6% compared to pure Holstein cows.
This article was published in the VikingGenetics magazine – Innovative breeding, no.1 2021.
“The primary reason is that crossbred cows live longer, so you don’t need as many replacement animals, resulting in a smaller youngstock herd. When you have fewer animals, you lower methane emissions at herd level. The reason why crossbred cows live longer is that they are more robust, healthier, and are more fertile; thus, there is no need to replace them as quickly as the pure Holstein cows”.
The study was conducted using the simulation model, SimHerd, and is part of the DairyCross project, founded by Green Innovation and Demonstration Foundation in Denmark, in which other key institutions are also participating.
Ruth Davis Kring, Consultant at SimHerd, explains that in the simulation model they have plenty of different specifications to measure heterosis and breed differences.
“All those parameters were put into the model so that when we run it the model can predict what the effect would be in the herd going from a pure breed Holstein to a crossbred herd with given breed combinations. Some of those effects may be related to methane emissions. The main driver of the decrease in methane is the reduction of youngstock”
Different crossbreeding strategies
A case herd was modeled in the study, with 200 purebred Holstein cows. The replacement rate for pure Holstein was 40.7%, for the different crossbreeding strategies, this was reduced to -6.3% for the two-way cross with RDM, -7.7% for the breeds under the ProCROSS concept, and -7.8% for the breeds marketed as VikingGoldenCross. Davis is convinced of crossbreeding’s ability to reduce methane gas emissions at the farm level.
“It can be part of the solution to face climate change and global warming challenges”,
The amount of methane per kg ECM is lower for both the two-way and three-way crosses, 4.2%,4.7%, and 6.6 % respectively. This is due to more healthy animals which live longer, and because fewer replacement heifers are required.