Breeding low-emitting sheep
New Zealand sheep breeders can now measure their sheep and rank them for breeding based on methane emissions, thanks to research funded by the NZAGRC and the PGgRc.
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Research into the potential to breed for low methane-emitting traits in sheep has been underway in New Zealand since 2007, initially funded by PGgRc and MPI’s Sustainable Land Management and Climate Change (SLMACC) fund. This work established that some sheep naturally emit less methane per kilogram of food eaten than others. The research found that this variation is statistically significant. Subsequent NZAGRC funding has enabled low-emitting animals to be genotyped for markers that identify the low-emission trait.
In 2012, flocks of low- and high-emitting sheep were established by measuring the methane emissions and daily feed intakes of over 1,300 animals. Since then, NZAGRC research has confirmed a genetic basis for the variation in methane emissions between animals, meaning the reduced-emission trait is passed on from generation to generation. Two additional generations have subsequently been bred from these flocks and the low and high-emitting sheep are now estimated to differ on average by around 16% since selection started in 2008. Ongoing NZAGRC funding ensures that these flocks are maintained over time.
The sheep breeding programme is unique in the world and, in 2019, research breeding values for low methane emissions were made available to selected ram breeders through Beef + Lamb Genetics. This is a major step forward, with researchers predicting that a 1% decrease in methane emissions per year is achievable. At the farm level, Portable Accumulation Chambers (PAC) are a simple, low-cost tool that breeders can use to measure methane in their own sheep to identify low emitters for breeding.
Researchers have monitored the animals for growth, reproduction and other performance parameters and have observed interesting physiological changes such as smaller rumens, smaller and more frequent feeding patterns and an increase in lean muscle tissue with a greater content of branched chain fatty acids.
There is no evidence that important production traits, such as growth rates, wool production and disease resistance, are compromised in the low-emitting line. In fact, preliminary economic analysis shows that low-emitting sheep could lead to higher profits, primarily due to higher growth rates, a greater proportion of meat, and increased wool production.
Research using the selection lines is ongoing and continues to yield positive results for the low-emitting line in terms of animal physiology, productivity and health. The resulting dataset is one of the most comprehensive in the world and provides a unique resource to study the associations between rumen microbial composition, methane emissions, circulating volatile fatty acids in the blood and detailed fatty acid profiles in milk.
Learnings from this research are now being applied to other ruminant livestock systems, including dairy cattle.