Livestock account for up to 35-40% of world methane production. Around 80% of this comes from fermentation in the digestive tracts of animals, especially ruminants, and around 20% from anaerobic digestion in liquid manure. There are essentially three routes through which genetic improvement of livestock can help to reduce emissions per unit of product, per head and/or at a national level: 1) as a result of improved productivity and efficiency at the individual animal or herd/flock level; 2) as a result of reducing ‘wastage’ (including infertility, disease and mortality) at the animal, or herd/flock level; and 3) as a response to direct selection on emissions, if or when these are measurable. This project will, through analytical reviews and modelling, help to define the relative contributions that these routes can make to reducing emissions. The effect of current genetic tools on reduction in emissions will be compared with advances that can be achieved by utilising emerging molecular genetic technologies. The project will also consider logistical and economic aspects of implementing the technology in UK sheep and beef breeding.
For 25 years there has been much promise of new techniques from molecular biology that will accelerate genetic improvement of livestock. In practice, there are still relatively few DNA-based tests in widespread use. A fundamental problem is that most traits of interest in livestock breeding are thought to be influenced by hundreds of genes, most with a small effect, so it is difficult to identify them. This requires a new approach, such as that underlying ‘genome-wide selection’ (GWS). There is significant and increasing global interest in the potential value of this new approach, and it could lead to dramatic future changes in breeding programme design in several species. GWS is becoming feasible as a result of the availability of dense single nucleotide polymorphism (SNP) maps (maps identifying tens of thousands of sites throughout the genomes of farm livestock where there is variability in the DNA bases present in different animals) and the falling costs of genotyping large numbers of markers.
There are two steps involved in GWS. In the first step, the effects of the markers are estimated in a ‘reference’ population where the individuals are genotyped and accurately measured for the traits of interest. In the second step, these estimates of marker effects are used to obtain an estimate of the genetic merit of other animals, of any age, that are only genotyped, but not measured. Results from theoretical and limited experimental studies suggest that GWS has the potential to substantially acceleraterate the rate of genetic improvement of farm livestock. It is expected to be particularly valuable for traits that are difficult to improve via traditional selection (e.g., disease resistance, efficiency, environmental impact, and product quality).
This project will investigate the scope for accelerating genetic improvement of traits associated with sustainability in ruminant livestock - traits associated with improving economic performance, animal health and welfare, and environmental impact - in this case, especially greenhouse gas emissions. In particular, the project will investigate, through desk-based and computer simulation studies, the potential added value of GWS.
It is vital that there is effective dialogue between those with public and private interests in livestock breeding if policy makers are to have influence in industry, and breeders are to respond to policy signals. The creation of a Ruminant Genetic Improvement Network (GIN) - a forum connecting key stakeholders with private and public interests in ruminant livestock breeding - could be one way of promoting such a dialogue. This project will identify the scope of a potential Ruminant GIN, including potential functions, priority areas of activity and membership.