Future-proofing our breeding goals - Breeding for climate resilience in UK dairy systems

Our climate is changing, and we can expect to see increases in temperature and the frequency of extreme weather events, such as heat waves, flooding and drought, over the coming century. Previous work on the effects of weather on livestock has focused on animals' responses to heat stress. Dairy cows produce less milk under high temperatures and humidities and the quality of their milk is reduced. In addition, heat stress can interfere with cows' abilities to conceive and can increase susceptibility to disease and early mortality. Our preliminary analyses show that dairy cows are not only affected by heat stress under current UK weather conditions but also by a range of other weather elements, such as precipitation, wind speed and solar radiation, sometimes even while they are housed. Further preliminary work estimated the cost of the UK's future climate (2050-2080, UKCP09) on the UK dairy industry at up to £80 million/yr in net present terms based on lost milk production and female fertility and increased mortality. The need to address production losses will become increasingly important as the global population continues to grow.

For many decades, agriculture has benefited from knowledge of the genetic quality of livestock, whereby genes associated with high productivity are identified, and animals with those genes are selected for breeding. Livestock breeding is a globalised industry controlled by multinational companies that disseminate semen (and therefore genetic improvements) across continents. Breeding plans have traditionally focused on improving productivity without attention to other characteristics, such as the ability of animals to cope with heat stress. High producing dairy cattle are usually poor at tolerating heat, especially those bred for temperate climates. Furthermore, dairy cattle are becoming more sensitive to heat stress as the pressure to produce more milk from fewer animals rises. The health and performance of high yielding cows can only be maintained if they receive an adequate intake of feed and water. However, little is known about how unfavourable weather conditions and extreme events will affect their requirements for nutrients and water. For example, cows might change the overall quantities of food and water they consume, and also aspects of feeding and drinking behaviour. An understanding of animal requirements for water under increasing temperatures will be a key component of efficient water management, especially given that water shortages are predicted to become more frequent over the next century.

Here we aim to identify the characteristics that indicate how well dairy cows cope with the challenges of a changing climate, along with the genes that control the various aspects of this ability. We will also assess the economic costs and benefits of breeding for cows with an improved tolerance to unfavourable weather to ensure that our findings can be applied in a cost-effective way . Our team at SRUC consists of experts in livestock genetics, climate change, animal behaviour and environmental economics with a strong track record of successful projects. We will work closely with established contacts within the dairy industry (e.g. Genus) to ensure that the knowledge generated from this project is of practical value to farmers in helping them to maintain or improve livestock productivity, health and welfare, and thus farm profitability. This work will provide clear benefits to the farming community, the broader UK dairy industry and consumers, helping to maintain productivity through sustainable, socially-acceptable means in the face of climate and food security risks.

Climate change will impact livestock directly through increases in heat stress and the frequency of extreme weather events (e.g. drought). In dairy cows, heat stress can reduce milk yield and quality, and fertility, and increase susceptibility to disease. Our preliminary analyses show that cows are not only affected by heat stress under current UK conditions but also by a range of other weather elements, such as precipitation, wind speed and solar radiation. Here we aim to develop tools that will increase the capacity of dairy cows to maintain productivity and fitness in the face of stresses associated with climate change. We will thus:
1. Quantify the effects of weather and extreme events on a range of phenotypic traits (e.g. milk yield, health, survival, fertility) on a local (research farm: >25 years of fine-scale data) and national (UK-wide, commercial) scale using UK Met Office data.
2. Evaluate the potential for novel phenotypes (e.g. feeding/drinking patterns, mid-infrared (MIR) spectral measurements of milk) to be used as indicators of climate resilience.
3. Estimate genetic parameters for climate resilience to assess the potential to breed for it, and conduct a genome wide association scan (GWAS) for the resilience traits.
4. Perform cost-benefit and quantitate risk analyses for climate resilience to select breeding strategies that are cost-effective, socially acceptable and policy-relevant, resulting in a prototype 'Climate Smart' breeding programme.
The project team consists of experts in livestock genetics, climate change and environmental economics with a strong track record of successful projects. We will work closely with dairy industry contacts to ensure that this knowledge is of practical value to farmers. In helping to maintain productivity, animal health and welfare through sustainable means in the face of climate and food security risks, the project will benefit the farming community, the broader UK dairy industry and consumers.

The sustainability of the UK dairy industry hinges on the ability of farmers to respond to key challenges, such as those arising from climate change and extreme weather events. This project aims to characterise the phenotypic and genetic traits that enable dairy cows to cope with weather-related stresses. By combining animal science and environmental economics, it offers an innovative approach to equipping the UK dairy industry with the tools necessary to breed more resilient animals in a sustainable and profitable manner. We will work closely with contacts within the dairy industry to ensure that this project is of practical value to farmers. The PI has previously worked with the dairy industry to successfully deliver genetic improvement tools to dairy farmers to enhance animal fertility, health, welfare and survival. These tools have helped UK dairy producers become more sustainable by adapting to a range of challenges. Adoption of new indices have improved animal health and profitability compared to continued use of previous selection practices, and have cumulatively reduced greenhouse gas emissions per breeding cow per year by 1.4% (reduction in CO2 equivalents). The overall economic benefits of the genetic improvement that took place in the years 1980-2009 is worth £105.7 million/year to the UK dairy industry. A large proportion (~50%) has been realised by including health, fertility and longevity traits in UK dairy breeding goals.

Our project is expected to benefit the scientific community, the farming community, the broader UK dairy industry, consumers and public policy.

DAIRY FARMERS AND INDUSTRY
1. Better understanding of the response of animals to extreme weather events and the genetic basis of resilience,
2. Novel indicators of climate resilience (e.g. mid-infrared spectral measurements from milk),
3. Calibration of breeding goals to future climates, including prototype Climate Smart breeding goal geared to a temperate climate. Such a tool can be implemented into dairy breeding programmes (e.g. Genus' Genetic Management System offers customised programmes based on farmers' individual breeding goals - letter of support). Incorporating resilience traits into these programmes would minimise economic loss due to climate change balancing farmer profitability and sustainability.
4. Improved farm management strategies. For example, a better understanding of changes in water intake patterns by cattle under different weather conditions will be particularly important given predictions for increases in drought intensity and spatial extent.

CONSUMERS AND POLICY
5. Improved farm welfare from minimising weather-related stress. This should improve consumer image
6. Projections for future dairy performance. These will help us to predict cost of climate change to the UK dairy industry and identify geographic regions where productivity will decline or increase over the next decades. Such projections could help the UK prepare for potential changes in productivity and economic viability in different regions. In addition, the project will quantify the economic costs and benefits of resilience to climate, which will be an important tool for informing policy.

SCIENTIFIC DEVELOPMENT
7. Training for two postdoctoral researchers in interdisciplinary approaches to addressing societal challenges
8. Collaboration with INIA, Spain will enable methods to be shared to provide broader knowledge on genetics of thermal stress in cattle

All members of society who work to improve or depend upon the competitiveness and sustainability of agriculture will benefit from the downstream applications. The application of the research by breeding companies will lead to faster and more sustainable genetic progress, producing food that is more resource-efficient and affordable. Increased efficiencies in agriculture have direct societal benefits in greater food security with less environmental impact.