Project Lead
Challenges
Large advances in animal and forage genetics, as well as changes in feeding systems, over many decades have driven the profitability of dairy farming. Increased productivity is linked to improved cow health and fertility. The global climate emergency and biodiversity crises, recognised by the Scottish Government, mean that future developments must prioritise the environmental effects of dairying, as well as resilience to climate change. This requires a matching of cow genetics and systems, as well as refinement of management within systems.
Larger herds, increased stocking rates and the nutrient requirements of high-producing cows can have negative effects on the environment and biodiversity, as well as greater susceptibility to the effects of climate change. It is not expected that climate change will have many direct effects (for example, heat stress) in Scotland, but we anticipate effects on feed supply and quality, particularly when targeting increased forage utilisation. Climate change will likely affect key components, the metabolizable energy (ME) and metabolised protein (MP) supply and the fermentation quality of forages affecting dried matter intakes.
Studies over five years at the University of Reading showed considerable temporal variation in the protein content of diet components, whilst a preliminary United States study suggested that oscillation in dietary protein is tolerated short-term. However, there is no information about responses to temporal variation in other feed components, or on longer time scales. We need to optimise genetics and feeding systems for productivity, efficiency, and climate resilience and investigate the inter-relationships between productivity, resource-use efficiency, climate resilience and effects on carbon footprints.
Questions
- How can we protect genetic diversity in livestock whilst promoting wider biodiversity in agriculture?
Solutions
The overall aim of this project is to design, develop and evaluate alternative breeding strategies for genetic improvement and monitoring of genetic diversity. We are identifying optimal strategies that enhance animal resilience and adaptability, reduce methane emissions, and continue to improve key animal functions associated with disease resistance, fertility, and productivity, while at the same time preserving and enriching genetic diversity. The outcomes are informing future breeding programmes to underpin the environmental and productive efficiency of livestock farming while protecting biodiversity.
Strategies to reduce carbon footprint and increase climate resilience
To do this, we are incorporating strategies to reduce carbon footprint and increase climate resilience into the feeding systems for cows at the Langhill Breeding Study – the longest-running genetic selection trial worldwide - to quantify effects on overall performance. These strategies include the use of mixtures of forages, increased use of forage and grain legumes to reduce nitrogen fertiliser use, and formulation of concentrates using carbon footprints that include embedded emissions. These principles are being applied within ‘high forage’ and ‘high concentrate’ strategies and with cows of average and very high genetic potential for milk production, thereby representing most Scottish dairy farms.
Developing metrics to describe ‘feed variation’ for home-produced forages
We are also developing metrics to use data recorded within the Langhill database and wider feed analysis records to describe ‘feed variation’ for home-produced forages. Other farmers in the region are developing cross-bred lines designed for extensive grazing systems. We are using historical and current recordings from the Langhill study, as well as these comparator herds, to describe feed variability for different systems.
Evaluating the effects of feed variability on performance
This project is evaluating the effects of feed variability on the performance of different genotypes and system combinations. To do this, we are using historical data in this analysis, as well as recording the effects of transitioning these diets to take account of climate resilience and carbon footprints across 2022-2027.
Exploring feed variability and the variability in the performance of individual cows
We are exploring the relationships between feed variability and variability in the performance of individual cows to enhance animal resilience. We are focusing on Holsteins cows and exploring resilience associated with crossbreeding in the comparator herds. We are estimating the heritability and genetic correlation with other traits and compared with earlier results. Genomic markers and regions affecting animal resilience and adaptability are being identified and characterised.
Evaluating alternative breeding strategies for genetic improvement and monitoring of genetic diversity
Results from the previous steps are being collectively considered as input into simulation studies aiming to design, develop and evaluate alternative breeding strategies for genetic improvement and monitoring of genetic diversity. Optimal strategies are being identified that enhance animal resilience and adaptability, reduce methane emissions, and continue to improve key animal functions associated with disease resistance, fertility, and productivity, while at the same time preserving and enriching genetic diversity. Thus, outcomes are informing future breeding programmes to underpin the environmental and productive efficiency of livestock farming, while protecting biodiversity.
Project Partners
Progress
Objective 1: Evaluate the effects on overall cow performance of feeding strategies designed to reduce carbon footprint and increase sward biodiversity and climate change resilience
Working with the existing 2 x 2 Langhill study (i.e., two genetic lines selected for milk solids output x two diets with divergent concentrate levels), we have implemented plans to increase forage diversity in diets (particularly through the introduction of red clover that will also reduce N fertiliser use) and reduce the carbon footprint of diets by using Global Feed LCA Institute metrics. We will continue to increase the use of red clover within the reseeding cycle for our silage fields. The high-profile and detailed ongoing recording of Langhill cows provide an excellent basis for Knowledge Exchange (KE) activities with farmers and other industry stakeholders regarding low carbon and resilient diets.
We are working on plans for redevelopment of our dairy herds to focus on the dominant 'cow-led' and 'resource-led' systems adopted in Scotland. This will involve focussing the Langhill study on high concentrate inputs, whilst continuing our developments to minimise carbon footprints; it will also reduce consequences of forage variability for these high producing animals. We also plant to establish a 'resource-led' Spring-calving herd focussed on grazing diverse swards with more resilient cross-bred cows as a comparator. This approach would provide comparisons within Scotland's Rural College's herds and further KE opportunities.
Objective 2: Develop metrics to describe variation in feed composition ('feed variability') over different time-scales
Here the focus has been on variability in feed percentage dry matter (DM%) as we have daily records over many years. We will extend the focus to consider other feed chemical components (where weekly bulked values are available from the Langhill database) and have also started exploring the availability (but not yet analysed) of national forage testing records as a basis for modelling relationships between forage composition and weather conditions over different periods of time.
Objective 3: Characterise feed variability and its effects on overall performance for different Scottish dairy systems
We have explored variability in feed DM% for four previous study diets and effects on feed intake and milk production. Diets with a high proportion of concentrates and/or purchased forage (straw) had the least variation in feed DM%. Variation in feed DM% was significantly positively related to dry matter intake, reflecting the poorer fermentation quality and greater bulk of wetter forages. However, cows were able to buffer for this variation and there were no significant effects on milk yields. In fact, the least variable ('by-product') diet based on purchased dry feeds had the highest variation in dry matter intake and milk, yield, probably because high levels of oil-rich concentrates lead to rumen upset.
Objectives 4 and 5 (focusing on interactions with cow performance and variability in resilience to diet issues) will be explored in the remaining years of this project.
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