Measurements of telomere length at different life stages as predictive biomarkers of health, reproduction and longevity in dairy cattle

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The key concept of the proposed work is based on three tenets:1. Health, reproduction and longevity are key factors influencing the sustainability and profitability of the livestock industry in the UK and internationally. In addition to bearing considerable economic significance, these factors affect animal welfare, the environmental footprint of livestock operations, and the acceptability of animal products by consumers. Therefore, improvement of these traits will yield multi-faceted benefits.2. Given the complexities and time requirements affecting the accurate recording of these traits, there is a need for reliable, early-life predictors that could provide early warnings for poor health, reproduction and longevity, effectively contributing practical tools for improvement.3. Recent advances in human and laboratory animal research have revealed potentially useful biological markers that are associated with lifespan, as well as age and age-related conditions.The proposed project aims to identify an early-life biomarker to predict health, reproduction and longevity in dairy cattle. For this reason, the project will use a comprehensive database of cows raised in the experimental herd of the Crichton Royal Farm in Scotland. Animals belong to two different genetic lines (selected for high vs. average production) and two diet groups (high vs. low protein intake) and are closely monitored from the time of birth until they die or are removed from the herd. The database comprises records of individual animal pedigree, performance, feed intake, disease and reproductive events, and longevity. Detailed environmental descriptors associated with these records are also included in the database.Approximately 1,000 animals from this herd have already been blood sampled at birth and then in 6-month intervals. These samples will be used to measure the length of the telomeres of each cow across her lifetime. Telomeres are small structures capping the chromosomes' ends in the animal cells and are known to be associated with aging in humans. Changes in telomere length measures obtained in the proposed study will be monitored throughout the animals' life and analysed together with data pertaining to health events, reproductive issues and length of productive life. These analyses will establish the link between animal telomere length and health, reproduction and longevity.To achieve its objectives, the project will draw on complementary expertise in animal science, genetics, biotechnology, physiology and biology.The potential applications and benefits of this study are as follows:1. This is the first ever study in food producing animals that looks at the way telomeres change across time and how this change may relate to important animal traits. Also for the first time the effect of many genetic and environmental factors on telomeres and longevity will be examined.2. The outcome of the project will bring a better understanding of the process of ageing of milk producing cows and will identify an early-life indicator that predicts the animals' future health, reproduction and longevity. 3. The end result will be an easily applicable, animal-friendly biomarker that could be used as a management and selection tool to improve the robustness, welfare and survival of dairy cattle, and reduce the rate of involuntary removal of high yielding animals from the herds. Further ramifications of the envisaged improvement include a healthier background for the production and consumption of animal products, and a lower environmental footprint of the sector as a whole. 4. Knowledge acquired in this project may have longer reaching consequences for animal conservation programmes to improve survival of rare animal breeds and endangered species, as well as detailed studies to better understand the aging process in other species including humans.