Genome-wide association study for skin thickness and skin temperature traits in FocusPrimeᵀᴹ New Zealand sheep : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Animal Science at Massey University, Manawatū, New Zealand
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2024
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Massey University
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This study investigated the genetic basis of skin traits in New Zealand FocusPrime sheep and their implications for lamb survival, with a particular focus on skin thickness and temperature, both of which play critical roles in the thermoregulation and overall survivability of lambs during the early stages of life. The primary objective was to identify genetic markers associated with these skin traits and to understand their heritability and correlation, thereby providing insights that could inform selective breeding programs aimed at improving lamb survival rates. The research employed a comprehensive genome-wide association analysis to analyse a large dataset of New Zealand FocusPrime sheep, meticulously measuring skin thickness and skin temperature, and correlating these phenotypic traits with genotypic data. The study found significant heritability estimates for both skin thickness and skin temperature, suggesting that these traits are genetically controlled and can be effectively targeted in breeding strategies. Specifically, the heritability of skin thickness was found to be high (values that exceed 0.40), indicating that a considerable proportion of the variation in this trait is due to genetic differences among individuals. Similarly, the heritability of skin temperature was also significant, underscoring the potential for genetic improvement through selective breeding. A key finding of this study was the negative correlation between skin thickness and skin temperature. Thicker skin, while beneficial in providing a barrier against environmental stressors, tends to be associated with lower skin temperatures, indicating a complex interplay in the thermoregulatory mechanisms of lambs. This finding highlights the need for a balanced approach in selective breeding, where both traits must be considered to optimize lamb survival. Breeding programs that focus solely on increasing skin thickness may inadvertently affect the thermoregulatory efficiency of lambs, thereby underscoring the importance of a holistic breeding strategy. The genome wide association study identified several significant genetic markers associated with skin thickness and skin temperature, providing valuable targets for future genetic selection. These markers offer a promising avenue for improving lamb survival through genetic means. The study also delves into the practical applications of these findings, suggesting that by incorporating these genetic markers into a breeding program, it is possible to enhance the resilience of lambs against harsh environmental conditions, thereby improving animal welfare and economic outcomes for sheep farmers. This research contributes to a broader understanding of the genetic factors influencing lamb survival, a topic of critical importance given the economic and welfare implications of lamb mortality. The findings have the potential to transform breeding practices in the New Zealand sheep industry, moving towards more scientifically informed strategies that enhance the overall sustainability and profitability of sheep farming. The implications of this research extend beyond New Zealand, offering insights that can be applied to sheep populations globally. Future research should continue to refine the genetic associations identified in this study and explore their practical implementation in diverse sheep populations. Further studies could also investigate the interaction of these genetic markers with environmental factors, providing a more comprehensive understanding of the determinants of lamb survival. By integrating genetic analysis with practical breeding strategies, there is significant potential to reduce lamb mortality rates and improve the resilience of sheep to environmental challenges. In conclusion, this study provides a robust framework for understanding the genetic basis of key skin traits in New Zealand sheep and their impact on lamb survival. The identification of heritable genetic markers associated with skin thickness and skin temperature paves the way for targeted breeding programs that can enhance lamb resilience and reduce mortality rates. This research not only advances scientific knowledge in the field of animal genetics but also offers practical solutions for improving the sustainability and economic viability of the sheep industry in New Zealand and beyond.