Osei-Amponsah, R.; Dunshea, F.R.; Leury, B.J.; Abhijith, A.; Chauhan, S.S. Association of Phenotypic Markers of Heat Tolerance with Australian Genomic Estimated Breeding Values and Dairy Cattle Selection Indices. Animals2023, 13, 2259.
Osei-Amponsah, R.; Dunshea, F.R.; Leury, B.J.; Abhijith, A.; Chauhan, S.S. Association of Phenotypic Markers of Heat Tolerance with Australian Genomic Estimated Breeding Values and Dairy Cattle Selection Indices. Animals 2023, 13, 2259.
Osei-Amponsah, R.; Dunshea, F.R.; Leury, B.J.; Abhijith, A.; Chauhan, S.S. Association of Phenotypic Markers of Heat Tolerance with Australian Genomic Estimated Breeding Values and Dairy Cattle Selection Indices. Animals2023, 13, 2259.
Osei-Amponsah, R.; Dunshea, F.R.; Leury, B.J.; Abhijith, A.; Chauhan, S.S. Association of Phenotypic Markers of Heat Tolerance with Australian Genomic Estimated Breeding Values and Dairy Cattle Selection Indices. Animals 2023, 13, 2259.
Abstract
Dairy cattle predicted by genomic breeding values to be heat tolerant are known to have less milk production decline and lower core body temperature increases in response to elevated temperatures. In a study conducted at the University of Melbourne’s Dookie Robotic Dairy Farm during summer, we identified the most 20 heat-susceptible and 20 heat-tolerant cows in a herd of 150 Holstein Friesian lactating cows based on their phenotypic responses (changes in respiration rate, surface body temperature, panting score, and milk production). Hair samples were collected from the tip of the cows' tail following standard genotyping protocols. The results indicated variation in feed saved and HT genomic estimated breeding values (GEBVs) (P≤0.05) across age, indicating a potential for their selection. As expected, the thermotolerant group had higher GEBVs for HT and feed saved but lower for milk production. In general, younger cows had superior GEBVs for Balanced Performance Index (BPI), Type Weighted Index (TWI) and Australian Selection Index (ASI), whilst older cows were superior in fertility, feed saved (FS) and HT. The study demonstrated highly significant (P≤ 0.001) negative correlations (-0.28 to -0.74) between HT and GEBVs for current Australian Dairy cattle selection indices (BPI, TWI, ASI, HWI) and significant (P≤ 0.05) positive correlations between HT and GEBVs for traits like FS (0.45) and fertility (0.25). Genomic selection for HT will help improve cow efficiency and sustainability of dairy production under hot summer conditions. However, a more extensive study involving more lactating cows across multiple farms is recommended to confirm the associations between the phenotypic predictors of HT and GEBVs.
Keywords
genomic selection; genotyping; heat stress; robotic dairy; selection index
Subject
Biology and Life Sciences, Animal Science, Veterinary Science and Zoology
Copyright:
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