Association of Phenotypic Markers of Heat Tolerance with Australian Genomic Estimated Breeding Values and Dairy Cattle Selection Indices
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Date
2023
Journal Title
Journal ISSN
Volume Title
Publisher
Animals
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 20 most heat-susceptible and 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’ tails 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 values for milk production. In general, younger cows had superior GEBVs for
the Balanced Performance Index (BPI) and Australian Selection Index (ASI), whilst older cows were
superior in fertility, feed saved (FS), and HT. This 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, 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.
Description
Research Article
Keywords
genomic selection, genotyping, heat stress, robotic dairy, selection index
Citation
Citation: 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. https://doi.org/10.3390/ ani13142259