Dairy cattle

Genomics of ultrasound-derived phenotypes and liver metabolic status during the transition period in Holstein cattle

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Abstract

The transition from late gestation to early lactation is highly demanding for dairy cows, making them vulnerable to metabolic disorders like hepatic lipidosis and ketosis that impair health, welfare, and productivity. Liver biopsy is the gold standard for diagnosing hepatic lipidosis, but ultrasound (US) imaging has been proposed as a non-invasive tool to assess liver alterations in dairy cows. The aim of this study was to investigate the genomic variability of US-derived traits to explore the genetic mechanisms underlying liver alterations associated with hepatic lipidosis. A total of 231 Holstein-Friesian cows from a single herd were monitored longitudinally at five time points: −60 days (pre-dry-off), −15 days pre-calving, +5 days, +30 days, and +60 days post-calving. Liver ultrasonography was performed on cows using a portable MyLab OneVET scanner to capture hepatic parenchyma and identify potential focal lesions. Liver depth (LD, mm), portal vein area (PVA, mm2), and portal vein depth (PVD, mm) were measured using MyLab Desk software, while hepatic texture was assessed with MaZda software. The regression equation used to predict the liver triacylglycerol content (pTAG, mg/g) was derived from a previous study. In addition, milk composition was assessed, and a comprehensive panel of 31 metabolites was quantified, including biomarkers of energy metabolism, hepatic function, oxidative stress, inflammation, innate immune response, and minerals. A total of approximately 1,155 US measurements were available for the analysis. All cows were also genotyped with the GGP Bovine 100K array. Genetic variance components and heritability of liver-status traits were estimated using a repeatability animal model fitted with single-trait genomic BLUP (GBLUP) and genetic correlations between liver traits, productive performance, and metabolic indicators were obtained using bivariate GBLUP implemented under a Bayesian framework. The model included as fixed effects the sampling time point, parity, season of calving and as random effects the additive genetic effect of the cow, the permanent environmental effect of the cow, and the residual. Posterior mean (SD) heritability estimates were 0.15 (± 0.06), 0.26 (± 0.06), and 0.34 (± 0.075) for pTAG, PVA, and PVD, respectively, indicating exploitable genetic variation for all liver- related phenotypes. Additive genetic correlation between pTAG and plasma β-hydroxybutyrate was 0.75 (± 0.12) and between pTAG and plasma non-esterified fatty acids was 0.50 (± 0.15). These strong correlations confirm the traits as indicators of metabolic dysfunction, but the remaining unexplained variation shows that additional work is needed to understand what links hepatic lipidosis and ketosis. Ongoing analyses of genetic associations with the full metabolite panel will provide a more comprehensive assessment of liver dysfunction and offer deeper insight into the relationships among negative energy balance, hepatic damage, and inflammation.Acknowledgements. carried out within the project PRIN "CowHolic"- MUR 20228APWKN

Keywords: 2026

How to Cite:

Mota, L., Giannuzzi, D., Bisutti, V., Ramirez-Mauricio, M., Bertarello, M., Toscano, A., Rovetta, C., Secchi, G., Giannotta, G., Fiore, E., Trevisi, E., Pegolo, S. & Cecchinato, A., (2026) “Genomics of ultrasound-derived phenotypes and liver metabolic status during the transition period in Holstein cattle”, World Congress on Genetics Applied to Livestock Production Digital Archive 2026(1): 2286803. doi: https://doi.org/10.31274/wcgalp.24124

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