Phenomics

Genetic Architecture of MIR-Predicted Metabolic Traits during Early Lactation in Hokkaido Holsteins: Effects of Housing Systems

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Abstract

Metabolite-related traits predicted from mid-infrared (MIR) spectroscopy exhibit favorable genetic correlations with metabolic disorders during the transition period, making them useful indicators for improving dairy cattle fitness. However, transition management practices and production levels differ among common housing systems, including free-stall (FS), tie-stall (TS), and pasture-grazing (GZ), potentially leading to genotype-by-environment interactions. This study aimed to estimate genetic parameters of MIR-predicted metabolic traits during early lactation across the three common housing systems in Hokkaido, Japan. The dataset combined management practice survey records from 1,146 farms with 356,389 test-day records of milk beta-hydroxybutyrate (BHB) and 168,901 test-day records of de novo (DnF) and preformed (PrF) fatty acid proportions in total milk fatty acids, collected between 7 and 36 days in milk during the first three lactations. BHB was log-transformed to improve normality. The same metabolic trait from three housing systems or lactations was treated as a distinct trait, resulting in a nine-trait animal model for each metabolic indicator. The model included the fixed effects of calving year, month, and age; a fixed lactation curve fitted with a Wilmink function and fourth-order Legendre polynomials; and random effects of herd, additive genetics, and residuals. Variance components were estimated using Gibbs sampling with gibbsf90+ software.Inspection of the fixed effect of calving month revealed that BHB in GZ showed distinct seasonal variations compared with those in FS or TS. Within-herd heritability for BHB, DnF, and PrF ranged from 0.18-0.25, 0.11-0.22, and 0.15-0.27, respectively, generally higher in GZ than in FS or TS. Within-herd heritability decreased with parity for most traits, whereas that for BHB in GZ increased. Genetic correlations among housing systems ranged from 0.77-0.97 for BHB, 0.54-0.97 for DnF, and 0.65-0.97 for PrF. Across traits, genetic correlations between GZ and FS (0.59-0.89) or between GZ and TS (0.54-0.94) were lower than between FS and TS (0.91-0.97). As genetic correlations for metabolite-related traits among housing systems were moderate to strong, these results suggest that a uniform national genetic evaluation may be feasible if fixed interactions between herd and calving month are properly accounted for. Nevertheless, to support selection decisions aimed at improving dairy cattle fitness, future studies are required to elucidate the genetic relationships between metabolite-related traits and wellness traits within each housing system.

Keywords: 2026

How to Cite:

Huang, C., Yamazaki, T., Yamaguchi, S., Abe, H., Nakahori, Y., Kawakami, J. & Hagiya, K., (2026) “Genetic Architecture of MIR-Predicted Metabolic Traits during Early Lactation in Hokkaido Holsteins: Effects of Housing Systems”, World Congress on Genetics Applied to Livestock Production Digital Archive 2026(1): 2283753. doi: https://doi.org/10.31274/wcgalp.23510

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