Sustainability & efficiency

Genetic parameter estimates of indigestible feed markers in Holsteins and correlations with production

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Abstract

Fecal undigestible neutral detergent fiber (uNDF) and n-alkanes may provide markers to estimate genetic merit for digestive efficiency and feed sorting tendency, as their relative abundance varies among feedstuffs and between different parts of plants. This study was designed to estimate genetic parameters for uNDF and fecal n-alkane traits and to determine associations with milk yield and fat %. Fecal samples (n=1,314) from 1,064 lactating cows were collected in the morning and afternoon from 3 Pennsylvania, 1 New York, 1 Ohio, and 1 Florida herd. Samples were dried in a forced-air oven for 48 h at 55°C, with morning and afternoon samples composited on an equal dry-weight basis. Of these, 1,047 composite fecal samples from 872 cows were evaluated for n-alkane concentrations (mg/kg of DM) using gas chromatography (GC), whereas uNDF was determined following a 240-h in-vitro digestion for all samples. Neutral detergent fiber (NDF) digestibility (NDFD) and potentially degradable NDF (pdNDF: lower values favored) were derived as measures of digestive efficiency, whereas ratios of n-nonacosane (C29), n-hentriacontane (C31), and n-tritriacontane (C33) to uNDF were used as indicators of feed sorting as C29 and C31 are more prevalent in leaves than plant stems relative to uNDF. Production data included 67,773 test-day records on 4,869 cows and 78,690 SNP genotypes of 5,581 cows were available for genomic analysis. Traits were evaluated in a series of single-step three-trait animal models that considered fixed effects of contemporary group, bi-weekly stage of lactation for milk and fat %, GC batch for alkane traits, parity, random additive genetic, random permanent environment for milk and fat %, and error. NDFD and pdNDF had heritability estimates of 0.11 ± 0.02 and 0.15 ± 0.03, respectively, and had unfavorable genetic correlations with milk yield (-0.74 ± 0.07 and 0.59 ± 0.10, respectively), but favorable correlations (0.28 ± 0.09 and -0.37 ± 0.11, respectively) with fat %. Heritability estimates were 0.08 ± 0.08, 0.15 ± 0.10, and 0.12 ± 0.10 for ratios of C29, C31, and C33 to uNDF, respectively. Genetic correlations for ratios of C29 and C31 with fat % were favorable (0.21 ± 0.46 and 0.18 ± 0.34, respectively), but with large standard errors. We concluded that fecal uNDF and naturally occurring odd-chain n-alkane traits can be collected in commercial dairy farms with the potential to facilitate selection for feed utilization.

Keywords: 2026

How to Cite:

Adeniji, Y., Dechow, C., Harvatine, K. & Yousaf, W., (2026) “Genetic parameter estimates of indigestible feed markers in Holsteins and correlations with production”, World Congress on Genetics Applied to Livestock Production Digital Archive 2026(1): 2287218. doi: https://doi.org/10.31274/wcgalp.24236

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