Dairy cattle

Crossbreeding parameters for milk fatty acid composition in pasture-based dairy cows

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Abstract

The objective of this study was to estimate additive breed, heterosis, and recombination effects for milk fatty acid (FA) composition in pasture-based dairy cows in New Zealand. Monthly herd-test records (n = 790) were collected during the 2023-2024 lactation season from 33 Friesian, 26 Jersey, and 31 Friesian×Jersey crossbred cows allocated to three pasture-management systems: standard (ryegrass-clover)-contemporary, diverse-contemporary, and diverse-regenerative. The diverse pastures contained mixtures of grasses, legumes, and herbs. Each milk sample provided contents of fat and protein and mid-infrared spectral data. Concentration of FA in milk (g/100 g milk) were predicted using partial least-squares regression models. The calibration equations were derived based on 120 samples with FA determined by gas chromatography. Friesians produced more milk than Jerseys (+4.5 kg/day) but had lower fat (-1.0%) and protein (-0.43%) concentrations. Breed differences were significant for most FA: Friesian milk contained less palmitic acid (C16:0, -0.33 g/100 g milk), less stearic acid (C18:0, -0.16 g/100 g milk), and a lower proportion of total saturated FA (-0.83 g/100 g milk), resulting in a higher unsaturated to saturated ratio. Heterosis effects were small, with most estimates near zero. Only linoleic acid (C18:2 n-6) showed significant negative heterosis (-0.006 g/100 g milk). Recombination effects were near zero and not significant for all traits. Crossbreeding between Friesian and Jersey did not substantially modify milk composition or FA profile beyond the additive breed effects. The main differences between purebreds persisted in crossbreds, and non-additive effects (heterosis or recombination) were minimal.

Keywords: 2026

How to Cite:

Donaghy, D., Holroyd, S., López, I., Lopez-Villalobos, N., MacGibbon, A. & Moreno-Gonzalez, Y., (2026) “Crossbreeding parameters for milk fatty acid composition in pasture-based dairy cows”, World Congress on Genetics Applied to Livestock Production Digital Archive 2026(1): 2258282. doi: https://doi.org/10.31274/wcgalp.23391

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