Assessing short-term feed efficiency and its association with biological markers in herbage-fed dairy cows.

Autor:	Haak T; Ruminant Nutrition and Emissions, Agroscope, Tioleyre 4, Posieux, Switzerland; Institute of Animal Science, University of Bonn, Endenicher Allee 15, Bonn, Germany., Münger A; Ruminant Nutrition and Emissions, Agroscope, Tioleyre 4, Posieux, Switzerland., Ampuero Kragten S; Method Development and Analytics, Agroscope, Tioleyre 4, Posieux, Switzerland., Bruckmaier RM; Veterinary Physiology, Vetsuisse Faculty, University of Bern, Bremgartenstrasse 109a, 3012 Bern, Switzerland., Südekum KH; Institute of Animal Science, University of Bonn, Endenicher Allee 15, Bonn, Germany., Schori F; Ruminant Nutrition and Emissions, Agroscope, Tioleyre 4, Posieux, Switzerland. Electronic address: fredy.schori@agroscope.admin.ch.
Jazyk:	angličtina
Zdroj:	Animal : an international journal of animal bioscience [Animal] 2024 Jul; Vol. 18 (7), pp. 101211. Date of Electronic Publication: 2024 Jun 04.
DOI:	10.1016/j.animal.2024.101211
Abstrakt:	Feed efficiency is an important trait of dairy production. However, assessing feed efficiency is constrained by the associated cost and difficulty in measuring individual feed intake, especially on pastures. The objective of this study was to investigate short-term feed efficiency traits of herbage-fed dairy cows and screening of potential biomarkers (n = 238). Derived feed efficiency traits were ratio-based (i.e., feed conversion ratio (FCR) and N use efficiency (NUE)) or residual-based (i.e., residual feed intake (RFI), residual energy intake (REI), and residual N intake (RNI)). Thirty-eight Holstein and 16 Swiss Fleckvieh dairy cows underwent a 7-d measurement period during mid- and/or late-lactation. The experimental data (n = 100 measurement points) covered different lactational and herbage-fed system situations: mid-lactation grazing (n = 56), late-lactation grazing (n = 28), and late-lactation barn feeding (n = 16). During each measuring period, the individual herbage intake of each cow was estimated using the n-alkane marker technique. For each cow, biomarkers representing milk constituents (n = 109), animal characteristics (n = 13), behaviour, and activity (n = 46), breath emissions (n = 3), blood constituents (n = 35), surface, and rectal temperature (n = 29), hair cortisol (n = 1), and near-infrared (NIR) spectra of faeces and milk (n = 2) were obtained. The relationships between biomarkers and efficiency traits were statistically analysed with univariate linear regression and for NIR spectra using partial least squares regression with feed efficiency traits. The feed efficiency traits were interrelated with each other (r: -0.57 to -0.86 and 0.49-0.81). The biomarkers showed varying R 2 values in explaining the variability of feed efficiency traits (FCR: 0.00-0.66, NUE: 0.00-0.74, RFI: 0.00-0.56, REI: 0.00-0.69, RNI: 0.00-0.89). Overall, the feed efficiency traits were best explained by NIR spectral characteristics of milk and faeces (R 2 : 0.25-0.89). Biomarkers show potential for predicting feed efficiency in herbage-fed dairy cows. NIR spectra data analysis of milk and faeces presents a promising method for estimating individual feed efficiency upon further validation of prediction models. Future applications will depend on the ability to improve the robustness of biomarkers to predict feed efficiency in a greater variety of environments (locations), managing conditions, feeding systems, production intensities, and other aspects. (Copyright © 2024 Agroscope, Tioleyre 4, 1725 Posieux, Switzerland. Published by Elsevier B.V. All rights reserved.)
Databáze:	MEDLINE
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