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Doctoral thesis, 2018

Genetic properties of feed efficiency and related traits in dairy cattle

Li, Bingjie

Abstract

Feed accounts for the largest proportion of operating costs in dairy production. Improving feed efficiency (FE) is expected to increase the profits of dairy farmers and reduce the ecological footprint of dairy production. The aim of this thesis is to study the genetic properties of alternative FE definitions and FE-related traits in several dairy breeds in order to investigate the possibility of including FE in Nordic dairy cattle breeding. In Papers I–IV, we discuss two FE traits, dry matter intake (DMI) and residual feed intake (RFI), to investigate the genetic properties of these traits across lactation. In Papers I and II, we study genetic parameters for DMI, energy-corrected milk (ECM), and body weight (BW) across lactation for Holstein, Nordic Red (RDC), and Jersey cows. Further, in Paper II, we study the genetic heterogeneity of DMI, ECM, and BW across lactation stages and genetic correlations among these traits by random regression models. In Papers III and IV, we focus on alternative modelling methods for RFI. In Paper III, we investigate the influence of lactation stages in modelling RFI, and in Paper IV, we employ multivariate analyses as a novel way to derive RFI of dairy cattle. We found moderate heritability for DMI in Holstein, RDC, and Jersey cows. The heritability for DMI was in a similar range as that for ECM and was lower than that for BW. Further, we found that DMI has a positive genetic correlation with ECM and BW across lactation stages. Cows of different breeds generally shared a similar pattern of genetic parameters of DMI. Different modelling strategies for RFI affected the genetic properties of RFI and yielded different rankings of animals for RFI efficiency. The genetic variance and heritability for RFI were both lower than those for DMI. Genetically, DMI or RFI were not the same across lactation stages. Thus, the genetic heterogeneity for DMI and RFI across lactation stages should be carefully considered in the recording and selection of FE in dairy cattle.

Keywords

feed efficiency, dairy cattle, genetic heterogeneity, genetic parameter, random regression model, multiple breeds

Published in

Acta Universitatis Agriculturae Sueciae
2018, number: 2018:55
ISBN: 978-91-7760-250-7, eISBN: 978-91-7760-251-4
Publisher: Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences

Authors' information

Li, Bingjie
Swedish University of Agricultural Sciences, Department of Animal Breeding and Genetics

UKÄ Subject classification

Animal and Dairy Science
Genetics and Breeding

URI (permanent link to this page)

https://res.slu.se/id/publ/104218