Please use this identifier to cite or link to this item: https://hdl.handle.net/1959.11/29163
Title: Genetic Parameters of First Lactation Milk Yield Under Low, Medium and High Production Systems in Kenya, using Test-Day Random Regression Model
Contributor(s): Wahinya, P K  (author)orcid ; Magothe, T M (author); Swan, A A  (author)orcid ; Jeyaruban, M G  (author)orcid 
Publication Date: 2019-11
Open Access: Yes
Handle Link: https://hdl.handle.net/1959.11/29163
Open Access Link: http://www.aaabg.org/aaabghome/fullproc23.phpOpen Access Link
Abstract: The aim of this study was to estimate genetic parameters for test-day milk yield in different production systems in Kenya. 10,923, 19,049 and 26,287 first lactation test-day records from multiple breeds under low, medium and high production systems, respectively, were analysed. On average cows under high production systems were younger and had a higher test-day milk yield than in low and medium production systems. A model fitting fourth order Legendre polynomials was found to be the most parsimonious and was therefore used to model the data. Additive genetic and permanent environmental variances were heterogeneous along different days in milk and between production systems. Heritability and repeatability were also different between days in milk and production systems. Heritability was on average 27%, 48% and 48% and repeatability 72%, 83% and 78% under low, medium and high production systems, respectively. Genetic correlations ranged from -32%, 34% and 45% to unity between daily milk yield in different days in milk under low, medium and high production systems, respectively. These parameters indicate that random regression using Legendre polynomial order four can be used to model test-day milk yield under the three production systems in Kenya. The observed heterogeneity of variance indicates that genetic parameters should be estimated within production systems for sustainable genetic improvement.
Publication Type: Conference Publication
Conference Details: AAABG 2019: 23rd Conference of the Association for the Advancement of Animal Breeding and Genetics, Armidale, Australia, 27 October-1 November
Source of Publication: Proceedings of the Association for the Advancement of Animal Breeding and Genetics, v.23, p. 127-130
Publisher: Association for the Advancement of Animal Breeding and Genetics (AAABG)
Place of Publication: Armidale, Australia
ISSN: 1328-3227
Fields of Research (FoR) 2008: 070201 Animal Breeding
Fields of Research (FoR) 2020: 300305 Animal reproduction and breeding
Socio-Economic Objective (SEO) 2008: 830302 Dairy Cattle
Socio-Economic Objective (SEO) 2020: 100402 Dairy cattle
Peer Reviewed: Yes
HERDC Category Description: E1 Refereed Scholarly Conference Publication
Publisher/associated links: http://www.aaabg.org/aaabghome/
Appears in Collections:Animal Genetics and Breeding Unit (AGBU)
Conference Publication

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