J Anim Breed Genet. 2019;00:1–16. wileyonlinelibrary.com/journal/jbg
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1 © 2019 Blackwell Verlag GmbH
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INTRODUCTION
Worldwide exportations of Spanish native Murciano-
Granadina goats have increased during the last decades,
given the high ability of the breed to adapt to very diverse
systems (Delgado et al., 2017). Consequently, the economical
repercussion of Murciano-Granadina breed's milk, the main
ingredient for the manufacture of fresh, semi-aged and aged
cheeses with denomination of origin (Cheese of Murcia), has
experienced a remarkable increase.
Received: 20 August 2019
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Revised: 6 October 2019
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Accepted: 28 October 2019
DOI: 10.1111/jbg.12457
ORIGINAL ARTICLE
Non-parametric association analysis of additive and dominance
effects of casein complex SNPs on milk content and quality in
Murciano-Granadina goats
María Gabriela Pizarro Inostroza
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Vincenzo Landi
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Francisco Javier Navas González
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José Manuel León Jurado
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María del Amparo Martínez Martínez
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Javier Fernández Álvarez
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Juan Vicente Delgado Bermejo
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Department of Genetics, Faculty of
Veterinary Sciences, University of Córdoba,
Córdoba, Spain
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Animal Breeding Consulting SL, Córdoba
Science and Technology Park, Córdoba,
Spain
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Centro Agropecuario Provincial de
Córdoba, Diputación Provincial de
Córdoba, Córdoba, Spain
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National Association of Breeders of
Murciano-Granadina Goat Breed, Granada,
Spain
Correspondence
Francisco Javier Navas González,
Department of Genetics, Faculty of
Veterinary Sciences, University of Córdoba,
Córdoba 14071, Spain.
Email: fjng87@hotmail.com
Abstract
Goat milk casein proteins (αS1, αS2, β and κ) are encoded by four loci (CSN1S1,
CSN1S2, CSN2 and CSN3, respectively) clustered within 250 kb in chromosome 6.
In this study, 159 Murciano-Granadina goats were genotyped for 48 SNPs within
the entire casein region. Phenotypes on milk yield and components were obtained
from 2,594 dairy registries. Additive and dominance effects on milk composition and
quality were studied using non-parametric tests and principal component analysis to
prevent SNPs multicollinearity. Two deletions in exon 4 (CSN1S1 and CSN3), one in
exon 7 (CSN2) and one in exon 15 (CSN1S2) have been found at frequencies rang-
ing from 0.12 to 0.50. Bonferroni-corrected significant SNP additive and dominance
effects were found for milk yield, fat, protein, dry matter and lactose, and somatic
cells. Exons 15 and 7 were significantly associated with milk yield and components
except for lactose and somatic cells, while exon 4 was significantly associated with
milk yield and components except for protein and dry matter. SNPs' associations
with somatic cells were less frequent and weaker than those with milk yield and com-
ponents. As caseins increase, somatic cells decrease, reducing milk enzymatic activ-
ity and consumption suitability. Hence, including molecular information in breeding
schemes may promote production efficiency, as selecting against undesirable alleles
could prevent the compromises derived from their dominance effects.
KEYWORDS
associations, caseins, non-parametric tools, snps, somatic cells