A quantitative trait locus for live weight maps to bovine
Kari T. Elo, Johanna Vilkki, Dirk-Jan de Koning,
Riikka J. Velmala, Asko V. Ma¨ki-Tanila
Agricultural Research Centre MTT, Animal Production Research, Animal Breeding, FIN-31600 Jokioinen, Finland
Received: 14 December 1998 / Accepted: 28 March 1998
Abstract. A multiple-marker mapping approach was used to
search for quantitative trait loci (QTLs) affecting production,
health, and fertility traits in Finnish Ayrshire dairy cattle. As part
of a whole-genome scan, altogether 469 bulls were genotyped for
six microsatellite loci in 12 families on Chromosome (Chr) 23.
Both multiple-marker interval mapping with regression and maxi-
mum-likelihood methods were applied with a granddaughter de-
sign. Eighteen traits, belonging to 11 trait groups, were included in
the analysis. One QTL exceeded experiment level and one QTL
genome level significance thresholds. Across-families analysis
provided strong evidence (P
ס 0.0314) for a QTL affect-
ing live weight. The QTL for live weight maps between markers
BM1258 and BoLA DRBP1. A QTL significant at genome level
ס 0.0087) was mapped for veterinary treatment, and the
putative QTL probably affects susceptibility to milk fever or ke-
tosis. In addition, three traits exceeded the chromosome 5% sig-
nificance threshold: protein percentage of milk, calf mortality
(sire), and milking speed. In within-family analyses, protein per-
centage was associated with markers in one family (LOD score ס
In domestic animals, the ultimate goal of genome mapping is to
identify and characterize genes that control the variation in traits of
economical interest. Dense marker maps and advanced statistical
methods have made it feasible to search for quantitative trait loci
(QTLs) over the whole genome (see Lander and Kruglyak 1995).
The main advantage of this approach is that searches can be done
without any prior knowledge about physiological or biochemical
functions of QTLs. Recent studies have utilized this methodology,
and putative QTLs have been identified in domestic animals; for
example, growth rate, fatness, and length of small intestine
(Andersson et al. 1994; Knott et al. 1998) and for body propor-
tions, carcass composition, and meat quality in pigs (Andersson-
Eklund et al. 1998), for milk production (Georges et al. 1995;
Spelman et al. 1996; Vilkki et al. 1997; Arranz et al. 1998), for
milk production and health (Ashwell et al. 1997; Zhang et al.
1998), and for ovulation rate in cattle (Blattman et al. 1996).
Before dense marker maps were available, associations be-
tween a single marker and a quantitative trait were studied. Single
markers were usually candidate genes, or loci which had a known
function that was expected to be important in determining a quan-
titative trait. In domestic animals, particular interest has been taken
in the major histocompatibility complex (MHC) genes. The MHC
consists of a group of linked genes that code for highly polymor-
phic cell-surface glycoproteins. The glycoproteins have important
roles in the immune system, and thus MHC genes are candidate
genes for disease resistance or disease susceptibility.
The bovine MHC, bovine lymphocyte antigen (BoLA) com-
plex, has been assigned to cattle Chr 23. A number of reports on
significant associations between BoLA polymorphisms and dis-
eases have been published. For instance, in Swedish Red and
White breed, Lunde´n and associates (1990) found a significant
association with clinical mastitis. Mejdell and colleagues (1994)
suggested associations with mastitis, ketosis, and fertility in Nor-
wegian cattle. In Holstein cattle, Dietz and coworkers (1997) stud-
ied associations between BoLA alleles and 20 immunological vari-
ables. They found that the alleles of the BoLA DRB3 locus were
associated with 13 immune system traits, and they suggested that
their observations may provide physiological explanations for pre-
viously identified disease associations with BoLA genotypes
(Dietz et al. 1997). In addition, there are indications that the BoLA
complex is associated with milk production traits (e.g., Simpson et
al. 1990) or growth traits (Batra et al. 1989; Stear et al. 1989b), but
also contradictory results have been reported (Lunde´n et al. 1993
and references therein).
It is known in rodents and humans that the MHC region harbors
numerous other coding genes not directly involved in the immune
system. Thus, some of the claimed associations between quantita-
tive traits and the MHC region may actually be caused by genes
that are tightly linked to the MHC. In cattle, it is evident that in
addition to the BoLA complex, some other linked genes are can-
didates for QTLs. For instance, physiological functions of prolac-
tin, steroid 21-hydroxylase (CYP21), and vascular endothelial
growth factor (VEGF) are interesting with respect to economically
important traits of cattle (see Guyette et al. 1979; Cowan et al.
1990; Mustonen and Alitalo 1995; Blattman et al. 1996).
Our objective was to search for QTLs affecting 18 quantitative
traits in Finnish Ayrshire dairy cattle, using a whole-genome scan.
Previously, Vilkki et al. (1997) reported the main characteristics of
material and methodology in our study; Ma¨ki-Tanila et al. (1998)
give information about the stage of genome scan, and Velmala et
al. (1999) report milk production QTLs on BTA6. In this paper, we
report a QTL for live weight on the bovine Chr 23. A putative QTL
affecting veterinary treatments was mapped on the same chromo-
some, and an association between milk protein percentage and
genetic markers was found in one family.
Materials and methods
Population and traits.
Semen samples from Finnish Ayrshire dairy
cattle were collected from five Artificial Insemination (AI) stations.
Records on phenotypes were obtained form Agricultural Data Processing
Centre Ltd (Finland). Estimates of breeding values of bulls were obtained
from the cow evaluation of spring 1996 with an animal model. A grand-
daughter design was used (see Weller et al. 1990). The total number of sons
genotyped was 469. The number of sons and the mean number of
* Present address: Wageningen Institute of Animal Science, Animal
Breeding and Genetics Group, Wageningen Agricultural University, P.O.
Box 338, 6700 AH Wageningen, The Netherlands.
Correspondence to: K.T. Elo
Mammalian Genome 10, 831–835 (1999).
© Springer-Verlag New York Inc. 1999