Lama glama αS1-casein: Identification of new polymorphisms in the CSN1S1 gene.

South American camelids have been poorly genetically investigated and little information is available in llamas (Lama glama) regarding the diversity of the caseins at the protein and gene level. Exon skipping and duplication events previously reported in the αS1-casein gene (CSN1S1) led us to investigate the genetic variability at this locus. Seventy-two positive clones for the αS1-casein transcripts were analyzed and randomly sequenced. The comparative analysis of the sequences revealed 2 transitions, c.366A>G and c.690T>C, at the 10th nucleotide of exon 12 and 94 bp of exon 19, respectively. These SNP are responsible for 2 amino acid changes, Ile→Val in position 86 and Tyr→His in position 194 of the mature protein. Both polymorphisms clarify the genetic events behind the protein variants A and B. This result was confirmed by isoelectric focusing analysis of llama milk samples. Quick methods based on PCR-RFLP and allele-specific PCR were set up for allelic discrimination in a population of 128 animals. Based on genotyping results, 4 haplotypes were observed and the estimated frequencies indicated B as the most common haplotype (0.629) in the investigated population. These data add knowledge to the genetic variability of a species little investigated, and open opportunity for new investigation in the field of milk protein for South American camelids, including the possibility, in the future, to select alleles with favorable characteristics.

Effect of dietary fish oil on the expression of genes involved in lipid metabolism in liver and skeletal muscle of lactating sows.

This study investigated the hypothesis that dietary supplementation of fish oil as a source of n-3 polyunsaturated fatty acids (PUFA) influences the expression of target genes of sterol regulatory element-binding proteins (SREBP)-1 and (SREBP)-2 involved in triacylglycerol (TAG) synthesis and fatty acid and cholesterol metabolism in the liver, and moreover activates the expression of target genes of peroxisome proliferation-activated receptor (PPAR)-α involved in TAG and fatty acid catabolism in liver and skeletal muscle. Twenty lactating sows were fed a control diet or a fish oil diet with either 50 g of a mixture of palm oil and soya bean oil (4:1, w/w) or fish oil per kg. The diet of the fish oil group contained 19.1 g of n-3 PUFA (mainly 20:5 n-3 and 22:6 n-3) per 100 g of total fatty acids, while the diet of the control group contained 2.4 g of n-3 PUFA (mainly 18:3 n-3) per 100 g of total fatty acids. The fish oil group had reduced relative mRNA concentrations of various target genes of SREBP-1 involved in fatty acid and TAG synthesis in comparison with the control group (p < 0.05). Relative mRNA concentrations of target genes of PPARα involved in fatty acid catabolism in both liver and muscle, and mRNA concentrations of target genes of SREBP-2 involved in cholesterol synthesis and uptake were not influenced by fish oil supplementation. Concentrations of cholesterol and TAG in plasma, fat content of milk and weight gains of litters during the suckling period were not different between the two groups of sows. In conclusion, this study suggests that fish oil has only minor effects on hepatic lipid metabolism, which are non-critical with respect to milk production in sows.

Wingless-type MMTV integration site family member 2 (WNT2) gene is associated with resistance to MAP in faecal culture and antibody response in Holstein cattle.

Mycobacterium avium subspecies paratuberculosis (MAP) is a pathogenic bacterium responsible for the lethal Johne's disease in cattle. So far, several genome-wide association studies (GWAS) have been carried out to identify chromosomal regions highly associated with Johne's disease. The aim of this study was to investigate the genetic variability within a pool of seven genes (LAMB1, DLD, WNT2, PRDM1, SOCS5, PTGER4 and IL10) indicated by former GWAS/RNA-Seq studies as putatively associated with MAP infections and to achieve a confirmation study of association with paratuberculosis susceptibility in a population of 324 German Holstein cattle (162 cases MAP positive and 162 controls MAP negative) using ELISA and fecal cultural tests. SNP validation and genotyping information are provided, quick methods for allelic discrimination were set up and transcription factor binding analyses were performed. The rs43390642:G>TSNP in the WNT2 promoter region is associated with paratuberculosis susceptibility (P = 0.013), suggesting a protective role of the T allele (P = 0.043; odds ratio 0.50 [0.25-0.97]). The linkage disequilibrium with the DLD rs134692583:A>T might suggest a combined mechanism of action of these neighboring genes in resistance to MAP infection, which is also supported by a significant effect shown by the haplotype DLD(T) /WNT2(T) (P = 0.047). In silico analysis predicted rs43390642:G>T and rs134692583:A>T as essential parts of binding sites for the transcription factors GR, C/EBPß and GATA-1, hence suggesting a potential influence on WNT2 and DLD gene expression. This study confirmed the region on BTA 4 (UMD 3.1: 50639460-51397892) as involved in tolerance/resistance to Johne's disease. In addition, this study clarifies the involvement of the investigated genes in MAP infection and contributes to the understanding of genetic variability involved in Johne's disease susceptibility.

Genetic association between NOD2 polymorphism and infection status by Mycobacterium avium ssp. paratuberculosis in German Holstein cattle.

The aim of the study was the analysis of the nucleotide-binding oligomerization domain containing 2 (NOD2, formerly CARD15) as a candidate gene for Mycobacterium avium ssp. paratuberculosis infection in cattle. Eleven SNPs in the NOD2 gene were identified, and finally, four SNPs were included in a case-control study using 324 German Holstein cows tested for paratuberculosis using fecal culture and ELISA. The SNP (GenBank) AY518738S04:g.521G>A in exon 4 showed a significant association between the fecal culture status of the animals and NOD2 allele variants. The other three SNPs showed no associations in German Holstein cows.

Immunoglobulin E epitope mapping by microarray immunoassay reveals differences in immune response to genetic variants of caseins from different ruminant species.

The allergenicity of the caseins (CN), one of the major allergens in cow milk, is well characterized and their immunoglobulin E (IgE)-binding epitopes have been identified. However, investigations about the allergenic potential of the genetic variants occurring in the caseins are lacking. Therefore, this study determined the influence of the genetic polymorphism on IgE binding to epitopes of bovine casein variants. Furthermore, differences in IgE binding between epitopes of goats and water buffaloes were analyzed. A set of 187 peptides, covering the previously identified sequential IgE-binding epitopes of αS1-, αS2-, ß-, and κ-CN variants from cows and the corresponding homologous peptides of water buffaloes and goats, were synthesized and tested by means of peptide microarray for IgE binding, using sera from 16 cow milk-sensitized individuals. Seven of the 16 sera samples showed positive signals on microarrays and were included in this study. In 5 αS1-CN variants (A, B, C, E, and I), the AA substitution or deletion affected the immunoreactivity of epitopes AA 4 to 23, AA 17 to 36, AA 83 to 102, AA 173 to 192, and AA 175 to 194, as well as of the variant-specific peptides AA 184 to 196, AA 187 to 199, AA 174 to 193, and AA 179 to 198, which were found to resist gastrointestinal digestion. Variation in IgE binding was further detected for peptides AA 103 to 123 and AA 108 to 129 of 3 ß-CN variants (A(1), A(2), and B). The majority of sera showed IgE binding to αS1-CN peptides of cows and the homologous counterpart of goats and water buffaloes. However, αS1- and ß-CN epitopes from goats and water buffaloes had lower immunoreactivity than those of cows, but, in some cases, higher or exclusive IgE binding was observed. The results of this study indicate that genetic variants of the caseins differ in their allergenicity. This might be useful in the search for a suitable protein source for cow milk-allergic patients. In addition, milk from water buffaloes and goats harbor an allergenic potential due to cross-reactivity of IgE antibodies with cow milk caseins and are, therefore, not an acceptable alternative in the nutrition of cow milk-allergic patients.

Dual-color high-resolution fiber-FISH analysis on lethal white syndrome carriers in sheep.

Molecular defects occurring in the endothelin receptor type-B (EDNRB) gene are known to be associated with pigmentary anomalies and intestinal aganglionosis in humans, rodents and horses. We carried out a cytogenetic investigation in 2 ewes heterozygous for the deletion of the EDNRB gene and in 2 more females as control. The RBA-banding showed that all 4 ewes were karyologically normal. EDNRB gene-specific probes were produced by PCR and cloning. The application of the R-banding and propidium iodide-staining fluorescent in situ hybridization allowed mapping the gene to OAR 10q22 and confirmed the heterozygous status of the ewes investigated for the EDNRB gene deletion. For the fine estimation of the gene length in sheep and for the correct sizing of the chromosomal gap, a dual-color FISH was applied to high-resolution DNA fibers in combination with digital imaging microscopy. The comparison of the DNA fiber barcodes indicated a chromosomal deletion larger than the EDNRB gene itself. The length of the gene, not known for sheep until now, was estimated to be ∼21 kb, whereas the microchromosomal deletion was ∼100 kb. EDNRB is located in a chromosomal region previously shown to be a fragile site. The applied method allowed locating the potential breakpoints, thus permitting further interesting prospective investigations also in the field of the fragile sites in sheep.

Genetic variants of bovine ß- and κ-casein result in different immunoglobulin E-binding epitopes after in vitro gastrointestinal digestion.

Immunoglobulin E-mediated allergy to cow milk is a common allergy in industrialized countries, mainly affecting young children and infants. ß-Casein (CN) and κ-CN belong to the major allergens in cow milk. Within these milk proteins, genetic polymorphisms occur, which are characterized by substitutions or deletions of AA, resulting in different variants for each protein. Until now, these variants have not been considered when discussing the allergenic potential of bovine milk. In this study, the focus was placed on the arising peptide pattern after in vitro gastrointestinal digestion of several ß- and κ-CN variants to determine resistant fragments containing IgE-binding epitopes and to identify potential differences between these variants. ß-Casein A(1), A(2), and B, as well as κ-CN A, B, and E, were separated and isolated from milk of cows homozygous for these variants and digested with an in vitro gastrointestinal digestion model. The resulting peptides were identified using mass spectrometry and compared with previously determined epitopes. Seven ß-CN and 4 κ-CN peptides, common in all ß- or κ-CN variants, remained of sufficient size to harbor IgE-binding epitopes. In addition, some peptides and, consequently, epitopes differ from each other due to the AA substitution occurring in the individual variants. The distinct peptides AA 108 to 129 of ß-CN A(1) and A(2), AA 103 to 123 of ß-CN B, as well as AA 59 to 72, AA 59 to 80, and AA 58 to 80 of all 3 ß-CN variants correspond to the IgE-binding epitopes AA 107 to 120 and AA 55 to 70, respectively. In κ-CN, the 2 variant-specific peptides AA 136 to 149 (κ-CN A, E) and AA 134 to 150 (κ-CN B) are congruent with the IgE-binding epitope AA 137 to 148. The present study shows that genetic polymorphisms affected the arising peptide pattern of the caseins and thus modifications in the IgE-binding epitopes occurred. As a consequence, the casein variants could show differences in their allergenicity. Studies investigating the allergenic potential of these different peptides are currently in progress.

Molecular genetic characterization of ovine CSN1S2 variants C and D reveal further important variability within CSN1S2.

Within this study, the recently identified ovine CSN1S2 variants C and D were characterized at the molecular genetic level. Sequencing of the cDNA and of parts of the DNA identified several sequence differences within CSN1S2*C and D in comparison to CSN1S2*A and B. CSN1S2*C is characterized by two non-synonymous single nucleotide polymorphisms (SNPs) within exon 7 (c.178A>G, c.187G>T) leading to the amino acid substitutions p.Val45Ile and p.Ala48Ser. CSN1S2*D is caused by the SNP c.183G>C, leading to an amino acid replacement at position 46 (p.Arg46Ser). A very common c.527G>A-SNP within exon 15, resulting in the amino acid substitution p.Arg161His and producing the new variant CSN1S2*G, not detectable by isoelectric focusing and previously misidentified as CSN1S2*A, was also identified. On the basis of the identified sequence differences, a new nomenclature is proposed and a possible phylogenetic pathway shown for ovine CSN1S2 variants.

Genetic diversity and admixture of indigenous cattle from North Ethiopia: implications of historical introgressions in the gateway region to Africa.

Microsatellite variation was surveyed to determine the genetic diversity, population structure and admixture of seven North Ethiopian cattle breeds by combining multiple microsatellite data sets of Indian and West African zebu, and European, African and Near-Eastern taurine in genetic analyses. Based on allelic distribution, we identified four diagnostic alleles (HEL1-123 bp, CSSM66-201 bp, BM2113-150 bp and ILSTS6-285 bp) specific to the Near-Eastern taurine. Results of genetic relationship and population structure analyses confirmed the previously established marked genetic distinction between taurine and zebu, and indicated further divergence among the bio-geographical groupings of breeds such as North Ethiopian, Indian and West African zebu, and African, European and Near-Eastern taurine. Using the diagnostic alleles for bio-geographical groupings and a Bayesian method for population structure inference, we estimated the genetic influences of major historical introgressions in North Ethiopian cattle. The breeds have been heavily (>90%) influenced by zebu, followed by African, European and the Near-Eastern taurine. Overall, North Ethiopian cattle show a high level of within-population genetic variation (e.g. observed heterozygosity = 0.659-0.687), which is in the upper range of that reported for domestic cattle and indicates their potential for future breeding applications, even in a global context. Rather low but significant population differentiation (F(ST) = 1.1%, P < 0.05) was recorded as a result of multiple introgression events and strong genetic exchanges among the North Ethiopian breeds.

Heritability estimates for Mycobacterium avium subspecies paratuberculosis status of German Holstein cows tested by fecal culture.

The objective of this study was to estimate genetic manifestation of Mycobacterium avium ssp. paratuberculosis (MAP) infection in German Holstein cows. Incorporated into this study were 11,285 German Holstein herd book cows classified as MAP-positive and MAP-negative animals using fecal culture results and originating from 15 farms in Thuringia, Germany involved in a paratuberculosis voluntary control program from 2008 to 2009. The frequency of MAP-positive animals per farm ranged from 2.7 to 67.6%. The fixed effects of farm and lactation number had a highly significant effect on MAP status. An increase in the frequency of positive animals from the first to the third lactation could be observed. Threshold animal and sire models with sire relationship were used as statistical models to estimate genetic parameters. Heritability estimates of fecal culture varied from 0.157 to 0.228. To analyze the effect of prevalence on genetic parameter estimates, the total data set was divided into 2 subsets of data into farms with prevalence rates below 10% and those above 10%. The data set with prevalence above 10% show higher heritability estimates in both models compared with the data set with prevalence below 10%. For all data sets, the sire model shows higher heritabilities than the equivalent animal model. This study demonstrates that genetic variation exists in dairy cattle for paratuberculosis infection susceptibility and furthermore, leads to the conclusion that MAP detection by fecal culture shows a higher genetic background than ELISA test results. In conclusion, fecal culture seems to be a better trait to control the disease, as well as an appropriate feature for further genomic analyses to detect MAP-associated chromosome regions.

Short communication: milk protein genetic variation and casein haplotype structure in the Original Pinzgauer cattle.

Milk protein genetic polymorphisms are often used for characterizing domesticated mammalian species and breeds, and for studying associations with economic traits. The aim of this work was to analyze milk protein genetic variation in the Original Pinzgauer, a dual-purpose (dairy and beef) cattle breed of European origin that was influenced in the past by human movements from different regions as well as by crossbreeding with Red Holstein. A total of 485 milk samples from Original Pinzgauer from Austria (n=275) and Germany (n=210) were typed at milk proteins alpha(S1)-casein, beta-casein, kappa-casein, alpha-lactalbumin, and beta-lactoglobulin by isoelectrofocusing to analyze the genetic variation affecting the protein amino acid charge. The Original Pinzgauer breed is characterized by a rather high genetic variation affecting the amino acid charge of milk proteins, with a total of 15 alleles, 12 of which were found at a frequency >0.05. The most polymorphic protein was beta-casein with 4 alleles detected. The prevalent alleles were CSN1S1*B, CSN2*A(2), CSN1S2*A, CSN3*A, LGB*A, and LAA*B. A relatively high frequency of CSN1S2*B (0.202 in the whole data set) was found, mainly occurring within the C-A(2)-B-A haplotype (in the order CSN1S1-CSN2-CSN1S2-CSN3), which seems to be peculiar to the Original Pinzgauer, possibly because the survival of an ancestral haplotype or the introgression of Bos indicus.

Short communication: molecular genetic characterization of ovine alpha(S1)-casein allele H caused by alternative splicing.

Sequencing of ovine CSN1S1*H cDNA showed an absence of exon 8 in comparison with GenBank sequences; the absence was confirmed by protein sequencing. We demonstrated that this allelic aberration is the result of a deletion of 4 nucleotides, the last 3 of exon 8 and the first 1 of intron 8, which are replaced by an insertion of 13 nucleotides in the DNA sequence. The insertion is a precise duplication of a part of the adjacent intronic sequence of CSN1S1*C''. These sequence differences result in an inactivation of the splice donor sequence distal to exon 8, leading to upstream exon skipping during the serial splice reactions of the ovine CSN1S1*H pre-mRNA, and may affect the specific casein expression as well as protein characteristics.

Genetic variation in monoamine oxidase A and analysis of association with behaviour traits in beef cattle.

Husbandry of beef cattle requires animals that do not behave aggressively or timidly. The enzyme monoamine oxidase A and the coding gene (MAOA) play an important role in the complex regulation of behaviour. The complete coding region and a part of the non-coding sequence of the bovine MAOA gene have been analysed in 20 German Angus and 20 German Simmental bulls and cows with the aim of detecting genetic variability. These two cattle breeds are known to differ regarding their behaviour during handling. Five single nucleotide polymorphisms (SNPs) were identified, three of which were found in the coding region of the gene (exons III and XV). One of the SNPs located in exon XV (NC_007331.3:g.80340C>T) was found to be a non-synonymous mutation. The minor allele frequency of this resulting amino acid substitution was significantly different between 543 German Angus and 417 German Simmental calves (0.39 and 0.49, respectively). The potential functional impact of this polymorphism has been tested by in silico analysis, as well as by association analysis using behaviour scores of the genotyped calves for three behaviour tests that assessed the animals' temperament during tethering, weighing or social separation. In silico analysis did not deliver consistent results arguing for or against a functional impact of the studied amino acid substitution on the function of the biological protein. No significant association was found between this MAOA polymorphism and the behaviour-related scores analysed in the study.

Refined mapping of quantitative trait loci for somatic cell score on BTA02 in the German Holstein.

The aim of this study was to more precisely map a previously reported quantitative trait locus (QTL) affecting somatic cell score on Bos taurus autosome 2 by increasing the number of markers fourfold, analysing more families and exploiting within-population linkage disequilibrium (LD). A granddaughter design of 10 German Holstein grandsire families with 1121 progeny tested sons was used. Twenty-six markers with an average marker spacing of 3.14 cM were genotyped along 81.6 cM. Linkage analysis (LA) was performed using variance-component methodology. The incorporation of LD was first done using variance-component methods followed by regression on marker alleles. LA revealed genome-wide significance (LOD > 3) at 15 contiguous marker-intervals, with the maximum test-statistic between DIK2862 and BMS778 and a 1-lod drop-off interval of 38 cM. While the variance-component methods could not detect any LD, two individual markers with a significant effect (ILSTS098, p < 0.05; BMS778, p < 0.01) were found by regression analysis. Compared with previous results QTL-localisation was substantially narrowed; further fine-mapping should focus on the close vicinity of BMS778.

Genetic characterization of a sheep-dwarf goat hybrid.

Twelve weeks after repeated spontaneous mating between a Bentheimer Landschaf ram and a West African dwarf doe was observed, the doe aborted a dead fetus. The aim of this study was to verify the parentage and the species of the supposed parents and the hybrid status of the fetus, using cytogenetic and molecular genetic methods. For this purpose, karyotypes were prepared using fresh blood samples from the ram and the doe, and genomic DNA was extracted from blood of the suspected parents and tissue of the aborted fetus. Fragments of the nuclear DNA-encoded interleukin-2 gene and the mitochondrial DNA-encoded 16S ribosomal RNA were sequenced and 19 microsatellites were genotyped in all 3 animals. The karyotypes and DNA sequences of the ram and the doe corresponded to domestic sheep and goat, respectively. The interleukin-2 sequence of the fetus was heterozygous at all positions where sheep and goat have different nucleotides. None of the 19 microsatellites excluded the ram and the dwarf doe as parents of the fetus. Taken together, we can conclude that the ram and the dwarf doe were from the species Ovis aries and Capra hircus, respectively, and that they were most likely the parents of the aborted fetus, which itself proved to be a hybrid of these 2 species.

Characterization and genetic analysis of bovine alpha S1-casein I variant.

The aim of this study was to identify the molecular genetic origin underlying the I variant of alpha(s1)-casein and to develop a DNA-based test for this polymorphism as a tool for genetic analyses independent of milk sample testing. All coding exons and flanking regions of the alpha(s1)-casein gene were sequenced in DNA samples from cattle of known alpha(s1)-casein genotypes (BI, CI, II, CC), determined by isoelectric focusing of milk samples. A nucleotide substitution (A>T) in exon 11 (g.19836A>T) leads to the exchange of Glu with Asp at amino acid position 84 of the mature protein (p.Glu84Asp) and perfectly co-segregated with the presence of the alpha(s1)-casein I variant in the milk of the analysed animals. Genotyping of a total of 680 DNA samples from 31 Bos taurus and Bos indicus cattle breeds and from Bos grunniens, Bison bison and Bison bonasus by restriction fragment length polymorphism analysis revealed the occurrence of Asp at position 84 at low frequencies in Bos taurus and Bos indicus breeds and established its origin from the alpha(s1)-casein C variant (p.Glu192Gly). Ten different intragenic haplotypes in the gene region from intron 8 to intron 12 were observed by sequencing, of which two occurred in Bison bison and one in Bison bonasus only. Using available casein gene complex information, an association of Asp at position 84 to beta-casein A(2) and kappa-casein B was shown in the Bos indicus breed Banyo Gudali. Taken together, we can postulate that the alpha(s1)-casein variant I is caused by a non-synonymous nucleotide substitution in exon 11 of the gene and that it originated within Bos indicus and spread to Bos taurus subsequently.

Short communication: bovine kappa-casein variants result in different angiotensin I converting enzyme (ACE) inhibitory peptides.

Proteins in bovine milk are a common source of bioactive peptides. The peptides are released by the digestion of caseins and whey proteins. Peptides derived from the different genetic variants A, B, C, E, F1, F2, G1, G2, H, I, and J of bovine kappa-casein (CSN3) were investigated for their inhibitory activities against angiotensin I converting enzyme (ACE). Amino acid sequences of the CSN3 variants were analyzed in silico to detect potential ACE inhibitory peptides. Besides known biologically active peptides, exclusive peptides were identified in some CSN3 variants and their biological activity was determined: within CSN3*B and CSN3*C, the ACE inhibitory peptide ASP (IC50 = 242.3; the IC50 value is equivalent to the micromolar concentration of peptide mediating a 50% inhibition of ACE activity) and within CSN3*C the peptide AHHP (IC50 = 847.6) was detected. Furthermore, the peptides VSP (IC50 = 21.8) and ACHP (IC50 = 360.7) were identified in CSN3*F1 and CSN3*G2, respectively.

Invited review: milk protein polymorphisms in cattle: effect on animal breeding and human nutrition.

The 6 main milk proteins in cattle are encoded by highly polymorphic genes characterized by several nonsynonymous and synonymous mutations, with up to 47 protein variants identified. Such an extensive variation was used for linkage analysis with the description of the casein cluster more than 30 yr ago and has been applied to animal breeding for several years. Casein haplotype effects on productive traits have been investigated considering information on the whole casein complex. Moreover, mutations within the noncoding sequences have been shown to affect the specific protein expression and, as a consequence, milk composition and cheesemaking. Milk protein variants are also a useful tool for breed characterization, diversity, and phylogenetic studies. In addition, they are involved in various aspects of human nutrition. First, the occurrence of alleles associated with a reduced content of different caseins might be exploited for the production of milk with particular nutritional qualities; that is, hypoallergenic milk. On the other hand, the frequency of these alleles can be decreased by selection of sires using simple DNA tests, thereby increasing the casein content in milk used for cheesemaking. Furthermore, the biological activity of peptides released from milk protein digestion can be affected by amino acid exchanges or deletions resulting from gene mutations. Finally, the gene-culture coevolution between cattle milk protein genes and human lactase genes, which has been recently highlighted, is impressive proof of the nonrandom occurrence of milk protein genetic variation over the centuries.

Association between single nucleotide polymorphisms in the CXCR1 gene and somatic cell score in Holstein dairy cattle.

In addition to its position in a quantitative trait locus for somatic cell score (SCS) and its function in the immune response, the CXCR1 chemokine receptor gene located on Bos taurus autosome 2 is an auspicious candidate gene for udder health in dairy cattle. An association analysis was conducted in the German Holstein-Friesian population to test the association between the single nucleotide polymorphism (SNP) at position +777 within the CXCR1 gene and the SNP at position -1768 in the 5' upstream region of this gene (rs41255711) and the indicator trait SCS by using a grand-daughter design. Data were analyzed for 3 families, with a total of 749 genotyped bulls and an extended pedigree of 8,071 animals from the national German bovine genome mapping project. Variance component estimation was used to determine the source of phenotypic variation in the chromosomal area of interest. A 20-cM window surrounding the 2 SNP in the CXCR1 gene was examined. Although the percentage of variance caused by the putative quantitative trait locus in the area studied was relatively large (12 and 11%, respectively), no statistically significant association of the SNP CXCR1+777 or CXCR1-1768 with SCS was found. These results contradict previously published studies.