Technical note: A new and cost-effective method for detection of the bovine acyl-CoA:diacylglycerol acyltransferase 1 K232A polymorphism in cattle

A new, quick, and inexpensive method for detecting the bovine acyl-CoA:diacylglycerol acyltransferase1 (DGAT1) polymorphism (K232A) through tetra-primer amplification refractory mutation system by PCR (ARMS-PCR) was developed in the present investigation. The DGAT1 gene was recently identified as underlying variation in milk production traits. To date, PCR techniques such as PCR-RFLP have been used for detecting the DGAT1 K232A polymorphism, despite being expensive and laborious. The method proposed here, a tetra-primer ARMS-PCR, showed 100% sensitivity and specificity when compared with PCR-RFLP results obtained in a sample of 80 animals tested in a double-blind system. Our results suggest that the use of tetra-primer ARMS-PCR for DGAT1 K232A polymorphism genotyping could greatly reduce costs providing information for both research purposes and for dairy cattle breeders who perform DGAT1 genotyping for gene-assisted selection.     

Characterization of the DGAT1 mutations and the CSN1S1 promoter in the German Angeln dairy cattle population

The identification of quantitative trait loci (QTL) and genes with influence on milk production traits has been the objective of various mapping studies in the last decade. In the centromeric region of Bos taurus autosome (BTA) 14, the acyl-CoA:diacylglycerol acyltransferase1 gene (DGAT1) has been identified as the most likely causative gene underlying a QTL for milk fat yield and content. Recently, a second polymorphism in the promoter of DGAT1 emerged as an additional source of variation. In this study, the frequencies and the effects of alleles at the DGAT1 K232A and at the DGAT1 promoter variable number of tandem repeat (VNTR) locus on BTA14, and of alleles at the CSN1S1 (α_S1-casein-encoding gene) promoter on BTA6 in the German Angeln dairy cattle population were investigated. Analyzed traits were milk, fat, protein, lactose, and milk energy yield, fat, protein, lactose, and milk energy content and somatic cell score. The lysine variant of the DGAT1 K232A mutation showed significant effects for most of the milk production traits. A specific allele of the DGAT1 promoter VNTR showed significant effects on the traits lactose yield and content, milk energy content, and SCS compared with the other alleles. Additionally, a regulation mechanism between the DGAT1 K232A mutation and the DGAT1 promoter VNTR was found for fat yield and content, which could be caused by an upper physiological bound for the effects of the DGAT1 gene. At the CSN1S1 promoter, 2 of 4 alleles showed significant allele substitution effects on the milk yield traits.     

Characterization of the DGAT1 K232A and variable number of tandem repeat polymorphisms in French dairy cattle

A quantitative trait locus (QTL) underlying different milk production traits has been identified with a high significance threshold value in the genomic region containing the acylCoA:diacylglycerol acyltransferase (DGAT1) gene, in the 3 main French dairy cattle breeds: French Holstein, Normande, and Montbéliarde. Previous studies have confirmed that the K232A polymorphism in DGAT1 is responsible for a major QTL underlying several milk production traits in Holstein dairy cattle and several other bovine breeds. In this study, we estimate the frequency of the 2 alternative alleles, K and A, of the K232A polymorphism in French Holstein, Normande, and Montbéliarde breeds. Although the K allele segregates in French Holstein and Normande breeds with a similar effect on production traits, the existence of additional mutations contributing to the observed QTL effect is strongly suggested in both breeds by the existence of sires heterozygous at the QTL but homozygous at the K232A polymorphism. One allele at a variable number of tandem repeats (VNTR) locus in the 5′ noncoding region of DGAT1 has been recently proposed as a putative causative variant. In our study, this marker was found to present a high mutation rate of 0.8% per gamete and per generation, making the allele diversity observed compatible with that expected under neutrality. Moreover, among the sires homozygous at the K232A polymorphism, no allele at the VNTR can fully explain their QTL status. Finally, no allele at the VNTR was found to be significantly associated with the fat percentage variation in the 3 breeds simultaneously after correction for the effect of the K232A polymorphism. Therefore, our results suggest the existence of at least one other causative polymorphism not yet described. Because the A allele is nearly fixed in the Montbéliarde breed, this breed represents an interesting model to identify and confirm other mutations that have a strong effect on milk production traits.     

Strong evidence for association between K232A polymorphism of the DGAT1 gene and milk fat and protein contents: A meta-analysis

The relationship between K232A polymorphism of the DGAT1 gene and milk yield and composition was evaluated by meta-analysis of pooled data of more than 10,000 genotyped cattle. Four genetic models, including dominant (AA+KA vs. KK), recessive (AA vs. KA+KK), additive (AA vs. KK), and co-dominant (AA+KK vs. KA) were used to analyze the data. The standardized mean difference (SMD) was used to measure the size of the effects of the A and K alleles of K232A polymorphism on milk-related traits. The results showed that additive model was the best model for describing the effects of K232A polymorphism on studied traits. Under additive model, milk fat content was strongly decreased in cows having the AA genotype (SMD = −1.320). Furthermore, the AA genotype reduced the protein content of milk (SMD = −0.400). A significant difference in daily milk yield (SMD = 0.225) and lactation yield (SMD = 0.697) was found between cows carrying AA and KK genotypes, suggesting the positive effects of the K allele on these traits. Cook's distance measurement suggested some studies as outliers and sensitivity analyses by removing influential studies revealed that the results of meta-analyses for daily milk yield, fat content and protein content were not sensitive to outliers. However, the outcome of the meta-analysis for lactation yield was strongly influenced by outlier studies. Egger's test and Begg's funnel plots showed no evidence of publication bias in included studies. In conclusion, the K allele of K232A polymorphism showed a tremendous effect on increasing fat and protein contents in the milk of cattle, especially when 2 copies of this allele are inherited together, whereas the A allele of K232A polymorphism had negative effects on these traits.     

Milk fatty acid unsaturation: genetic parameters and effects of stearoyl-CoA desaturase (SCD1) and acyl CoA: diacylglycerol acyltransferase 1 (DGAT1)

With regard to human health aspects of milk fat, increasing the amount of unsaturated fatty acids in milk is an important selection objective. The cow's diet has an influence on the degree of unsaturation, but literature suggests that genetics also plays a role. To estimate genetic variation in milk fatty acid unsaturation indices, milk fatty acid composition of 1,933 Dutch Holstein Friesian heifers was measured and unsaturation indices were calculated. An unsaturation index represents the concentration of the unsaturated product proportional to the sum of the unsaturated product and the saturated substrate. Intraherd heritabilities were moderate, ranging from 0.23 ± 0.07 for conjugated linoleic acid (CLA) index to 0.46 ± 0.09 for C16 index. We genotyped the cows for the SCD1 A293V and DGAT1 K232A polymorphisms, which are known to alter milk fatty acid composition. Both genes explain part of the genetic variation in unsaturation indices. The SCD1 V allele is associated with lower C10, C12, and C14 indices, and with higher C16, C18, and CLA indices in comparison to the SCD1 A allele, with no differences in total unsaturation index. In comparison to the DGAT1 K allele, the DGAT1 A allele is associated with lower C10, C12, C14, and C16 indices and with higher C18, CLA, and total indices. We conclude that selective breeding can contribute to higher unsaturation indices, and that selective breeding can capitalize on genotypic information of both the SCD1 A293V and the DGAT1 K232A polymorphism.     

Effects of milk fat composition, DGAT1, and SCD1 on fertility traits in Dutch Holstein cattle

Recently, selective breeding was proposed as a means of changing the fatty acid composition of milk to improve its nutritional quality. Before implementing such breeding objectives, effects on other economically important traits should be investigated. The objectives of this study were to examine 1) the effect of milk fat composition, and 2) the effect of polymorphisms of DGAT1 and SCD1 genes on female fertility in commercial Dutch Holstein-Friesian cattle. Data on 1,745 first-lactation cows were analyzed by fitting linear mixed models. We found that higher concentrations of trans fatty acids within total milk fat negatively affected reproductive performance. Furthermore, results suggested a potential effect of the DGAT1 polymorphism on nonreturn rates for insemination 28 and 56 d after the first service. Our results can be used to assess the correlated effects of breeding for improved milk fat composition on reproduction, thereby allowing for better evaluation of breeding programs before implementation.     

Short communication: evidence for a major gene by polygene interaction for milk production traits in German Holstein dairy cattle

The present study investigated putative interaction effects between the DGAT1 K232A mutation and the polygenic term (i.e., all genes except DGAT1) for 5 milk production traits in the German Holstein dairy cattle population. Mixed models were used, and the test for interaction relied on the comparison of polygenic variance components depending on the sire's genotypes at DGAT1 K232A. Substitution effects were highly significant for all traits. Significant interaction effects were found for milk fat and protein percentage.     

The DGAT1 K232A mutation is not solely responsible for the milk production quantitative trait locus on the bovine chromosome 14

The gene, acyl-CoA:diacylglycerol acyltransferase1 (DGAT1), was recently identified as the one underlying the quantitative trait locus (QTL) for milk production traits in the centromeric region of the bovine chromosome 14. Until now, 2 alleles, the lysine variant (increasing fat yield, fat and protein percentage) and the alanine variant (increasing protein and milk yield), were postulated at DGAT1. This study investigated whether the diallelic DGAT1 polymorphism is responsible for all the genetic variation at the centromeric region of this chromosome for milk, fat, and protein yield and fat and protein percentage. A statistical model was applied to a granddaughter design to analyze 16 German Holstein families. The model included the diallelic DGAT1 effect and the QTL transition probability estimated for each chromosomal position by a multiple marker approach. Because the regression coefficient of this probability was corrected for the diallelic DGAT1 polymorphism, it represented a putative conditional QTL effect. The effect of the DGAT1 gene was always highly significant. The conditional QTL effect was significant genomewise for fat percentage at the proximal end of the chromosome and for protein percentage at a more distal chromosomal region. Additional chromosomewise significance was found for fat and protein yield. Our results suggest an additional source of genetic variance on this chromosome for these traits; either one or more additional alleles segregating at DGAT1 that were not previously detected, a second quantitative trait locus affecting these traits, or both.     

Effect of polymorphisms in the leptin, leptin receptor, and acyl-coenzyme A:diacylglycerol acyltransferase 1 (DGAT1) genes and genetic polymorphism of milk proteins on cheese characteristics

Cheese production has increased worldwide during the last decade and is expected to increase within the coming decade as well. Despite this, the relations between cow genetics and cheese characteristics are not fully known. The aim of this study was to determine if polymorphisms in the leptin (LEP), leptin receptor (LEPR), and acyl-coenzyme A:diacylglycerol acyltransferase 1 (DGAT1) genes as well as genetic variants of β-casein (β-CN), κ-CN, and β-lactoglobulin (β-LG) affect technological properties important for cheese production and, hence, could act as genetic makers for cheese quality. Individual milk samples from the Swedish Red and the Swedish Holstein breeds were analyzed for sizes of CN micelles and fat globules as well as rennet-induced gel strength, gelation time, and yield stress. Model cheeses were produced to study yield, hardness, and pH of the cheeses. The A1457G, A252T, A59V, and C963T single nucleotide polymorphisms (SNP) were analyzed on the LEP gene, the T945M SNP on the LEPR gene, and the Nt984+8(A-G) SNP on the DGAT1 gene. In addition, genetic variants of β-CN, κ-CN, and β-LG were determined. The results indicate that technological properties were influenced by the LEPR_T945M polymorphism, which had an association with gel strength, yield stress, and cheese hardness (T > C). However, also LEP_A252T was shown to affect gel strength (T > A), whereas the LEP_A59V had an effect on fat globule size (T > C). For the milk protein genes, favorable effects were found for the A and B variants of β-LG and κ-CN, respectively, on gel strength, gelation time, and yield stress. In addition, the B variant of κ-CN was shown to be associated with smaller CN micelles than the A variant. Thus, the results demonstrate potential genetic markers for cheese characteristics. However, milk composition traits also affected the obtained results, thus making it necessary to thoroughly assess the different aspects regarding the influence of gene effects on cheese characteristics before directly selecting for certain alleles or genetic variants to improve the processing and quality of cheese.     

Characterization of the DGAT1 gene in the New Zealand dairy population

Recently, DGAT1 was identified as the gene that underlies the QTL for bovine milk production on chromosome 14. This study investigated the effect of the reported polymorphism in three dairy breeds in New Zealand. Statistically significant results were identified for milk fat, milk protein, and volume for Jersey and Holstein-Friesian breeds, and only milk volume for Ayrshires. The average allele substitution effects were 2 to 3 kg of protein and 120 to 130 l milk for both the Jersey and Holstein-Friesian breeds. For milk fat, the average allele substitution effect was 6 kg for Holstein-Friesians and 3 kg for Jerseys. In all breeds, where the polymorphism increased milk fat yield, it decreased milk protein yield and milk volume.     

Impact of single nucleotide polymorphisms in leptin, leptin receptor, growth hormone receptor, and diacylglycerol acyltransferase (DGAT1) gene loci on milk production, feed, and body energy traits of UK dairy cows

The impact of 9 single nucleotide polymorphisms (SNP) in the leptin (LEP), leptin receptor (LEPR), growth hormone receptor (GHR), and diacylglycerol acyltransferase (DGAT1) gene loci on daily milk production, feed intake, and feed conversion, and weekly measures of live weight, BCS, and body energy traits was evaluated using genetic and phenotypic data on 571 Holstein cows raised at the Langhill Dairy Cattle Research Center in Scotland. Six SNP were typed on the LEP gene and 1 on each of the other 3 loci. Of the 6 LEP SNP, 3 were in very high linkage disequilibrium, meaning there is little gain in typing all of them in the future. Seven LEP haplotypes were identified by parsimony-based analyses. Random-regression allele-substitution models were used to assess the impact of each SNP allele or haplotype on the traits of interest. Diacylglycerol acyltransferase had a significant effect on milk yield, whereas GHR significantly affected feed intake, feed conversion, and body energy traits. There was also evidence of dominance in allelic effects on milk yield and BCS. The LEP haplotype CCGTTT (corresponding to leptin SNP C207T, C528T, A1457G, C963T, A252T, and C305T, respectively) significantly affected milk yield and feed and dry matter intake. Animals carrying this haplotype produced 3.13 kg more milk daily and consumed 4.64 kg more feed. Furthermore, they tended to preserve more energy than average. Such results may be used to facilitate genetic selection in animal breeding programs.     

Characterization of genetic polymorphism of the bovine lymphocyte antigen DRB3.2 locus in Kankrej cattle (Bos indicus)

Bovine lymphocyte antigen DRB 3.2 (BoLA-DRB3.2) gene encodes for the beta chain of the major histocompatibility complex (MHC) class II molecule in cattle, which is a glycoprotein present on the surface of antigen-presenting cells. This locus shows extensive polymorphism in it. The objective of the present study was to genotype the BoLA-DRB3.2 locus in Kankrej cattle (n = 50) by PCR-RFLP. Bovine DNA was isolated from aliquots of whole blood. Primers specific for exon 2 of the bovine lymphocyte antigen (BoLA)-DRB3 gene were used to amplify the region. The 304-bp amplified product of the DRB3 gene was separately digested with restriction endonucleases RsaI, BstYI, and Hae III. Twenty-four BoLA-DRB 3.2 alleles were identified with frequencies ranging from 1 to 22.0%. Twenty-one alleles of the total 24 alleles were similar to those reported earlier; 3 alleles were new and had not been reported previously. The allele BoLA-DRB3.2*34 occurred at the highest frequency of 22% (approx.) in the Kankrej animals studied. Six alleles (BoLA-DRB3.2 *34, *15, *06, *20, *37, and *20) accounted for almost 71% of the total alleles observed to be present in the Kankrej animals. All the new alleles observed were present at frequencies of 1%. The results obtained in the present study demonstrated that the BoLA DRB3.2 locus is highly polymorphic in the Kankrej cattle.     

The association of bovine PPARGC1A and OPN genes with milk composition in two independent Holstein cattle populations

Many studies have reported quantitative trait loci on chromosome 6 that affect milk production traits in dairy cattle. Osteopontin (OPN) and peroxisome proliferator activated receptor gamma coactivator 1 alpha (PPARGC1A) are located in the middle of chromosome 6 about 6 Mb apart, which is approximately 12 cM. The objective of this study was to investigate the association of OPN and PPARGC1A variants with milk production traits in 2 independent Holstein cattle populations: the University of Wisconsin (UW) daughter design and the Cooperative Dairy DNA Repository (CDDR) granddaughter design resource populations. For OPN, 891 cows from the UW resource population were genotyped for the C/T polymorphism reported previously in the CDDR population. Additive effects were significant for fat percentage, protein percentage, and fat yield in the UW resource population. These results are consistent with previous studies that have shown significant association of OPN variants with milk composition traits. The association between PPARC1A variants was investigated in UW and CDDR resource populations using 2 single nucleotide polymorphisms. For the UW resource population, additive effects were significantly increased for protein percentage and decreased for milk yield. Dominance effects were not significant for any of the examined traits. For the CDDR population, PPARGC1A was associated with a significant increase in milk protein percentage and in SCS. Thus, in UW and CDDR populations, PPARGC1A was associated with a significant increase in milk protein percentage in contrast to association results previously reported for the German Holstein population.     

Changes in the dynamics of Coxiella burnetii infection in dairy cattle: An approach to match field data with the epidemiological cycle of C. burnetii in endemic herds

This study aimed to evaluate changes in the epidemiological status of Coxiella burnetii in dairy cattle herds to better understand the epidemiology of the infection and to predict its evolution. Bulk-tank milk (BTM) and serum samples were collected from 94 dairy cattle herds and analyzed by ELISA (BTM and sera) and PCR (BTM) in study 1 (S₁). Two years later (study 2; S₂), the same farms were visited with a similar sampling approach. To estimate seroconversion during this period, blood samples were collected from the maximum possible number of animals surveyed in S₁. Environmental samples were collected in S₂ to identify active shedding. Farms were allocated into 3 different categories in each study according to PCR and ELISA results: category A, with BTM ELISA and PCR positive herds and at least 1 seropositive animal; category B, with BTM ELISA or PCR positive herds or individual sera positive; and category C, with all negative results among herds. Changes in herd category between S₁ and S₂ were grouped in 9 classes. Two statistical models, one to search for drives of within-herd changes in C. burnetii infection status and another to look for variables modulating individual changes in C. burnetii antibody level, were built. Several herds in category A in S₁ remained in that category 2 yr later, indicating that C. burnetii can remain within a herd for a long time. Most of the herds with seroconversion and detection of the bacterium in the environment belonged to category A, suggesting active and recent infections. Changes in the epidemiological status of herds were driven by local densities of domestic ruminants, showing the implication of neighbor reservoirs; whereas individual changes in antibody levels were modulated by variation in the epidemiological status of herds. Observed changes in epidemiological status allowed depiction of the hypothesized life cycle of C. burnetii within dairy cattle herds, which should be tested by future long-term series studies on C. burnetii infection to help fitting control measures (e.g., vaccination) to within-herd C. burnetii status.     

Short communication: Association analysis of diacylglycerol acyltransferase (DGAT1) mutation on chromosome 14 for milk yield and composition traits,somatic cell score,and coagulation properties in Holstein bulls

The aim of the present study was to determine the allele frequencies of the diacylglycerol acyltransferase (DGAT1) K232A mutation in Italian Holstein bulls and to estimate the effect of the mutation on milk yield, composition, somatic cell score, and coagulation traits (rennet coagulation time and curd firmness). For this purpose, 349 Italian Holstein bulls were genotyped for the DGAT1 mutation on chromosome 14. Association analysis was performed by regressing the number of copies for the K allele on the deregressed estimated breeding value of the individual. Breeding values were calculated using field data routinely collected in Northeast Italy. The frequencies of the AA, KA, and KK genotypes were 59.6, 32.1, and 8.3%, respectively, and the minor allele frequency (K variant) was 24.7%. The K allele was significantly associated with greater fat yield and fat, protein, and casein percentages and with reduced protein:fat ratio. The association between the DGAT1 mutation and somatic cell score was not significant, whereas a favorable association between presence of the K allele and milk coagulation properties was found. Results from the present study confirmed the effect of the diallelic DGAT1 polymorphism K232A on milk production traits and, for the first time, provided evidence that this mutation also affects milk coagulation properties in the Italian Holstein breed.     

Population structure of rumen Escherichia coli associated with subacute ruminal acidosis (SARA) in dairy cattle

Previous studies indicated that only subacute ruminal acidosis (SARA), induced by feeding a high-grain diet, is associated with an inflammatory response and increased abundance of Escherichia coli in the rumen. We hypothesized that ruminal E. coli in grain pellet-induced SARA carried virulence factors that potentially contribute to the immune activation during SARA. One hundred twenty-nine E. coli isolates were cultured from the rumens of 8 cows (4 animals per treatment) in which SARA had been nutritionally induced by feeding a high-grain diet (GPI-SARA) or a diet containing alfalfa pellets (API-SARA). The population structure of the E. coli was evaluated with the ABD genotyping system and repetitive sequence-based (rep)-PCR fingerprinting. Twenty-five virulence factors were evaluated with PCR. Escherichia coli numbers were higher in the GPI-SARA treatment than in the API-SARA treatment. The genetic structure of the E. coli was significantly different between SARA challenge models. Isolates from GPI-control (46%), API-control (70%), and API-SARA (53%) were closely related and fell into one cluster, whereas isolates from GPI-SARA (54%) grouped separately. The ABD typing indicated a shift from an A-type E. coli population to a B1-type population only due to GPI-SARA. Of the 25 virulence factors tested, curli fiber genes were highly associated with GPI. Curli fibers were first identified in E. coli mastitis isolates and are potent virulence factors that induce a range of immune responses. Results suggest that under low rumen pH conditions induced by a grain diet, there is a burst in the number of E. coli with virulence genes that can take advantage of these rumen conditions to trigger an inflammatory response.     

Short communication: Genotyping and single nucleotide polymorphism analysis of bovine leukemia virus in Chinese dairy cattle

Bovine leukemia virus (BLV) causes enzootic leucosis in cattle and is classified into 10 genotypes with a worldwide distribution, except for several European countries, Australia, and New Zealand. Although BLV is widespread in Chinese cows with the positive rate of 49.1% at the individual level, very little is known about the BLV genotype in dairy cattle in China. To determine BLV genetic variability in cows in China, 112 BLV-positive samples from 5 cities in China were used for BLV molecular characterization in this study. Phylogenetic analysis using the neighbor-joining method on partial env sequence encoding gp51 obtained from 5 Chinese cities and those available in GenBank (n = 53, representing BLV genotype 1–10) revealed the Chinese strains belonged to genotype 6. Seven unique SNP were identified among Yancheng, Shanghai, and Bengbu strains out of the total 12 SNP identified in Chinese strains. The genotyping coupled with SNP analysis of BLV can serve as a useful molecular epidemiological tool for tracing the source of pathogens. This study highlights the importance of genetic analysis of geographically diverse BLV strains to understand BLV global genetic diversity.     

Short communication: The effect of linseed oil and DGAT1 K232A polymorphism on the methane emission prediction potential of milk fatty acids

Several in vivo CH₄ measurement techniques have been developed but are not suitable for precise and accurate large-scale measurements; hence, proxies for CH₄ emissions in dairy cattle have been proposed, including the milk fatty acid (MFA) profile. The aim of the present study was to determine whether recently developed MFA-based prediction equations for CH₄ emission are applicable to dairy cows with different diacylglycerol o-acyltransferase 1 (DGAT1) K232A polymorphism and fed diets with and without linseed oil. Data from a crossover design experiment were used, encompassing 2 dietary treatments (i.e., a control diet and a linseed oil diet, with a difference in dietary fat content of 22 g/kg of dry matter) and 24 lactating Holstein-Friesian cows (i.e., 12 cows with DGAT1 KK genotype and 12 cows with DGAT1 AA genotype). Enteric CH₄ production was measured in climate respiration chambers and the MFA profile was analyzed using gas chromatography. Observed CH₄ emissions were compared with CH₄ emissions predicted by previously developed MFA-based CH₄ prediction equations. The results indicate that different types of diets (i.e., with or without linseed oil), but not the DGAT1 K232A polymorphism, affect the ability of previously derived prediction equations to predict CH₄ emission. However, the concordance correlation coefficient was smaller than or equal to 0.30 for both dietary treatments separately, both DGAT1 genotypes separately, and the complete data set. We therefore concluded that previously derived MFA-based CH₄ prediction equations can neither accurately nor precisely predict CH₄ emissions of dairy cows managed under strategies differing from those under which the original prediction equations were developed.     

Identification of a single nucleotide polymorphism at intron 16 of the caprine acyl-coenzyme A: diacylglycerol acyltransferase 1 (DGAT1) gene

The DGAT1 gene encodes a microsomal enzyme that catalyses the only committed step in triacylglycerol synthesis by joining diacylglycerol and fatty acyl coenzyme A. In cattle, a K232A substitution in the DGAT1 molecule has a significant effect on enzyme activity and milk fat content. The prominent role of this gene in lipid metabolism led us to undertake the structural characterization of DGAT1 in goats. In this way, we have sequenced a 1552 bp fragment of the goat DGAT1 cDNA, which encompasses most of the coding sequence (from exon 1 to 17), and a genomic fragment covering exons 12 to 17. Multiple alignment of the goat DGAT1 sequences revealed the existence of a single nucleotide polymorphism (SNP) involving a T to C substitution at intron 16. We optimized a primer extension based genotyping method that allowed us to determine that the C variant is a minority allele with frequencies ranging from 0.062 (Murciano-Granadina) to 0.109 (Malague?a). This SNP, although not expected to have any functional effect, might be useful as a genetic marker in association studies to detect additional DGAT1 polymorphisms which might influence fat milk content and other traits of economic interest.