Effect of Marcha Exercise on Serum Electrolytes and Acid–Base Balance in Mangalarga Marchador Horses

The marcha competition is a functional evaluation, without similar in the world. In this competition, the animals perform marcha at average speed between 9 and 12 km/hr for 50 minutes, covering roughly 6 to 7 km with no rest. The aim of this study was to evaluate and compare the effect of batida gait competition on acid–base balance in Mangalarga Marchador horses during an official marcha competition. The study was conducted on 24 Mangalarga Marchador horses, 12 stallions, and 12 mares (aged 4–6 years and 399 ± 45 kg of body weight). Venous blood samples were collected before and after competition. Blood samples were analyzed for acid–base balance, as well as biochemical and electrolyte parameters. In stallions, a significant (P < .05) postexercise increase in pH, partial pressure of oxygen, bicarbonate concentration, base excess, and glucose was noted. Decrease (P < .05) in pCO₂ (partial pressure of carbon dioxide), chloride and ionized calcium were observed after exercise only in stallions. No changes (P > .05) in hematocrit, hemoglobin, sodium, and potassium were observed after exercise in all animals. The changes in the acid–base balance and electrolyte profile of the Mangalarga Marchador stallions after marcha competition resulted in hypochloremic metabolic alkalosis. Marcha competition did not cause acid–base disturbance in mares. This study enables an evaluation and comparison of physical effort caused by the marcha exercise on acid–base balance in Mangalarga Marchador horses and provides further evidence of the existence of gender differences in sports horses.     

Gender Differences–Induced Changes in Serum Hematologic and Biochemical Variables in Mangalarga Marchador Horses After a Marcha Gait Competition

The aim of this study was to investigate whether marcha exercise results in changes in serum hematologic and biochemical variables and whether this condition differs in male and female horses. Thirty-five Mangalarga Marchador horses, 18 males and 17 females were included in the study. Blood samples were obtained before and immediately after a marcha competition. Samples were used for measurement of hematocrit (HCT), hemoglobin concentration (HGB), red blood cell (RBC), total and differential white blood cell (WBC), total protein (TP), albumin (Alb), aspartate aminotransferase (AST), gamma glutamyltransferase (GGT), creatine kinase (CK), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), creatinine (Crea), and urea (BUN) levels. Data were submitted to analysis of variance using the SAS statistical program, and means were compared by the Tukey test (P < .05). In both males and females, RBC, HCT, AST, and GGT activity increased in response to exercise, but there were no significant differences between genders. In females, significant increases in TP, BUN, Crea, CK, and LDH levels were detected after the marcha gait, but no such changes were detected in males. Total WBC concentrations increased in response to the exercise in both, males and females; however, there were no differences between genders. Plasma HGB, Alb, and ALP levels after marcha gait did not differ in both genders. Marcha exercise–induced significant hematologic and biochemical changes in serum of Mangalarga Marchador horses, independently of gender. However, females presented more blood changes after marcha gait. Gender differences should be taken into consideration in experiments with athletic horses.     

Polymorphisms in MCT1, CD147, PDK4, and DMRT3 genes in Arabian and Quarter Horses

Monocarboxylate transporter isoform 1 (MCT1) and its ancillary protein, CD147 function to transport H⁺ and lactate ions, retarding systemic acidosis and fatigue. The PDK4 gene is involved in the adenosine triphosphate production, and the DMRT3 gene is involved in the locomotor system. This study investigated polymorphisms of MCT1, CD147, PDK4, and DMRT3 in Arabian and Quarter Horses to associate polymorphisms with performance. Arabian Horses were divided into high performance and untrained horses groups based on success in endurance competition, whereas Quarter Horses were separated by a speed index. Polymorphisms were analyzed by sequencing (MCT1 and CD147), ARMS-PCR (PDK4), and PCR-RFLP (DMRT3). To compare the frequencies of SNPs, the Fisher's exact test was performed in the software R at 5% of significance. The A alleles from the polymorphisms Lys457Gln:1573A>C of MCT1 and Ile51Val:168A>G of CD147 were essentially fixed in both breeds. Only two Arabian from the high performance and one from the untrained horses group appeared AC in MCT1. For the DMRT3 polymorphism (g.22999655C>A:ECA23), all the animals were CC, except one Arabian in the high and two Quarter Horses in the low performance group that were AC. For the PDK4 polymorphism (g.38973231A>G:ECA4), Arabian showed a significantly greater frequency of the G allele than Quarter Horses (P < .01). Considering the kind of exercise practiced by each breed, it is likely that the PDK4 polymorphism influences the pathway to energy production.     

The effect of the ‘Gait keeper’ mutation in the DMRT3 gene on gaiting ability in Icelandic horses

A nonsense mutation in DMRT3 (‘Gait keeper’ mutation) has a predominant effect on gaiting ability in horses, being permissive for the ability to perform lateral gaits and having a favourable effect on speed capacity in trot. The DMRT3 mutant allele (A) has been found in high frequency in gaited breeds and breeds bred for harness racing, while other horse breeds were homozygous for the wild‐type allele (C). The aim of this study was to evaluate further the effect of the DMRT3 nonsense mutation on the gait quality and speed capacity in the multigaited Icelandic horse and demonstrate how the frequencies of the A‐ and C‐ alleles have changed in the Icelandic horse population in recent decades. It was confirmed that homozygosity for the DMRT3 nonsense mutation relates to the ability to pace. It further had a favourable effect on scores in breeding field tests for the lateral gait tölt, demonstrated by better beat quality, speed capacity and suppleness. Horses with the CA genotype had on the other hand significantly higher scores for walk, trot, canter and gallop, and they performed better beat and suspension in trot and gallop. These results indicate that the AA genotype reinforces the coordination of ipsilateral legs, with the subsequent negative effect on the synchronized movement of diagonal legs compared with the CA genotype. The frequency of the A‐allele has increased in recent decades with a corresponding decrease in the frequency of the C‐allele. The estimated frequency of the A‐allele in the Icelandic horse population in 2012 was 0.94. Selective breeding for lateral gaits in the Icelandic horse population has apparently altered the frequency of DMRT3 genotypes with a predicted loss of the C‐allele in relatively few years. The results have practical implications for breeding and training of Icelandic horses and other gaited horse breeds.     

Post-exercise endoscopic and cytologic diagnosis of equine asthma syndrome in asymptomatic Brazilian pacers

The objectives were: 1. to investigate the occurrence of equine asthma syndrome (EAS) in a group of Campolina and Mangalarga Marchador horses through post-exercise respiratory endoscopy and cytology; 2. compare the efficiency of different diagnostic criteria; and 3. compare the incidence of EAS by breed, age group and sex. A standardised exercise test was conducted in the field, followed by respiratory endoscopy and bronchoalveolar lavage and fluid collection 30 min post-exercise. Clinical evaluation pre- and post-exercise, respiratory endoscopy post-exercise and bronchoalveolar lavage, also post-exercise, were conducted in 30 horses (15 Campolina and 15 Mangalarga Marchador) aged 3–18 years, without a history of respiratory illness and without clinical evidence of active respiratory disease. All horses were in active training and were considered fit to participate in equestrian competition characteristic of these breeds. Post-collection, the horses were subdivided into healthy or EAS-positive, depending on several diagnostic criteria. Statistical comparisons between breeds, age brackets (up to 7 years of age and above 7 years of age) and sex were conducted using appropriate statistical tests. According to bronchoalveolar lavage fluid (BALF) cytology, 56.7% of the horses showed at least one inclusion criteria that contributed to classification as EAS-positive. Of those, only one was classified as moderate EAS, while the others were classified as mild. Total cell count in the BALF above 530 cells/µL was the single most common diagnostic criteria (100%), followed by increased tracheal mucus (53%) at endoscopy, eosinophilia (47%) and neutrophilia (35%) in BALF. Significant differences were found between macrophage and lymphocyte numbers according to breed, but no other differences between breeds, age brackets, sex or status (healthy vs. EAS-positive). A high occurrence of EAS was found in competition-ready Mangalarga and Campolina pacer horses in this study.     

玉树马和德保矮马SLC36A1基因多态性研究

 控制马香槟毛色的CH（Champagne gene）基因家族包含4个候选基因（SLC36A1、SLC36A2、SLC36A3、SPARC）,研究发现SLC36A1基因外显子2的突变是造成马香槟毛色的关键位点。为揭示中国马SLC36A1基因遗传多态性,本研究以玉树马和德保矮马共74个样本为研究对象,以马DNA池为模板扩增SLC36A1基因的10个外显子及部分内含子序列并进行测序分析。共发现马SLC36A1基因5个SNPs,分别位于内含子3（g.26699953 A>G, g.26699851 G>C, g.26699850 G>C）,外显子4（g.26699562 G>A）及外显子6（g.26697018 C>T）。利用PCR RFLP方法对74个家马样本进行基因分型,发现外显子6的SNP有基因型CC、CT;外显子4的SNP有基因型GG、GA;内含子3的g.26699850 G>C突变有基因型GG、GC;内含子3的另外2个SNPs（g.26699953 A>G, g.26699851 G>C）通过测序,发现有AA、AG、GG与GG、GC、CC基因型。所有5个马SNPs均为野生型占主要优势。由此界定了马SLC36A1基因有9种单倍型（H1 H9）,其中H5是最主要的单倍型。德保矮马遗传多样度为0.4190,比玉树马（0.2228）高,表明德保矮马香槟毛色遗传多态性比玉树马更丰富。玉树马与德保矮马的平均单倍型多样度为0.3160,表明其香槟毛色遗传多态性相对较低。     

Evaluation of the sexual dimorphism in Mangalarga Marchador horses using discriminant analysis

This study used discriminant analysis to evaluate body measures and sexual dimorphism in Mangalarga Marchador horses. Discriminant analysis is a multivariate method that generates functions to classify animals using a prior criterion. In this study a prior criterion is male or female. The study analyzed 25 linear and 11 angular measures obtained from 25 stallions and 56 mares registered with the Mangalarga Marchador Brazilian Breeders Association. Knee girth, cannon girth, chest width, chest girth, back-loin length, hip width, distance from elbow to knee, hind limb hoof length, head width, shoulder length, and body length were found to be linear measures that provided evidence of sexual dimorphism. Angular measures with evidence of sexual dimorphism were shoulder–humerus, metacarpal–phalanx, coxae–femur, and femur–tibial angles. Stallions were larger than mares for almost all linear measures, except for back-loin length, hip width, and distance from elbow to knee. Shoulder–humerus and coxal–femur angles were larger in mares, while metacarpal–phalanx and femur–tibial angles were larger in stallions. Using linear measures, two mares were classified as stallions and three stallions were classified as mares. For angular measures, two other mares were classified as stallions and three other stallions were classified as mares. The discriminant functions can be useful for the selection of horses and to avoid registration of animals not meeting the phenotypic standards of the breed association.     

Genetic Characterization of Mangalarga Marchador Breed Horses Based on Microsatellite Molecular Markers

The Mangalarga Marchador (MM) horse breed has expressive importance in the Brazilian economy. Thus, the aim of this study was to investigate diversity in the MM breed. A database with a total of 3,193 genotyped horses was used (MM, n = 2,829; Andalusian – AND, n = 67; Pure Blood Lusitano – LUS, n = 43; English Thoroughbred – THO, n = 54; Arabian – ARA, n = 99; Campolina – CAM, n = 61; and Mangalarga – MAN, n = 40) for 13 microsatellite. Diversity parameters were estimates, such as mean number of alleles (Nm_a) and the number of rare alleles (AR), expected heterozygosity (He), F statistics, genetic distances, Hardy-Weinberg equilibrium test (HWE), population structure, and others. The Nm_a was 10.85, the AR was prevalent in the MM, and the He was 0.7402. In MM, the values of Fis (−0.0195), Fit (0.0566), Fst (0.0748), and deviations of HWE were observed. The genetic distances of the ARA and THO breeds with the other breeds were greater than the distances between the Brazilian breeds and between these and the breeds in the Iberian Peninsula. The population structure indicated that MM was substructured, yet there were some more genetically defined breeding farms. The genetic diversity is satisfactory for MM conservation, but the population is substructure, and parameters indicate moderate gene flow and the existence, though few, of crosses with other horse breeds. Immediate implementation of a genetic breeding program is required, especially seeking to conserve the structure of the MM breed as a well-defined genetic entity.     

Genotype distribution and allele frequencies of the genes associated with body composition and locomotion traits in Myanmar native horses

Myanmar native horses are small horses used mainly for drafting carts or carriages in rural areas and packing loads in mountainy areas. In the present study, we investigated genotype distributions and allele frequencies of the LCORL/NCAPG, MSTN and DMRT3 genes, which are associated with body composition and locomotion traits of horses, in seven local populations of Myanmar native horses. The genotyping result of LCORL/NCAPG showed that allele frequencies of C allele associated with higher withers height ranged from 0.08 to 0.27, and 0.13 in average. For MSTN, allele frequencies of C allele associated with higher proportion of Type 2B muscular fiber ranged from 0.05 to 0.23, and 0.09 in average. For DMRT3, allele frequencies of A allele associated with ambling gait ranged from 0 to 0.04, and 0.01 in average. The presences of the minor alleles of these genes at low frequencies suggest a possibility that these horse populations have not been under strong selection pressure for particular locomotion traits and body composition. Our findings of the presence of these minor alleles in Southeast Asian native horses are also informative for considering the origins of these minor alleles associated with body composition and locomotion traits in horse populations.     

Distribution of the mutant allele of the DMRT3 gene associated with ambling gaits in Japanese native horse populations

There are currently eight native horse populations in Japan, namely, Hokkaido, Kiso, Noma, Taishu, Misaki, Tokara, Miyako, and Yonaguni horses. Since locomotion traits, including gaitedness, are important for riding and packing horses, the genetic properties associated with these traits could be informative for understanding the characteristics and history of these horses. In this study, we investigated the distribution of the mutant allele of DMRT3 gene (DMRT3:p.Ser301Ter) associated with ambling gaits in the Japanese native horse. We also examined haplotypes of SNPs in the 83‐kb region including DMRT3 gene by genotyping four SNPs in this region. The results revealed the presence of DMRT3:p.Ser301Ter in the Hokkaido and Yonaguni populations at allele frequencies of 0.18 and 0.02, respectively, and the observed haplotype associated with DMRT3:p.Ser301Ter was estimated as the most common haplotype in the horses in the world. Since DMRT3:p.Ser301Ter has been hypothesized to spread across Eurasian continent from Medieval England after 850 to 900 CE, our findings of the presence of DMRT3:p.Ser301Ter with the common haplotype in the Japanese native horses will provide a new insight into the history of the Japanese native horse, such as considerable level of gene flow from Eurasian continent after 850 to 900 CE.     

Quantitative analysis of short‐ and long‐distance racing performance in young and adult horses and association analysis with functional candidate genes in Spanish Trotter horses

The association of five candidate genes with sporting performance in young and adult Spanish Trotter horses (STHs) was performed according to a previous selection based on quantitative analysis of the trait time per kilometre (TPK). A total of 334 516 records of TPK from 5958 STHs were used to estimate the estimated breeding values (EBVs) at different age groups (young and adults horses) throughout the range of distances (1600–2700 m) using a bicharacter random regression model. The heritability estimated by distance ranged from 0.16 to 0.40, with a different range for the two age groups. Considering the animals with the best and the worst deregressed EBV, 321 STHs were selected for SNP genotyping in MSTN, COX4I2, PDK4, DMRT3 and CKM genes. An association analysis based on ridge and logistic regression revealed that the young trotters with genotype GG in PDK4 (p < 0.05) and AA of DMRT3 (p < 0.001) SNPs show the best potential in short‐distance races, while those carrying the genotype AA in DMRT3 (p < 0.001) and CC in CKM (p < 0.05) genes seem to be the best in long‐distance races. Adult trotters with genotype AA in DMRT3 also display greater speed (p < 0.05) and endurance (p < 0.001).     

Correcting Campylorrhinus Lateralis in a Foal by Bone Distraction: A Case Report

Campylorrhinus lateralis, also known as “wry nose,” is a congenital malformation that mainly affects Thoroughbreds. These horses have a unilateral deviation of the maxillae that may be to one side or the other side, and it causes airway obstruction and dental malocclusion. The choice of treatment is not necessarily operation; however, the treatment of choice, which aims to repair the maxillae deviation, is surgical to improve the horse’s respiratory condition and correct the dental occlusion. There are currently no reports describing the first surgical technique for such deformity described by Valdez et al. The present study describes the case of a 2-month-old foal of the Mangalarga Marchador breed that was diagnosed with wry nose. The foal presented with accentuated maxillae deviation to the right side, malocclusion of the incisor teeth, and respiratory noises. After diagnosis and physical examination, the foal was treated by surgical correction of the deviation. To correct the deviation, the bone distraction technique with unilateral osteotomy of the right maxillae and fixation of the external bone distractor was chosen. After 90 days, the bone distractor was removed; consequently, malocclusion of the incisors was greatly improved, and respiratory noises were eliminated.     

Association between melanocortin 4 receptor (MC4R) gene haplotypes and carcass and production traits in Italian Large White pigs evaluated with a selective genotyping approach

Melanocortin 4 receptor (MC4R) plays a key role in controlling energy homeostasis. Several studies have already reported effects on production traits of polymorphisms identified in the porcine MC4R gene. In this study we analysed data on 6 MC4R polymorphisms (c.-780C>G; c.-135C>T; c.175C>T; c.707G>A or p.Arg236His; and c.892G>A or p.Asp298Asn; c.?430A>T) genotyped from (1) two groups of Italian Large White pigs (280+280 animals) with extreme estimated breeding values (EBVs) for back fat thickness (BFT), selected among a performance tested population of about 12,000 pigs, and from (2) 19 Italian Duroc pigs. Two haplotypes, differentiated by the c.892G>A, were identified in the Duroc populations. Four haplotypes were identified in the Italian Large White population, one of which (haplotype 4) was identified for the first time in this study. Single marker and haplotype association analyses for BFT were obtained by comparing allele and haplotype frequency differences from the two extreme tails using χ² and Cochran–Armitage trend tests. Results confirmed the effects of the c.892G>A single nucleotide polymorphism (SNP) on BFT, as also defined by different distributions in the two tails of haplotypes carrying the alternative nucleotides at this polymorphic site (P<0.01). In addition different distributions of haplotype 4 in the two extreme groups suggested that it might affect the same trait (P<0.10). Association analyses for several other traits (average daily gain, ADG; feed gain ratio, FGR; weight of lean cuts; ham weight) were carried out by using EBVs and Random Residuals: significant effects (P<0.05) were only found for the p.Asp298Asn mutation on ADG and FGR. Results did not support any relevant effect of the p.Arg236His mutation on any trait. Data reported in this study contribute to better understand the role of MC4R variants in affecting production traits in pigs, a prerequisite to consider polymorphisms in this gene for marker assisted selection.     

Association between novel variants in BMPR1B gene and litter size in Mongolia and Ujimqin sheep breeds

Prolificacy is an important trait of animals, specifically for sheep. The Bone morphogenetic protein receptor 1B (BMPR1B) is a major gene affecting the litter size of many sheep breeds. The well-known FecB mutation (Q249R) was associated fully with the hyper prolific phenotype of Booroola Merino. However, the identification of variation in all exonic regions of BMPR1B was rare. In this study, we sequenced all exonic regions of BMPR1B gene of Mongolia sheep breed, and ten novel variants were detected by direct sequencing. Among them, the litter size of the Mongolia ewes with the CC genotype was significantly higher (0.34 additional lambs, p < .05) than those with the TT genotype of the g.29346567C>T single nucleotide polymorphism (SNP). The litter size of the Mongolia ewes with the TT genotype was significantly higher (0.19 additional lambs, p < .05 and .31 additional lambs, p < .01, respectively) than those with the GT and GG genotypes of the c.1470G>T SNP. The silent c.1470G>T mutation is predicted to increase the stability of the mRNA secondary structure through reducing minimum free energy and is predicted to change the mRNA secondary structure of BMPR1B. Our findings may give potentially useful genetic markers for increasing litter size in sheep.     

Breed Differences in Dopamine Receptor D4 Gene (DRD4) in Horses

Genetic polymorphisms in genes related to neurotransmitters or hormones affect personality or behavioral traits in many animal species including humans. In domestic animals, the allele frequency of such genes has been reported to be different among breeds and it may account for breed differences in behavior. In this study, we investigated breed differences in horses in the dopamine receptor D4 gene (DRD4), which has been reported to affect horse personality. We collected samples from seven horse breeds including those native to Japan and Korea, and compared the sequence of the DRD4 exon3 region among these breeds. We found that there were two types of polymorphisms (VNTR and SNPs) in the exon3 region, and some of them seemed to be breed-specific. In addition, we found that the allele frequency of G292A, reported to be associated with horse personality, differed greatly between native Japanese horses and Thoroughbred horses. The frequency of the A allele which is associated with low curiosity and high vigilance, was much lower in native Japanese horses (Hokkaido, 0.03; Taishu, 0.08) than in Thoroughbreds (0.62). This difference may account for breed differences in personality or behavioral traits. Further studies of the function of these polymorphisms and their effect on behavior are indicated.     

Association of a novel SNP in exon 10 of the IGF2 gene with growth traits in Egyptian water buffalo (Bubalus bubalis)

Insulin-like growth factor 2 (IGF2) plays an important role in muscle growth and it might be used as a marker for the growth traits selection strategies in farm animals. The objectives of this study were to detect polymorphisms in exon 10 of IGF2 and to determine associations between these polymorphisms and growth traits in Egyptian water buffalo. PCR-single-strand conformation polymorphism (SSCP) and DNA sequencing methods were used to detect any prospective polymorphism. A novel single nucleotide polymorphism (SNP), C287A, was detected. It was a non-synonymous mutation and led to replacement of glutamine (Q) amino acid (aa) by histidine (H) aa. Three different SSCP patterns were observed: AA, AC, and CC, with frequencies of 0.540, 0.325, and 0.135, respectively. Association analyses revealed that the AA individuals had a higher average daily gain (ADG) than other individuals (CC and AC) from birth to 9 months of age. We conclude that the AA genotype in C287A SNP in the exon 10 of the IGF2 gene is associated with the ADG during the age from birth to 9 months and could be used as a potential genetic marker for selection of growth traits in Egyptian buffalo.     

UTS2R gene polymorphisms are associated with fatty acid composition in Japanese beef cattle

Fatty acid composition of beef adipose tissue is one of its important traits because a high proportion of monounsaturated fatty acid is related to favorable beef flavor and tenderness. In this study, we searched polymorphisms in full length coding DNA sequence of urotensin 2 recepter and investigated the effects on fatty acid composition (C14:0, C14:1, C16:0, C16:1, C18:0, C18:1, C18:2, monounsaturated fatty acid, saturated fatty acid). Eight single nucleotide polymorphisms (SNP) were identified by sequence comparison among eight animals, including five Japanese Black and three Holstein cattle. One of these SNP (c.866C>T) was predicted to cause amino acid substitutions (P289L) and the other seven synonymous SNP, including c.267C>T, were presumed to be in linkage disequilibrium. Therefore we selected two SNP (c.267C>T and c.866C>T) for further analysis. We investigated associations between these genotypes and fatty acid composition in three Japanese Black populations (n = 560, 245 and 287) and a Holstein population (n = 202). Tukey‐Kramer's honestly significant difference test revealed that CC genotype in c.267C>T indicated lower C14:0 and higher C18:1 than the other genotypes in Japanese Black cattle and CC genotype in c.866C>T showed lower C16:1 than CT genotype in Holstein cattle (P < 0.05). These results suggested that these genotypes would contribute to production of high‐grade meat as selection markers in beef cattle.     

Identification of genomic regions that exhibit sexual dimorphism for size and muscularity in cattle

Sexual dimorphism, the phenomenon whereby males and females of the same species are distinctive in some aspect of appearance or size, has previously been documented in cattle for traits such as growth rate and carcass merit using a quantitative genetics approach. No previous study in cattle has attempted to document sexual dimorphism at a genome level; therefore, the objective of the present study was to determine whether genomic regions associated with size and muscularity in cattle exhibited signs of sexual dimorphism. Analyses were undertaken on 10 linear-type traits that describe the muscular and skeletal characteristics of both males and females of five beef cattle breeds: 1,444 Angus (AA), 6,433 Charolais (CH), 1,129 Hereford, 8,745 Limousin (LM), and 1,698 Simmental. Genome-wide association analyses were undertaken using imputed whole-genome sequence data for each sex separately by breed. For each single-nucleotide polymorphism (SNP) that was segregating in both sexes, the difference between the allele substitution effect sizes for each sex, in each breed separately, was calculated. Suggestively (P ≤ 1 × 10⁻⁵) sexually dimorphic SNPs that were segregating in both males and females were detected for all traits in all breeds, although the location of these SNPs differed by both trait and breed. Significantly (P ≤ 1 × 10⁻⁸) dimorphic SNPs were detected in just three traits in the AA, seven traits in the CH, and three traits in the LM. The vast majority of all segregating autosomal SNPs (86% in AA to 94% in LM) had the same minor allele in both males and females. Differences (P ≤ 0.05) in allele frequencies between the sexes were observed for between 36% (LM) and 66% (AA) of the total autosomal SNPs that were segregating in both sexes. Dimorphic SNPs were located within a number of genes related to muscularity and/or size including the NAB1, COL5A2, and IWS1 genes on BTA2 that are located close to, and thought to be co-inherited with, the MSTN gene. Overall, sexual dimorphism exists in cattle at the genome level, but it is not consistent by either trait or breed.