Homozygosity of single nucleotide polymorphisms in the 3′ region of the canine estrogen receptor 1 gene is greater in Toy Poodles than in Miniature Dachshunds and Chihuahuas

Differences in the distribution of single nucleotide polymorphisms (SNPs) and haplotypes in the estrogen receptor α gene (ESR1) were examined in Miniature Dachshunds (n = 48), Chihuahuas (n = 20) and Toy Poodles (n = 18). Five DNA fragments located in the 40‐kb region at the 3′ end of ESR1 were amplified by polymerase chain reaction and were directly sequenced. We compared allele, genotype and estimated haplotype frequencies at each SNP in the 3′ end of ESR1 for these three breeds of small dog. The frequency of the major allele and the genotype frequency of the major allele homozygotes, were significantly higher in Toy Poodles for five SNPs (SNP #5, #14–17) than in Miniature Dachshunds, and significantly higher in Toy Poodles than Chihuahuas for three SNPs (SNP #15–17). A common haplotype block was identified in an approximately 20‐kb region encompassing four SNPs (SNPs # 14–17). The frequencies of the most abundant estimated haplotype (GTTG) and GTTG homozygotes were significantly higher in Toy Poodles than in the other two breeds. These results imply that homozygosity for the allele, genotype and haplotype distribution within the block at the 3′ end of ESR1 is greater in Toy Poodles than in Miniature Dachshunds and Chihuahuas.     

Ophthalmic and cone derived electrodiagnostic findings in outbred Miniature Long-haired Dachshunds homozygous for a RPGRIP1 mutation

Objective To investigate ophthalmic and cone‐derived electrodiagnostic findings in outbred Miniature Long‐haired Dachshunds (MLHD) homozygous for a mutation in the RPGRIP1 gene previously associated with cone‐rod dystrophy 1 (cord1). Animals A total of 36 MLHD homozygous for the RPGRIP1 mutation and 23 dogs clear of the mutation (control group). Procedures The dogs underwent ophthalmic examination and photopic electroretinogram (ERG) recordings. Results None of the control dogs presented with clinical or ophthalmic signs consistent with cord1. Amongst the dogs homozygous for the mutation one presented with bilateral symmetrical total retinal atrophy. None of the other dogs in this group showed signs consistent with cord1. Photopic ERG recordings were available in 23 control dogs and 34 dogs homozygous for the mutation. Photopic a‐ and b‐waves following four light stimuli (3 cdS/m²) at a rate of 5.1 Hz were not significantly different between groups. The amplitudes of the 30 Hz flicker (128 flashes, 3 cdS/m²) response were significantly reduced in the dogs homozygous for the PRGRIP1 mutation. The difference in age between the two groups did not significantly affect the difference. Conclusion Homozygosity of the RPGRIP1 mutation does not invariably result in early onset cord1. However, cone derived ERG recordings show evidence of a reduced cone or inner retinal function in homozygous but clinically normal MLHD. Modifying genes that have yet to be identified may influence an individual dog’s risk of developing the blinding cord1 and also the age of onset and rate of progression.     

Evaluation of canine heat shock transcription factor 4 (HSF4) as a candidate gene for primary cataracts in the Dachshund and the Entlebucher Mountain dog

OBJECTIVE: Testing of the cataract-causing insertion/deletion mutation in the canine HSF4 gene for its linkage and association with primary cataracts (CAT) in Dachshunds and Entlebucher Mountain dogs. MATERIALS: Exon 9 with flanking intronic regions of the canine HSF4 gene was sequenced in 24 Dachshunds and 20 Entlebucher Mountain dogs. The HSF4 cDNA sequence of lens tissue was analyzed in a CAT-unaffected mixed-breed dog and in three CAT-affected dogs of different breeds, including a Wire-haired Dachshund, a Dachshund-mix and a German Shepherd dog. RESULTS: In all dogs investigated here, the previously reported CAT-causing mutation did not exist. We found a single nucleotide polymorphism (SNP) in intron 9, which was neither associated nor linked with the CAT phenotype in the two dog breeds. CONCLUSION: The CAT phenotype in the two dog breeds investigated here was not caused by the same mutation found to be associated with early-onset CAT in the Staffordshire Bull Terrier and Boston Terrier. The intronic SNP may be useful to test HSF4 for linkage with CAT in further dog breeds.     

Scanning 17 candidate genes for association with primary cataracts in the wire-haired Dachshund

Primary cataracts are breed-related eye diseases and are common in many dog breeds. In this study, 17 genes (BFSP2, EYA1, FOXE3, FTL, GCNT2, GJA3, GJA8, HSF4, MAF, MIP, PAX6, PITX3, SIX5, SORD, SOX1, SPARC, TRNT1) were evaluated as candidates for primary non-congenital cataracts (CAT) in the Dachshund using microsatellites adjacent to the candidate genes. Linkage and association with CAT was tested in 15 affected and six unaffected wire-haired Dachshunds. Non-parametric linkage analysis and association tests did not reveal significant linkage or association for the candidate gene flanking microsatellites tested. Thus, it is unlikely that the 17 investigated candidate genes harbour a causative mutation for CAT in these Dachshunds.     

A morphometric investigation on breed-specific features affecting sagittal rotational and lateral bending mobility in the canine cervical spine (c3-c7)

Vertebral and inter-vertebral parameters obtained in large breeds (n = 74), small breeds (n = 35), and Dachshunds (n = 30) were compared to reveal potential differences in the range of motion of the cervical spine between these three groups of breeds. Body size normalized dimensions of vertebral and inter-vertebral parameters and correlations between these indicate large canine breeds to have a tendency towards higher range of motion in sagittal rotation and lateral bending compared with Dachshunds and small breeds. Higher mobility in large breeds is based on significantly (P < 0.05) lower vertebral endplate heights and widths, shorter vertebral bodies and longer inter-vertebral discs, wider but shorter cranial and caudal articular surfaces, larger differences in width between caudal and cranial joining facets (compared with Dachshunds from C3/4 to C6/7, compared with small breeds from C4/5 to C5/6), and larger differences in length between caudal and cranial joining facets. Large differences in width between caudal and cranial joining facets were associated with small distances between the most medial (C3/4 to C6/7) and lateral (C3/4 to C5/6) aspects of the articular surfaces as well as with small differences in length between caudal and cranial joining facets (C3/4 to C5/6). This suggests that from C3/4 to C5/6 a higher range of motion in lateral bending is coupled to a lower range of motion in sagittal rotation. The present findings contribute also to explain the higher incidence of degenerative lesions of the cervical spine in large dogs.     

Holter monitoring in clinically healthy Cavalier King Charles Spaniels, Wire-haired Dachshunds, and Cairn Terriers

Background: Few reported studies describe normal values from 24‐hour ECG (Holter) recordings of small breed dogs. Objectives: To investigate influence of breed, age, sex, body weight, degree of recording artifact, and mitral valve prolapse (MVP) on Holter recordings of 3 breeds of small dogs that have differing predispositions for myxomatous mitral valve disease. The study also assessed if heart rate (HR) at clinical examination (HRex) was associated with HR during Holter monitoring and evaluated the reproducibility of Holter variables. Animals: Fifty clinically healthy, privately owned dogs of the breeds Cavalier King Charles Spaniel (CKCS), Wire‐haired Dachshund (wD), or Cairn Terrier (CT). Methods: Prospective, longitudinal observational study. Dogs were recruited for clinical examination, echocardiography, and Holter monitoring. In 8 CKCS, Holter recordings were performed twice with a 7‐day interval. Arrhythmia and heart rate variability (HRV) analysis (time and frequency domain analysis) were performed on Holter recordings. Results: Fifteen out of 27 Holter derived variables were significantly associated with breed (P < .03), but not with age (P > .7), sex (P > .2), body weight (P > .7), degree of recording artifact (P > .4), or MVP (P > .6). During Holter recording, minimum (P= .0001) and mean HR (P= .0001) were higher in CKCS compared with wD. CKCS had significantly lower values than wD, CT, or both in 10 out of 13 HRV variables (P < .03). Minimum and mean HR during Holter recording were correlated with HRex (r= 0.55, P= .0003). HR and time domain variables had a coefficient of variation <10%. Conclusions and Clinical Importance: There is an influence of breed on Holter‐derived variables in 3 breeds of small dogs. Arrhythmia and HRV analysis can be performed on 24‐hour ambulatory ECG (Holter) recordings. Arrhythmia analysis includes HR measurements and identification of arrhythmias.     

Osteological features in pure-bred dogs predisposing to thoracic or lumbar spinal cord compression

Consistent with those vertebral sites most commonly clinically affected by spinal cord compression, body size normalised midsagittal diameters of the caudal vertebral foramen limits T10-T12 were significantly (P<0.05) lower in Dachshunds relative to other breeds. Minimal midsagittal diameters in Yorkshire Terriers and Maltese were noted at T11cd/12cr. However, these diameters were always larger (P<0.05) in small breeds compared to those in Dachshunds and large breeds suggesting that the small breeds investigated are at lower risk of developing clinical signs if a compressive disease occurs at that site. In large breeds, minimal values were present at L1cd/L2cr and in agreement with clinical findings correlate with those spinal sites most susceptible to spinal cord compression in nonchondrodystrophic large breeds. Caudal displacement of the lumbosacral enlargement of the spinal cord relative to the position previously noted in large breeds was confirmed for the Dachshunds and 50% of small breeds. However, caudal displacement was also noticed in the German Shepherd dogs.     

Novel polymorphism of the canine dopamine receptor D4 gene intron II region

Various dog breeds are remarkably different from each other not only in their sizes and shapes but also in behavioral traits, suggesting that some of these characteristics are under genetic control. However, little is known about genes related to behavioral traits in canine species. In humans, it has been reported that the dopamine receptor D4 gene (DRD4) includes polymorphism at several regions that relate to personality or psychiatric disorders. In an earlier study by the authors of the present study, the polymorphisms in canine DRD4 exon III and exon I regions were reported. In the present study, a novel polymorphism in canine DRD4 intron II was found based on a 17 base pair insertion/deletion, and the two alleles detected were named P (shorter allele) and Q (longer allele). The allelic distribution in 28 breeds of dog, including a total of 1114 unrelated individuals, were then investigated. Both P and Q alleles were detected in most of the breeds investigated; however, the frequencies of P and Q differed greatly between breeds. With respect to classification based on breed origin, P and Q alleles were frequent in Occidental and Oriental breeds, respectively. Furthermore, two subspecies of wolves, the ancestors of dogs, were analyzed for the comparison of allele frequencies with dogs, and the P allele was predominant in both European and Chinese wolves.     

Characteristic features of porcine endogenous retroviruses in Vietnamese native pigs

We aimed to clarify the genomic characteristics of porcine endogenous retroviruses (PERVs) in Vietnamese native pig (VnP) breeds. First, we investigated genetic polymorphisms in β‐ and γ‐like PERVs, and we then measured the copy numbers of infectious γ‐like PERVs (PERV‐A, B, and C). We purified genomic DNA from 15 VnP breeds from 12 regions all over the country and three Western pig breeds as controls, and investigated genetic polymorphisms in all known PERVs, including the beta (β)1–4 and gamma (γ)1–5 groups. PERVs of β1, β2, β3, and γ4 were highly polymorphic with VnP‐specific haplotypes. We did not identify genetic polymorphisms in β4, γ1, or γ2 PERVs. We then applied a real‐time polymerase chain reaction–based method to estimate copy numbers of the gag, pol, and env genes of γ1 PERVs (defined as A, B, and C). VnP breeds showed significantly lower copy number of the PERV genes compared with the Western pig breeds (on average, 16.2 and 35.7 copies, respectively, p < .05). Two VnP breeds showed significantly higher copy number compared with the other VnPs (p < .05). Our results elucidated that VnPs have specific haplotypes and a low copy number of PERV genes.     

Coat colour genes in diversity studies

In this paper we describe the use of polymorphic genes affecting coat colour as a tool in diversity studies of domestic animals. Although phenotypic data has been the main criteria for establishing different breeds, calculation of genetic distances between breeds is normally performed using noncoding microsatellite markers. As anticipated, MC1‐R (melanocyte stimulating hormone receptor) allele frequencies vary greatly between cattle breeds expressing different coat colours. In multicoloured breeds, like Icelandic cattle, a high frequency of the E⁺ allele appears to be essential for colour variation. Whereas black breeds have a high frequency of the dominant acting allele E^D, entirely red breeds have no E^D. Animals being homozygous for the defective allele e occurred frequently in some cattle breeds, indicating that the MC1‐R does not have crucial impact on animal physiology other than coat colour. The E⁺ and e alleles were observed in the closely related river buffalo as well. None of the breeds included in this study express the roan phenotype. Consequently, they were monomorphic at the MGF locus. As for the MC1‐R locus, a correlation to colour pattern was observed for two c‐kit alleles as well, confirming that selection of specific phenotypes strongly affect the allelic variation of underlying loci. Information on genes affecting the phenotype is therefore well suited for describing different breeds of livestock and, consequently, a practical tool in breed conservation.     

An insight into population structure and gene flow within pure‐bred cats

Investigation of genetic structure on the basis of pedigree information requires indicators adapted to the specific context of the populations studied. On the basis of pedigree‐based estimates of diversity, we analysed genetic diversity, mating practices and gene flow among eight cat populations raised in France, five of them being single breeds and three consisting of breed groups with varieties that may interbreed. When computed on the basis of coancestry rate, effective population sizes ranged from 127 to 1406, while the contribution of founders from other breeds ranged from 0.7 to 16.4%. In the five breeds, F_IS ranged between 0.96 and 1.83%, with this result being related to mating practices such as close inbreeding (on average 5% of individuals being inbred within two generations). Within the three groups of varieties studied, F_IT ranged from 1.59 to 3%, while values were estimated between 0.04 and 0.91%, which was linked to various amounts of gene exchanges between subpopulations at the parental level. The results indicate that cat breeds constitute populations submitted to low selection intensity, contrasting with relatively high individual inbreeding level caused by close inbreeding practices.     

Production of bioactive bovine fibroblast growth factor 4 in E. coli based on the common nucleotide sequence of its structural gene in three breeds

Fibroblast growth factor 4 (FGF4) is considered a crucial gene in the proper development of bovine embryos. We recently determined the FGF4 gene sequence in eight cattle derived from three breeds and revealed a common nucleotide sequence of the structural gene encoding FGF4, which leads to the deletion and mutation of amino acid sequences in the mature FGF4 (Pro³²‐Leu²⁰⁶) compared with the sequence previously reported. In the present study, HisbFGF4, a 6× histidine‐tagged bovine FGF4 (Pro³²‐Leu²⁰⁶), was produced in Escherichia coli based on the validated nucleotide sequence and purified by heparin column chromatography. In primary bovine fibroblasts, HisbFGF4 showed significant mitogenic activity, whereas, intriguingly, the activity of a commercially available recombinant human FGF4 (Gly²⁵‐Leu²⁰⁶) produced in E. coli was weaker than that of HisbFGF4. In conclusion, the present study provides a simple method for the production of a bioactive bovine FGF4 derivative in E. coli utilizing its structural gene elucidated by us.     

Characterization of the biological behaviour of appendicular osteosarcoma in Rottweilers and a comparison with other breeds: a review of 258 dogs*

The purpose of this retrospective study was to compare Rottweilers diagnosed with osteosarcoma (OSA) with other breeds to determine whether Rottweilers experienced a more aggressive form of the disease. Two hundred and fifty‐eight dogs were evaluated (102 clinical and 156 necropsy cases). In the necropsy population, Rottweilers had a younger mean age at death (7.3 versus 9 years, P= 0.006). There were no significant differences between Rottweilers and other breeds in age at diagnosis, median disease‐free interval or survival time. However, Rottweilers were more likely to have metastasis to the brain (7 versus 0%, P= 0.03). These results suggest that OSA in Rottweilers may have a different biological behaviour, but this study did not confirm that these differences were associated with a worse outcome.     

Gain‐of‐function mutation in PTPN11 in histiocytic sarcomas of Bernese Mountain Dogs

Histiocytic sarcoma (HS) is an aggressive malignant neoplasm of dendritic cell origin that is common in certain breeds of dogs. High prevalence of fatal, disseminated HS has been described in Bernese Mountain Dogs (BMDs). Support for genetic predisposition to develop HS has been presented in several studies, but to date, causative genetic events have not been reported. In addition, no driver mutations have been identified in tumours. Recently, E76K gain‐of‐function mutation in SHP2 encoded by the PTPN11 gene has been described in human histiocytic malignancies. In our study, we identified the PTPN11^E76K in HS of BMDs. Amplification of exon 3 of the PTPN11 gene followed by Sanger sequencing was used to detect the mutation and estimate the prevalence in HS from 30 BMDs, 13 Golden Retrievers and 10 other dog breeds. The overall prevalence of PTPN11^E76K in HS of BMDs was 36.67% compared with 8.69% in other breeds. No mutation was identified in normal tissues from 10 BMDs with HS that carried the mutation and 12 control dogs with no neoplastic disease, including 6 BMDs. Increased immunoreactivity for AKT, phosphorylated ERK1/2 and phosphorylated AKT in a small subset of BMDs with PTPN11^E76K suggests that a gain‐of‐function might be mediated by the ERK and AKT pathways. These data suggest PTPN11^E76K as an important driver mutation of HS in BMDs. This information may not only aid in unravelling the tumourigenic events associated with HS in BMDs, but also help in identifying more promising therapeutic strategies.     

Brain penetration of emodepside is increased in P‐glycoprotein‐deficient mice and leads to neurotoxicosis

The antiparasitic drug emodepside (EMO) is a substrate of the P‐glycoprotein multidrug efflux carrier (P‐gp; syn. MDR1, ABCB1), which has an important function in protecting the brain from potentially toxic compounds by functional drug efflux at the blood–brain barrier (BBB). Many dogs of the Collie breed and even dogs of many other breeds have a loss‐of‐function 4‐bp deletion mutation in the MDR1 gene. In these dogs, brain penetration of many P‐gp‐transported drugs is increased and so their therapeutic usage is restricted. To elucidate the role of P‐gp at the BBB for the brain penetration of EMO, we applied EMO at 1 mg/kg to mdr1‐deficient (PGP^mut) and mdr1‐intact (PGP^WT) CF1 mice. Whereas in the brain of the PGP^WT mice, EMO was below the detection level of 10 ng/g, its concentration was at 43.7 ng/g in the PGP^mut mice. Furthermore, appearance of neurological toxicity was analyzed in these mice after application of 1 mg/kg EMO using a rotarod setup. In all PGP^mut mice, but not in the PGP^WT mice, the walking performance on the rotarod was impaired by EMO with clear differences in the degree and duration of neurological toxicity. Some of the mice were completely unable to walk on the rotarod already at 2 h after drug application and showed long‐lasting ataxia over >24 h. Others even showed significantly reduced walking performance, but completely recovered within 1 day. In conclusion, P‐gp restricts brain penetration of EMO and prevents neurological toxicity of this drug in mice.     

The novel polymorphism of the beta 3-adrenergic receptor gene and its distribution in domestic pigs and wild boars in Asia

The beta 3‐adrenergic receptor (ADRB3) is a G protein‐coupled receptor that is involved in regulating energy homeostasis. We have studied DNA sequences of porcine ADRB3 to find candidate genetic polymorphisms for economically important growth and performance traits in pigs. Five novel haplotypes derived from the three In/dels and 44 SNPs were identified among domestic pigs and wild boars. Three of them encode non‐synonymous amino acid sequences by five missense polymorphisms and a frameshift by a thymine insertion. The amino acid polymorphic sites were distributed as follows: one substitution was in extracellular loop 1, three substitutions were in intracellular loop3 and one substitution and the deletion of two amino acids were at the carboxyl‐terminal. There was no polymorphism in the transmembrane domains. In addition, we surveyed the allelic frequency of the thymine insertion that cause frameshift in South‐east Asian local pigs, including some commercial breeds and wild boars. This thymine insertion was distributed widely in the domestic pigs and wild boars. The frequencies of this allele were relatively low in Western improved breeds, while they were very common in Asian breeds and wild boars in Asia. This result indicates that this insertion originally occurred in ancient Asian wild boars and then circulated among Asian domestic pigs. This allele also spread over Western breeds, probably through the introgression of Asian pigs into European stocks during the 18th and 19th centuries.     

Reoperative neurosurgery in dogs with thoracolumbar disc disease

OBJECTIVE: To characterize the subset of dogs in our neurosurgical practice that underwent spinal surgery for thoracolumbar (TL) disc herniation and subsequently underwent additional decompressive TL surgery. STUDY DESIGN: A retrospective case series. SAMPLE POPULATION: Thirty dogs that underwent reoperation for TL disc herniation. A comparison group of Dachshunds that underwent only one decompressive TL disc surgery was also studied. METHODS: Dogs that underwent reoperation were divided into two groups based on the interval between their first and second surgery. The early reoperation group included those dogs having a second surgery less than 4 weeks after the initial operation. The late reoperation group included those dogs having a second surgery more than 4 weeks after the initial operation. For each Dachshund in the late reoperation group, two Dachshunds that underwent only one decompressive TL disc surgery were selected and formed the comparison group. Dogs in the comparison group were matched with reoperated cases based on the severity of preoperative neurologic deficit and site of disc herniation. These two groups were compared to determine: (1) if age and body weight were risk factors for reoperation, and (2) if dogs had a poorer functional outcome after their second decompressive surgery than did those in the comparison group after their first (and only) decompressive surgery. RESULTS: A total of 30 of 467 (6.4%) dogs that underwent decompressive TL disc surgery were reoperated. In the early reoperative cases (n = 5 dogs), the inciting cause in all cases was residual compression from disc material at the site of the initial surgery. In the late reoperation group, 22 of 25 (88%) cases had a second disc herniation at a site distinct from the initial lesion. Dachshunds had a significantly higher risk for late reoperation (odds ratio and 95% CI = 3.67, 1.46 to 10.03); other small and medium-sized breeds (<20 kg) were underrepresented. Age and body weight were not significant predictors for reoperation. A total of 21 of 23 (91%) dogs had functional recovery after late reoperation. Complete sensorimotor loss was a significant negative predictor of functional recovery in the late reoperative cases (P = .01). Likelihood of functional recovery in dogs after their second decompressive surgery was identical to the functional recovery of dogs in the comparison group. CONCLUSIONS AND CLINICAL RELEVANCE: Our results show that a second disc herniation occurring at a site distinct from the initial lesion is the most common cause for reoperation and that Dachshunds have a significantly greater risk than other breeds.     

P‐59 Three cases of opportunistic dermatoses associated with internal diseases in cats

Opportunistic dermatoses can occur in case of immunosuppressive diseases. The first case was a 12‐year‐old domestic short‐haired cat suffering from diabetes with a phaeohyphomycosis due to Scytalidium spp.associated with cutaneous hemangiosarcoma. A painless and ulcerated nodule was observed on a digit with fistulous tracts over the metatarsal joint. Histopathological examination of the nodule revealed a hemangiosarcoma in which brownish fungal colonies were found. Itraconazole (5 mg/kg twice daily), then amputation, allowed 12 months of survival (pulmonary metastases). The second case concerned a 13‐year‐old Siamese cat with cheyletiellosisassociated with spontaneous Cushing's disease and diabetes mellitus. This cat exhibited scales and miliary dermatitis on the trunk associated with polyuria, polydipsia and a pot‐belly. Acetate tape impression showed Cheyletiella blakei mites and eggs. Blood analysis revealed diabetes mellitus and spontaneous hyperadrenocorticism. The owner refused treatment. The third case was a 14‐year‐old domestic short‐haired cat with generalized demodicosis associated with iatrogenic Cushing's disease and diabetes mellitus. Long‐acting glucocorticoids had been used for treatment of plasma cell stomatitis for 5 years. This cat exhibited erythema, scales, self‐induced alopecia, thin skin and moderate pruritus associated with polyuria and polydipsia. Cutaneous lesions principally developed on the abdomen and flanks. Skin scrapings and trichogram showed numerous Demodex cati mites. Routine blood work demonstrated diabetes mellitus and iatrogenic Cushing's disease. Treatment was based on insulin therapy, milbemycin oxime (1 mg/kg once daily) and chlorambucil (0.2 mg/kg once daily). The demodicosis was cured after 4 months, but the cat died of cutaneous and ocular herpesvirus infection 10 months later. Funding: Self‐funded.     

Role of Sperm Velocity Variables Associated with Poultry Breed in ‘Last Male Precedence’

It is well known that when a hen mates with multiple roosters, it is the sperm of the last male that usually fertilizes most of the eggs (‘last male precedence’). Sperm quality varies between males within a breed, but also between breeds, and thus, sperm competitiveness after mating may depend on the breeds of the roosters involved. The aim of the present work was to identify differences in sperm competitiveness between breeds, especially with respect to motility. A multibreed mating model was used. Blue Andaluza (BA) and Black Castellana (BC) hens left for 21 days with BA and BC roosters, respectively, were then left with Black‐barred Andaluza (Bb) roosters for another 21 days (experimental groups hBA‐rBC‐rBb and hBC‐rBA‐rBb). Bb roosters (as the second breed replacing the first) fertilized the majority of eggs in both the hBC‐rBA‐rBb and hBA‐rBC‐rBb groups. The percentage of offspring sired by BA roosters (8.0%) was higher (p < 0.05) than the percentage of chicks sired by BC roosters (2.1%). The fertility of the BC hens in the hBC‐rBA‐rBb group was higher (p < 0.01) than that of the BA hens in the hBA‐rBC‐rBb group. No difference in sperm concentration was seen between the breeds. Within the rapid sperm subpopulation (sperm velocity, >50 μm/s), Bb sperm showed a higher straight‐line velocity (VSL) and average path velocity (VAP) (p < 0.05) than BC sperm. The VSL and VAP values for Bb and BA sperm were similar. In conclusion, the present results show that the sperm of the BA breed, traditionally regarded as of moderate fertility, compensates for this drawback via sperm movement characteristics that afford it an advantage in competition scenarios involving males of other breeds. The VSL and VAP of the rapid sperm subpopulation may play the most important role in securing last male precedence.