White Dorper Sheep Research Articles

Seroprevalence and risk factors of Toxoplasma gondii in sheep and goats of North West Province, South Africa

BackgroundThe protozoan parasite Toxoplasma gondii causes toxoplasmosis, one of the most prevalent parasitic zoonotic diseases with significant economic and public health implications worldwide. Infection with the parasite has a significant adverse effect on sheep and goat production and can frequently go undetected in the herd, resulting in abortions and weak or dead offspring. Although there are few studies on seroprevalence and risk factors associated with T. gondii infections in livestock in other provinces of South Africa, there is no data in the North West province. Therefore, a cross-sectional study was conducted to investigate the seroprevalence of T. gondii and risk factors associated with exposure in sheep and goats of the North West province of South Africa. Sera from 439 livestock (164 sheep and 285 goats) were collected and analysed for the presence of T. gondii IgG antibodies using indirect ELISA (Enzyme-linked immunosorbent assay). An assessment of potential risk factors in farms associated with seropositivity was also conducted using a structured questionnaire.ResultsOut of the 439 tested sheep and goats, 13.9% (61/439) were positive for IgG antibodies against T. gondii. Sheep and goats had seroprevalences of 19.5% (32/164) and 10.5% (29/275) respectively. In the multivariable logistic regression model, the risk of acquiring T. gondii was significantly higher in the mixed breed [Odds ratio (OR) = 71.07; 95% confidence interval (CI): 266.8-1893.1; p < 0.011)] animals than white dorper sheep and in farms that burn or bury aborted material (OR = 42.04; CI: 179.9-982.5; p = 0.020) compared to those that only burn aborted material. The risk was lower for the farms in Kagisano-Molopo (OR = 0.00; CI: 0.0-25.4; p = 0.015) and Mahikeng (OR = 0.00; CI: 0.0-4.9; p < 0.001) local municipalities than Greater Taung local municipality, and for the animals that drink water from dams (OR = 0.03; CI: 0.2–58.8; p = 0.021) than those that drink from boreholes.ConclusionThe seroprevalence and risk factors associated with transmission observed show that T. gondii infection is widespread in sheep and goats of the North West province.

Different doses of pFSH are effective to promote follicular growth, superovulatory response, and embryo yield in White Dorper ewes

This study evaluated the effect of 250, 333, or 400 IU of a commercial porcine stimulating-follicle hormone (pFSH) on follicular growth, superovulatory (SOV) response, and embryo yield in White Dorper sheep. Ewes received an induced-ovulation protocol (D0 = progesterone (P4) device insertion) and superovulation starting 60 h before P4 withdrawal (D9), which consisted of six decreasing doses of 250 IU (G250; n = 15), 333 IU (G333; n = 15), or 400 IU (G400; n = 14) of pFSH. Ewes also received 50 µg of gonadotropin-releasing hormone (GnRH) analog on D10 and 300 IU of hCG on D13. Ewes were mated and submitted to non-surgical embryo recovery (NSER). Ultrasound evaluations were performed on D6, D7, D8, D9, and D16. The overall responding donor rate (≥3 CL) was 86.4% (38/44). The mean number of large follicles was higher (P < 0.05) in all groups on D8 (6.2 ± 0.9, 7.7 ± 0.9, and 8.3 ± 1.1) and D9 (11.1 ± 0.6, 10.4 ± 1.0, and 11.5 ± 0.9). Non-surgical embryo recovery procedures were successfully performed in 60.5% (23/38) of females. The CL count in successfully flushed ewes was greater (P < 0.05) in G333 (12.7 ± 2.3) and G400 (12.0 ± 1.3) than in G250 (6.0 ± 1.1). The recovery rate (44.4%, 57.3%, and 50.0%) and numbers of transferable embryos (2.3 ± 1.1, 6.1 ± 2.6, and 4.5 ± 1.3) did not differ (P > 0.05) among groups. All protocols were efficient in promoting follicular growth and adequate superovulatory response and embryo yield.

Variation in the ovine KRT34 promoter region affects wool traits

The hard α-keratins are the main component of wool fibre and are assembled in a highly organized fashion into the keratin intermediate filaments (KIFs). Variation in the keratins affects wool structure and fibre characteristics, and thus their genes make ideal candidates for the development of gene-markers. A total of 300 sheep were used for the variation study and 460 Merino × Southdown-cross lambs were used subsequently for the association study. The KRT34 promoter region was investigated using PCR-SSCP. Two different banding patterns (named variants A and B) were observed and a total of three SNPs (c.-435C/T, c.-364A/G and c.-323C/T) were identified in three different sheep breeds. Among the different breeds of sheep that were investigated, the overall frequencies of variants A and B were 37.88 % and 62.12 % respectively. The B variant was the most common in White Dorper sheep (94.83 %), when compared to the Merino (50.00 %) and New Zealand Romney (46.67 %) sheep. The two variants were also observed in the Merino × Southdown-cross lambs, where the presence of A appeared to be associated with decreased fibre diameter standard deviation (FDSD) (P = 0.030) and mean staple length (MSL) (P = 0.039). Associations with genotype were detected with mean fibre diameter (MFD) (P = 0.005) and FDSD (P = 0.008). These results suggest that variation in the KRT34 promoter fragment may affect MFD, FDSD and MSL, it could be a potential marker to improve wool quality.

Nucleotide variation in the ovine KRT31 promoter region and its association with variation in wool traits in Merino-cross lambs

AbstractKeratins are the main structural proteins of wool fibres, and it is thought that variation in the keratins may affect wool fibre characteristics. Polymerase chain reaction-single stranded conformational polymorphism (PCR-SSCP) analyses were used to investigate four regions of the ovine keratin gene KRT31 including a portion of the promoter, the exon 1, exon 3 and exon 7 regions. Initially, in a screening panel of 300 New Zealand Romney, Merino and White Dorper sheep obtained from 26 farms, three, two, two and two PCR-SSCP banding patterns were observed for these four regions, respectively. The promoter region, the exon 1 and exon 3 regions contained two single nucleotide polymorphisms (SNPs) and the exon 7 region contained one SNP. The effect of the variation found in the promoter region on wool traits was subsequently investigated in 485 Southdown × Merino-cross lambs from seven sire-lines. The three variants identified in the original 300 sheep (named A, B and C) were observed with frequencies of 56, 29 and 15%, respectively. The presence of A and B had no significant effect on wool traits, but the presence of C was found to be associated with an increase in greasy fleece weight (GFW), clean fleece weight (CFW) and mean staple length (MSL). There was an effect of genotype on CFW and MSL, with BC sheep producing wool of higher CFW and MSL than AA, AB, AC and BB sheep. These results suggest that ovine KRT31 might be a useful candidate gene for improving wool traits.

Effect of semen and donor factors on multiple ovulation and embryo transfer (MOET) in sheep.

Multiple ovulation and embryo transfer (MOET) is an important tool in the sheep industry for increasing numbers of genetically superior individuals. The objective of this study was to evaluate the effect of semen source (frozen or fresh), the number of embryo collection procedures for each donor (NECP), the season in which embryo transfer and collection was performed, and the age and breed of the donor, on the number of recovered embryos and pregnancy rates after embryo transfer. The Alamos Genetics' flushing station database was used. This consisted of 140 embryo collection procedures, from 53 Dorper and White Dorper sheep donors, aged between one and eight years, totalling 1,200 collected embryos. Neither the number of retrieved embryos nor the pregnancy rate was affected by the semen preservation method (fresh or frozen), NECP or the age and breed of donor. The season did not affect the number of collected embryos but had a significant effect (p<0.05) on the recipient pregnancy rate, with higher pregnancy rates reported in the winter (65.57%±25.33%) compared with spring (37.11%±33.27%), summer (29.95%±28.33%) or autumn (35.03%±31.66%). There is an estimated increase of 98.4% and 71.5% of embryos recovered in the spring and summer seasons, respectively, when winter is used as reference. The survival of embryos is significantly higher when implanted during the breeding season, more specifically in winter. Embryo collection can be carried out throughout the year in sheep, but there may be a marginal advantage in the use of superovulation and fresh embryo transfer programmes in the autumn and winter.

Deepening the knowledge about dermatosparaxis in Brazilian White Dorper population: Basis for the development and implementation of a genetic disease eradication program in sheep

The objectives of this study were to develop a molecular test to identify the dermatosparaxis associated mutation in Brazilian White Dorper sheep and to investigate aspects involved with introduction and dissemination probability of this disease. Partial sequences of the ADAMTS2 gene were used to design a TETRA-ARMS genotyping approach to identify the dermatosparaxis associated mutation. This procedure was validated using 15 samples with known genotypes. After the validation, 19 White Dorper individuals were genotyped with the newly developed test. To deepen the knowledge about the aspects involved with introduction and dissemination probability of dermatosparaxis trough Brazilian White Dorper population, the genotypes and individual identification of 131 individuals used in two independent studies were merged to the 19 newly genotyped individuals and the complete genealogical information was retrieved from the Brazilian Sheep Breeders Association database. The newly developed TETRA-ARMS genotyping approach permitted a perfect match when compared with other methodologies. Observed allele frequency for the dermatosparaxis associated allele was 7.00%. Geneprob Analysis permitted the prediction of 63 individuals as putative wild type homozygotes and 12 as putative heterozygotes. MRCA analysis permitted the identification of seven individuals divided in six clusters. Pedigree analysis indicate that this process was complex because there are, at least, two Australian and four South African lineages carrying the mutated allele that were introduced in Brazil. Finally, it can be highlighted that the development and implementation of a program aiming to eradicate/control the dermatosparaxis associated mutation is needed in Brazil and that the combination of a low cost molecular test and genealogical analysis can be an alternative to reduce genotyping costs and to ensure the effectiveness of the program.

Polymorphism of KRT83 and its association with selected wool traits in Merino-cross lambs

Keratins are structural proteins in the cortex of wool fibres. It is thought that variation in the keratin genes (KRTs) affects wool structure and characteristics. Polymerase chain reaction-single stranded conformational polymorphism (PCR-SSCP) analysis was used to investigate three regions of ovine KRT83. These regions were a portion of the promoter, the exon 2 region (including part of intron 1) and a region encompassing exon 3-4 (including all of exon 3, intron 3, exon 4 and part of intron 4). Initially, in 300 New Zealand Romney, Merino and White Dorper sheep obtained from 26 farms, one, two and four PCR-SSCP banding patterns were observed for these regions respectively. The exon 2 region contained two single nucleotide polymorphisms (SNPs) and the exon 3-4 region contained five SNPs. Investigation of the effect of the variation in the exon 3-4 region on variation in some wool traits were subsequently undertaken in 489 Merino×Southdown-cross sheep from seven sire-lines. The four variants identified in the original 300 sheep (designated A-D) and a new variant (E containing a new SNP) were observed with a frequency of 64.6%, 15.4%, 6.6%, 10.1% and 3.3%, respectively. General linear mixed-effects models (GLMMs) were used to investigate associations between the presence or absence of the variants and the wool traits, with a second set of models testing associations between common genotypes and those traits. The presence of A was associated with a decrease in fibre diameter standard deviation (FDSD) and coefficient of variation of fibre diameter (CVFD). The presence of C was associated with an increase in mean fibre diameter (MFD), mean fibre curvature (MFC) and prickle factor (PF), and a decrease in wool yield (Yield) [clean fleece weight (CFW)/greasy fleece weight (GFW)×100%]. A trend for association between the presence of C and increased FDSD was also detected. The presence of D was associated with an increase in MFD and PF, and a decrease in Yield. The presence of E was associated with a decrease in CVFD. Genotype AD had a higher GFW and a lower Yield than AA, and AC and AD tended to have increased MFD compared to AA and AB. These results suggest that ovine KRT83 might be a useful candidate gene for improving wool traits.

Dermatosparaxis in White Dorper sheep: confirmation of a causative nonsense mutation in ADAMTS2.

Dermatosparaxis in White Dorper sheep: confirmation of a causative nonsense mutation in ADAMTS2.

Dermatosparaxia em um ovino: achados clínicos, anatomopatológicos e moleculares

Background: Dermatosparaxis is an autosomal recessive genetic disease that affects the connective tissue of animals. Collagen proteins form fibrillar structures that provide strength and structure to the extracellular matrix of tissues and organs in the body. Therefore, changes in collagen synthesis result in hyperextensibility and skin fragility. Similar to dermatosparaxis in animals, some cases of Ehlers-Danlos syndrome type VIIC have been reported in humans. The objective of this study was to describe the clinical, anatomopathological, and molecular findings of a case of dermatosparaxis in a sheep bred by crossing the Santa Inês and White Dorper breeds.Case: A case of dermatosparaxis was reported in a 20-day-old female sheep, a cross between the Santa Inês and White Dorper breeds. The sheep exhibited hyperextensibility of the skin with minimal tension and increased joint volume shortly after birth. Because of clinical worsening and the poor prognosis of the disease, the owners opted for euthanasia. The necropsy revealed large ulcerated areas in several parts of the body, including the cervical, sternal, scapular, and thoracic regions, and the inner and outer thighs. The skin was extremely easy to be removed during the necropsy and the use of a scalpel was not necessary. Extensive areas of hemorrhage were observed in the subcutaneous tissue and small intestine. The histopathological findings of the skin lesions evidenced the presence of dermatosparaxis, particularly regarding the disorganization of collagen fibers. The tests involving Masson’s trichrome staining, picrosirius red staining, and Gomori’s trichrome staining under polarized light evidence of collagen fiber dysplasia.Discussion: The diagnosis of dermatosparaxis in this study was based on clinical, anatomopathological, and molecular analysis. Molecular diagnosis was confirmed by identification of SNP c.421G&gt;T on the ADAMTS2 gene in both the mother and the sheep under study. In humans, in addition to hyperextensibility and skin fragility, other rare clinical signs include ligamentous laxity, bone abnormalities, vascular abnormalities, uterine rupture, ocular abnormalities, and extensive areas of hemorrhage in the intestine. In this case, the humeral-radial-ulnar joints of both thoracic limbs were substantially enlarged and, when sectioned, a moderate amount of dark yellow fluid was released. Dermatosparaxis is well documented in the White Dorper sheep breed. In the present study, the genetic test revealed that the mother (Santa Inês breed) was heterozygous and phenotypically normal. All the rams in the animal herd (White Dorper breed) were phenotypically normal. Extensive hemorrhage in organs of the abdominal cavity and the high likelihood of skin rupture have been reported in other species that are affected by the disease. The histopathological findings of cutaneous lesions in this sheep agree with the descriptions in the literature on the disorganization of collagen fibers. The tests involving Masson’s trichrome staining, Gomori’s trichrome, and picrosirius red staining under polarized light were crucial for providing evidence of collagen fiber dysplasia. Even when phenotypically normal, the heterozygous sheep in the herd can produce recessive homozygous animals, which may be clinically affected, mainly, if there is a history of uncontrolled crossing in the herd.

Behavior and body surface temperature as welfare indicators in selected sheep regularly brushed by a familiar observer

Research on emotions in farm animals has increasingly contributed to their welfare. We aimed to study behavioral and body temperature responses of dorper and white dorper sheep regularly brushed on their ventral neck, lateral chest, and withers. We performed 3-minute assessments in prebrushing, brushing, and postbrushing phases. Vocalization, ear postures and changes, half-closed eyes, and tail wagging were assessed. We also recorded withers (Tw), anal (Ta), and nasal (Tn) temperatures with an infrared thermometer. Vocalization was infrequent throughout the phases. We identified 3 ear postures frequently performed by the animals: raised up (R), horizontal (H), and backward (B). We noted a longer duration of R rather than H posture before brushing than during brushing. By comparing B and H, we observed that dorper sheep performed the B posture for longer, mainly during than postbrushing. When B and R were compared, sheep expressed the B posture for longer during brushing than both prebrushing and postbrushing phases; dorpers and male sheep also performed the B posture for longer. The results suggest higher performance of B and H postures during the stimulus and that their expression might be associated with a positive, relaxing state of the animals. No significant result was found for ear changes. Sheep showed half-closed eyes mainly in brushing and postbrushing phases, in comparison with the prebrushing phase, indicating that brushing might have elicited a relaxing state in the animals, which might have persisted after the stimulus. Only 4 male sheep wagged their tails, mostly when brushed. We also noted attention-seeking behaviors, including following the observer, leaning against the brush with the head or neck, and stretching the neck when brushed. The results on body temperatures indicated higher variance for Tw in relation to Tn and Ta, which had similar variances. Pairwise comparisons indicated that Tw was higher in postbrushing than in the prebrushing phase; Tn was also higher in the postbrushing phase than in both prebrushing and brushing phases, suggesting an increase in Tw and Tn temperatures after the stimulus. No significant differences were reported for Ta. Brushing might have elicited a positive state in sheep. Ear postures and half-closed eyes may be useful tools for assessing emotions in sheep, as well as withers and nasal temperatures. Furthermore, breed may be a highly significant effect on the expression of ear postures in sheep.

Molecular and genealogical analyses reveal multiple sources of the mutation associated with dermatosparaxis in Brazilian White Dorper sheep

Dermatosparaxis, also known as Ehlers-Danlos syndrome, is a recessive genetic disorder characterized by defects in collagen production, leading to skin fragility and delayed wound healing. In sheep this disease is associated to a transversion c.421G>T located on exon 2 of the gene ADAMTS2 and presents a special importance for the White Dorper breed. This study aims to identify carriers for the mutation associated with dermatosparaxis in Brazilian White Dorper herds and also to better understand the origin and the possibility of dissemination of this disease combining molecular and genealogical approaches. Genotyping by PCR-RFLP revealed the presence of seven out 66 heterozygotes, resulting in an estimated frequency of 5.3% for the dermatosparaxis associated allele in Brazilian White Dorper sheep. Pedigree analysis permitted the identification of two separate groups of individuals carrying the dermatosparaxis associated allele, one represented by descendants from individuals imported from South Africa and the second originated from animals imported from Australia. These findings suggest that the implementation of a program aiming to eradicate/control of dermatosparaxis in Brazilian White Dorper sheep is needed and the success of this strategy initially depends on the utilization of a molecular testing to detect carriers.

Prevalence study of SNP c.421G&gt;T in the ADAMTS2 gene responsible for dermatosparaxis in White Dorper sheep in Brazil

Abstract: Dermatosparaxis is an autosomal recessive disorder of connective tissue; the disorder is clinically characterized by skin fragility and hyperextensibility. Dermatosparaxis in White Dorper sheep is caused by a single nucleotide polymorphism (SNP) (c.421G&gt;T) in the ADAM metalloproteinase with thrombospondin type 1 motif, 2 (ADAMTS2) gene. The aim of this study was to investigate the prevalence of this SNP in a White Dorper herd in São Paulo state, Brazil. In this study, we collected blood DNA samples from 303 White Dorper sheep and performed polymerase chain reaction to amplify the SNP region. The samples were sequenced to determine the presence of the SNP in the ADAMTS2 gene. The SNP prevalence in the studied population was 15.5%; this finding indicates that more effective control measures should be used to prevent the inheritance of SNP c.421G&gt;T in the ADAMTS2 gene in Brazilian White Dorper herds.

Reproduction Efficiency and Health Traits in Dorper, White Dorper, and Tsigai Sheep Breeds under Temperate European Conditions.

The objective of the current pilot study was to evaluate the reproductive performance and health indicators in Dorper, White Dorper, and Tsigai breed ewes managed semi-intensively under European temperate conditions. A total of 544 ewe-year units were observed, with ewes (ranging from 1.5 to 8 years of age) managed under identical rearing conditions for a period of two consecutive production cycles (2012 through 2013 and 2013 through 2014). In general, significant (p≤0.001) genotype-related disparities were found in occurrence rates for all health parameters taken into study. Clinical mastitis incidence was significantly lower (p≤0.05) in Dorper (9.4%) and White Dorper (10.8%) breeds compared to that of Tsigai ewes (17.4%). Significant differences (p≤0.05) for lameness were found between Dorper and Tsigai breeds, with occurrence rates of 8.0% and 2.9%, respectively. Incidence for pneumonia and abortion was not influenced (p>0.05) by the ewes’ genotype. Litter size was significantly lower (p≤0.05) in White Dorper breed than for Dorper and Tsigai ewes, of 1.21, 1.40, and 1.45, respectively. Conception rates and lambs survival were not affected (p>0.05) by genotype. Results suggest that South African Dorper and White Dorper sheep breeds have adapted well to the specific rearing conditions.

Aspectos clínicos, histopatológicos e moleculares da dermatosparaxia em ovinos White Dorper

Dermatosparaxia em animais é uma doença autossômica recessiva do tecido conjuntivo caracterizada por fragilidade e hiperextensibilidade cutânea. A doença em ovinos White Dorper é provocada pela mutação c.421G&gt;T no gene ADAMmetalopeptidase com trombospondina tipo 1 motif, 2 (ADAMTS2). O objetivo deste estudo foi descrever os achados clínicos, moleculares e histopatológicos da dermatosparaxia em ovinos White Dorper de um rebanho localizado no Centro-Oeste Paulista. O rebanho era composto por nove animais, sendo um reprodutor, quatro matrizes e seus respectivos borregos. Dos nove animais examinados, dois apresentavam sinais clínicos compatíveis com dermatosparaxia. O exame histopatológico de amostras cutâneas das lesões destes dois animais revelou também achados compatíveis com dermatosparaxia, sendo caracterizados por epiderme e anexos cutâneos preservados e sem características atípicas; colágeno displásico arranjado em feixes pequenos, fragmentados e com focos de degeneração, anexos cutâneos proeminentes e na região da derme foco hemorrágico intenso associado a moderado infiltrado neutrofílico na derme profunda. Com o objetivo de realizar o diagnóstico molecular da enfermidade, uma PCR foi padronizada utilizando primers específicos desenhados para amplificar a região do gene ADAMTS2 que continha a mutação c.421G&gt;T e o DNA obtido de amostras de sangue de todos os animais do rebanho. O sequenciamento direto dos produtos da PCR, comprovou que os dois animais clinicamente afetados possuíam a mutação responsável pela dermatosparaxia. A metodologia descrita neste estudo possibilitou o diagnóstico definitivo da doença. Segundo a literatura consultada, esta é a primeira vez que a dermatosparaxia é descrita em ovinos White Dorper no Brasil. A metodologia aqui descrita poderá ser empregada em estudos futuros que avaliem a prevalência desta mutação no Brasil, possibilitando a adoção de medidas que previnam a disseminação dessa mutação no rebanho brasileiro de ovinos White Dorper.

A premature stop codon in the ADAMTS2 gene is likely to be responsible for dermatosparaxis in Dorper sheep

We have used polymerase chain reaction-single-strand conformational polymorphism analysis to investigate variation in exon 2 of the ADAM metalloproteinase with thrombospondin type I motif, 2 (ADAMTS2) gene in 598 sheep, including three white Dorper lambs that had a pathology consistent with dermatosparaxis. Four sequence variants (A, B, C and D) were identified at this exon, with the lambs having the dermatosparaxis phenotype being uniquely B homozygous and their mothers being B-containing heterozygous for ADAMTS2. Analysis of the amplified exon 2 sequences revealed the B variant had a nucleotide substitution that creates a premature stop codon and would notionally abbreviate the ADAMTS2 peptide. The B variant was not found in any other breed aside from the white Dorper sheep that were studied.

Dermatosparaxis in two White Dorper lambs

CASE HISTORY AND CLINICAL FINDINGS: Two White Dorper lambs from the North Island of New Zealand, 2 and 4 weeks of age, were presented with large skin flaps hanging from the flanks, separation of skin from the subcutis over mobile joints, and de-gloving injuries of the limbs and tail. The lambs were subject to euthanasia on humane grounds. PATHOLOGICAL FINDINGS: Large skin tears with associated haemorrhage, periarticular S/C oedema and generalised skin fragility were observed in both lambs at post-mortem examination. Histology of the affected skin revealed diffuse hyalinisation of dermal collagen compared with control lambs, protein-filled peri-adnexal clefts and areas of deep dermal and S/C granulation tissue consistent with previous separation of skin from the subcutis. Analysis of hair follicles, collected from one of the lambs, using a commercially available genetic test in Australia was consistent with the lamb being homozygous for the mutation responsible for ovine dermatosparaxis. DIAGNOSIS: Likely dermatosparaxis. CLINICAL RELEVANCE: These findings strongly suggest that the mutation responsible for dermatosparaxis in White Dorper sheep is present in New Zealand. Dermatosparaxis should be considered when investigating skin fragility in lambs with White Dorper genetics. Confirmation of the disorder is possible through genetic analysis of hair follicles.