An evaluation of the International Society for Animal Genetics recommended parentage and identification panel for the domestic pigeon (Columba livia domestica).

In this study, the International Society for Animal Genetics (ISAG) recommended panel for the identification of the domestic pigeon (Columba livia domestica) is characterized based on commonly used statistical parameters. The marker panel is based on 16 short tandem repeat (STR) loci (PIGN15, PIGN10, PIGN57, PIGN26, CliµD16, CliµD19, PIGN12, CliµD17, CliµT17, PIGN04, CliµD01, CliµD11, CliµD35, CliµT02, CliµT13, CliµT43). The alleles of the 16 loci consist of a mixture of tri-, tetra-, penta- and hexameric repeat patterns. A sex determination marker was included in the multiplex for quality control. The repeat sequence of the PIGN markers was previously unpublished and therefore sequenced to reveal the sequence pattern. In total, 1421 pigeons were genotyped on 16 STR loci to generate allele frequency data for each locus. For all 16 markers combined, a PE1 (combined non-exclusion probability, first parent) of 0.9986 and PE2 (combined non-exclusion probability, second parent) of >0.9999 was observed. Comparing the alleged father and mother, a PE value of >0.9999 was observed. Two of the markers, CliµD19 and PIGN12, were found to have relatively high Hardy-Weinberg equilibrium and F(null) values. Therefore these markers may be considered to be replaced by other STRs. Another point of discussion may be to add a gender identification marker to the recommended ISAG panel. Not only can this serve as an extra identification marker, but this can also confirm the sex of a sample, because it is challenging to determine the sex based on phenotypical characteristics, especially for chicks. In conclusion, the set of 16 STR markers can be used in routine parentage verification and the identification of individuals.

Application of allflex conservation buffer in illumina genotyping.

This experiment was designed to study if liquid conservation buffer used in the novel Tissue Sampling Technology (TST) from Allflex can be used for Illumina BeadChip genotyping. Ear punches were collected from 6 bovine samples, using both the Tissue Sampling Unit (TSU) as well as the Total Tagger Universal (TTU) collection system. The stability of the liquid conservation buffer was tested by genotyping samples on Illumina BeadChips, incubated at 0, 3, 15, 24, 48, 72, 168, 336, 720 h after sample collection. Additionally, a replenishment study was designed to test how often the liquid conservation buffer could be completely replenished before a significant call rate drop could be observed. Results from the stability study showed an average call rate of 0.993 for samples collected with the TSU system and 0.953 for samples collected with the TTU system, both exceeding the inclusion threshold call rate of 0.85. As an additional control, the identity of the individual animals was confirmed using the International Society of Animal Genetics (ISAG) recommended SNP panel. The replenishment study revealed a slight drop in the sample call rate after replenishing the conservation buffer for the fourth time for the TSU as well as the TTU samples. In routine analysis, this application allows for multiple experiments to be performed on the liquid conservation buffer, while maintaining the tissue samples for future use. The data collected in this study shows that the liquid conservation buffer used in the TST system can be used for Illumina BeadChip genotyping applications.

The effects of positioning, reason for screening and the referring veterinarian on prevalence estimates of canine hip dysplasia.

Although the prevalence of canine hip dysplasia (HD) has been the subject of a number of published studies, estimates vary widely. This study evaluated several possible causes for these differences. Sixty Belgian, Dutch and German veterinarians were asked to submit all hip radiographs obtained for screening purposes (irrespective of HD status) over a 2-year period, resulting in a database of 583 dogs. Each set of radiographs was accompanied by information on the reason for screening (breeding soundness examination, clinical complaint, assistance dogs, or other reasons), and dog breed, date of birth and age. Dog positioning exerted an effect at multiple levels. The agreement among different observers regarding correct or incorrect positioning was limited and incorrect positioning itself reduced the inter-observer agreement for radiographic hip conformation. Dysplastic dogs were more commonly positioned incorrectly than non-dysplastic dogs. The clinical complaint population had a high prevalence of dysplastic dogs (>70%) compared with the breeding population (11%) and the assistance dogs (6%). There was a significantly lower prevalence of HD among cases referred by veterinarians who frequently submitted hip-extended radiographs for evaluation (P = 0.002) compared to those who refer less frequently. However, this was likely to be selection bias, as radiographs that were from dogs suspected to be dysplastic were not submitted by frequent senders. The prevalence of dysplastic dogs varied widely between breeds (16.7-71.4%). Dogs diagnosed with dysplasia were significantly older than dogs considered healthy (P = 0.001) and dogs classified as borderline dysplastic (P = 0.035). Inter-observer agreement for hip conformation was moderately low, resulting in >7% variation in prevalence estimates for dysplasia.

Population studies of 17 equine STR for forensic and phylogenetic analysis.

As a consequence of the close integration of horses into human society, equine DNA analysis has become relevant for forensic purposes. However, the information content of the equine Short Tandem Repeat (STR) loci commonly used for the identification or paternity testing has so far not been fully characterized. Population studies were performed for 17 polymorphic STR loci (AHT4, AHT5, ASB2, ASB17, ASB23, CA425, HMS1, HMS2, HMS3, HMS6, HMS7, HTG4, HTG6, HTG7, HTG10, LEX3 and VHL20) including 8641 horses representing 35 populations. The power of parental exclusion, polymorphic information content, expected and observed heterozygosity and probability of identity were calculated, showing that the set of 17 STRs has sufficient discriminating power for forensic analysis in almost all breeds. We also explored the reliability of individual assignment tests in identifying the correct breeds of origin for unknown samples. The overall proportion of individuals correctly assigned to a population was 97.2%. Finally, we demonstrate the phylogenetic signal of the 17 STR. We found three clusters of related breeds: (i) the cold-blooded draught breeds Haflinger, Dutch draft and Friesian; (ii) the pony breeds Shetland and Miniature horse with the Falabella, Appaloosa and Icelandic; and (iii) The Warmblood riding breeds, together with the hot-blooded Standard-bred, Thoroughbred and Arabian.

A single nucleotide polymorphism set for paternal identification to reduce the costs of trait recording in commercial pig breeding.

In animal breeding, recording of correct pedigrees is essential to achieve genetic progress. Markers on DNA are useful to verify the on-farm pedigree records (parental verification) but can also be used to assign parents retrospectively (parental identification). This approach could reduce the costs of recording for traits with low incidence, such as those related to diseases or mortality. In this study, SNP were used to assign the true sires of 368 purebred animals from a Duroc-based sire line and 140 crossbred offspring from a commercial pig population. Some of the sires were closely related. There were 3 full sibs and 17 half sibs among the true fathers and 4 full sibs and 35 half sibs among all putative fathers. To define the number of SNP necessary, 5 SNP panels (40, 60, 80, 100, and 120 SNP) were assembled from the Illumina PorcineSNP60 Beadchip (Illumina, San Diego, CA) based on minor allele frequency (>0.3), high genotyping call rate (≥90%), and equal spacing across the genome. For paternal identification considering only the 66 true sires in the data set, 60 SNP resulted in 100% correct assignment of the sire. By including additional putative sires (n = 304), 80 SNP were sufficient for 100% correct assignment of the sire. The following criteria were derived to identify the correct sire for the current data set: the logarithm of odds (LOD) score for assigning the correct sire was ≥5, the number of mismatches was ≤1, and the difference in the LOD score between the first and the second most likely sire was >5. If the correct sire was not present among all putative sires, the mean LOD for the most likely sire was close to zero or negative when using 100 SNP. More SNP would be needed for paternal identification if the number of putative sires increased and the degree of relatedness was greater than in the data set used here. The threshold for the number of mismatches can be adjusted according to the practical situation to account for the trade-off between false negatives and false positives. The latter can be avoided efficiently, ensuring that the correct father is being sampled. Nevertheless, a restriction on the number of putative sires is advisable to reduce the risk of assigning close relatives.

Population studies of 16 bovine STR loci for forensic purposes.

As a consequence of the close integration of cattle into the food chain of humans, forensically relevant cases involving cattle (Bos taurus) DNA analysis are common. However, scientific publications reporting the information content of the commonly used bovine short tandem repeat (STR) loci remains scarce. Population studies were performed for 16 polymorphic STR loci (BM1818, BM1824, BM2113, CSRM60, CSSM66, ETH3, ETH10, ETH225, HAUT27, ILSTS006, INRA023, SPS115, TGLA53, TGLA122, TGLA126, and TGLA227) including 4,162 randomly selected cattle representing 20 distinct breeds. The power of parental exclusion, expected and observed heterozygosity, probability of identity, and non-amplifying ("null") allele frequencies were calculated. Major differences existed in the information content between different cattle breeds. The selection of 16 STR loci, partially recommended by International Society for Animal Genetics as the minimum standard needed for bovine STR typing, was sufficient for forensic analysis. Furthermore, the efficacy of the loci was assessed in assigning unknown individuals to the correct breed based on genotype data. The individual assignment tests provided excellent success in several breeds.

Field comparison of real-time polymerase chain reaction and bacterial culture for identification of bovine mastitis bacteria.

Fast and reliable identification of the microorganisms causing mastitis is important for management of the disease and for targeting antimicrobial treatment. Methods based on PCR are being used increasingly in mastitis diagnostics. Comprehensive field comparisons of PCR and traditional milk bacteriology have not been available. The results of a PCR kit capable of detecting 11 important etiological agents of mastitis directly from milk in 4h were compared with those of conventional bacterial culture (48h). In total, 1,000 quarter milk samples were taken from cows with clinical or subclinical mastitis, or from clinically healthy quarters with low somatic cell count (SCC). Bacterial culture identified udder pathogens in 600/780 (77%) of the clinical samples, whereas PCR identified bacteria in 691/780 (89%) of the clinical samples. The PCR analysis detected major pathogens in a large number of clinical samples that were negative for the species in culture. These included 53 samples positive for Staphylococcus aureus by PCR, but negative by culture. A total of 137 samples from clinical mastitis, 5 samples from subclinical mastitis, and 1 sample from a healthy quarter were positive for 3 or more bacterial species in PCR, whereas culture identified 3 or more species in 60 samples from clinical mastitis. Culture identified a species not targeted by the PCR test in 44 samples from clinical mastitis and in 9 samples from subclinical mastitis. Low SCC samples provided a small number of positive results both in culture (4/93; 4.3%) and by PCR (7/93; 7.5%). In conclusion, the PCR kit provided several benefits over conventional culture, including speed, automated interpretation of results, and increased sensitivity. This kit holds much promise as a tool to complement traditional methods in identification of pathogens. In conventional mastitis bacteriology, a sample with 3 or more species is considered contaminated, and resampling of the cow is recommended. Further study is required to investigate how high sensitivity of PCR and its quantitative features can be applied to improve separation of relevant udder pathogens from likely contaminants in samples where multiple species are detected. Furthermore, increasing the number of species targeted by the PCR test would be advantageous.

A proposal for standardization in forensic equine DNA typing: allele nomenclature for 17 equine-specific STR loci.

In this study, a proposal is presented for the allele nomenclature of 17 polymorphic STR loci (AHT4, AHT5, ASB2, ASB17, ASB23, CA425, HMS1, HMS2, HMS3, HMS6, HMS7, HTG4, HTG6, HTG7, HTG10, LEX3 and VHL20) for equine genotyping (Equus caballus). The nomenclature is based on sequence data of the polymorphic region of the STR loci as recommended by the DNA commission of the International Society for Forensic Genetics for human DNA typing. For each STR locus, several alleles were selected and animals homozygous for those alleles were subjected to sequence analysis. The alleles of the 17 STR loci consisted either of simple (10), compound (6) or complex repeat patterns (1). Only a limited number of alleles with the same fragment size showed different repeat structures. The allele designation described here was based on the number of repeats, including all variable regions within the amplified fragment.

A proposal for standardization in forensic bovine DNA typing: allele nomenclature of 16 cattle-specific short tandem repeat loci.

In this study, a proposal is presented for the allele nomenclature of 16 polymorphic short tandem repeat (STR) loci (BM1824, BM2113, ETH10, ETH225, INRA023, SPS115, TGLA122, TGLA126, TGLA227, ETH3, TGLA53, BM1818, CSRM60, CSSM66, HAUT27 and ILSTS006) for bovine genotyping (Bos taurus). The nomenclature is based on sequence data of the polymorphic region(s) of the STR loci as recommended by the DNA commission of the International Society of Forensic Genetics for human DNA typing. To cover commonly and rarely occurring alleles, a selection of animals homozygous for the alleles at these STR loci were analysed and subjected to sequence studies. The alleles of the STR loci consisted either of simple or compound dinucleotide repeat patterns. Only a limited number of alleles with the same fragment size showed different repeat structures. The allele designation described here was based on the number of repeats including all variable regions within the amplified fragment. The set of 16 STR markers should be propagated for the use in all bovine applications including forensic analysis.

Cytogenetic screening of livestock populations in Europe: an overview.

Clinical animal cytogenetics development began in the 1960's, almost at the same time as human cytogenetics. However, the development of the two disciplines has been very different during the last four decades. Clinical animal cytogenetics reached its 'Golden Age' at the end of the 1980's. The majority of the laboratories, as well as the main screening programs in farm animal species, presented in this review, were implemented during that period, under the guidance of some historical leaders, the first of whom was Ingemar Gustavsson. Over the past 40 years, hundreds of scientific publications reporting original chromosomal abnormalities generally associated with clinical disorders (mainly fertility impairment) have been published. Since the 1980's, the number of scientists involved in clinical animal cytogenetics has drastically decreased for different reasons and the activities in that field are now concentrated in only a few laboratories (10 to 15, mainly in Europe), some of which have become highly specialized. Currently between 8,000 and 10,000 chromosomal analyses are carried out each year worldwide, mainly in cattle, pigs, and horses. About half of these analyses are performed in one French laboratory. Accurate estimates of the prevalence of chromosomal abnormalities in some populations are now available. For instance, one phenotypically normal pig in 200 controlled in France carries a structural chromosomal rearrangement. The frequency of the widespread 1;29 Robertsonian translocation in cattle has greatly decreased in most countries, but remains rather high in certain breeds (up to 20-25% in large beef cattle populations, even higher in some local breeds). The continuation, and in some instances the development of the chromosomal screening programs in farm animal populations allowed the implementation of new and original scientific projects, aimed at exploring some basic questions in the fields of chromosome and/or cell biology, thanks to easier access to interesting biological materials (germ cells, gametes, embryos ...).

An international parentage and identification panel for the domestic cat (Felis catus).

Seventeen commercial and research laboratories participated in two comparison tests under the auspices of the International Society for Animal Genetics to develop an internationally tested, microsatellite-based parentage and identification panel for the domestic cat (Felis catus). Genetic marker selection was based on the polymorphism information content and allele ranges from seven random-bred populations (n = 261) from the USA, Europe and Brazil and eight breeds (n = 200) from the USA. Nineteen microsatellite markers were included in the comparison test and genotyped across the samples. Based on robustness and efficiency, nine autosomal microsatellite markers were ultimately selected as a single multiplex 'core' panel for cat identification and parentage testing. Most markers contained dinucleotide repeats. In addition to the autosomal markers, the panel included two gender-specific markers, amelogenin and zinc-finger XY, which produced genotypes for both the X and Y chromosomes. This international cat parentage and identification panel has a power of exclusion comparable to panels used in other species, ranging from 90.08% to 99.79% across breeds and 99.47% to 99.87% in random-bred cat populations.

Detection of universal variable fragments as markers for genetic studies. A novel technology for DNA fingerprinting.

A novel DNA technology enables the detection of universal variable fragments (UVF), thus revealing genetic variation without a priori sequence information. The detection of UVF markers is based on two amplifications of genomic DNA with the polymerase chain reaction. In the first amplification, two short oligonucleotide primers produce a large number of fragments. One primer is based on a microsatellite sequence, whereas the second primer can have any sequence. In the second amplification, the length of the primers is increased in order to decrease the number of amplicons. This enables the selection of polymorphic fragments. Restriction digestion can be used to further increase the number of polymorphisms. Until now, we have demonstrated UVF in several different species. In addition, with the present study we have contributed to the linkage map of the rabbit by localizing 11 UVF markers on different linkage groups. Mendelian inheritance was shown in this linkage study through a backcross of two inbred rabbit strains. The power of the UVF technique is based on the selection for microsatellite variation in combination with the detection of single-nucleotide polymorphisms. UVF thus offers the possibility of increasing the clustering of markers and localizing genes in species for which sequence information is either not present or only scarcely present.

Mapping of a QTL for serum HDL cholesterol in the rabbit using AFLP technology.

The amplified fragment length polymorphism (AFLP) technique is a DNA technology that generates the so-called AFLP markers. These markers are genomic restriction fragments detected after two rounds of polymerase chain reaction (PCR) without prior knowledge of nucleotide sequence. Here we describe the first application of the AFLP technique in the rabbit. We have tested two primer combinations. The results obtained with the DNA from rabbits of different breeds justify the conclusion that AFLP analysis is an effective tool for genetic studies in the rabbit. In addition, we contribute to the linkage map of the rabbit by localizing two AFLP markers on rabbit linkage group VI (LG VI). For this purpose the progeny of a IIIVO/JU x [IIIVO/JU x AX/JU]F(1) backcross were genotyped for 12 AFLP markers and 3 LG VI classical markers [one coat color marker (e) and two biochemical markers (Es-1 and Est-2)]. AX/JU is a dietary cholesterol-susceptible (hyperresponding) inbred strain and IIIVO/JU is a dietary cholesterol resistant (hyporesponding) inbred strain. Moreover, it is possible to evoke dietary cholesterol-induced aorta atherosclerosis in a relatively short time period in AX/JU rabbits, in contrast to IIIVO/JU rabbits. A significant cosegregation was found between basal serum HDL cholesterol level (i.e., the level on a low-cholesterol, control diet) and an AFLP marker on LG VI. It is concluded that one or more genes of LG VI are regulating the basal serum HDL cholesterol level in rabbits. Thus the present study with rabbits clearly illustrates the value of AFLP markers for the construction of linkage maps and mapping of quantitative trait loci (QTL).

Heterozygosity excess at the cattle DRB locus revealed by large scale genotyping of two closely linked microsatellites.

A method for MHC DRB typing in cattle based on two closely linked and highly polymorphic microsatellites is described. The two microsatellites DRBP1ms and DRB3ms are located in intron 2 of the corresponding DRB gene. The very strong linkage disequilibrium between the two loci made it possible to establish DRB microsatellite haplotypes. The typing results with this method on reference samples followed closely that obtained with RFLP and direct sequence analysis of DRB3 exon 2. The method is well suited for large scale genotyping and was successfully applied for typing more than 600 unrelated animals representing 23 breeds. The data were used to test whether the observed DRB allele frequency distributions were consistent with that expected for selectively neutral alleles in populations at mutation-drift equilibrium. A significant heterozygosity excess was detected and there was an obvious trend across breeds towards a more even allele frequency distribution than expected. The deviation may be due to balancing selection acting on the DRB locus or by recent population bottlenecks.

[Control of the identity of blood samples for the surveillance of research on swine vesicular disease and Aujeszky's disease]. / Identiteitscontrole van bloedmonsters voor de bewaking van het onderzoek op swine vesicular disease en de ziekte van aujeszky.

A surveillance programme for swine vesicular disease (SVD) and Aujeszky disease was set up in 1993 in the Netherlands. Blood samples are taken from pigs by local veterinarians to enable testing for the presence of antibodies against these viruses. A programme to guarantee the identity of pigs tested for these diseases has been in operation since late 1995. In this programme, pigs are identified on the basis of the DNA profiles of blood and hair samples. The hair samples are collected by the department of Animal Health Control. Analysis proves whether blood and hair samples are from the same animal. A total of 655 animals have been tested from 94 farms. In 38.6% of these farms differences were found between blood and hair samples.

Polymorphic microsatellite DNA markers in the rabbit (Oryctolagus cuniculus).

By searching the EMBL nucleotide database a total of 157 rabbit nuclear gene microsatellites were obtained (VAN LITH and VAN ZUTPHEN, Animal Genetics 27, 387-395, 1996). Thirteen of these were analysed by PCR to examine the degree of polymorphism of the amplified fragments in rabbits from different breeds. The 13 pairs of primers resulted in polymorphic products with an average of four alleles per microsatellite sequence (ranging between 2-11). There was a positive relationship between the longest repeat unit number in the nucleotide sequence and the number of alleles detected. The results obtained so far justify the conclusion that rabbit microsatellites extracted from the EMBL nucleotide sequence database are sufficiently polymorphic to be useful as Type 1 markers in rabbit genetic studies.