Microsatellite marker-based genetic analysis of relatedness between commercial and heritage turkeys (Meleagris gallopavo)

Discriminant canonical analysis as a tool for genotype traceability testing based on turkey meat and carcass traits

The present study aims to develop a statistical tool for turkey breed traceability testing based on meat and carcass quality characteristics. To this end, a comprehensive meta-analysis was performed, collecting data from a total of 75 studies approaching meat and carcass attributes of 37 turkey strains and landraces since the late 1960s. A total of 22 meat and carcass traits were considered variables, grouped in the following clusters: carcass dressing traits, muscle fiber properties, pH, colorimetry, water-capacity traits, texture-related attributes, and nutritional composition of the meat. Once the multicollinearity analysis allowed the deletion of redundant variables, cold carcass weight, slaughter weight, muscle fiber diameter, sex-female, carcass/piece weight, meat redness, ashes, pH24, meat lightness, moisture, fat, and water-holding capacity showed explanatory properties in the discriminating analysis (p < 0.05). In addition, strong positive and negative correlations were found among those variables studied. Carcass traits were positively associated, particularly slaughter weight and cold carcass weight (+0.561). Among meat physical traits, pH showed positive correlations with drip loss (+0.490) and pH24 (+0.327), and water-holding capacity was positively associated with cholesterol (+0.434) and negatively associated with collagen (-0.398). According to nutritional traits, fat and ash showed a strong correlation (+0.595), and both were negatively associated with moisture (-0.375 and -0.498, respectively). Strong negative correlations were found as well between meat protein and fat (-0.460) and between collagen and cholesterol (-0.654). Finally, the Mahalanobis distance suggested a clustering pattern based on meat and carcass characteristics that report information about interbreeding and variety proximity. This study establishes a departure point in the development of a tool for breed traceability guaranteeing aimed at enhancing distinguished, local breed-based turkey meat.

Morphological Characterization of Two Light Italian Turkey Breeds

Simple Summary

Genetic resources on turkeys are scarce, considering both domestic and wild birds. Smaller, dark-colored Italian heritage breeds such as Brianzolo and Nero d’Italia have been selected for centuries in outskirt areas due to their coping ability in poor environments and high brooding ability. However, they are in danger of extinction. EC Council Regulations on organic farming strongly recommend using local genetic resources and conserving biodiversity. Phenotypical characterization is a basic step in biodiversity conservation; therefore, in this article, we present morphometric and colorimetric analysis results of 46 birds belonging to each of the considered breeds. We considered 18 parameters: morphometries, morphological indexes, linear evaluation, and colorimetric indexes as characterizing factors in breeds differentiation. Differences in weight with clear sexual dimorphism were recorded. Massiveness indexes were in favor of the slightly more compact Brianzolo breed. The extremely fair skin and dark shank of the Nero d’Italia turkey were revealed by colorimetric analysis. The effectiveness of morphological analysis in breeds differentiation, useful data in heritage breeds conservation, and characterization were considered control parameters in classifying animal products.

Abstract

We aimed to investigate the variability within turkeys’ phenotypical traits in two Italian heritage breeds: Brianzolo (BRZ) and Nero d’Italia (NIT), as analyzed through morphometry, morphometrical indexes, linear scoring, and colorimetric indexes. A total of 92 birds were measured, weighed, and scored (46 NIT: M/F = 19/27; 46 BRZ: M/F = 19/27). Live weight (LW), total body length (BL, excluding feathers), keel length (KL), chest circumference (BC), wingspan (WS), shank length (SL), shank diameter (SD), and shank circumference (SC). Massiveness (MASS), stockiness (STOCK), and long-leggedness (LLEG) indexes were also calculated. The body condition score (BCS) applied a linear evaluation to nutritional status and muscular development. Colorimetric indexes (L*, a*, b*) were recorded, sampling skin and shank. Data were analyzed using GLM procedures and PCA. NIT was the heaviest breed (4.89 vs. 4.07 kg; p ≤ 0.05). In both breeds, sexual dimorphism was visible in the LW trait with males (M) weighing significantly heavier than females (F) (p ≤ 0.05). NIT birds recorded the highest BL values: 58.44 vs. 57.15 cm (p ≤ 0.05). MASS was higher in NIT (8.26 vs. 7.0; p ≤ 0.05), and STOCK was higher in BRZ (82.62 vs. 85.37; p ≤ 0.05). Colorimetric indexes revealed significant differences in skin lightness (L*) and redness (a*). For shank color, the breed significantly affected differences in the indexes. This study characterizes these breeds at high risk of genetic erosion and extinction, which will help the morphological standardization of birds and the enhancement of genetic variability

Copy Number Variants in Four Italian Turkey Breeds

Simple Summary

Hybrid Turkey selection is focusing on meat production traits characterized by high genetic heritability; the strong directional selection is well known to produce a constant loss in genetic diversity. Genetic characterization is one of the essential activities in the management of populations at risk of extinction. In addition, the genetic structure at the population level and the relationships between individuals are nowadays analysable at the genomic level. In this paper, the genome of 4 different Italian turkey breeds included in the Autochthonous Italian Poultry Breeds Register are analysed in order to obtain a genome-wide Copy Number Variant scan to ameliorate the existing knowledge of the genomic structure of Italian local turkey breeds. Differences have been described at genomic level for physiological, reproductive, and behavioral traits. The analyzed breeds are clearly distinguishable at the genomic level, and their relationships are clearly linked to their geographical origin and to the history of the rural structure of their developing regions. Genome information based on Copy Number Variant (CNV) detection has generated important information in this study concerning the uniqueness of the Italian local turkey breeds.

Abstract

Heritage breeds can be considered a genetic reservoir of genetic variability to be conserved and valorized considering their historical, cultural, and adaptive characteristics and possibly for their high potential in commercial hybrid genetic improvement by gene introgression. The aim of the present research is to investigate via Copy Number Variant (CNVs) the genomic makeup of 4 Italian autochthonous turkey breeds (Bronzato Comune—BrCI, 24; Ermellinato di Rovigo—ErRo, 24; Parma e Piacenza—PrPc, 25; Romagnolo—RoMa, 29). CNVs detection was performed using two different software and an interbreed CNVs comparison was carried out. A total of 1077 CNVs were identified in 102 turkeys, summarized into 519 CNV regions (CNVRs), which resulted after merging in 101 and 18 breed and shared regions. Biodiversity was analyzed using the effective information supplied by CNVs analysis, and BrCI and ErRo were characterized by a low mapped CNV number. Differences were described at a genomic level related to physiological, reproductive, and behavioral traits. The comparison with other three Italian turkey breeds (Brianzolo, Colle Euganei, and Nero Italiano) using a CNV data set available in the literature showed high clustering properties at the genomic level, and their relationships are strictly linked to the geographical origin and to the history of the rural structure of their native regions.

Tracing Worldwide Turkey Genetic Diversity Using D-loop Sequence Mitochondrial DNA Analysis

Simple Summary

The development of new production lines of turkeys has relegated native breeds to a second position. This has increased the need for new research to ensure the conservation of local turkey breeds and the maintenance of biodiversity. The objective of the present study was to identify turkey populations, their origins, and maternal lines through mitochondrial DNA analysis. For this study, mitochondrial DNA samples from 93 turkeys (Meleagris gallopavo) were used. The animals belonged to populations in Brazil, Mexico, Spain (Andalusia and Majorca) Italy, Iran, Egypt, and the United States. The haplogroup network that formed suggested that turkey domestic populations group into a single haplotype. However, genetic differences within the haplogroup were found. The present study may provide a better approach for the implementation of conservation strategies for domestic turkey populations.

Abstract

According to recent archeological evidence, turkey (Meleagris gallopavo gallopavo) domestication may have occurred in Mexico around 2000 years ago. However, little is known about the phylogenetic and genealogical background underlying domestic turkey populations. This study aimed to further understand the domestication process and identify inter- or intraspecific connections between turkey populations to determine their origins, trace their global expansion, and define the species’ genetic value. Ninety-three domestic turkeys (local breeds) were sampled from populations in Brazil, Mexico, USA, Spain, Italy, Iran, and Egypt. Publicly available sequences from previous studies were also included. Standard mitochondrial DNA, genetic diversity, and haplotype network analyses were performed. Seventy-six polymorphic sites were identified. Turkeys from Mexico showed the greatest number of polymorphic sites (40), while turkeys from Italy and Brazil reported only one site each. Nucleotide diversity was also highest in Mexico and the USA (π = 0.0175 and 0.0102, respectively) and lowest in Brazil and Italy. Of the six major haplogroups defined, the Mexican and USA populations appeared to have remained more stable and diverse than the other populations. This may be due to conservative husbandry policies in the rural areas of other populations, which have prevented the introduction of commercial turkey lines.

An Evaluation of the Genetic Structure of Geese Maintained in Poland on the Basis of Microsatellite Markers

The aim of this study was to evaluate the genetic variability of the White Kołuda® goose and 12 conservative flocks: Kielecka, Podkarpacka, Garbonosa, Pomerian, Rypinska, Landes, Lubelska, Suwalska, Kartuska, Romanska, Slowacka, and Kubanska, maintained in Poland using microsatellite data. The genetic diversity of geese kept in Poland remains poorly analyzed at the molecular level. In total 392 samples were examined with the usage of 15 microsatellite markers. 119 alleles were identified and the number of alleles per locus ranged from 1 to 13. The highest number of alleles was observed in TTUCG5 (16) and the lowest in CAUD-G007 (2), while CKW47 was monomorphic. The lowest value of expected heterozygosity (He) was observed in Landes, while the highest in Romanska. Similarly, the observed heterozygosity (Ho) was the lowest in Landes but the highest in Kartuska. The polymorphism information content (PIC) indicates loci TTUCG5 as the most valuable microsatellite marker among those examined. The Structure software was used for the first time to identify goose populations, revealing high admixture between breeds and their close genetic propinquity. Moreover, the presented panel of microsatellite markers remained polymorphic and is useful for population studies of geese and assessment of genetic diversity.

Establishment of an in vivo turkey model for the study of flexor tendon repair

Flexor tendon injuries are common and pose a clinical challenge for functional restoration. The purpose of our study was to assess the adequacy of the turkey as a large animal model for flexor tendon injuries in vivo. Twenty-four male turkeys underwent surgical flexor tendon cut and repair. Turkeys were allocated to five groups postoperatively: (1) foot casted in extension and sacrificed after 3 weeks; (2) foot casted in extension and sacrificed after 6 weeks; (3) foot casted in flexion and sacrificed after 3 weeks; (4) foot casted in flexion and sacrificed after 6 weeks; and (5) foot casted in flexion for 6 weeks and then free roaming allowed for an additional 3 weeks before sacrifice. After sacrifice, digits were collected and analyzed for adhesion formation, healing at the macrolevel and histologically, and biomechanical properties-including friction, work of flexion, stiffness, and strength of repair. All turkeys survived anesthesia and surgery. Tendon rupture occurred in all extension casts and in 11% of those casted in flexion. Friction and work of flexion were significantly higher in the repaired digit than the control digit. There was a correlation between duration of immobilization and repair strength. Histologically, the tendon healed with tenocytes migrating into the gap and producing collagen fibers. We have, for the first time, studied flexor tendon injury and repair using turkeys in terms of anesthesia, surgical procedures, postoperative care, and animal husbandry. The findings regarding functional and histological results from this novel avian model were comparable to the most commonly used mammal model. © 2018 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2497-2505, 2018.

Evolutionary history of Mexican domesticated and wild Meleagris gallopavo

Background

The distribution of the wild turkey (Meleagris gallopavo) extends from Mexico to southeastern Canada and to the eastern and southern regions of the USA. Six subspecies have been described based on morphological characteristics and/or geographical variations in wild and domesticated populations. In this paper, based on DNA sequence data from the mitochondrial D-loop, we investigated the genetic diversity and structure, genealogical relationships, divergence time and demographic history of M. gallopavo populations including domesticated individuals.

Results

Analyses of 612 wild and domesticated turkey mitochondrial D-loop sequences, including 187 that were collected for this study and 425 from databases, revealed 64 haplotypes with few mutations, some of which are shared between domesticated and wild turkeys. We found a high level of haplotype and nucleotide diversity, which suggests that the total population of this species is large and stable with an old evolutionary history. The results of genetic differentiation, haplotype network, and genealogical relationships analyses revealed three main genetic groups within the species: mexicana as a population relict (C1), merriami (C2), and mexicana/intermedia/silvestris/osceola (C3). Haplotypes detected in domesticated turkeys belong to group C3. Estimates of divergence times agree with range expansion and diversification events of the relict population of M. gallopavo in northwestern Mexico during the Pliocene–Pleistocene and Pleistocene–Holocene boundaries. Demographic reconstruction showed that an expansion of the population occurred 110,000 to 130,000 years ago (Kya), followed by a stable period 100 Kya and finally a decline ~ 10 Kya (Pleistocene–Holocene boundary). In Mexico, the Trans-Mexican Volcanic Belt may be responsible for the range expansion of the C3 group. Two haplotypes with different divergence times, MGMDgoB/MICH1 and MICH2, are dominant in domesticated and commercial turkeys.

Conclusions

During the Pleistocene, a large and stable population of M. gallopavo covered a wide geographic distribution from the north to the center of America (USA and Mexico). The mexicana, merriami, and mexicana/intermedia/silvestris/osceola genetic groups originated after divergence and range expansion from northwestern Mexico during the Pliocene–Pleistocene and Pleistocene–Holocene boundaries. Old and new maternal lines of the mexicana/intermedia/silvestris/osceola genetic group were distributed within the Trans-Mexican Volcanic Belt where individuals were captured for domestication. Two haplotypes are the main founder maternal lines of domesticated turkeys.

Electronic supplementary material

The online version of this article (10.1186/s12711-018-0388-8) contains supplementary material, which is available to authorized users.

Mitochondrial DNA-Based Analyses of Relatedness Among Turkeys, Meleagris gallopavo

The domesticated turkey, Meleagris gallopavo, is believed to be a single breed with several varieties whose relatedness and origins remain poorly understood. Using the mitochondrial genome sequence (GenBank accession no. EF153719) that our group first reported, we investigated the relationships among 15 of the most widely occurring turkey varieties using D-loop and 16S RNA sequences. We included, as a non-traditional outgroup, mtDNA sequence information from wild turkey varieties. A total of 24 SNPs, including 18 in the D-loop and 6 in the 16S rRNA, was identified, validated and used. Of the 15 haplotypes detected based on these SNPs, 7 were unique to wild turkeys. Nucleotide diversity estimates were relatively low when compared to those reported for chickens and other livestock. Network and phylogenetic analyses showed a closer relationship among heritage varieties than between heritage and wild turkeys. The mtDNA data provide additional evidence that suggest a recent divergence of turkey varieties.

Whole genome SNP discovery and analysis of genetic diversity in Turkey (Meleagris gallopavo)

Background

The turkey (Meleagris gallopavo) is an important agricultural species and the second largest contributor to the world’s poultry meat production. Genetic improvement is attributed largely to selective breeding programs that rely on highly heritable phenotypic traits, such as body size and breast muscle development. Commercial breeding with small effective population sizes and epistasis can result in loss of genetic diversity, which in turn can lead to reduced individual fitness and reduced response to selection. The presence of genomic diversity in domestic livestock species therefore, is of great importance and a prerequisite for rapid and accurate genetic improvement of selected breeds in various environments, as well as to facilitate rapid adaptation to potential changes in breeding goals. Genomic selection requires a large number of genetic markers such as e.g. single nucleotide polymorphisms (SNPs) the most abundant source of genetic variation within the genome.

Results

Alignment of next generation sequencing data of 32 individual turkeys from different populations was used for the discovery of 5.49 million SNPs, which subsequently were used for the analysis of genetic diversity among the different populations. All of the commercial lines branched from a single node relative to the heritage varieties and the South Mexican turkey population. Heterozygosity of all individuals from the different turkey populations ranged from 0.17-2.73 SNPs/Kb, while heterozygosity of populations ranged from 0.73-1.64 SNPs/Kb. The average frequency of heterozygous SNPs in individual turkeys was 1.07 SNPs/Kb. Five genomic regions with very low nucleotide variation were identified in domestic turkeys that showed state of fixation towards alleles different than wild alleles.

Conclusion

The turkey genome is much less diverse with a relatively low frequency of heterozygous SNPs as compared to other livestock species like chicken and pig. The whole genome SNP discovery study in turkey resulted in the detection of 5.49 million putative SNPs compared to the reference genome. All commercial lines appear to share a common origin. Presence of different alleles/haplotypes in the SM population highlights that specific haplotypes have been selected in the modern domesticated turkey.