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The American Shire horse breed is currently listed in “critical condition”, the most serious threat category assigned by the American Livestock Breeds Conservancy. Despite concern for the breed's future, however, a thorough genetic analysis of the breed has not been conducted to date. Pedigree data from 85 671 Shire horses born between 1806 and 201...
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Context 1
... Shire ( Figure 1) is known as the largest of all horse breeds, standing up to 2 m (19.2 hands) tall at the shoulder (ALBC, 2012a). Originating in England, the breed des- cends from “ The Great Horse ” , a heavy horse developed for medieval warfare. Later bred as a general-purpose agricultural and urban draught horse, the average Shire horse weighs about 910 kg and can pull a 4 500 kg load. Shire horses played a key role in early American history. In the early nineteenth century, 80 percent of Americans lived on farms. Draft horses were in high demand, repla- cing oxen in terms of agricultural ef fi ciency and general draught power. To satisfy demand for quality heavy horses, agents were sent to France, the Netherlands and the United Kingdom to purchase pedigreed stock (Moore-Colyer, 2000). Shire horses were fi rst introduced to the United States in the mid-1800s, and the American Shire Horse Association (ASHA) was established in 1885 to oversee registration of animals, genetic preser- vation and breed promotion. The registry has been active continuously except for the period between 1955 and 1961, when most breeding activity ceased and the Shire horse nearly became extinct in the United States. Although some Shires are still used as agricultural or urban work horses or in promotional hitches for breweries and other commercial businesses, the widespread mechanization of the early twentieth century and subsequent urbanization of rural farmland has resulted in a worldwide drop in Shire numbers and a shift to more recreational uses for the breed. Today, the American Livestock Breeds Conservancy has assigned the American Shire horse “ critical ” status, its most serious threat category reserved for populations with less than 200 new registrations annually in the United States, and an estimated global population of less than 2 000 animals (ALBC, 2012b). Despite concern for the breed ’ s future in the United States, however, no assessment of population history or genetic variability has been completed to date. Such data are critical to allow for determination of breed conservation strategies and metrics of success once genetic management programmes are implemented. Therefore, the objective of this study was to evaluate current and historic levels and inbreeding, population demographics, and the number and contributions of ancestors and founders to the American Shire horse population. Pedigree information was obtained from the World Wide Shire Studbook (www.shirestudbook.com), an online database cre- ated in a joint effort between the AHSA, the Canadian Shire Horse Association, and the Shire Horse Society, the Shire horse organization for the United Kingdom. Animal ( n = 86 494) data included sire, dam, animal registration number, birth date and gender. After edits and corrections, the dataset included 85 767 horses born between 1806 and 2011 registered in the American and/or English studbooks. From this dataset, a reference population including only American horses of the most current generation (2003 – 2011) was de fi ned ( n = 1 142). Pedigrees of these animals were traced as far back as possible ( n = 4 718 ancestors), with founders de fi ned as animals with both parents unknown. Population descriptive statistics were calculated using SAS/STAT software version 9.2 (SAS Inst., Cary, NC). Pedigree completeness, complete generation equivalents, length and number of generation intervals, inbreeding coef fi cients, effective population size and effective number of founders, ancestors and founder genomes were calculated using PEDIG software (Boichard, 2002) as previously described by Bhatnagar, East and Splan (2011). Total and marginal contributions of ancestors were also calculated for in fl uential males and females. Finally, contributions of founder males to contemporary sire lines were determined by tracing the paternal lineages of all animals at 10-year intervals from 1922 to 2011. Generation intervals were calculated for stallion daughter, stallion – son, mare – daughter and mare – son pathways (Boichard, 2002). Values were not signi fi cantly different among pathways (range 8.27 – 9.04) and the average generation interval was determined to be 8.65 years. This value was used to determine which years to include in the reference population (i.e. 2003 – 2011), representing the most current generation of American Shire horses. Estimates of genetic variability depend largely on the amount of available pedigree information, which may be measured via pedigree completeness. Within the total Shire horse population, pedigree completeness peaks at Demographic 90 percent in data the for rst American-registered generation and then horses steadily are shown decreases in Figure 3. as more generations Animal numbers are included rose in the (Figure 2). late 1930s In contrast, before falling pedigree to less completeness than fi ve registered for the animals reference born popu- per lation remains near 100 percent for fi ve generations before it begins to decline. Maximal pedigree depth extended to 19 generations in contemporary animals. The average complete generation equivalent for the reference population was 9.12, and was 8.22 for the total population. Demographic data for American-registered horses are shown in Figure 3. Animal numbers rose in the late 1930s before falling to less than fi ve registered animals born per year Average between inbreeding 1952 and coef 1957. cients Recovery were 2.4 was percent slow but consider- animal numbers ing all available increased generations, linearly between and 1.3 1970 percent and when 2000, only and peaked in 2004 with more than 175 registered and domestically bred foals born that year. Figure 4 illustrates the number of Shire horses in the reference population database by year of birth, sex and percent imported stock, and indicates that the majority of horses in the pedigrees of the reference population were imported. Only after 1990 does the percentage of imported horses drop below 50 percent. Average inbreeding coef cients were 2.4 percent consider- ing all available generations, and 1.3 percent when only the most recent ve generations were considered (Figure 5). With the reference population, representing the most recent generation, average inbreeding was 4.0 percent. Non-zero inbreeding coef fi cients were found for 71.7 percent of horses. Considering all pedigree information, inbreeding levels remained under 1 percent until the bottleneck of the 1950s, and have risen steadily afterward. Despite a short lag period, a lower value, but a very similar trend, is seen when only the last fi ve generations are used, with identical peaks and troughs from 1992-on. Table 1 summarizes results from pedigree analysis of the Shire horse reference population. The ten most in fl uential male and female ancestors, along with their respective marginal and total contributions to the reference population, and number of progeny, are shown in Table 2. Together, the top ten stallions accounted for nearly half (48.5 percent) of the male in fl uence on modern day pedigrees, while the top ten mares accounted for only an 11.6 percent contribution. Investigation into paternal lineages revealed only six sire lines present in the current generation, with 96 percent of horses tracing to just three foundation sires (Figure 6). Population demographics reported here are consistent with the widely accepted history of the breed as it developed in the United States (ASHA, 2012). Most early foundation stock was imported between 1880 and 1918. After World War I, imports for Shires and other draft horses dropped drastically. Despite an initial rise in domestically bred horses in the 1930s, numbers fell through the 1940s and 1950s, as increasing mechanization reduced the usage of heavy horses in agricultural and urban sectors. In 1955, it is reported that there were less than 50 Shire horses in the entire United States (ASHA, 2012). During this time, the registry became inactive, reopening six years later in 1961. After this bottleneck event, numbers rose steadily during the last three decades of the twentieth century before reaching a peak in 2004. The percentage of imported horses contributing to the reference population dataset, which represents all domestically born animals in the most current generation as well as their ancestors, remained high until the 1970s. Measures of genetic variability based on studbook records rely heavily on pedigree completeness. Lack of complete pedigree information can result in underestimation of inbreeding coef fi cients and incorrect assignment of in fl uence to founders and ancestors (MacCluer et al. , 1983; Teegan, Edel and Thaller, 2008). Pedigree completeness among the American Shire breed was similar to that found in other horse populations (Aberle, Wrede and Distl, 2004; Valera et al. , 2005; Hamann and Distl, 2008; Olsen et al. , 2010; Bhatnagar, East and Splan, 2011). The average complete generation equivalent found for the American Shire horse population (8.22) is similar to that reported for Andalusian horses (8.26; Valera et al. , 2005) and German Hanoverian horses (8.34; Hamann and Distl, 2008), but much lower than values described for the Lipizzan horse (15.22; Zechner et al. , 2002). Generation interval for the Shire horse was similar to the 10-year span that has been reported for many horse breeds (Moureaux et al. , 1996; Bhatnagar, East and Splan, 2011; Schurink, Arts and Ducro, 2012; Vicente, Carolino and Gama, 2012). Longer generation intervals are often present in breeds with an extensive evaluation or a breeding approval process, while shorter generation intervals may be seen in populations with the ...
Context 2
... urban draught horse, the average Shire horse weighs about 910 kg and can pull a 4 500 kg load. Shire horses played a key role in early American history. In the early nineteenth century, 80 percent of Americans lived on farms. Draft horses were in high demand, repla- cing oxen in terms of agricultural ef fi ciency and general draught power. To satisfy demand for quality heavy horses, agents were sent to France, the Netherlands and the United Kingdom to purchase pedigreed stock (Moore-Colyer, 2000). Shire horses were fi rst introduced to the United States in the mid-1800s, and the American Shire Horse Association (ASHA) was established in 1885 to oversee registration of animals, genetic preser- vation and breed promotion. The registry has been active continuously except for the period between 1955 and 1961, when most breeding activity ceased and the Shire horse nearly became extinct in the United States. Although some Shires are still used as agricultural or urban work horses or in promotional hitches for breweries and other commercial businesses, the widespread mechanization of the early twentieth century and subsequent urbanization of rural farmland has resulted in a worldwide drop in Shire numbers and a shift to more recreational uses for the breed. Today, the American Livestock Breeds Conservancy has assigned the American Shire horse “ critical ” status, its most serious threat category reserved for populations with less than 200 new registrations annually in the United States, and an estimated global population of less than 2 000 animals (ALBC, 2012b). Despite concern for the breed ’ s future in the United States, however, no assessment of population history or genetic variability has been completed to date. Such data are critical to allow for determination of breed conservation strategies and metrics of success once genetic management programmes are implemented. Therefore, the objective of this study was to evaluate current and historic levels and inbreeding, population demographics, and the number and contributions of ancestors and founders to the American Shire horse population. Pedigree information was obtained from the World Wide Shire Studbook (www.shirestudbook.com), an online database cre- ated in a joint effort between the AHSA, the Canadian Shire Horse Association, and the Shire Horse Society, the Shire horse organization for the United Kingdom. Animal ( n = 86 494) data included sire, dam, animal registration number, birth date and gender. After edits and corrections, the dataset included 85 767 horses born between 1806 and 2011 registered in the American and/or English studbooks. From this dataset, a reference population including only American horses of the most current generation (2003 – 2011) was de fi ned ( n = 1 142). Pedigrees of these animals were traced as far back as possible ( n = 4 718 ancestors), with founders de fi ned as animals with both parents unknown. Population descriptive statistics were calculated using SAS/STAT software version 9.2 (SAS Inst., Cary, NC). Pedigree completeness, complete generation equivalents, length and number of generation intervals, inbreeding coef fi cients, effective population size and effective number of founders, ancestors and founder genomes were calculated using PEDIG software (Boichard, 2002) as previously described by Bhatnagar, East and Splan (2011). Total and marginal contributions of ancestors were also calculated for in fl uential males and females. Finally, contributions of founder males to contemporary sire lines were determined by tracing the paternal lineages of all animals at 10-year intervals from 1922 to 2011. Generation intervals were calculated for stallion daughter, stallion – son, mare – daughter and mare – son pathways (Boichard, 2002). Values were not signi fi cantly different among pathways (range 8.27 – 9.04) and the average generation interval was determined to be 8.65 years. This value was used to determine which years to include in the reference population (i.e. 2003 – 2011), representing the most current generation of American Shire horses. Estimates of genetic variability depend largely on the amount of available pedigree information, which may be measured via pedigree completeness. Within the total Shire horse population, pedigree completeness peaks at Demographic 90 percent in data the for rst American-registered generation and then horses steadily are shown decreases in Figure 3. as more generations Animal numbers are included rose in the (Figure 2). late 1930s In contrast, before falling pedigree to less completeness than fi ve registered for the animals reference born popu- per lation remains near 100 percent for fi ve generations before it begins to decline. Maximal pedigree depth extended to 19 generations in contemporary animals. The average complete generation equivalent for the reference population was 9.12, and was 8.22 for the total population. Demographic data for American-registered horses are shown in Figure 3. Animal numbers rose in the late 1930s before falling to less than fi ve registered animals born per year Average between inbreeding 1952 and coef 1957. cients Recovery were 2.4 was percent slow but consider- animal numbers ing all available increased generations, linearly between and 1.3 1970 percent and when 2000, only and peaked in 2004 with more than 175 registered and domestically bred foals born that year. Figure 4 illustrates the number of Shire horses in the reference population database by year of birth, sex and percent imported stock, and indicates that the majority of horses in the pedigrees of the reference population were imported. Only after 1990 does the percentage of imported horses drop below 50 percent. Average inbreeding coef cients were 2.4 percent consider- ing all available generations, and 1.3 percent when only the most recent ve generations were considered (Figure 5). With the reference population, representing the most recent generation, average inbreeding was 4.0 percent. Non-zero inbreeding coef fi cients were found for 71.7 percent of horses. Considering all pedigree information, inbreeding levels remained under 1 percent until the bottleneck of the 1950s, and have risen steadily afterward. Despite a short lag period, a lower value, but a very similar trend, is seen when only the last fi ve generations are used, with identical peaks and troughs from 1992-on. Table 1 summarizes results from pedigree analysis of the Shire horse reference population. The ten most in fl uential male and female ancestors, along with their respective marginal and total contributions to the reference population, and number of progeny, are shown in Table 2. Together, the top ten stallions accounted for nearly half (48.5 percent) of the male in fl uence on modern day pedigrees, while the top ten mares accounted for only an 11.6 percent contribution. Investigation into paternal lineages revealed only six sire lines present in the current generation, with 96 percent of horses tracing to just three foundation sires (Figure 6). Population demographics reported here are consistent with the widely accepted history of the breed as it developed in the United States (ASHA, 2012). Most early foundation stock was imported between 1880 and 1918. After World War I, imports for Shires and other draft horses dropped drastically. Despite an initial rise in domestically bred horses in the 1930s, numbers fell through the 1940s and 1950s, as increasing mechanization reduced the usage of heavy horses in agricultural and urban sectors. In 1955, it is reported that there were less than 50 Shire horses in the entire United States (ASHA, 2012). During this time, the registry became inactive, reopening six years later in 1961. After this bottleneck event, numbers rose steadily during the last three decades of the twentieth century before reaching a peak in 2004. The percentage of imported horses contributing to the reference population dataset, which represents all domestically born animals in the most current generation as well as their ancestors, remained high until the 1970s. Measures of genetic variability based on studbook records rely heavily on pedigree completeness. Lack of complete pedigree information can result in underestimation of inbreeding coef fi cients and incorrect assignment of in fl uence to founders and ancestors (MacCluer et al. , 1983; Teegan, Edel and Thaller, 2008). Pedigree completeness among the American Shire breed was similar to that found in other horse populations (Aberle, Wrede and Distl, 2004; Valera et al. , 2005; Hamann and Distl, 2008; Olsen et al. , 2010; Bhatnagar, East and Splan, 2011). The average complete generation equivalent found for the American Shire horse population (8.22) is similar to that reported for Andalusian horses (8.26; Valera et al. , 2005) and German Hanoverian horses (8.34; Hamann and Distl, 2008), but much lower than values described for the Lipizzan horse (15.22; Zechner et al. , 2002). Generation interval for the Shire horse was similar to the 10-year span that has been reported for many horse breeds (Moureaux et al. , 1996; Bhatnagar, East and Splan, 2011; Schurink, Arts and Ducro, 2012; Vicente, Carolino and Gama, 2012). Longer generation intervals are often present in breeds with an extensive evaluation or a breeding approval process, while shorter generation intervals may be seen in populations with the heavy use of arti fi cial insemination. The mean coef fi cient of inbreeding remained low until the bottleneck of the mid-1950s, and then began to rise. The clear lag and parallel rate in increase of inbreeding coef fi cients based on fi ve-generation pedigrees indicates that higher levels of inbreeding have occurred in recent generations. This is consistent with the marked rise in animal numbers and steep drop in the number of imported horses Inbreeding within the last levels 30 in years. the English Although or American the mean Shire inbreeding ...
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Citations
... Both observed ratios for the Breton population also indicate a stringent founder efect [5]. Comparatively, the Breton has higher Nfe/Nae ratios than other horse populations as the Crioulo (1.21) [18], BH (1.72) [8], Turkish Arab (1.81) [15], Pura Raza Espanola (1.78) [17], Lusitano (2.34) [19], Maremmano (2.47) [16]; yet lower than the Hanoverian (3.15) [20] and American Shire (3.7) [21]. Tese studies also noted strong signals of genetic drift in their populations, although Nfe/Ng reported ratios were lower than the Breton RP (6.06), as the BH (2.74) [8], Turkish Arab (4,16) [15], Lusitano (4.57) [19], and Maremmano (5.39) [16]. ...
The genetic diversity of Breton horses in Brazil is a critical concern, mainly due to the small population size and low number of births per year. Given that the inbreeding was overlooked by breeders for multiple generations, we estimated the genetic diversity of this population utilizing pedigree-based measures of population diversity. A total of 1394 six-generation pedigrees representing the full population of registered Breton horses in Brazil defined a total population (TP, N = 2679), with horses born between 2000 and 2022, reproductively active and alive, as reported by the breed association, representing the reference population (RP, N = 731). Using the R package PurgeR, we estimated inbreeding coefficient (Fped), maternal inbreeding coefficient (Fda m), paternal inbreeding coefficient (Fsire), individual reproductive values, number of equivalents to complete generations (t), and unbiased ancestral inbreeding coefficient (Fa). We established the equivalent complete generations (ECG), effective population size (Ne), total number of founders (Nf), effective number of founders (Nfe), total number of ancestors (Na), effective number of ancestors (Nae), founder genomes (Ng), and the inbreeding coefficient estimated with effective population size (Ne) and generation numbers (t) (FNe:t), as well as Nfe/Nae and Nfe/Ng ratios for the RP. The RP inbreeding levels have stabilized, although they are still significantly rising by generation (t), and the Nfe/Ng ratio strongly suggests genetic drift. Pedigree-based analysis demonstrates that only five stallions have sired 52.83% of the RP individuals, which along with the Nae value of 36.73 implies that the observed inbreeding can be arising from patrilines. Our results suggest that observed inbreeding is due to Popular Sire Effect, highlighting the importance of monitoring breeding schemes and genetic diversity to maintain health.
... The relationships between N e , f e , and f a provide information about the occurrence of bottlenecks in a population. A f e /f a ratio close to 1 indicates a high balance between the founders' contributions and, consequently, an absence of the bottleneck effect (BOICHARD et al., 1997), and a high f e /f a ratio indicates the disproportionate use of breeding animals (STEPHENS and SPLAN, 2013). ...
Busha is recognized as the most numerous autochthonous cattle breed in Croatia. In small populations, using the same sire repeatedly can increase inbreeding rates. This can lead to fewer high-quality, and high inbred breeding sires over time. Genealogical records of the Busha cattle breed registered from 1987 to 2022 were used to investigate the population structure and the genetic variability of the male individuals. The dataset included 10,411 animals, of which 3,962 were males. The average equivalent complete generation reached 2.92 in the total population and 3.05 in the reference population, when considering only living animals. The average inbreeding coefficient in the male population was 1.59%. Over the studied period, inbreeding rose to an average value of 2.07% in the last birth year cohort (2017-2022). The unequal contribution of the effective number of founders indicates the more frequent use of particular breeding sire lines. Nevertheless, despite the controlled inbreeding rate observed among breeding sires, and the absence of any evident population bottleneck, our study highlighted the need for breeding strategies to optimize the contribution of breeding animals in the next generations to ensure long-term conservation of the Busha cattle breed.
... For example, a f e /f a ratio close to 1 suggests that bottlenecks have not occurred in the population (Boichard et al., 1997). A high f e /f a ratio indicates disproportionate use of breeding animals (Stephens and Splan, 2013). The f e /f a ratio in Istrian cattle is currently 1.03, indicating that there is no obvious bottleneck in the population. ...
... Moreover, demographic analyses may help to understand the factors that have affected the genetic history of a population [9]. In the last years, a number of studies have been carried out on the population structure and genetic variability of horse breeds by analyzing pedigree data [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26]. Classically, monitoring of genetic diversity via the use of genealogical information has been carried out by assessing inbreeding (F) and relationships (R) in the population of interest, converted into effective population size (N e ), which is regarded as a good indicator to estimate genetic diversity for conservation purposes. ...
... Furthermore, the Maremmano horse breed from Italy [21] was reported to have values for complete and equivalent complete generations very close to those observed in the Murgese. On the other side, for several horse breeds, most of them having a long breeding tradition, such as the Arab [20,41], the Pura Raza Español [10], the Lipizzan [9], the Slovack Hucul [15], the American Shire [17], the Noriker [14] and the Hanoverian warmblood horses [13], deeper pedigrees were reported. ...
... When a population suffers a demographic decrease, such as that experienced by the MH at the beginning of the last century, fe is overestimated by ignoring some genetic bottleneck effects, but the ratio (f e /f a ) allows us to consider the loss of genetic variation promoted by the overuse of few sires. The bottleneck ratio (f e /f a ) in the MH population was 1.89, which is similar to that observed in the Czech-Moravian Belgian horse (1.86), more favorable compared to the Austrian Noriker (4.00) [14] and American Shire (3.65) [17], but lower than that found in the Slovak and Hungarian Hucul horse and the Croatian Posavina, that were 1.6, 1.41 and 1.29, respectively [15,22,37]. The value of the fa/fe ratio in Table 1 indicates a 50% reduction of the genetic diversity as expected by the fact that for the MH current population, the effective founders are 34 and the effective ancestors only 17. ...
The Murgese horse (MH) is a native breed from Apulia (Italy). This study aimed to evaluate the population status with regard to the available pedigree information (6923 animals born between 1900 and 2020), as well as its demographic and morphological evolution. The mean equivalent generations were 5.88. The average relatedness, inbreeding coefficient and increase in inbreeding by equivalent generation (ΔF) were 9.88%, 5.22%, 1.05%, respectively. The effective population size based on ΔF was 47.46. The effective number of founders (fe) was 36, and that of ancestors (fa) was 19. The ratio fe/fa was 1.89 witnessing a bottleneck effect. The ratio fa/fe indicates a 52% reduction of the genetic diversity as expected, given the fact that, for the current population (now recovered to 5000 breeding animals), the fe is 34 and the fa only 17, with 50% of diversity being explained by only six ancestors. Basically, the results reflect a substantial loss of genetic diversity in the MH breed over generations since its official founding, and unbalanced use of sires in the population, highlighting the importance of continuous monitoring and implementation of more effective conservation measures, especially in view of the growing request for boosting genetic improvement for MH morpho-functional traits.
... In the Amiata, Andalusian, Asinina de Miranda and Martina Franca donkeys, the fe/fa ratio is similar (0.85, 1.08, 1.12, 1.22) [6][7][8]10]. The high fe/fa ratio suggests a disproportionate use of some breeding animals, presumably stallions, resulting in a loss of genetic diversity compared with that expected under random mating conditions [55]. The results of the current study did not indicate a bottleneck, so the Littoral-Dinaric donkey and the Istrian donkey populations were stable. ...
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... Turkish Arabian horses have a deeper pedigree (7.8) compared to Spanish Arabian horses (5.7) [13,41]. The American Shire horse also has a favorable pedigree depth (8.22) [42], similar to the Andalusian horse (8.26) [8], but less than the Austrian Noriker horse (12.3) [10]. Although the average number of generations that can be traced in the pedigrees of CPH is not large, in the program of breed conservation, the pedigree records are of great importance. ...
... A lower f e value was observed in the Slovak, Polish, and Hungarian Hucul horse (26, 40, and 22, respectively) [11,14,44]; Andalusian horse (39.6) [8]; Spanish and Turkish Arabian horse (38.6 and 40.0) [13,41]; Maremmano horse (74) [43]; Lipizzaner (94) [11]; American Shire horse (104.5) [42]; and Austrian Noriker (117.2) [10]. The effective number of ancestors was 107 or 7.76% of the total ancestors (1435). ...
... A larger ratio reflects a more severe bottleneck effect [24]. The bottleneck ratio (f e /f a ) in the CPH population was 1.29, which is more favorable compared to the Austrian Noriker (4.00) [10]; American Shire (3.65) [42]; Silesian Norik, Noriker horse, and Czech-Moravian Belgian horse (3.11, 2.33, and 1.86, respectively) [45]; and Maremmano horse (2.4-2.5) [43]. ...
Simple Summary
Conservation of local horse breeds as part of animal genetic resources is of national and global importance. Monitoring of local breeds is often fragmentary, i.e., it involves analysis of pedigrees, phenotype, and genetic structure. Using the Croatian Posavina horse as an example, we analyzed the status of the population with regard to available pedigree information, phenotype measures of stallions and mares, and genetic structure based on microsatellites. The generation interval is about eight years, indicating relatively early involvement of animals in reproduction for economic use of the breed. The depth of the pedigree is relatively modest due to a relatively short period of systematic breeding work (two decades). The number of active sire-lines and mare-lines is favorable and forms a good basis for the preservation of the breed. Regarding conformation, the Croatian Posavina horse kept the recognizability of the small-sized horse breed in the coldblooded type, in which there are clear traces of the earlier controlled introduction of the Arabian and other breeds. Its genetic diversity component has been preserved. The above results are a guide for further implementation of effective programs for the conservation of endangered local horse breeds.
Abstract
The Croatian Posavina horse (CPH) is native Croatian breed under a conservation program and under various programs of economic use (ecosystem services, agrotourism, and meat production). The aim of this study was to analyze the status of the CPH population through an analysis of their pedigree (28,483 records), phenotype (292 licensed stallions, 255 mares), and genetic structure (292 licensed stallions). The average generation interval was 8.20 years, and the number of complete generations was 1.66. The effective number of founders and ancestors was 138 and 107, respectively, with a ratio of 1.29, and the genetic conservation index was 4.46. As for the morphometric characteristics, the average withers height of the stallions was 142.79 cm, the chest circumference was 194.28 cm, and the cannon bone circumference was 22.34. In mares, the withers height, chest, and cannon bone circumference were lower (139.71 cm, 190.30 cm, and 20.94 cm, respectively). Genetic microsatellite analysis of the 29 sire-lines showed high genetic diversity, expressed as the mean allele number (7.7), allele richness (4.0), and expected heterozygosity (0.740). There was no evidence of high inbreeding or a genetic bottleneck. The genetic and phenotypic data indicate that the CPH is an important and diverse reservoir of genetic diversity and can be conserved because of its special characteristics (adaptability).
... Food producing animals have been the main targets for conservation actions [5], but horses, dogs, cats, rabbits that in many countries are primarily used for other purposes are becoming increasingly recognized as of conservation value [6,7]. Countries are reviewing their national domestic animal breeds [8], and in Sweden the Swedish National Board of Agriculture has identified 63 such breeds historically originating in Sweden, and has declared them of national conservation concern. ...
... 6 Average mean kinship values for living individuals. 7 Range of MKs among living dogs. 8 The proportion of the initial number of founder alleles (defined as 2 x the number of founders) that is retained in one or more copies among living dogs. ...
Increasing concern is directed towards genetic diversity of domestic animal populations because strong selective breeding can rapidly deplete genetic diversity of socio-economically valuable animals. International conservation policy identifies minimizing genetic erosion of domesticated animals as a key biodiversity target. We used breeding records to assess potential indications of inbreeding and loss of founder allelic diversity in 12 native Swedish dog breeds, traditional to the country, ten of which have been identified by authorities as of conservation concern. The pedigrees dated back to the mid-1900, comprising 5–11 generations and 350–66,500 individuals per pedigree. We assessed rates of inbreeding and potential indications of loss of genetic variation by measuring inbreeding coefficients and remaining number of founder alleles at five points in time during 1980–2012. We found average inbreeding coefficients among breeds to double–from an average of 0.03 in 1980 to 0.07 in 2012 –in spite of the majority of breeds being numerically large with pedigrees comprising thousands of individuals indicating that such rapid increase of inbreeding should have been possible to avoid. We also found indications of extensive loss of intra-breed variation; on average 70 percent of founder alleles are lost during 1980–2012. Explicit conservation goals for these breeds were not reflected in pedigree based conservation genetic measures; breeding needs to focus more on retaining genetic variation, and supplementary genomic analyses of these breeds are highly warranted in order to find out the extent to which the trends indicated here are reflected over the genomes of these breeds.
... Moreover, demographic analyses may also help us to understand the important factors affecting the genetic history of a population (Zechner et al., 2002;Valera et al., 2005). In recent years, a number of studies have been carried out on the population structure and genetic variability of horse breeds (Zechner et al., 2002;Głażewska and Jezierski, 2004;Valera et al., 2005;Hamann and Distl, 2008;Cervantes et al., 2008b;Druml et al., 2009;Teegen et al., 2009;Álvarez et al., 2010;Bartolomé et al., 2011;Pjontek et al., 2012;Vicente et al., 2012;Siderits et al., 2013;Stephens and Splan, 2013;Maciel et al., 2014;Medeiros et al., 2014). The purpose of this study was to evaluate the pedigree information of the Turkish Arab horses to measure existing population genetic variability in terms of inbreeding levels and the relative contributions of founder to the current population. ...
... This study shows that PCL was over 70% until the seventh generation, contrasting with reports that this level in Spanish Arab horses was 74% and more until the fourth generation before subsequently decreasing (Cervantes et al., 2008b). The PCL remained at 90% until the fourth generation in Andalusian horses (Valera et al., 2005), until the tenth generation in Lipizzan horses (Zechner et al., 2002) and until the first generation in American Shire horses (Stephens and Splan, 2013). Looking at the mean of equivalent generations (7.8) for the RP in Turkish Arab horse, it can be said that this pedigree is of quality and depth. ...
... Bokor et al. (2013) reported that nearly 95% of the pedigree Hungarian horses in their study were inbred, and out of those horses 56% had an inbreeding coefficient >10%. The average F (4.6%) for the RP in present study is higher than values reported in the literature, for example, 0.5% in German Paint horses (Siderits et al., 2013), 0.6% in Spanish Sport horses (Bartolomé et al., 2011), 1.3% in Hanoverian horses (Hamann and Distl, 2008), 2.6% in Slovak Sport Pony horses, 3.9% in Shagya Arabian horses (Pjontek et al., 2012) and 2.4% in American Shire horses (Stephens and Splan, 2013). Some values from previous studies are similar, for example, 4% in Lipizzan horses (Pjontek et al., 2012), 4.1% in Brazilian Sport horses (Medeiros et al., 2014), 5% in Austrian Noriker horses (Druml et al., 2009) and 5.3% in the Dutch Racing horse (Schurink et al., 2012), whereas it was lower than some others, for example, 6.2% in Hucul horses (Pjontek et al., 2012), 7% in Spanish Arab horses (Cervantes et al., 2008b), 8.5% in Andalusian horses (Valera et al., 2005), 9.6% in Hungarian Thoroughbred horses (Bokor et al., 2013) and 9.6% in Lusitano horses (Vicente et al., 2012). ...
The aim of this study was to evaluate genetic variability in the Turkish Arab horse population using pedigree information. This study is the first detailed pedigree analysis of the breed in Turkey. Pedigree data were collected from the National Studbook. The pedigree data for 23 668 horses, born between 1904 and 2014, were used in the analysis. From this data set, a reference population (RP) of 14 838 animals symbolising the last generation was defined. Demographic parameters, the inbreeding level (F), the average relatedness (AR), the effective population size (Ne), the effective number of founders (fe), the effective number of ancestors (fa) and the number of founder genome equivalents (fg) were calculated for the population. The average generation interval for the RP was 12.2±4.6 years, whereas the calculated pedigree completeness levels were 98.2%, 96.6% and 95.0% for the first, second and third known generations. The mean equivalent generations (t), the average complete generations and the mean maximum generations for the RP were 7.8, 5.4 and 12.2, respectively, whereas the mean F and AR were 4.6% and 9.5% for the RP. The rate of inbred animals was 94.2% for the RP, whereas the number of founders, the number of ancestors and the fe, fa and fg were 342, 223, 40, 22 and 9.6 for the RP. The large differences observed between fe, and the number of founders demonstrates that genetic diversity decreased between the founder and the RP. Contribution of the 14 most influential founder to the RP was 50.0%, whereas just eight ancestral horses can account for 50% of the genetic variability. Ne estimated via an individual increase in inbreeding per generation ( ), and paired increase in coancestry , were 74.4±3.9 and 73.5±0.58, respectively. The inbreeding increases with the pedigree knowledge. In addition, the decrease in inbreeding in last years is more noticeable.
The research is devoted to determining the relationship of milk productivity of mares of the Novoolexandrivskii Draft with their morph functional indicators: torso and udder measurements. in two independent experiments (in two different farms), the indicator of milk productivity of mares of the Novoolexandrivskii Draft was studied depending on morph functional indicators – torso and udder measurements. the highest level of milk productivity was established in large-type mares by height at the Withers (150 cm) and chest circumference (190 cm). At the same time, minor correlations were established between the indicator of milk productivity and height at the withers (r=0.112) and oblique trunk length (r=0.109). In the second experiment, milk productivity was most correlated with chest circumference (r=0.280), metacarpal circumference (r=0.245), and trunk circumference (r=0.232). Body measurements of the studied mares are quite closely related: height at the withers × circumference of the body (r=0.811), circumference of the body × circumference of the metacarpus (r=0.573), chest circumference × circumference of the metacarpus (r=0.559), height at the withers × circumference of the metacarpus (r=0.520). By determining the development indicators of foals from Mares of various types, it was established that both foals and mares obtained from large-type mares prevailed over peers obtained from small-type mares by live weight in the development periods from birth to 18 months of age. It was found that large-type mares are also characterized by higher indicators of udder girth and length, while small-type mares predominated in udder depth. Positive correlation coefficients of the average bond strength were found between the milk productivity of mares and udder circumference (r=0.370) and udder length (r=0.301), with udder depth the bond is weak and negative (r=-0.113). A fairly strong relationship was found between udder measurements: girth × length (r=0.665), length × depth (r=0.570), girth × depth (r=0.361). The udder girth index significantly and positively correlated with the indicators of body structure indices: format (r=0.654), massiveness (r=0.514), Bony (r=0.391). The udder length index is positively and significantly correlated with the bony index (r=0.486) and format index (r=0.323).
The Hungarian Coldblood horse was developed in the 1920s by crossing local mares with draft horses imported from Belgium and France, and was approved as an official horse breed in 1954. The aim of the study was to analyze the quality of the pedigree, generation interval, gene origin, and inbreeding. The pedigree information was received from the Hungarian Coldblood Horse Breeding Association. The studbook data of the registered animals up to 2023 were evaluated. Two reference populations were chosen: horses having offspring in 1989 and 2023. The final database contained 21,699 horses. Pedigree data of the total population and the actual breeding stock were analyzed using Endog 4.8. and Grain 2.2. software. The complete generation equivalent was 4.64 and 7.72, whereas the average maximum generations was 7.90 and 13.06 for the total and reference population, respectively. There were significant differences between the parent–offspring pathways of generation intervals. In the total stock, the first 10 individuals are present in 26.71%, while in the actual breeding stock, they are present in 37.84%. The average Wright’s inbreeding coefficient was 1.13% and 2.35% in the total population and the actual breeding stock. Kalinowski’s new decomposition of inbreeding showed that inbreeding does not originate from the past; inbreeding is stronger in more recent generations. There was a reasonable bottleneck effect. A more careful mating design might be needed to avoid inbreeding in the future.
