Pedigree analysis of the closed nucleus of Iranian Baluchi sheep

A study was conducted to characterise genetic diversity in the closed nucleus of Baluchi sheep using pedigree analysis. Herdbook information collected between 1979 and 2008, including pedigree records on 21,721 animals, was used to compute inbreeding and average generation intervals. Effective population size and parameters derived from probability of gene origin were computed for ewes born between 2005 and 2008 with both parents known (female reference population). The average complete generation equivalent of the female reference population was 5.47. The mean generation interval was 3.33 years in the studied period. From 1983 to 1994, the rate of increase in inbreeding was approximately 0.2% per year, but, after 1994, inbreeding did not increase as in the preceding years and had an approximately flat trend over time. The mean relationship coefficients among rams, among ewes and between rams and ewes in active animals were calculated to predict the future level of inbreeding. The effective number of founders, effective number of ancestors and founder genome equivalent of the reference population were 80, 47 and 19.5, respectively. The realised effective population size was 134 animals. The results of this study indicated that the population under study has fairly good genetic variability.     

Inbreeding in reintroduced populations: the effects of early reintroduction history and contemporary processes

Maintaining genetic variation and minimizing inbreeding are central goals of conservation genetics. It is therefore crucial to understand the important population parameters that affect inbreeding, particularly in reintroduction programs. Using data from 41 reintroduced Alpine ibex (Capra ibex ibex) populations we estimated inbreeding since the beginning of reintroductions using population-specific Fst, and inbreeding over the last few generations with contemporary effective population sizes. Total levels of inbreeding since reintroduction of ibex were, on average, close to that from one generation of half-sib mating. Contemporary effective population sizes did not reflect total inbreeding since reintroduction, but 16% of variation in contemporary effective population sizes among populations was due to variation in current population sizes. Substantial variation in inbreeding levels among populations was explained by founder group sizes and the harmonic mean population sizes since founding. This study emphasizes that, in addition to founder group sizes, early population growth rates are important parameters determining inbreeding levels in reintroduced populations.     

Pedigree analysis of the Turkish Arab horse population: structure,inbreeding and genetic variability

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 (N_e), the effective number of founders (f_e), the effective number of ancestors (f_a) and the number of founder genome equivalents (f_g) 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 meanFand 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 thef_e,f_aandf_gwere 342, 223, 40, 22 and 9.6 for the RP. The large differences observed betweenf_e, 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.N_eestimated via an individual increase in inbreeding per generation (${\overline{N}}_{\text{e}}$), and paired increase in coancestry$\left(\text{}{\overline{N}}_{eC}\right)$, 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.     

Parentage analysis in a managed free ranging population of southern white rhinoceros: genetic diversity,pedigrees and management

Small populations are vulnerable to the consequences of breeding within closed groups as the loss of genetic variability can lead to inbreeding depression. Here, we use microsatellite genotypes to assess variability and parentage within a small, managed population of southern white rhinoceros in northern Namibia. Tissue samples gathered from either a modified biopsy darting technique or ear notches allowed us to obtain genotypic data for all individuals in the population. As expected for this species, genetic variability in the population was relatively low (overall H _obs 0.45). In combination with detailed management records for the period 1993–2009, we were able to assign both parents for all 23 offspring. Only one calf of seven in the F₂ generation arose from father–daughter inbreeding within the population. Our analysis revealed that paternity was initially dominated by a single founder bull siring 10 of 13 calves over 9 years; paradoxically, the other founder bull was selected for removal based on observations suggesting he was behaviourally dominant and therefore the likely sire of most calves. We also found that young introduced bulls were breeding successfully within 6 months of their arrival, well before having established their home ranges. We argue that in order to optimally manage and conserve the southern African white rhinoceros meta-population it is essential to have accurate pedigree information and genetic data for all individuals in the numerous small populations that are key to the survival of the species.     

Analysis of founders and performance test effects on an autochthonous horse population through pedigree analysis: structure,genetic variability and inbreeding

The Maremmano is an autochthonous Italian horse breed, which probably descended from the native horses of the Etruscans (VI century B.C.); the Studbook was acknowledged in 1980, and it includes 12 368 horses born from that year up to 2015. The aim of this study was to evaluate the effect of the selection program on the genetic variability of the Maremmano population; the analysis was performed using both the ‘Endog v 4.8’ program available at http://webs.ucm.es/info/prodanim/html/JP_Web.htm and in-house software on official pedigree data. Four Reference Populations were considered, and the most important one was the population of the 12 368 Maremmano horses officially registered in the National Studbook. The pedigree completeness of this population was very good because it was more than 90% at the third parental generation and more than 70% at the fifth generation; the pedigree traced back to a maximum of 10.50 generations with an average of 3.30 complete generations and 5.70 equivalent complete generations. The average generation interval was 10.65±4.72 years, with stallions used for longer periods than mares. The intervals ranged from 10.15±4.45 (mother–daughter) to 10.99±4.93 (father–daughter). The effective number of founders (f_e) was 74 and the effective number of ancestors (f_a) was 30 so that the ratio f_e/f_a was 2.47. The founder genome equivalents (f_g) was 13.72 with a ratio f_g/f_e equal to 0.18. The mean of the genetic conservation index was 5.55±3.37, and it ranged from 0.81 to 21.32. The average inbreeding coefficient was 2.94%, with an increase of 0.1%/year, and the average relatedness coefficient was 5.52%. The effective population size (N_e) computed by an individual increase in inbreeding was 68.1±13.00; the N_e on equivalent generations was 42.00, and this value slightly increased to 42.20 when computed by Log regression on equivalent generations. The analysis confirmed the presence of seven traditional male lines. The percentage of Thoroughbred blood in the foals born in 2015 was 20.30% and has increased 0.21%/year since 1980; in particular, it increased more than twice (0.51%/year) until 1993 and afterwards slightly fluctuated. The pedigree analysis confirmed the completeness of genealogical information and the traditional importance that breeders gave to the male lines; although the genetic diversity of Maremmano seemed to be not endangered by the selection program, some effects on the population structure were found and a more scientific approach to genetic conservation should be incorporated in the selection plans.     

Identification of Bovine Leucocyte Adhesion Deficiency (BLAD) Carriers in Holstein and Brown Swiss AI Bulls in Iran

BLAD is a hereditary disease in Holstein dairy cattle. The defective allele of CD18 gene, which is responsible for this disease, has recessive inheritance. The recessive homozygous form (BL/BL) is lethal and since carrier animals have viability, BLAD frequency increases by use of carrier bulls in Artificial Insemination (AI). BLAD carriers can be detected easily by means of polymerase chain reaction followed by restriction analysis of the amplicons. In this study DNA samples from Holstein (n = 30) and Brown Swiss (n = 10) bulls from Abbas Abad AI center (Khorasan state of Iran) were analysed. A 101-bp fragment from the polymorphic region of CD18 gene located on chromosome 1 was amplified by PCR. Restriction enzymes TaqI and HaeIII were used to identify genotypes. Digestion products were screened by electrophoresis on 8% non-denaturing polyacrylamide gel and visualized by ethidium bromide staining. Frequencies of BL/TL (carrier) genotypes in Holstein and Brown Swiss bulls were 3.33% and 0%, respectively. Our pedigree studies of the carrier bull in this experiment revealed that the mutation was inherited by him from Hawkeye bull (CANM 369995, BL). Although the elimination of BLAD-carrier bulls from the Holstein world would be the most efficient method to control this genetic disorder, many BLAD-carrier bulls are still listed commercially for AI, and BLAD is still occurring in Iran. Monitoring the prevalence of BLAD carriers in random selected herds may be helpful in judging the effectiveness of the BLAD-control program.     

Sustainable long-term conservation of rare cattle breeds using rotational AI sires

The development of inbreeding in rotation breeding schemes, sequentially using artificial insemination (AI) sires over generations, was investigated for a full AI scheme. Asymptotic prediction formulae of inbreeding coefficients were established when the first rotation list of AI sires (possibly related) was in use. Simulated annealing provided the optimal rotation order of sires within this list, when the sires were related. These methods were also used for subsequent rotation lists, needed by the exhaustion of semen stores for the first bulls. Simulation was carried out starting with groups of independent sires, with different sizes. To generate a yearly inbreeding rate substantially lower than 0.05% (considered to be within reach by conventional conservation schemes using frequent replacements), the results obtained showed that the number of sires should be at least 10–15 and that the same sires should be used during at least 50 years. The ultimate objective was to examine the relevance of implementing rotation in breeding schemes on the actual rare French cattle breeds under conservation. The best candidate for such a test was the Villard-de-Lans breed (27 bulls and 73 000 doses for only 340 females) and it turned out to be the best performer with an inbreeding coefficient of only 7.4% after 500 years and five different sire lists. Due to the strong requirements on semen stores and on the stability of population size, actual implementation of this kind of conservation scheme was recommended only in special (''niche'') cattle populations.     

Modeling problems in conservation genetics using captive Drosophila populations: Consequences of equalizing founder representation

Equalizing founder representation is a recommended practice for maintaining captive populations. However, this procedure has not been subject to controlled experimental evaluation. The effects on inbreeding, genetic variation, and reproductive fitness of maintaining small captive populations by equalizing founder representation (EFR) versus randomly choosing parents (RC) were compared. Ten replicate lines were created with unequal founder representations, split into EFR and RC lines, and maintained for a further eight generations. Founder representations computed from pedigrees were closer to equality in the EFR lines than in the RC lines or the base population, most of the changes being evident after one generation. Significant benefits of EFR were found in lowered inbreeding (mean inbreeding coefficients of 0.35 and 0.41, respectively, for EFR and RC lines) and average heterozygosity (0.141 for EFR, 0.084 for RC, compared with 0.216 in the base population). However, EFR was not significantly better than RC in moving allele frequencies towards equalized founder representation. No significant difference was found in reproductive fitness between EFR and RC (relative fitnesses compared to the base population were 0.179 for EFR and 0.182 for RC). The use of equalization of founder representation for a few generations can be recommended in the genetic management of captive populations derived from a small number of founders that contribute unequally. © 1992 Wiley-Liss, Inc.     

Modelling problems in conservation genetics using Drosophila: consequences of fluctuating population sizes

Many natural populations fluctuate widely in population size. This is predicted to reduce effective population size, genetic variation, and reproductive fitness, and to increase inbreeding. The effects of fluctuating population size were examined in small populations of Drosophila melanogaster of the same average size, but maintained using either fluctuating ( FPS ) or equal ( EPS ) population sizes.FPS lines were maintained using seven pairs and one pair in alternate generations, and EPS lines with four pairs per generation. Ten replicates of each treatment were maintained. After eight generations, FPS had a higher inbreeding coefficient than EPS (0.60 vs. 0.38), a lower average allozyme heterozygosity (0.068 vs. 0.131), and a much lower relative fitness (0.03 vs. 0.25). Estimates of effective population sizes for FPS and EPS were 3.8 and 7.9 from pedigree inbreeding, and 4.9 vs. 7.1 from changes in average heterozygosities, as compared to theoretical expectations of 3.3 vs. 8.0. Results were generally in accordance with theoretical predictions. Management strategies for populations of rare and endangered species should aim to minimize population fluctuations over generations.     

Pedigree analysis and inbreeding effects over morphological traits in Campolina horse population

Genetic improvement, without control of inbreeding, can go to loss of genetic variability, reducing the potential for genetic gains in the domestic populations. The aim of this study was to analyze the population structure and the inbreeding depression in Campolina horses. Phenotype information from 43 465 individuals was analyzed, data provided by the Campolina Breeders Association. A pedigree file containing 107 951 horses was used to connected the phenotyped individuals. The inbreeding coefficient was performed by use of the diagonal of the relationship matrix and the genealogical parameters were computed using proper softwares. The effective population size was estimated based on the rate of inbreeding and census information, and the stratification of the population was verified by the average relationship coefficient between animals born in different regions of Brazil. The effects of inbreeding on morphological traits were made by the use of inbreeding coefficient as a covariate in the model of random regression. The inbreeding coefficient increased from 1990 on, impacting effective population size and, consequently, shrinking genetic variability. The paternal inbreeding was greater than maternal, which may be attributed to the preference for inbred animals in reproduction. The average genetic relationship coefficient of animals born in different states was lower than individuals born within the same state. The increase in the inbreeding coefficient was negatively associated with all studied traits, showing the importance to avoid genetic losses in the long term. Although results do not indicate a severe narrowing of the population until the present date, the average relationship coefficient shows signs of increase, which could cause a drastic reduction in genetic variability if inbred mating is not successfully controlled in the Campolina horse population.     

Pedigrees and microsatellites among endangered ungulates: what do they tell us?

Relationships between pedigree coefficients of inbreeding and molecular metrics are generally weak, suggesting that measures of heterozygosity estimated using microsatellites may be poor surrogates of genome-wide inbreeding. We compare three endangered species of gazelles ( Gazella ) with different degrees of threat in their natural habitats, for which captive breeding programmes exist. For G. dorcas, the species with the largest founding population, the highest and most recent number of founding events, the correlation between pedigree coefficient of inbreeding and molecular metrics was higher than for outbred populations of mammals, probably because it has both higher mean f and variance. For the two species with smaller founding populations, conventional assumptions about founders, i.e. outbred and unrelated, are unrealistic. When realistic assumptions about the founders were made, clear relationships between pedigree coefficients of inbreeding and molecular metrics were revealed for G. cuvieri. This population had a small founding population, but it did experience admixture years later; thus, the relationship between inbreeding and molecular metrics in G. cuvieri is very similar to the expected values but lower than in G. dorcas . In contrast, no relationship was found for G. dama mhorr which had a much smaller founding population than had been previously assumed, which probably had high levels of inbreeding and low levels of genetic variability, and no admixture. In conclusion, the strength of the association between pedigree coefficient of inbreeding and molecular metrics among endangered species depends on the level of inbreeding and genetic variability present in the founding population, its size and its history.     

A definition of unknown parent groups based on bull usage patterns across herds

In genetic evaluations, the definition of unknown parent groups (UPG) is usually based on time periods, selection path and flows of foreign founders. The definition of UPG may be more complex for populations presenting genetic heterogeneity due to both, large national expansion and coexistence of artificial insemination (AI) and natural service (NS). A UPG definition method accounting for beef bull flows was proposed and applied to the French Charolais cattle population. It assumed that, at a given time period, unknown parents belonged to the same UPG when their progeny were bred in herds that used bulls with similar origins (birth region and reproduction way). Thus, the birth period, region and AI rate of a herd were pointed out to be the three criteria reflecting genetic disparities at the national level in a beef cattle population. To deal with regional genetic disparities, 14 regions were identified using a factorial approach combining principal component analysis and Ward clustering. The selection nucleus of the French cattle population was dispersed over three main breeding areas. Flows of NS bulls were mainly carried out within each breeding area. On the contrary, the use and the selection of AI bulls were based on a national pool of candidates. Within a time period, herds of different regions were clustered together when they used bulls coming from the same origin and with an estimated difference of genetic level lower than 20% of genetic standard deviation (σg) for calf muscle and skeleton scores (SS) at weaning. This led to the definition of 16 UPG of sires, which were validated as robust and relevant in a sire model, meaning numerically stable and corresponding to distinct genetic subpopulations. The UPG genetic levels were estimated for muscle and SS under sire and animal models. Whatever the trait, differences between bull UPG estimates within a time period could reach 0.5 σg across regions. For a given time period, bull UPG estimates for muscle and SS were generally larger by 0.30 to 0.75 σg than those of cows. Including genetic groups in the evaluation model increased the estimated genetic trends by 20% to 30%. It also provoked re-ranking in favor of bulls and cows without pedigree.     

The effect of genomic information on optimal contribution selection in livestock breeding programs

Background

Long-term benefits in animal breeding programs require that increases in genetic merit be balanced with the need to maintain diversity (lost due to inbreeding). This can be achieved by using optimal contribution selection. The availability of high-density DNA marker information enables the incorporation of genomic data into optimal contribution selection but this raises the question about how this information affects the balance between genetic merit and diversity.

Methods

The effect of using genomic information in optimal contribution selection was examined based on simulated and real data on dairy bulls. We compared the genetic merit of selected animals at various levels of co-ancestry restrictions when using estimated breeding values based on parent average, genomic or progeny test information. Furthermore, we estimated the proportion of variation in estimated breeding values that is due to within-family differences.

Results

Optimal selection on genomic estimated breeding values increased genetic gain. Genetic merit was further increased using genomic rather than pedigree-based measures of co-ancestry under an inbreeding restriction policy. Using genomic instead of pedigree relationships to restrict inbreeding had a significant effect only when the population consisted of many large full-sib families; with a half-sib family structure, no difference was observed. In real data from dairy bulls, optimal contribution selection based on genomic estimated breeding values allowed for additional improvements in genetic merit at low to moderate inbreeding levels. Genomic estimated breeding values were more accurate and showed more within-family variation than parent average breeding values; for genomic estimated breeding values, 30 to 40% of the variation was due to within-family differences. Finally, there was no difference between constraining inbreeding via pedigree or genomic relationships in the real data.

Conclusions

The use of genomic estimated breeding values increased genetic gain in optimal contribution selection. Genomic estimated breeding values were more accurate and showed more within-family variation, which led to higher genetic gains for the same restriction on inbreeding. Using genomic relationships to restrict inbreeding provided no additional gain, except in the case of very large full-sib families.     

Identification of bovine leucocyte adhesion deficiency (BLAD) carriers in Holstein and Brown Swiss AI bulls in Iran

BLAD is a hereditary disease in Holstein dairy cattle. The defective allele of CD18 gene which is responsible for this disease has a recessive inheritance. The recessive homozygous form (BL/BL) is lethal and since carrier animals have viability, BLAD frequency increases by use of carrier bulls in Artificial Insemination (AI). BLAD carriers can be detected easily by means of polymerase chain reaction followed by restriction analysis of the amplicons. In this study DNA samples from Holstein (n = 30) and Brown Swiss (n = 10) bulls from Abbas Abad AI center (Khorasan state of Iran) were analysed. A 101 bp fragment from the polymorphic region of CD18 gene located on chromosome 1 was amplified by PCR. Restriction enzymes TaqI and HaeIII were used to identify genotypes. Digestion products were screened by electrophoresis on 8% non-denaturing polyacrylamide gel and visualized by ethidium bromide staining. Frequencies of BL/TL (carrier) genotypes in Holstein and Brown Swiss bulls were 3.33% and 0%, respectively. Our pedigree studies of the carrier bull in this experiment revealed that the mutation inherited to him from Hawkeye bull (CANM 369995, BL). Although the elimination of BLAD-carrier bulls from the Holstein world would be the most efficient method to control this genetic disorder, many BLAD-carrier bulls are still listed commercially for AI and BLAD is still occurring in Iran. Monitoring the prevalence of BLAD-carriers in random selected herds may be helpful in judging the effectiveness of the BLAD-control program.     

Genetic Variation and Differentiation of Larix decidua Populations in Swiss Alps (in English)

Genetic diversity within and among six subpopulations of Larix decidua Mill. from two altitudinal transects of Swiss Alps was investigated using 6 enzyme systems coding for 8 loci. Globally, the mean proportion of polymorphic loci was 22.9%, the average number of alleles per locus was 1.3, and the mean expected heterozygosity was 0.095. Only 5.8% of the genetic variation resided among populations. The mean genetic distance was 0.006. Several significant differences of gene frequencies were found between different age classes. Positive values of the species mean fixation index observed in this study suggested a considerable deficit of heterozygotes in the populations of L. decidua of Swiss Alps. At one of the sites (Arpette), the highest subpopulation in elevation gave the lowest level of genetic diversity (as evidenced by the lowest proportion of polymorphic loci and the lowest mean expected heterozygosity) and the largest value of genetic distance when compared to other subpopulations. The genetic differences between the highest subpopulation and the other ones suggest that the founder effect may be an important factor influencing genetic differentiation of L. decidua populations at Arpette transect.     

瑞士阿尔卑斯山欧洲落叶松居群的遗传变异和分化

应用等位酶分析技术,沿两个海拔梯度在瑞士阿尔卑斯山研究了欧洲落叶松（Larix decidua Mill.)居群内和居群间的遗传多态性,结果表明,多态性位点的比例为22.9%,平均每个位点的等位基因数为1.3,平均期望杂合度为0.095,遗传变异的5.8%存在于居群之间,平均遗传距离为0.006。几个有统计意义的基因频率差别在不同树龄类被发现,正在繁育系数值表明在瑞士阿尔卑斯山欧洲落叶松居群有相当的杂合体缺乏,在阿尔拜特（Ar-pette),海拔最高的亚居群与其他亚居群相比较显示最低的遗传多态性（如显示最低的我态性位点比例和最低的平均期望杂合度）和最大的遗传距离值,在最高亚居群和其他亚居群间的遗传差别暗示奠基效应可能是影响这个定样场所欧洲落叶松居群遗传分化的主要因素。     

Analysis of founder representation in pedigrees: Founder equivalents and founder genome equivalents

The concepts of “founder equivalent” and “founder genome equivalent” are introduced to facilitate analysis of the founding stocks of captive or other populations for which pedigrees are available. The founder equivalents of a population are the number of equally contributing founders that would be expected to produce the same genetic diversity as in the population under study. Unequal genetic contributions by founders decrease the founder equivalents, portend greater inbreeding in future generations than would be necessary, and reflect a greater loss of the genetic diversity initially present in the founders. The number of founder genome equivalents of a population is that number of equally contributing founders with no random loss of founder alleles in descendants that would be expected to produce the same genetic diversity as in the population under study. The number of founder genome equivalents is approximately that number of wild-caught animals that would be needed to obtain the same amount of genetic diversity as is in the descendant captive population. Founder equivalents and founder genome equivalents allow comparison of the genetic merits of adding new wild-caught stock vs. further equalizing founder representations in a captive population.     

Impact of genomic selection of AI dairy sires on their likely utilization and methods to estimate fertility: a paradigm shift

Breeding of dairy cattle is undergoing a paradigm shift to genomic selection of potential sires and dams. This undoubtedly will affect how bulls are managed in an artificial insemination (AI) center and impact methods to estimate their ‘fertility'. Our goal is to help decision-makers understand the contents of a straw of semen, current estimates of sire fertility, and how estimates might evolve in a genomic era. Sire fertility is estimated from outcome (pregnant or not) after 300 to > 2,000 inseminations and reported in units (U) as a sire's deviation from a population (> 500 bulls) average pregnancy rate (PR). Too often users do not recognize that imprecision of an estimate encompasses a 3-U range, or more. ‘True fertility' of the sire whose semen is inseminated influences outcome far less than ‘true fertility' of each female and a myriad of microenvironment and management factors. Further, AI centers discard substandard collections and intentionally adjust number of sperm per straw so that differences in pregnancy rates achieved by different sires are minimized! For > 80% of Holstein bulls, estimated ‘sire conception rates' are within a 5.4-U range. In the future, most sires will be 15 to 40 mo old and services will accumulate at > 1,000/mo. Estimated sire conception rates still will be a deviation from the population mean, but should be based on records for the most recent 6 or 12 mo, rather than 48 or 60 mo. Repeated ‘snap shots' every 2 mo would allow AI centers to adjust number of sperm per AI straw from genomic-sires in a timely manner, to maintain high pregnancy rates, and to meet market demands with sires producing ∼40% as many sperm as mature ‘proven sires' of yesteryear.     

The influence of captive breeding management on founder representation and inbreeding in the ‘Alalā, the Hawaiian crow

The ‘Alalā (Corvus hawaiiensis), or the Hawaiian crow, was historically only found on the island of Hawai‘i, declined greatly in the twentieth century, and was last seen in the wild in 2002. A captive breeding program was initiated in the 1970s and 113 individuals were in captivity in 2014. All of the present day individuals are descended from nine founders. From pedigree analysis, 50 % of the initial ancestry was from a single founder pair and as of 2014, 45 % of the ancestry was still from this pair. Six other founders have also contributed substantially to the population and managed breeding has increased and evened out their contributions in recent years. Managed breeding has also kept the inbreeding level at the relatively low level of 0.120 in 2014. However, for most of the history of the population, all of the inbreeding was from the single founder pair and in 2014, 76 % of the inbreeding was still from this pair. As a result, the high inbreeding depression previously seen in this population appears to descend from this single pair. Breeding management to maximize founder genome equivalents, which takes into account loss of variation from genetic drift, could increase the genetic representation from the founders, particularly if ancestry from the single founder with only one living descendant is increased.