Birth weight,reproduction traits and effects of inbreeding in Nicaraguan Reyna Creole cattle

Reyna Creole cattle in Nicaragua comprise about 650 purebred animals, and the breed has been shown to have a high level of inbreeding. To characterize the breed, as basis for a conservation program, information from two herds on birth weight (BW, n = 1097), age at first calving (AFC, n = 449) and calving interval (CI, n = 1,347) was analysed. Overall averages were 27.8 kg for BW, 37.4 months for AFC and 424 days for CI. Large differences between the herds were observed for all traits. Thus, there would be opportunities for management interventions to improve reproduction results. The heritability for BW was 0.34. For CI, the heritability of 0.20 and the additive genetic standard deviation of 36 days were comparatively high values. No genetic variation was found in AFC. Estimated inbreeding effects were associated with large standard errors due to the small size of the data and incompleteness of pedigrees. Nevertheless, significant effects were shown of dam inbreeding level on all traits. For each percentage of increased inbreeding, BW decreased by 0.06 kg, AFC increased by 3.5 days and CI increased by 1.4 days. The effects of the inbreeding level of the individual itself were not significant. The relatively good reproduction traits of Reyna Creole cattle shown in this study, despite high inbreeding levels, will be supplemented with a characterization of milk production traits.     

Indicators of genetic erosion in an endangered population: the Alentejana cattle breed in Portugal

A study was conducted to characterize genetic diversity in the Alentejana breed of cattle based on its demographic trends and to investigate the major factors affecting genetic erosion in this breed. Herdbook information collected between 1940 and 2004, including pedigree records on 100,562 animals in 155 herds, was used to estimate demographic parameters. The mean generation intervals were 6.0 +/- 2.4 yr and 6.8 +/- 3.2 yr for sires and dams of calves, respectively. Average inbreeding increased steadily over the period analyzed, with an annual rate of inbreeding of 0.33 +/- 0.004% (P < 0.01) and an effective population size of 23.3. In the reference population (28,531 calves born between 2000 and 2003) the average inbreeding was 8.35 +/- 9.02% and nearly 80% of the calves were inbred, whereas the average relationship among all animals was 0.026 +/- 0.040. Nevertheless, the mean relationship was 0.328 +/- 0.264 and 0.022 +/- 0.026 for animals born in the same and in different herds, respectively. The computed genetic contributions to the reference population resulted in estimates for the effective number of founders, ancestors, founding herds, and herds supplying sires of 121.6, 55.0, 17.1, and 26.9, respectively, the 2 most influential herds and ancestors contributing 24.2 and 15.1%, respectively, of the current genetic pool. Of the 671 founding sires, only 24 Y-chromosomes are currently represented, but 1 sire alone contributes nearly 60% of this representation, such that the effective number of Y-chromosomes is only 2.73. The observed inbreeding per herd was, on average, 0.053 +/- 0.071 lower than expected from the relationship among the generation of parents of calves in the reference population, indicating that producers have followed breeding strategies that have kept inbreeding at lower levels than anticipated with random selection and mating. When compared with other cattle breeds, Alentejana has some of the highest levels of mean inbreeding and annual rate of inbreeding, and an effective population size that is nearly half of the minimum recommended for maintenance of genetic variability. These critical indicators demonstrate the need to adopt strategies aimed at minimizing inbreeding to avoid further losses of genetic diversity.     

Inbreeding trends and pedigree analysis of Irish dairy and beef cattle populations

The objective of this study was to determine the inbreeding levels and to analyze the pedigree of Irish purebred populations of Charolais, Limousin, Hereford, Angus, and Simmental beef cattle, as well as the Holstein-Friesian dairy breed. Pedigree analyses included quantifying the depth of known pedigree, average generation intervals, effective population size, the effective number of founders, ancestors, and founder genomes, as well as identifying the most influential animals within the current population of each breed. The annual rate of increase in inbreeding over the past decade was 0.13% (P < 0.001) in the Hereford, 0.06% (P < 0.001) in the Simmental, and 0.10% (P < 0.001) in the Holstein-Friesian breeds. Inbreeding in the other breeds remained relatively constant over the past decade. Herefords had the greatest mean inbreeding in 2004, at 2.19%, whereas Charolais had the lowest, at 0.54%. Over half of each purebred population in 2004 was inbred to some degree; the population with the greatest proportion of animals inbred was the Hereford breed (85%). All 6 breeds displayed a generation interval of approximately 6 yr in recent years. In the pure-bred females born in 2004, the 3 most influential animals contributed between 11% (Limousin) and 24% (Hereford) of the genes. Effective population size was estimated for the Hereford, Simmental, and Holstein-Friesian only, and was 64, 127, and 75, respectively. The effective number of founders varied from 55 (Simmental) to 357 (Charolais), whereas the effective number of ancestors varied from 35 (Simmental and Hereford) to 82 (Limousin). Thus, despite the majority of animals being inbred, the inbreeding level across breeds is low but rising at a slow rate in the Hereford, Simmental, and Holstein-Friesian.     

A note on the population structure of the Avileña breed of cattle in Spain

The objective of this study was to describe the population structure of the Avileña breed considering the flow of genes between herds, effective number of herds and generation intervals. Characteristics of the breed which modify either the increase of level of inbreeding or the hierarchical structure of the population were also considered.     

Diversity of the Icelandic goat breed assessed using population data

Abstract

The Icelandic goat breed is a closed population consisting of around 700 animals kept in 45 herds. Several population bottlenecks are known to have occurred and the population has at least twice declined below 100 animals. Here the genetic diversity of the breed was estimated using pedigree information, D-loop sequencing and microsatellite markers. The annual rate of inbreeding was estimated as 3% and the effective population size as 5.1 animals. The effective population size based on molecular markers was estimated in the range of 4.1–8.8 individuals and mtDNA D-loop sequencing identified only three haplotypes. The results presented here show the population to be highly inbred, fragmented and the level of genetic variation among the lowest found in livestock. The results will be an important input into conservation planning for the Icelandic goat.     

Genetic variability of Lizard canary breed inferred from pedigree analysis

The genealogical data of 471 (whole population: WP) Lizard canaries of an Italian breeder were analyzed to evaluate the genetic variability of the breed. The reference population (RP) comprised 346 living reproductive birds. Average generation interval was 1.61 ± 0.718 for males and 1.72 ± 0.863 for females. The average value of inbreeding (F) and relatedness (AR) in the RP were 15.83% and 22.63%, while the average increase in inbreeding was estimated to be 6.71% per generation (effective population size = 7.49). The results showed the need to reduce the level of inbreeding which would result in significant loss of genetic variation and in significant inbreeding depression.     

Pedigree analysis and inbreeding depression on growth traits in Brazilian Marchigiana and Bonsmara breeds

The study of population structure by pedigree analysis is useful to identify important circumstances that affect the genetic history of populations. The intensive use of a small number of superior individuals may reduce the genetic diversity of populations. This situation is very common for the beef cattle breeds. Therefore, the objectives of the present study were to analyze the pedigree and possible inbreeding depression on traits of economic interest in the Marchigiana and Bonsmara breeds and to test the inclusion of the individual inbreeding coefficient (F(i)) or individual increases in inbreeding coefficient (ΔF(i)) in the genetic evaluation model for the quantification of inbreeding depression. The complete pedigree file of the Marchigiana breed included 29,411 animals born between 1950 and 2003. For the Bonsmara breed, the pedigree file included 18,695 animals born between 1988 and 2006. Only animals with at least 2 equivalent generations of known pedigree were kept in the analyses of inbreeding effect on birth weight, weaning weight measured at about 205 d, and BW at 14 mo in the Marchigiana breed, and on birth weight, weaning weight, and scrotal circumference measured at 12 mo in the Bonsmara breed. The degree of pedigree knowledge was greater for Marchigiana than for Bonsmara animals. The average generation interval was 7.02 and 3.19 for the Marchigiana and Bonsmara breed, respectively. The average inbreeding coefficient was 1.33% for Marchigiana and 0.26% for Bonsmara. The number of ancestors explaining 50% of the gene pool and effective population size computed via individual increase in coancestry were 13 and 97.79 for Marchigiana and 41 and 54.57 for Bonsmara, respectively. These estimates indicate reduction in genetic variability in both breeds. Inbreeding depression was observed for most of the growth traits. The model including ΔF(i) can be considered more adequate to quantify inbreeding depression. The inclusion of F(i) or ΔF(i) in the genetic evaluation model may not result in better fit to the data. A genetic evaluation with simultaneous estimation of inbreeding depression can be performed in Marchigiana and Bonsmara breeds, providing additional information to producers and breeders.     

Genetic diversity of Afrikaner cattle in southern Africa

The Afrikaner is an indigenous South African breed of “Sanga” type beef cattle along with breeds such as the Drakensberger and Nguni. Six composite breeds have been developed from crosses with the Afrikaner. Additionally, Afrikaner has been the base from which exotic breeds were established in South Africa through backcrossing. The study examined genetic diversity of Afrikaner cattle by genotyping 1257 animals from 27 herds in different geographic areas of South Africa and Namibia using 11 microsatellite markers. Multiple-locus assignment, performed using the Bayesian clustering algorithm of STRUCTURE, revealed three underlying genotypic groups. These groups were not geographically localized. Across herds and markers, the proportion of unbiased heterozygosity ranged from 0.49 to 0.72 averaging 0.57; mean number of alleles per locus ranged from 3.18 to 7.09, averaging 4.81; and allelic richness ranged from 2.35 to 3.38, averaging 2.67. It is concluded that a low inbreeding level of 2.7% and a moderate to high degree of variation still persists within the Afrikaner cattle breed, despite the recent decline in numbers of animals.     

Population structure and genetic variability in the Murrah dairy breed of water buffalo in Brazil accessed via pedigree analysis

The objective of this study was to use pedigree analysis to evaluate the population structure and genetic variability in the Murrah dairy breed of water buffalo (Bubalus bubalis) in Brazil. Pedigree analysis was performed on 5,061 animals born between 1972 and 2002. The effective number of founders (fe) was 60, representing 6.32?% of the potential number of founders. The effective number of ancestors (fa) was 36 and the genetic contribution of the 17 most influent ancestors explained 50?% of the genetic variability in the population. The ratio fe/fa (effective number of founders/effective number of ancestors), which expresses the effect of population bottlenecks, was 1.66. Completeness level for the whole pedigree was 76.8, 49.2, 27.7, and 12.8?% for, respectively, the first, second, third, and fourth known parental generations. The average inbreeding values for the whole analyzed pedigree and for inbreed animals were, respectively, 1.28 and 7.64?%. The average relatedness coefficient between individuals of the population was estimated to be 2.05?%??the highest individual coefficient was 10.31?%. The actual inbreeding and average relatedness coefficient are probably higher than estimated due to low levels of pedigree completeness. Moreover, the inbreeding coefficient increased with the addition of each generation to the pedigree, indicating that incomplete pedigrees tend to underestimate the level of inbreeding. Introduction of new sires with the lowest possible average relatedness coefficient and the use of appropriate mating strategies are recommended to keep inbreeding at acceptable levels and increase the genetic variability in this economically important species, which has relatively low numbers compared to other commercial cattle breeds. The inclusion of additional parameters, such as effective number of founders, effective number of ancestors, and fe/fa ratio, provides better resolution as compared to the inclusion of inbreeding coefficient and may help breeders and farmers adopt better precautionary measures against inbreeding depression and other deleterious genetic effects.     

Microsatellite marker analysis of the genetic variability in Hanoverian Hounds

Genetic variability of the dog breed Hanoverian Hound was analysed using a set of 16 microsatellites. The sample of 92 dogs was representative for the total current population [n = 334, inbreeding coefficient 9.2%, relationship coefficient 11.2%] with respect to the level and distribution of the inbreeding and relationship coefficients. All microsatellites used were in Hardy–Weinberg equilibrium. The average number of alleles was 6.4. The average observed heterozygosity (H_O) was slightly higher than the expected heterozygosity (H_E). Dinucleotide microsatellites exhibited lower polymorphism information content (PIC) than tetranucleotide microsatellites (0.52 versus 0.66). The average PIC was 0.61. The individual inbreeding coefficient was negatively related to the average H_O of all microsatellites, whereas the proportion of genes from introducing of Hanoverian Hounds from abroad showed no relationships to H_O. We found that the genetic variability in the Hanoverian Hounds analysed here was unexpectedly higher than that previously published for dog breeds of similar population size. Even in dog breeds of larger population size heterogyzosity was seldom higher than that observed here. The rather high genetic variability as quantified by polymorphic microsatellites in Hanoverian Hounds may be due to a large genetic variation in the founder animals of this breed and to the fact that this genetic diversity could be maintained despite genetic bottlenecks experienced by this breed in the 1920s and 1950s and despite the presence of high inbreeding and relationship coefficients for more than 50 years.     

Monitoring of genetic diversity in the endangered Martina Franca donkey population

The Martina Franca (MF) donkey, an ancient native breed of Apulia, was mostly famous for mule production. The breed was at serious risk of extinction in the 1980s following the decrease in demand for draft animals because they were increasingly replaced by agricultural machinery. Much has been done in the last few decades to safeguard the existing donkey breeds, but the situation remains critical. Successful implementation of conservation measures includes an evaluation of the present degree of breed endangerment, so the aim of this work was to analyze the demographic and genetic parameters of this breed to suggest effective conservation strategies. With a current breed register counting less than 500 recorded animals, the pedigree data set included 1,658 MF donkeys born between 1929 and 2006. Analyses were carried out on the whole data set as well as on a smaller one consisting of 422 living animals. Demographic and genetic variability parameters were evaluated using the ENDOG (v4.6) software. The pedigree completeness level was evaluated as well as the generation length, which was calculated for each of the 4 gametic pathways. This information was obtained from animal birth date records together with those of their fathers and mothers. The effective number of founders (f(e)), the effective number of ancestors (f(a)), the founder genome (f(g)), individual inbreeding (F), average relatedness (AR), and the rate of inbreeding per generation were analyzed to describe the genetic variability of the population. Because pedigree depth and completeness were appropriate, especially regarding the current population, the parameters defining genetic variability, namely, f(e), f(a), f(g), F, and AR, could be reliably estimated. Analysis of these parameters highlighted the endangerment status of the MF donkey. Our special concern was with the increased percentage of males and females exhibiting increased AR values. Moreover, the effective size of the current population, 48.08, is slightly less than the range of the minimum effective size, and the rates of inbreeding per generation found in the current MF population exceed the maximum recommended level of 1%. Such a scenario heightens concerns over the endangered status of the MF breed and calls for proper conservation measures and breeding strategies, such as selecting individuals for mating when relationships are below 12.5%.     

Rates of inbreeding and genetic diversity in Iranian Holstein Cattle

The accumulation of inbreeding and the loss of genetic diversity is a potential problem in Holstein dairy cattle. The goal of this study was to estimate inbreeding levels and other measures of genetic diversity, using pedigree information from Iranian Holstein cattle. Edited pedigree included 1 048 572 animals. The average number of discrete generation equivalents and pedigree completeness index reached 13.4 and 90%, respectively. The rate of inbreeding was 0.3% per year. Effective number of founders, founder genomes, non‐founders and ancestors of animals born between 2003 and 2011 were 503, 15.6, 16.1 and 25.7, respectively. It was proven that the unequal founder contributions as well as bottlenecks and genetic drift were important reasons for the loss of genetic diversity in the population. The top 10 ancestors with the highest marginal genetic contributions to animals born between 2003 and 2011 and with the highest contributions to inbreeding were 48.20% and 63.94%, respectively. Analyses revealed that the most important cause of genetic diversity loss was genetic drift accumulated over non‐founder generations, which occurred due to small effective population size. Therefore, it seems that managing selection and mating decisions are controlling future co‐ancestry and inbreeding, which would lead to better handling of the effective population size.     

Patagonian Argentine Creole cattle polymorphism: comparison with North-West populations of this breed

The relict Patagonian Argentine Creole cattle population consist of a small feral population (Los Glaciares population) that is geographically isolated in the South-West of Patagonia. In order to determine the level of genetic variability of this population, the polymorphism of eight structural genes and two microsatellites loci were studied using the polymerase chain reaction (PCR). In addition, genetic characterisation was used to compare Los Glaciares population and the ACc breed of cattle. Results obtained in this study show that the value of average heterozygosity of the studied loci for the Los Glaciares were not significantly different from the ACc. Furthermore, the data of this report were consistent with the hypothesis that Los Glaciares originated from ACc brought to the area by colonialists in the last century. Such data may be useful in formulating management plans for Feral Patagonian Creole cattle populations.     

A seroepidemiological study of bovine pestivirus in Queensland beef and dairy herds conducted in 1994/95

OBJECTIVE: To describe the distribution and prevalence of cattle herds with detectable antibody to bovine pestivirus in Queensland in 1994/95. MATERIALS AND METHODS: The study used 7,838 serum samples collected from 250 herds in Queensland, as part of a structured animal health surveillance program conducted in 1994 and 1995. Samples were collected from female cattle bred on the property. In each herd, 10 to 20 heifers less than two years of age and 10 to 15 older cows were sampled giving a 95% probability of detecting one or more seropositive animals if the seroprevalence was approximately 10% or greater. Sera were analysed for antibodies to bovine pestivirus using a virus neutralisation test. RESULTS: Total cattle numbers in sampled herds varied from 62 to 24,600 head, while total area of properties sampled varied from 50 to 395,400 hectares. Eleven percent of herds contained no seropositive animals among those sampled, and in 38% of herds, all sampled cattle aged one to two years of age were seronegative. There was a trend for larger herds to have one or more animals seropositive for bovine pestivirus (chi-squared for Linear trend = 3.656, p = 0.056). Herds with more than 500 head of cattle were significantly more likely than herds with less than 500 head to contain one or more seropositive animals in any age group (prevalence ratio = 1.12; 95% confidence interval 1.01 - 1.23; p = 0.026). Age specific seroprevalence increased from around 10% in heifers, to between 75% and 85% in cows aged 10 years. The average annual incidence risk for bovine pestivirus infection varied from 0.12 to 0.24 seroconversions per cattle year at risk, and did not vary with age. The overall crude seroprevalence adjusted for herd size was 45%. There was a wide range of seroprevalence recorded for each level of stocking intensity. CONCLUSIONS: This survey provides valuable baseline data on bovine pestivirus infection in Queensland cattle herds.     

Inbreeding and effective population size of Japanese Black cattle

The objective of this research was to estimate the amount of inbreeding and effective population size of the Japanese Black breed using pedigree records from bulls and heifers registered between 1985 and 1997. Inbreeding was quantified by three F-statistics: actual inbreeding, inbreeding expected under random mating, and inbreeding due to population subdivision. During the period of 1985 to 1997, the inbreeding expected under random mating increased from 2.3% to 5.0%, whereas the increase of actual inbreeding was more gradual (from 4.7% to 5.4%). The inbreeding due to population subdivision decreased almost linearly and reached 0.5% in 1997, indicating that genetic subdivision of the Japanese Black cattle population has essentially disappeared. The effective size of the breed was estimated from the increasing rate of inbreeding expected under random mating. In the earlier half of this period (1986 to 1990), the breed maintained an effective size of approximately 30. However, after 1991 the effective size sharply decreased and the harmonic mean between 1993 and 1997 was only 17.2. The main cause of this reduction of the effective size was considered to be the intensive use of a few prominent sires. To increase the effective size, an upper limit in the use of AI semen per sire should be imposed.     

Changes in inbreeding of U.S. Herefords during the twentieth century

Genetic diversity in the U.S. Hereford population was characterized by examining the level and rate of inbreeding and effective population size. Pedigree records for 20,624,418 animals were obtained from the American Hereford Association, of which 96.1% had both parents identified. Inbreeding coefficients were computed and mean inbreeding (Fx) calculated by year from 1900 to 2001. Inbreeding increased rapidly between 1900 and 1945. From 1946, inbreeding increased linearly to a maximum of 11.5% in 1966. Throughout the 1970s and 1980s, mean inbreeding decreased to mid-century levels. Several alternatives were investigated to explain this decline. The average relationship between prominent sires fell from 20 to 12% during the time that the level of inbreeding decreased, which reflects an increase in the popularity of certain less fashionable sire lines that would have temporarily decreased inbreeding. Pedigrees were constructed for animals born after 1990. This subsample of animals with no missing ancestors in at least 12 generations did not exhibit a decrease in inbreeding. Missing ancestral information therefore contributed to the apparent decline. One cause of missing ancestry results from outcrossing to imported animals. The effect of missing ancestry was investigated by simulating the missing ancestors. In 2001, Fx was 9.8%, and approximately 95% of individuals were inbred. The maximal inbreeding coefficient was 76%. The annual change in mean inbreeding (DeltaFx) was estimated for Herefords born during five time periods from 1946 to 2001, where inbreeding was changing at different linear rates. The DeltaFx for the most recent generation (1990 to 2001) was 0.12%/yr. Assuming a generation interval of 4.88 yr, the estimated effective population size was 85. This study provides a benchmark of current genetic diversity in the Hereford population. Results indicate that inbreeding is accumulating linearly and below critical levels. Increases in the adoption of reproductive technologies could decrease genetic diversity, and in the future, we may need to consider strategies to minimize inbreeding.     

Limits to genetic rescue by outcross in pedigree dogs

Outcrossing should reduce inbreeding levels and associated negative effects in highly inbred populations. In this study, we investigated the effectiveness of different outcrossing schemes using computer simulations. The inbreeding rate estimated for a 25‐year period of 2.1% per generation in a highly inbred dog breed reduced to 1.8% when a single litter was produced by an outcross without backcrosses. To reduce the inbreeding rate below 1%, more than eight of the 14 litters born yearly in the recipient breed had to be outcrossed. However, outcrossing in pedigree dogs is usually followed by backcrossing and generally involves one or a few litters. Backcrossing reduced the effect of outcrossing considerably. When two litters were produced by an outcross followed by one generation of backcross, the inbreeding rate was 2.0% per generation. Continuously outcrossing was more effective than a single or a few outcrosses. When each newborn litter during 25 years had a 5% chance of being produced by an outcross, the inbreeding rate reduced to ?0.2%. To investigate the possibility that new alleles were introduced from the donor population into the recipient population, the fate of different type of alleles (varying from completely lethal to beneficial) before and after an outcross was investigated by first simulating 80 years of natural selection prior to the outcross and then different types of outcross. Because natural selection reduced the frequency of lethal alleles before outcrossing, the introduction of a lethal allele that was segregating in the donor breed but not in the recipient breed occurred rarely. Introduction of slightly detrimental alleles or neutral alleles occurred more frequently. In conclusion, outcrossing only had a limited short‐term effect unless repeated continuously. Nevertheless, it may help to buy time in which the population structure can be changed so that the effective population size increases.     

Prevalence and epidemiological features of bovine viral diarrhoea virus infection in Lithuania

The objectives of the present work were to estimate the level of bovine viral diarrhoea virus (BVDV) infection in cattle herds at the different Lithuanian districts and to determine factors influencing the course of BVDV infection. The studies were explored in 147 intensive dairy cattle breeding herds from 27 different Lithuanian regions in 1997-2001. BVDV infection was diagnosed in all investigated regions. The existing variations in the structure of cattle population determined different distribution patterns of BVDV infection. The number of seropositive animals ranged from 11.9 to 100%. It must be pointed out that 29.9% of the herds were not infected with BVDV and in 32.7% of the herds from 70 to 100% of cattle were seropositive to BVDV. A positive correlation between the number of seropositive cattle, and the size of herds and age of animals was determined. Sex of animal had no influence on the prevalence of BVDV. It was estimated that the annual incidence risk of infection with BVDV decreases with the animal age.     

Breeding programme for Piétrain pigs in Bavaria with an estimation of genetic trends and effective population size

Population structure, performance testing and breeding scheme of the sire breed Piétrain in Bavaria were analyzed as a basis for further optimization studies of the breeding programme. To evaluate the current breeding programme, genetic trends and effective population size were estimated. Four data sets were used which contained breeding animals born between 1981 and 2005, estimated breeding values of traits in the breeding goal, records from young boars in field test and records from purebred and crossbred progeny on test stations. The population is subdivided in many small herds. That has disadvantages with respect to a uniform breeding goal used across herds and with respect to selection intensity and the avoidance of inbreeding. The idealized selection practice consists of three selection stages. On the first two stages information from half and full sibs on test stations is most important so that the risk of co-selecting related animals is increased. The breeding scheme is a mixture of a half sib design and a progeny testing design, but both have disadvantages. Nevertheless, genetic trends are in the desired directions. To improve accuracy and intensity of selection, only AI-boars should be used instead of natural service sires. Though the effective population size is high, the recent trend of inbreeding shows that the extensive use of popular AI-boars can lead to a rapid increase of inbreeding.     

Population genetic structure of Santa Inês sheep in Brazil

This study aimed to describe the population genetic structure and evaluate the state of conservation of the genetic variability of Santa Inês sheep in Brazil. We used pedigree data of the Santa Inês breed available in electronic processing of the Brazilian Association of Sheep Breeders. A file with 20,206 records, which enabled the calculation of the genetic conservation index (GCI), individual inbreeding coefficient (F), change in inbreeding (ΔF), effective population size (Ne), effective number of founders (?_e), effective number of ancestors (?_ɑ), generation interval (L), average relatedness coefficient of each individual (AR), and Wright’s F-statistics (F _IT, F _IS, and F _ST). For pedigree analysis and calculation of population parameters, the program ENDOG was used. The average inbreeding coefficient (\( \overline{F} \)) was 0.97% and the mean average relatedness (\( \overline{\mathrm{AR}} \)) 0.49%. The effective numbers of founders and ancestors were, respectively, 199 and 161. The average values of F and AR increased significantly over the years. The effective population size fluctuated over the years concurrently to oscillations in inbreeding rates, wherein N _e reached just 68 in the year 2012. The mean average generation interval was 5.3 years. The Santa Inês breed in Brazil is under genetic drift process, with loss of genetic variation. It requires the implementation of a genetic management plan in the herd, for conservation and improvement of the breed.