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Lawson JM, Shilton CA, Lindsay-McGee V, Psifidi A, Wathes DC, Raudsepp T, de Mestre AM. Does inbreeding contribute to pregnancy loss in Thoroughbred horses? Equine Vet J 2024; 56:711-718. [PMID: 38221707 DOI: 10.1111/evj.14057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Accepted: 12/29/2023] [Indexed: 01/16/2024]
Abstract
BACKGROUND Excessive inbreeding increases the probability of uncovering homozygous recessive genotypes and has been associated with an increased risk of retained placenta and lower semen quality. No genomic analysis has investigated the association between inbreeding levels and pregnancy loss. OBJECTIVES To compare genetic inbreeding coefficients (F) of naturally occurring Thoroughbred Early Pregnancy Loss (EPLs), Mid and Late term Pregnancy Loss (MLPL) and Controls. The F value was hypothesised to be higher in cases of pregnancy loss (EPLs and MLPLs) than Controls. STUDY DESIGN Observational case-control study. METHODS Allantochorion and fetal DNA from EPL (n = 37, gestation age 14-65 days), MLPL (n = 94, gestational age 70 days-24 h post parturition) and Controls (n = 58) were genotyped on the Axiom Equine 670K SNP Genotyping Array. Inbreeding coefficients using Runs of Homozygosity (FROH) were calculated using PLINK software. ROHs were split into size categories to investigate the recency of inbreeding. RESULTS MLPLs had significantly higher median number of ROH (188 interquartile range [IQR], 180.8-197.3), length of ROH (3.10, IQR 2.93-3.33), and total number of ROH (590.8, IQR 537.3-632.3), and FROH (0.26, IQR 0.24-0.28) when compared with the Controls and the EPLs (p < 0.05). There was no significant difference in any of the inbreeding indices between the EPLs and Controls. The MLPLs had a significantly higher proportion of long (>10 Mb) ROH (2.5%, IQR 1.6-3.6) than the Controls (1.7%, IQR 0.6-2.5), p = 0.001. No unique ROHs were found in the EPL or MLPL populations. MAIN LIMITATIONS SNP-array data does not allow analysis of every base in the sequence. CONCLUSIONS This first study of the effect of genomic inbreeding levels on pregnancy loss showed that inbreeding is a contributor to MLPL, but not EPL in the UK Thoroughbred population. Mating choices remain critical, because inbreeding may predispose to MLPL by increasing the risk of homozygosity for specific lethal allele(s).
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Affiliation(s)
- Jessica M Lawson
- Department of Pathobiology and Population Sciences, The Royal Veterinary College, University of London, Hatfield, UK
| | - Charlotte A Shilton
- Department of Comparative Biomedical Sciences, The Royal Veterinary College, University of London, London, UK
| | - Victoria Lindsay-McGee
- Department of Clinical Science and Services, The Royal Veterinary College, University of London, London, UK
| | - Androniki Psifidi
- Department of Clinical Science and Services, The Royal Veterinary College, University of London, London, UK
| | - D Claire Wathes
- Department of Pathobiology and Population Sciences, The Royal Veterinary College, University of London, Hatfield, UK
| | - Terje Raudsepp
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas, USA
| | - Amanda M de Mestre
- Department of Comparative Biomedical Sciences, The Royal Veterinary College, University of London, London, UK
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Derisoud E, Auclair-Ronzaud J, Palmer E, Robles M, Chavatte-Palmer P. Female age and parity in horses: how and why does it matter? Reprod Fertil Dev 2021; 34:52-116. [PMID: 35231230 DOI: 10.1071/rd21267] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Although puberty can occur as early as 14-15months of age, depending on breed and use, the reproductive career of mares may continue to advanced ages. Once mares are used as broodmares, they will usually produce foals once a year until they become unfertile, and their productivity can be enhanced and/or prolonged through embryo technologies. There is a general consensus that old mares are less fertile, but maternal age and parity are confounding factors because nulliparous mares are usually younger and older mares are multiparous in most studies. This review shows that age critically affects cyclicity, folliculogenesis, oocyte and embryo quality as well as presence of oviductal masses and uterine tract function. Maternal parity has a non-linear effect. Primiparity has a major influence on placental and foal development, with smaller foals at the first gestation that remain smaller postnatally. After the first gestation, endometrial quality and uterine clearance capacities decline progressively with increasing parity and age, whilst placental and foal birthweight and milk production increase. These combined effects should be carefully balanced when breeding mares, in particular when choosing and caring for recipients and their foals.
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Affiliation(s)
- Emilie Derisoud
- Université Paris-Saclay, UVSQ, INRAE, BREED, 78350 Jouy-en-Josas, France; and Ecole Nationale Vétérinaire d'Alfort, BREED, 94700 Maisons-Alfort, France
| | | | - Eric Palmer
- Académie d'Agriculture de France, 75007 Paris, France
| | - Morgane Robles
- Université Paris-Saclay, UVSQ, INRAE, BREED, 78350 Jouy-en-Josas, France; and Ecole Nationale Vétérinaire d'Alfort, BREED, 94700 Maisons-Alfort, France; and INRS Centre Armand-Frappier Santé Biotechnologie, 531 Boulevard des Prairies, H7V 1B7 Laval, QC, Canada
| | - Pascale Chavatte-Palmer
- Université Paris-Saclay, UVSQ, INRAE, BREED, 78350 Jouy-en-Josas, France; and Ecole Nationale Vétérinaire d'Alfort, BREED, 94700 Maisons-Alfort, France
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Bene S, Szabó F, Polgár PJ, Juhász J, Nagy P. Genetic parameters of gestation length trait in dromedary camels (Camelus dromedarius). Acta Vet Hung 2021; 69:249-255. [PMID: 34487512 DOI: 10.1556/004.2021.00033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Accepted: 08/26/2021] [Indexed: 11/19/2022]
Abstract
Gestation length (GL) data of dromedary camels were analysed for the period from 2007 to 2018. The database of the largest dairy camel herds (Dubai, United Arab Emirates) was used in this study. The data of 4,084 camels included in the assessment were classified into six ecotypes (Emirati, Emirati cross, Black, Pakistani, Saudi-Sudanese and Saudi cross). The aim of the study was to describe the heritability of GL of camels and the breeding value (BV) of sires for this trait. The genetic parameters of GL were estimated by the General Linear Model method and two Best Linear Unbiased Prediction (BLUP) animal models as well. The mean (±SE) of GL of camels was 384.3 ± 0.2 days. The direct heritability of GL (0.26 ± 0.06-0.36 ± 0.08) was higher than the maternal heritability (0.00 ± 0.05-0.13 ± 0.06) obtained. The maternal permanent environmental effect (0.15 ± 0.05) was similar to the results estimated previously in dromedary camel, but higher than the data reported by relevant sources in other species. Based on the results of this study it can be concluded that the GL of dromedary camels is a species-specific value similar to that in cattle, which is less affected by the maternal influence. Considerable differences (16 days) exist among male dromedaries in their BV for the GL trait.
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Affiliation(s)
- Szabolcs Bene
- 1 Institute of Animal Sciences, Georgikon Campus, Hungarian University of Agriculture and Life Sciences, Deák F. u. 16, H-8360 Keszthely, Hungary
| | - Ferenc Szabó
- 2 Department of Animal Sciences, Faculty of Agricultural and Food Sciences, Széchenyi István University, Mosonmagyaróvár, Hungary
| | - Péter J. Polgár
- 1 Institute of Animal Sciences, Georgikon Campus, Hungarian University of Agriculture and Life Sciences, Deák F. u. 16, H-8360 Keszthely, Hungary
| | - Judit Juhász
- 3 Emirates Industry for Camel Milk and Products, Dubai, United Arab Emirates
| | - Péter Nagy
- 3 Emirates Industry for Camel Milk and Products, Dubai, United Arab Emirates
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Stepien BK, Vaid S, Huttner WB. Length of the Neurogenic Period-A Key Determinant for the Generation of Upper-Layer Neurons During Neocortex Development and Evolution. Front Cell Dev Biol 2021; 9:676911. [PMID: 34055808 PMCID: PMC8155536 DOI: 10.3389/fcell.2021.676911] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2021] [Accepted: 04/20/2021] [Indexed: 11/17/2022] Open
Abstract
The neocortex, a six-layer neuronal brain structure that arose during the evolution of, and is unique to, mammals, is the seat of higher order brain functions responsible for human cognitive abilities. Despite its recent evolutionary origin, it shows a striking variability in size and folding complexity even among closely related mammalian species. In most mammals, cortical neurogenesis occurs prenatally, and its length correlates with the length of gestation. The evolutionary expansion of the neocortex, notably in human, is associated with an increase in the number of neurons, particularly within its upper layers. Various mechanisms have been proposed and investigated to explain the evolutionary enlargement of the human neocortex, focussing in particular on changes pertaining to neural progenitor types and their division modes, driven in part by the emergence of human-specific genes with novel functions. These led to an amplification of the progenitor pool size, which affects the rate and timing of neuron production. In addition, in early theoretical studies, another mechanism of neocortex expansion was proposed—the lengthening of the neurogenic period. A critical role of neurogenic period length in determining neocortical neuron number was subsequently supported by mathematical modeling studies. Recently, we have provided experimental evidence in rodents directly supporting the mechanism of extending neurogenesis to specifically increase the number of upper-layer cortical neurons. Moreover, our study examined the relationship between cortical neurogenesis and gestation, linking the extension of the neurogenic period to the maternal environment. As the exact nature of factors promoting neurogenic period prolongation, as well as the generalization of this mechanism for evolutionary distinct lineages, remain elusive, the directions for future studies are outlined and discussed.
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Affiliation(s)
- Barbara K Stepien
- Max Planck Institute of Molecular Cell Biology and Genetics, Max Planck Society (MPG), Munich, Germany.,Institute of Anatomy, Faculty of Medicine Carl Gustav Carus, School of Medicine, Technische Universität Dresden, Dresden, Germany
| | - Samir Vaid
- Max Planck Institute of Molecular Cell Biology and Genetics, Max Planck Society (MPG), Munich, Germany
| | - Wieland B Huttner
- Max Planck Institute of Molecular Cell Biology and Genetics, Max Planck Society (MPG), Munich, Germany
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Laseca N, Anaya G, Peña Z, Pirosanto Y, Molina A, Demyda Peyrás S. Impaired Reproductive Function in Equines: From Genetics to Genomics. Animals (Basel) 2021; 11:393. [PMID: 33546520 PMCID: PMC7913728 DOI: 10.3390/ani11020393] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2021] [Revised: 01/29/2021] [Accepted: 01/31/2021] [Indexed: 12/15/2022] Open
Abstract
Fertility is one of the key factors in the economic and productive success of the equine industry. Despite this, studies on the genetic causes affecting reproductive performance are scarce, especially in mares, where the genetic architecture of the reproductive traits is extremely complex. Today, with the increasing availability of new genomic methodologies for this species, we are presented with an interesting opportunity to understand the genetic basis of equine reproductive disorders. These include, among others, novel techniques for detecting chromosomal abnormalities, whose association with infertility in horses was established over 50 years ago; new sequencing technologies permitting an accurate detection of point mutations influencing fertility, as well as the study of inbreeding and molecular homozygosity, which has been widely suggested as one of the main causes of low reproductive performance in horses. Finally, over the last few years, reproductive performance has also been associated with copy number variants and candidate genes detected by genome-wide association studies on fertility traits. However, such studies are still scarce, probably because they depend on the existence of large and accurate phenotypic datasets of reproductive and/or fertility traits, which are still difficult to obtain in equines.
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Affiliation(s)
- Nora Laseca
- Departamento de genética, Universidad de Córdoba, Campus de Rabanales Ctra, Madrid-Cádiz, km 396, 14071 Córdoba, Spain; (N.L.); (G.A.); (Z.P.); (A.M.)
| | - Gabriel Anaya
- Departamento de genética, Universidad de Córdoba, Campus de Rabanales Ctra, Madrid-Cádiz, km 396, 14071 Córdoba, Spain; (N.L.); (G.A.); (Z.P.); (A.M.)
| | - Zahira Peña
- Departamento de genética, Universidad de Córdoba, Campus de Rabanales Ctra, Madrid-Cádiz, km 396, 14071 Córdoba, Spain; (N.L.); (G.A.); (Z.P.); (A.M.)
| | - Yamila Pirosanto
- Departamento de Producción Animal, Facultad de Ciencias Veterinarias, Universidad Nacional de La Plata, La Plata 1900, Argentina;
- Consejo Superior de Investigaciones Científicas y Tecnológicas (CONICET), CCT-La Plata, La Plata 1900, Argentina
| | - Antonio Molina
- Departamento de genética, Universidad de Córdoba, Campus de Rabanales Ctra, Madrid-Cádiz, km 396, 14071 Córdoba, Spain; (N.L.); (G.A.); (Z.P.); (A.M.)
| | - Sebastián Demyda Peyrás
- Departamento de Producción Animal, Facultad de Ciencias Veterinarias, Universidad Nacional de La Plata, La Plata 1900, Argentina;
- Consejo Superior de Investigaciones Científicas y Tecnológicas (CONICET), CCT-La Plata, La Plata 1900, Argentina
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Todd ET, Hamilton NA, Velie BD, Thomson PC. The effects of inbreeding on covering success, gestation length and foal sex ratio in Australian thoroughbred horses. BMC Genet 2020; 21:41. [PMID: 32268877 PMCID: PMC7140579 DOI: 10.1186/s12863-020-00847-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Accepted: 03/24/2020] [Indexed: 11/10/2022] Open
Abstract
Background Horses produce only one foal from an eleven-month gestation period, making the maintenance of high reproductive rates essential. Genetic bottlenecks and inbreeding can increase the frequency of deleterious variants, resulting in reduced reproductive levels in a population. In this study we examined the influence of inbreeding levels on foaling rate, gestation length and secondary sex ratio in Australian Thoroughbred mares. We also investigated the genetic change in these traits throughout the history of the breed. Phenotypic data were obtained from 27,262 breeding records of Thoroughbred mares provided by three Australian stud farms. Inbreeding was estimated using the pedigree of each individual dating back to the foundation of the breed in the eighteenth century. Results While both gestation length and foaling rate were heritable, no measurable effect of inbreeding on either trait was found. However, we did find that the genetic value for both traits had decreased within recent generations. A number of environmental factors also had significant effects on foaling rate and gestation length. Secondary sex ratio had only an extremely small paternal heritable effect and was not susceptible to environmental influences. Conclusions In contrast to racing performance, inbreeding had no measurable effect on foaling rate or gestation length in Australian Thoroughbred horses. This could be because the level of inbreeding in the population examined is not high enough to show a discernible effect on reproductive traits. Populations that experience higher levels of inbreeding due to use of artificial reproductive technologies or extremely small population sizes may show a more pronounced reduction in natural foaling rate or gestation length. It is also possible that the intensive management techniques used in the Thoroughbred population masks any negative effects of inbreeding. The decrease in the genetic value of foaling rate is likely to be because horses with unfavourable genetic potential have not yet been selected out of the population. The change in genetic value of gestation length may be due to selective breeding favouring horses with shorter pregnancies. We also found that prioritising the mating of older mares, and avoiding out of season mating could lead to an increased breeding success.
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Affiliation(s)
- Evelyn T Todd
- School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, 2006, Australia.
| | - Natasha A Hamilton
- Racing Australia Equine Genetics Research Centre, Racing Australia, Sydney, NSW, 2000, Australia
| | - Brandon D Velie
- School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Peter C Thomson
- School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, 2006, Australia
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