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Flores JG, Bueno VLC, Bastos HBDA, Rechsteiner SMDEF. Foal sex in Thoroughbred horses: related factors. Anim Reprod 2024; 21:e20230073. [PMID: 39176003 PMCID: PMC11340788 DOI: 10.1590/1984-3143-ar2023-0073] [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: 06/02/2023] [Accepted: 06/03/2024] [Indexed: 08/24/2024] Open
Abstract
Reproductive biotechniques in the equine species have advanced in the last decade and horse breeders have started to question the possibilities of interfering in the determination of foal sex. The aim of the present study was to verify whether the variables mares and stallion's age, side of the ovary containing the preovulatory follicle, preovulatory follicle diameter, time between breeding and ovulation, and ovulation inducing hormones influence the sex of the foal. A total of 259 reproductive cycles of 160 mares and 22 Thoroughbred stallions were used. Statistical analysis was performed using R software, including Pearson's chi-square test and logistic regression. Of the total foals born, 136 were males (52.51%) and 123 were females (47.49%). In mares that ovulated with -24h after ovulation induction, 104 foals (54.74%) were males and 86 (45.26%) were females, while in mares that ovulated with +24h, 32 foals (46.38%) were males and 37 (53.62%) were females. Stallions up to 15 years old had 44.14% (n=49) females and those over 15 years had 49.66% (n=73) females. The simple logistic regression model showed that mares and stallions under 15 years old, mares with ovulation time less than 24 hours and treated with Deslorelin had a higher probability of having male foals, but the Pearson's chi-square test showed that foals gender were not influenced by the variables studied.
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Affiliation(s)
- Jonas Gomes Flores
- Histologia e Reprodução Equina (HISTOREP), Faculdade de Veterinária, Universidade Federal de Pelotas, Pelotas, RS, Brasil
- Laboratório de Reprodução Animal (REPROLAB), Faculdade de Veterinária, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brasil
| | - Verônica La Cruz Bueno
- Histologia e Reprodução Equina (HISTOREP), Faculdade de Veterinária, Universidade Federal de Pelotas, Pelotas, RS, Brasil
- Laboratório de Reprodução Animal (REPROLAB), Faculdade de Veterinária, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brasil
| | - Henrique Boll de Araujo Bastos
- Laboratório de Reprodução Animal (REPROLAB), Faculdade de Veterinária, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brasil
| | - Sandra Mara da Encarnação Fiala Rechsteiner
- Histologia e Reprodução Equina (HISTOREP), Faculdade de Veterinária, Universidade Federal de Pelotas, Pelotas, RS, Brasil
- Laboratório de Reprodução Animal (REPROLAB), Faculdade de Veterinária, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brasil
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Firman RC, Ellis CM, Thorn S, Mawson PR. Parental effects on offspring sex ratio in the Numbat ( Myrmecobius fasciatus): does captivity influence paternal sex allocation? J Mammal 2023; 104:1036-1046. [PMID: 38033358 PMCID: PMC10682968 DOI: 10.1093/jmammal/gyad067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 06/03/2023] [Indexed: 12/02/2023] Open
Abstract
Sex allocation theories predict that under different ecological conditions the production of sons and daughters will affect parental fitness differently. Skewed offspring sex ratios often occur under captive conditions where individuals are exposed to nutritional and social conditions that differ from nature. Here, we analyzed 29 years of offspring sex ratio data from a captive population of an endangered marsupial, the Numbat (Myrmecobius fasciatus). We partitioned variation in offspring sex ratio based on parental origin (captive- vs. wild-bred), parental weight, maternal age, and maternal reproductive history. Our analyses revealed no effect of parental weight or maternal origin on offspring sex ratio-however, there was a significant effect of paternal origin. Data visualization indicated that captive-bred males tended to produce male-biased litters. We discuss the result in relation to recent studies that have shown that male mammals have the capacity to be arbiters of sex allocation and highlight candidate mechanisms, but consider it with caution due to the small sample size from which the result was derived. We performed a population viability analysis (PVA) to explore the potential impact of a sex ratio skew on the sustainability of the captive Numbat population under hypothetical scenarios. Our PVA revealed that supplementation with wild individuals is critical to the persistence of the captive Numbat population and that a biased sex ratio will lead to extinction of the captive colony under certain conditions. Overall, our study demonstrates that covert sex ratio skews can persist undetected in captive populations, which have the potential to become impactful and compromise population sustainability under changed management processes.
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Affiliation(s)
- Renée C Firman
- Centre for Evolutionary Biology, School of Biological Sciences, University of Western Australia, 35 Stirling Hwy, Crawley, Western Australia 6009, Australia
- School of Biological Sciences, University of Western Australia, 35 Stirling Hwy, Crawley, Western Australia 6009, Australia
| | - Connor M Ellis
- Centre for Evolutionary Biology, School of Biological Sciences, University of Western Australia, 35 Stirling Hwy, Crawley, Western Australia 6009, Australia
- School of Biological Sciences, University of Western Australia, 35 Stirling Hwy, Crawley, Western Australia 6009, Australia
| | - Sian Thorn
- Centre for Evolutionary Biology, School of Biological Sciences, University of Western Australia, 35 Stirling Hwy, Crawley, Western Australia 6009, Australia
| | - Peter R Mawson
- School of Biological Sciences, University of Western Australia, 35 Stirling Hwy, Crawley, Western Australia 6009, Australia
- Perth Zoo, Department of Biodiversity, Conservation and Attractions, 20 Labouchere Road, South Perth, Western Australia 6151, Australia
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OUP accepted manuscript. J Mammal 2022. [DOI: 10.1093/jmammal/gyac041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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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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Rocha CE, de Carvalho EDC, de Castro FCGS, Xavier ILGDS, Young RJ, Palhares MS, da Silva Filho JM, Carvalho RR, Vasconcellos ADS, Valle GR. Is mare sexual behavior affected by age and can it predict ovulation? Appl Anim Behav Sci 2020. [DOI: 10.1016/j.applanim.2020.104937] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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Chiang C, Lewis LR, Borkowski G, Flaws JA. Late-life consequences of short-term exposure to di(2-ethylhexyl) phthalate and diisononyl phthalate during adulthood in female mice. Reprod Toxicol 2020; 93:28-42. [PMID: 31904422 DOI: 10.1016/j.reprotox.2019.12.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 12/12/2019] [Accepted: 12/31/2019] [Indexed: 10/25/2022]
Abstract
Di(2-ethylhexyl) phthalate (DEHP) is a known endocrine disruptor and diisononyl phthalate (DiNP) is a common DEHP replacement chemical. However, little is known about late-life consequences due to DEHP or DiNP exposure during adulthood. Thus, this study tested the hypothesis that adult exposure to DEHP or DiNP affects female reproductive parameters during late-life in female mice. Female CD-1 mice (age 39-40 days) were dosed with either vehicle control, DEHP (20 μg/kg/day-200 mg/kg/day), or DiNP (20 μg/kg/day-200 mg/kg/day) for 10 days and breeding trials were conducted at 12 and 15 months post-dosing. Further, ovaries and sera were collected at 12, 15, and 18 months post-dosing. DEHP and DiNP disrupted estrous cyclicity, increased pregnancy loss, decreased fertility, altered the sex ratio of pups, altered ovarian follicle populations, and disrupted hormone levels. Collectively, these data show that short-term exposure to DEHP or DiNP during adulthood has long-term consequences in late-life.
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Affiliation(s)
- Catheryne Chiang
- Department of Comparative Biosciences, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Lily R Lewis
- Department of Comparative Biosciences, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Grace Borkowski
- Department of Comparative Biosciences, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Jodi A Flaws
- Department of Comparative Biosciences, University of Illinois at Urbana-Champaign, Urbana, IL, United States; Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, United States.
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Martins ACL, Vaz MA, Macedo MM, Santos RL, Galdino CAB, Wenceslau RR, Valle GR. Maternal age, paternal age, and litter size interact to affect the offspring sex ratio of German Shepherd dogs. Theriogenology 2019; 135:169-173. [DOI: 10.1016/j.theriogenology.2019.06.022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2018] [Revised: 03/25/2019] [Accepted: 06/11/2019] [Indexed: 11/25/2022]
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Affiliation(s)
- Mathieu Douhard
- Département de Biologie; Université de Sherbrooke; 2500 boulevard de l’ Université Sherbrooke QC J1K 2R1 Canada
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