Genetic study of gestation length in Andalusian and Arabian mares.
Abstract: The length of gestation in Andalusian, or Spanish Purebred (SPB) and Arabian (AB) mares reared in Spain was analysed, based on 766 spontaneous full-term deliveries appertaining to 141 mares of SPB breed and 72 mares of AB breed in 31 breeding seasons. The data were obtained from the Yeguada Militar de Jerez de la Frontera stud farm in Cádiz, Spain. The mean length of gestation was of 336.8+/-0.48 days in the SPB mares and 340.3+/-0.63 days in AB mares. To assess the accurate prediction of time of birth the potential effect of a number of factors was investigated. The influences of the breed, mare, month and year of mating, age of the mother, number of births and sex of the foal were statistically significant. The factor have the greatest influence over the gestation length was the mare itself, with a correlation among consecutive births of around 0.4. The effect of inbreeding, both of the mare and foal, was negligible. Gestation length shortened as the breeding season progressed: in both breeds, a delay of 1 month in mating corresponded to a decrease of 3 days in the gestation length. According to our results, gestation length decrease as the mare gets older, with the shortest gestation periods when the mare is 10-12 years old, and from this point on, it slowly increases. The gestation period shortens as the 4th or 5th birth approaches, and then gets progressively longer. The range of variation in gestation length due to the number of births to the mare is of 2.9 days for the AB mares, and 2.2 days for SPB mares. The heritability for the gestation length for AB and the SPB breeds was 0.2, with a repeatability of 0.36 and 0.37, for SPB and AB breeds, respectively. With the data from both breeds, and using a classical approach, the response to selection was estimated if mares with extreme gestation lengths were culled, i.e. lengths which are under 310 days, or over 360 days. According to our results, in the case of SPB, a decrease of 14-45% would occur in the number of extreme gestation lengths, while in the AB breed, this value would decrease from 2 to 39%.
Publication Date: 2005-11-02 PubMed ID: 16271285DOI: 10.1016/j.anireprosci.2005.09.008Google Scholar: Lookup
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- Journal Article
Summary
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This research presents a detailed study on the length of gestation in Andalusian, or Spanish Purebred (SPB) and Arabian (AB) horse breeds. Based on analysis of 766 spontaneous full-term equine deliveries, it was concluded that several factors significantly influence the duration of gestation; the most significant factor being the individual mare itself.
Research Context and Methodology
- The study was conducted at the Yeguada Militar de Jerez de la Frontera stud farm in Cádiz, Spain, and analysed 766 spontaneous full-term deliveries over 31 breeding seasons from 141 SPB mares and 72 AB mares.
- The length of gestation averaged 336.8 days for SPB mares and 340.3 days for AB mares.
- The research aimed to accurately predict the time of birth by investigating the potential effect of various factors on the gestation period.
Main Findings
- The study found that breed, mare, month and year of mating, age of the mare, number of births, and sex of the foal significantly influenced the gestation period. Out of these factors, the individual mare had the greatest influence on gestation length with a correlation among consecutive births of around 0.4.
- Inbreeding did not significantly affect gestation length in either breed.
- Gestation length was found to shorten as the breeding season progressed, with a delay of 1 month in mating correlating with a decrease of 3 days in the gestation length.
- As mares aged, gestation lengths decreased peaking at the shortest duration when the mare was aged 10-12 years before slowly increasing again.
- Gestation period shortened approaching the 4th or 5th birth before getting progressively longer. The range of variation due to the number of births was 2.9 days for AB mares and 2.2 days for SPB mares.
- Heritability for the gestation length for AB and the SPB breeds was 0.2, with a repeatability of 0.36 and 0.37, for SPB and AB breeds, respectively.
Impact of Selection on Gestation Length
- The researchers estimated the response to selection if mares with extreme gestation lengths (less than 310 days or over 360 days) were culled.
- Results suggested that in the case of SPB mares, this would result in a decrease of 14-45% in the number of extreme gestation lengths. For the AB breed, the decrease would range from 2% to 39%.
Cite This Article
APA
Valera M, Blesa F, Dos Santos R, Molina A.
(2005).
Genetic study of gestation length in Andalusian and Arabian mares.
Anim Reprod Sci, 95(1-2), 75-96.
https://doi.org/10.1016/j.anireprosci.2005.09.008 Publication
Researcher Affiliations
- Departamento di Ciencias Agroforestales, Escuela Universitaria de Ingeniería Técnica Agrícola, Universidad de Sevilla, Ctra. De Utrera, km. 1, 41013 Sevilla, Spain.
MeSH Terms
- Age Factors
- Animals
- Animals, Newborn
- Female
- Gestational Age
- Horses / genetics
- Horses / physiology
- Male
- Parity
- Pregnancy
- Pregnancy, Animal / physiology
- Regression Analysis
- Retrospective Studies
- Seasons
- Sex Factors
- Spain
Citations
This article has been cited 8 times.- Aoki T, Violin G, Jikihara T, Shibata M, Higaki S, Ozawa T, Furukawa E, Yoshioka K. Prediction of Nocturnal Foaling Using Ventral Tail Base Surface Temperature Recorded by a Wearable Device Attached to the Mare's Tail. Animals (Basel) 2026 Jan 9;16(2).
- Rivero MJ, Cooke AS, Gandarillas M, Leon R, Merino VM, Velásquez A. Nutritional composition, fatty acids profile and immunoglobulin G concentrations of mare milk of the Chilean Corralero horse breed. PLoS One 2024;19(9):e0310693.
- Laseca N, Cánovas Á, Valera M, Id-Lahoucine S, Perdomo-González DI, Fonseca PAS, Demyda-Peyrás S, Molina A. Genomic screening of allelic and genotypic transmission ratio distortion in horse. PLoS One 2023;18(8):e0289066.
- Laseca N, Molina A, Ramón M, Valera M, Azcona F, Encina A, Demyda-Peyrás S. Fine-Scale Analysis of Runs of Homozygosity Islands Affecting Fertility in Mares. Front Vet Sci 2022;9:754028.
- 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 Feb 3;11(2).
- 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 Apr 8;21(1):41.
- Kuhl J, Stock KF, Wulf M, Aurich C. Maternal Lineage of Warmblood Mares Contributes to Variation of Gestation Length and Bias of Foal Sex Ratio. PLoS One 2015;10(10):e0139358.
- Nuñez CM, Adelman JS, Rubenstein DI. Immunocontraception in wild horses (Equus caballus) extends reproductive cycling beyond the normal breeding season. PLoS One 2010 Oct 26;5(10):e13635.
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