Genetic and Environmental Factors Influencing Gestation Length in Lusitano Horses

Rodrigues, Joana A.; Gonçalves, Ana Rita; Antunes, Luis Pequito; Bettencourt, Elisa; Gama, L. T.

doi:10.1016/j.jevs.2019.102850

Cited by 9 publications

(14 citation statements)

References 41 publications

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“…The maternal heritability estimate for gestation length based on our models was 0.562, higher than previous estimates in horses of 0.18-0.39 [12,30,31]. This increased heritability estimate may be because all mares in this study have been intensively managed in the same way, minimising the amount of environmental variation that can reduce such estimates.…”

Section: Discussioncontrasting

confidence: 63%

“…Sires were also estimated to have a smaller, but still significant genetic effect on the gestation length of the foal. Stallions have similarly been found to influence gestation length in other horse breeds [30,31], and such knowledge could assist in breeding management decisions. For example, avoiding the mating of mares and stallions genetically predisposed to longer gestation lengths, particularly towards the end of the season, could aid in avoiding delayed parturition dates.…”

Section: Discussionmentioning

confidence: 95%

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The effects of inbreeding on covering success, gestation length and foal sex ratio in Australian thoroughbred horses

et al. 2020

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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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Section: Discussioncontrasting

confidence: 63%

Section: Discussionmentioning

confidence: 95%

The effects of inbreeding on covering success, gestation length and foal sex ratio in Australian thoroughbred horses

et al. 2020

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“…The limiting factor for studying the effects of maternal environment on neocortical development, particularly in relation to the evolutionary lengthening of both gestation and neurogenic period, is the complexity of the interaction between maternal and fetal compartments. Studies of factors determining the physiological gestation length are few and far between, although most point to a primarily maternal nature of these factors, involving multiple genetic loci ( Murray et al, 2010 ; Zhang et al, 2017 ; Ewert et al, 2018 ; Rodrigues et al, 2020 ). In light of the multiplicity of genetic loci involved, a genetic manipulation of gestation period length that goes beyond small intraspecies variation appears to be challenging, if not impossible, in the near future.…”

Section: Future Directions—factors Controlling Neurogenic Period Lengthmentioning

confidence: 99%

Length of the Neurogenic Period—A Key Determinant for the Generation of Upper-Layer Neurons During Neocortex Development and Evolution

Stepien

Vaid

Huttner

2021

Front. Cell Dev. Biol.

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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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“…Nevertheless, a certain degree of genetic influence has been described and modelized from a quantitative viewpoint, in mares and stallions. For instance, gestation length in mares is affected by maternal lineage or inbreeding [2][3][4]. We also recently reported the influence of the breed and individual in six fertility traits in mares belonging to 8 different Spanish breeds [5].…”

Section: Introductionmentioning

confidence: 97%

Impaired Reproductive Function in Equines: From Genetics to Genomics

Laseca

Anaya

Peña

et al. 2021

Animals

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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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Genetic and Environmental Factors Influencing Gestation Length in Lusitano Horses

Cited by 9 publications

References 41 publications

The effects of inbreeding on covering success, gestation length and foal sex ratio in Australian thoroughbred horses

The effects of inbreeding on covering success, gestation length and foal sex ratio in Australian thoroughbred horses

Length of the Neurogenic Period—A Key Determinant for the Generation of Upper-Layer Neurons During Neocortex Development and Evolution

Impaired Reproductive Function in Equines: From Genetics to Genomics

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