Search results for "litter size"
showing 10 items of 29 documents
Oral administration of pharmacological doses of Vitamins C and E reduces reproductive fitness and impairs the ovarian and uterine functions of female…
2002
This study aims to ascertain whether oral administration of pharmacological doses of Vitamins C and E has any detrimental effect on reproductive fitness of female mice. We fed hybrid female mice from the first day of weaning a standard diet supplemented or not supplemented with pharmacological doses of Vitamins C and E. At the age of 28 weeks, we individually caged females with a male for the rest of their reproductive life. We performed a series of mating experiments to ascertain the number of oocytes ovulated and the potential for embryo development in vitro to the blastocyst stage and in vivo to Day 12 of gestation. The antioxidant diet decreased the frequency of litters, litter size, to…
Density and reproductive characteristics of female brown bears in the Cantabrian Mountains, NW Spain
2018
Here we present annual nearest-neighbour distances (as a proxy of density) between females with cubs-of-the-year (hereafter FCOY) and reproductive characteristics of brown bears Ursus arctos in the Cantabrian Mountains (NW Spain), from 1989 to 2017. FCOY nearest-neighbour distances and reproduction parameters of 19 focal females followed over several consecutive years (from 2004 to 2017) were obtained from bears inhabiting the western sector of the Cantabrian Mountains, where most of the bear population resides. In contrast, general reproductive characteristics were studied in the whole Cantabrian Mountains (western and eastern sectors together) on a sample of 362 litter sizes and 695 cubs.…
Postnatal Overfeeding in Rodents by Litter Size Reduction Induces Major Short- and Long-Term Pathophysiological Consequences
2013
Numerous studies have demonstrated that the early postnatal environment can influence body weight and energy homeostasis into adulthood. Rodents raised in small litters have been shown to be a useful experimental model to study the short- and long-term consequences of early overnutrition, which can lead to modifications not only in body weight but also of several metabolic features. Postnatal overfeeding (PNOF) induces early malprogramming of the hypothalamic system, inducing acquired persisting central leptin and insulin resistance and an increase in orexigenic signals. Visceral white adipose tissue, lipogenic activity, and inflammatory status are increased in PNOF rodents, while brown adi…
Effect of delayed breeding on the reproductive performance of female mice
2003
The aim of the present study was to determine, in the mouse, whether maintaining females as virgins until an advanced reproductive age was associated with decreased reproductive performance and reproductive lifespan compared with females of the same age that were first mated with males at an earlier reproductive age. Randomly selected virgin hybrid (C57BL/6JIco female × CBA/JIco male) female mice were housed individually with a randomly selected 12- to 14-week-old hybrid male either at the age of 28 weeks (normal breeding group; n = 20) or 51 weeks (delayed breeding group; n = 23) for the rest of their reproductive life. Females were checked once daily to determine the day of parturition an…
HORMONAL MANIPULATION OF OFFSPRING NUMBER: MATERNAL EFFORT AND REPRODUCTIVE COSTS
2002
We used exogenous gonadotropin hormones to physiologically enlarge litter size in the bank vole (Clethrionomys glareolus). This method allowed the study design to include possible production costs of reproduction and a trade-off between offspring number and body size at birth. Furthermore, progeny rearing and survival and postpartum survival of the females took place in outdoor enclosures to capture salient naturalistic effects that might be present during the fall and early winter. The aim of the study was to assess the effects of the manipulation on the growth and survival of the offspring and on the reproductive effort, survival, and future fecundity of the mothers. Mean offspring body s…
Sex–biased maternal investment in voles: importance of environmental conditions
2004
Adaptive bias in sex allocation is traditionally proposed to be related to the condition of mothers as well as to the unequal fitness values of produced sexes. A positive relationship between mother condition and investment into male offspring is often predicted. This relationship was also recently found to depend on environmental conditions. We studied these causalities experimentally using a design where winter food supply was manipulated in eight outdoor-enclosed populations of field voles Microtus agrestis. At the beginning of the breeding season in spring, food-supplemented mothers seemed to be in a similar condition, measured as body mass, head width, body condition index and parasite…
A trade-off between current and future sex allocation revealed by maternal energy budget in a small mammal.
2011
Sex-allocation theories generally assume differential fitness costs of raising sons and daughters. Yet, experimental confirmation of such costs is scarce and potential mechanisms are rarely addressed. While the most universal measure of physiological costs is energy expenditure, only one study has related the maternal energy budget to experimentally controlled offspring sex. Here, we experimentally test this in the bank vole (Myodes glareolus) by simultaneously manipulating the litter's size and sex ratio immediately after birth. Two weeks after manipulation, when mothers were at the peak of lactation and were pregnant with concurrent litters, we assessed their energy budget. We found that …
Negative frequency-dependent selection of sexually antagonistic alleles in Myodes glareolus.
2011
Sexually antagonistic genetic variation, where optimal values of traits are sex-dependent, is known to slow the loss of genetic variance associated with directional selection on fitness-related traits. However, sexual antagonism alone is not sufficient to maintain variation indefinitely. Selection of rare forms within the sexes can help to conserve genotypic diversity. We combined theoretical models and a field experiment with Myodes glareolus to show that negative frequency-dependent selection on male dominance maintains variation in sexually antagonistic alleles. In our experiment, high-dominance male bank voles were found to have low-fecundity sisters, and vice versa. These results show …
New In-Depth Analytical Approach of the Porcine Seminal Plasma Proteome Reveals Potential Fertility Biomarkers
2018
A complete characterization of the proteome of seminal plasma (SP) is an essential step to understand how SP influences sperm function and fertility after artificial insemination (AI). The purpose of this study was to identify which among characterized proteins in boar SP were differently expressed among AI boars with significantly different fertility outcomes. A total of 872 SP proteins, 390 of them belonging specifically to Sus Scrofa taxonomy, were identified (Experiment 1) by using a novel proteomic approach that combined size exclusion chromatography and solid-phase extraction as prefractionation steps prior to Nano LC-ESI-MS/MS analysis. The SP proteomes of 26 boars showing significan…
Reproductive costs and litter size in the bank vole.
1995
The potential reproductive costs for free-ranging bank vole (Clethrionomys glareolus) offspring and mothers were assessed by manipulating litter size and by determining the effects of nursing varied numbers of offspring. Litter enlargement did not increase the number of weanlings per mother. The mass of juveniles was significantly lower in the enlarged litters and higher in the reduced litters, compared to the control group. However, the survival of juveniles from weaning aged three months did not depend on their mass at weaning. Data from a previous study (Mappes et al. 1995) indicated that a higher mass at weaning may increase juveniles' abilities to maturate and breed during their summer…