Search results for "Litter"
showing 10 items of 315 documents
Offspring growth, survival and reproductive success in the bank vole: a litter size manipulation experiment.
1998
To estimate the optimality of brood size, it is essential to study the effects of brood size manipulation on offspring survival and reproductive success. Moreover, testing the generality of the hypothesis of reproductive costs requires experimental data from a diversity of organisms. Here I present data on the growth, survival and reproductive success of bank vole Clethrionomys glareolus individuals from manipulated litters. Furthermore, the survival of mothers whose litter size was manipulated was studied. At weaning, the mean weight of pups from enlarged litters was lower and from reduced litters higher compared to control litters. After winter, at the start of the breeding season, indivi…
Experimental manipulation of breeding density and litter size: effects on reproductive success in the bank vole
1999
1. Reproductive success of individual females may be determined by density-dependent effects, especially in species where territory provides the resources for a reproducing female and territory size is inversely density-dependent. 2. We manipulated simultaneously the reproductive effort (litter size manipulation: ± 0 and + 2 pups) and breeding density (low and high) of nursing female bank voles Clethrionomys glareolus in outdoor enclosures. We studied whether the reproductive success (number and quality of offspring) of individual females is density-dependent, and whether females can compensate for increased reproductive effort when not limited by saturated breeding density. 3. The females …
Reproductive Biology and Its Impact on Body Size: Comparative Analysis of Mammalian, Avian and Dinosaurian Reproduction
2011
Janis and Carrano (1992) suggested that large dinosaurs might have faced a lower risk of extinction under ecological changes than similar-sized mammals because large dinosaurs had a higher potential reproductive output than similar-sized mammals (JC hypothesis). First, we tested the assumption underlying the JC hypothesis. We therefore analysed the potential reproductive output (reflected in clutch/litter size and annual offspring number) of extant terrestrial mammals and birds (as "dinosaur analogs") and of extinct dinosaurs. With the exception of rodents, the differences in the reproductive output of similar-sized birds and mammals proposed by Janis and Carrano (1992) existed even at the …
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…
Estimation of genetic and phenotypic parameters for bacteriological status of the udder,somatic cell score,and milk yield in dairy sheep using a thre…
2013
Abstract The objective of this study was to estimate the genetic parameters for infection status (INF), as indicator of mastitis, SCS (i.e., log-transformed SCC), and milk yield (MY), by using a Gibbs sampling algorithm. The data comprised 17,843 test-day records of 2040 ewes. The pedigree file included 2948 animals. A bivariate variance component analysis was performed using the TM software. Fixed effects considered in the analysis were litter size, parity, flock by test-day interaction, year by season of lambing interaction, and stage of lactation; whereas the animal, and the permanent environmental effect within and across lactations were considered as random as well as the error. Flat p…
High population density in bank voles stimulates food hoarding after breeding.
1998
The effects of conspecific density (i.e. risk of intraspecific competition) on hoarding behaviour were studied in breeding pairs of bank voles, Clethrionomys glareolus. I simulated high population density by using odours of conspecifics, to exclude the direct effects of exploitation or interference competition for food. The pairs of bank voles hoarded only at the end of their breeding season. Hoarding was not correlated with whether the voles had a litter during the experiment or their litter size, but was more likely at the high population density and for pairs with small females. This may indicate that smaller females especially make caches in the autumn, possibly to ensure better winter …
Predictive Capacity of Boar Sperm Morphometry and Morphometric Sub-Populations on Reproductive Success after Artificial Insemination
2021
The aim of the study was to compare the morphometric features of sperm head sizeand shape from the Pietrain line and the Duroc×Pietrain boar crossbred terminal lines, and toevaluate their relationship with reproductive success after artificial insemination of sows producedfrom crossbreeding the York, Landrace and Pietrain breeds. Semen samples were collected from 11sexually mature boars. Only ejaculates with greater than 70% motility rate and <15% of abnormalsperm were used for artificial inseminations (AI) and included in the study. Samples were analyzedusing an ISAS®v1 computer-assisted sperm analysis system for eight morphometric parameters ofhead shape and size (CASA-Morph). Sub-populat…
Relationship between Fertility Traits and Kinematics in Clusters of Boar Ejaculates
2021
The aim was to determine the relationship between kinematic parameters of boar spermatozoa and fertility rates of sow, as well as to assess the effect of sperm clusters on the fertility capacity of the ejaculate. Semen samples were collected from 11 sexually mature boars. Samples were analyzed by an ISAS®v1 CASA-Mot system for eight kinematic parameters. Ejaculate clusters were characterized using multivariate procedures, such as principal factors (PFs) analysis and clustering methods (the k-means model). Four different ejaculate clusters were identified from two kinematic PFs which involved linear trajectory and velocity. There were differences (p 0.05) between dam lines and ejaculate clus…
Effects of a split 48-h doe-litter separation on productivity of free-nursing rabbit does and their litters
2004
To prevent the weight loss of litters, and the distress of both rabbit does and their litters due to doe-litter separation (DLS), without losing its beneficial effects on fertility, the DLS, lasting 48 h before artificial insemination (AI), was split into two periods of 24 h with a short controlled suckling. Initially, 105 does of different parity were divided into three groups. During the post partum, the free-nursing does were treated as follows: regular DLS (R-DLS), the nest-box was closed for 48 h, from days 9 to 11, before AI; split DLS (S-DLS), the nest-box was closed for 24 h and, after suckling, for other 24 h before AI; control, does had free access to the nest-box. Fertility impro…
Long-Term Effects of Postovulatory Aging of Mouse Oocytes on Offspring: A Two-Generational Study1
1999
Aims of this study were to analyze the long-term effects of postovulatory aging of mouse oocytes on 1) reproductive traits of parental (F(0)) and first (F(1))-generation females (pregnancy rate, gestation length, litter size, perinatal death, and sex ratio of offspring) and 2) developmental and behavioral variables of F(1) and second-generation (F(2)) offspring (birth weight and weight gain during preweaning development, postnatal day of attainment of immediate righting, spontaneous motor activity, and passive and active conditioned learning ability). Hybrid (C57BL/6JIco x CBA/JIco) females were artificially inseminated at 13 h (control group) or 22 h (oocyte-aged group) after GnRH injectio…