Self-organization and natural selection are fundamental forces that shape the natural world. Substantial progress in understanding how these forces interact has been made through the study of abstract models. Further progress may be made by identifying a model system in which the interaction between self-organization and selection can be investigated empirically. To this end, we investigate how...

This study aimed to evaluate effect of stage of feed restriction on performance and productivity of pregnant does. New Zealand white female rabbits were randomly divided into three groups. Control group was provided daily with 185 g of food increased to 200 g from the 15th day of gestation. R(1) was offered daily a restricted amount of food (60% restriction, 111 g) for the first half of pregnan...

Despite their importance in evolutionary biology, heritability and the strength of natural selection have rarely been estimated in wild populations of iteroparous species or have usually been limited to one particular event during an organism's lifetime. Using an animal-model restricted maximum likelihood and phenotypic selection models, we estimated quantitative genetic parameters and the stre...

Our objective was to evaluate the correlated responses to selection for litter size and its components after 10 generations of divergent selection for uterine capacity (UC). A total of 294 intact females from the 11th and 12th generations of divergent selection for high and low UC and from a cryopreserved control population was used (139, 112, and 43 females, respectively). Uterine capacity was...

Presence of major genes was investigated for two growth traits, backfat thickness, and two litter size traits in the F1 and F2 population of a cross between Meishan and European "White" pig lines. Segregation analyses were performed in a Bayesian setting, estimating the contribution of background polygenes and the contribution of a possible major gene to the expression of the traits considered....

Experimental studies have often been employed to study costs of reproduction, but rarely to study costs of gestation. Disentangling the relative importance of each stage of the reproductive cycle should help to assess the costs and benefits of different reproductive strategies. To that end, we experimentally reduced litter size during gestation in a viviparous lizard. We measured physiological ...

Selection for total number of piglets born (TNB) since 1992 has led to a significant increase in this trait in Danish Landrace and Danish Yorkshire but has also been accompanied by an increase in piglet mortality. The objective of this study was to estimate the genetic and phenotypic parameters for litter size and survival to find alternative selection criteria to improve litter size at weaning...

This review is focused on studies of vitamin E in immunity and reproductive performance in pigs. There are reports that vitamin E can have a positive effect on some parameters of the immune system in pigs. The optimal level of vitamin E needed to improve the immune system has not been determined because of several factors such as the composition of the diet, feed consumption, the rate of animal...

In species with repeated bouts of reproduction, a female's ability to retain sufficient tissue for self-maintenance is essential to her survival and capacity for future reproduction. Loss of bone mineral content results in bone fragility and the possibility of reduced survival, so females should guard against the overuse of their bone mineral during reproduction. Given these constraints, I pred...

The objective of this research was to determine whether plasma concentration of FSH was genetically correlated with ovulation rate and thus was a useful trait for indirect selection. Blood samples were collected from 619 animals from five lines of pigs. Line I was selected for increased index of ovulation rate and embryonal survival, and Line C was its randomly selected control. Pigs sampled fr...