Location: Reproduction Research
Project Number: 3040-31000-091-00-D
Project Type: In-House Appropriated
Start Date: Jul 31, 2012
End Date: Jul 30, 2017
1) Determine prenatal, postnatal and prepubertal factors influencing puberty onset and develop strategies to reduce puberty failure. - Sub-objective 1.A. Establish the effects of neonatal litter size on development of the reproductive tract of gilts. - Sub-objective 1.B. Establish the long-term effects of the size of neonatal litter in which the gilt is suckled on feeding behavior during prepubertal development and subsequent lactation performance as sows. - Sub-objective 1.C. Determine how prenatal development influences the onset of puberty. 2) Assess placental, fetal, maternal blood, genetic, epigenetic and postnatal factors contributing to conceptus loss and piglet preweaning mortality. - Sub-objective 2.A. Determine the genetic basis for uterine capacity, stillbirth and preweaning mortality. - Sub-objective 2.B. Assess how gene imprinting influences placental, fetal and postnatal development. - Sub-objective 2.C. Physiological mechanisms governing fetal blood flow distribution. - Sub-objective 2.D. Determine the influence of energy dynamics during prenatal and neonatal development on piglet survivability. - Sub-objective 2.E. Develop applied techniques to improve litter size and preweaning survival. 3) Evaluate the contribution of energetic demands during pre-, peri- and post-parturition on reproductive parameters and retention of sows in the breeding herd. - Sub-objective 3.A. Evaluate phenotypic factors and identified genetic regions that influence sow longevity. - Sub-objective 3.B. Investigate the influence of sow feed efficiency, metabolic activity and lactation performance during and after lactation on piglet survival, piglet growth and post-weaning reproduction performance of sows.
Sows must remain in the breeding herd for 3 to 4 parities to produce enough weaned piglets to be profitable. This plan describes experiments that focus on gilt development, the number of piglets weaned, and retention of sows in the breeding herd. These three factors have been identified by the National Pork Board as high priority research topics, because they each affect sow lifetime productivity. Genomic approaches will be used to develop genetic markers to improve these traits, taking advantage of animal numbers and critical expertise in genomics at USMARC. In addition, experiments focused on gilt development will elucidate factors contributing to the effects of litter birth environment of gilts before weaning on puberty, bone development and retention of sows in the herd. Factors contributing to litter size such as genetic imprinting, control of fetal blood flow, and arginine supplementation during pregnancy will be investigated. Factors contributing to preweaning survival such as development of energy stores within the fetus and neonate, the role of lactation and neonatal activity, and the effect of timing of farrowing induction will be investigated. Experiments focused on retention of sows in the breeding herd will investigate metabolic activity of the sow, with special attention to the demands and consequences of lactation on sow postweaning return to estrus. These experiments are enhanced by the expertise in these areas of the personnel assigned to the project. We expect to provide the swine industry with information, management strategies and genetic markers that will improve sow lifetime productivity.