The goal of the RRU is to increase reproductive efficiency in cattle and swine by decreasing the number of breeding-age males and females required to produce a given number of offspring. Maintaining animals for breeding is a significant cost in the production of domestic livestock, thus improvements in reproductive efficiency reduce costs, increase profitability and reduce meat prices paid by the U.S. consumer.

Reproduction research at the U.S. Meat Animal Research Center includes efforts to improve female components of reproduction, including puberty attainment (i.e., gilt and heifer development), conception rate, embryo-fetal development, the birth process, preweaning survival, and rebreeding performance post-weaning (i.e., sow productive lifetime). The RRU combines traditional endocrine and physiology studies with modern genomic, proteomic, and molecular biology techniques to provide an integrated approach to the complex problem of reproductive efficiency in livestock.

The RRU also includes scientists engaged in swine genomics. This effort is focused on developing genetic markers for quantitative traits that are useful to the swine industry. Current traits being mapped include reproductive, growth, skeletal structure, behavioral, and meat quality traits.

Physiology research successes of the unit include:

* demonstration of the role of Sertoli cells in boar fertility;

* elucidation of the role of fetal red blood cell production and placental function in uterine capacity and litter size;

* increasing the incidence of twinning in beef cattle; and

* demonstration of the role of antral follicle counts in cow fertility.

Genomics research successes include:

* generating microsatellite and SNP-based genetic maps in swine;

* providing swine EST sequence to help define gene expression in swine tissues; and

* discovering quantitative trait loci for a variety of reproductive, growth, and pork quality traits.

Current research efforts include defining the control of the farrowing in sows, exploring factors influencing preweaning survival of piglets, defining nutrition/reproduction interactions and physiological indicators of sow productive lifetime and beef cattle fertility, determining how the placenta develops in swine, and developing useful genetic markers for quantitative traits in pigs and cattle.

Staff Scientists

J.L. Vallet — Research Physiologist, Research Leader

R.A. Cushman — Research Physiologist

S.E. Echternkamp — Research Physiologist

B.A. Freking — Research Geneticist

J.R. Miles — Research Physiologist

D.J. Nonneman — Molecular Biologist

L.A. Rempel — Research Physiologist

G.A. Rohrer — Research Geneticist