Gestation is the only phase of production during which sows can replenish lost body reserves.
Development of fat reserves during gestation is necessary for satisfactory reproductive performance, but excessive fat deposition can have negative effects on reproduction. Thus, there is an optimal range of backfat that is necessary to sustain reproduction. While it is apparent from carcass evaluations that these layers differ in chemical, structural and textural properties, their relative contributions to growth and physiology in the live animal remain unknown. At the present time, we are analyzing the growth of individual backfat layers in market hogs, and further characterizing each layer in terms of cellularity, fatty acid composition and gene expression. This trial is a preliminary investigation of how the energy demands of gestation and lactation affect growth and depletion of individual backfat layers.