Effects of Nutrition During Gilt Development on Lifetime Productivity of Sows of Two Prolific Maternal Lines: Growth Characteristics of Replicate 1, 2, and 3 Gilts

University of Nebraska 2007 Swine Report. A study was designed to evaluate the effects of energy intake during the gilt development period (day 123 to day 226 of age) on sow lifetime productiv- ity in two prolifi c sow lines. Elaboration of the design and preliminary results are available in the 2005 and 2006 University of NebraskaLincoln Swine Reports. The two populations used were created by crossing a maternal line boar available from the industry with either sows from the UNL Nutri- tion Herd (designated LW LR) or the Nebraska Index Line (designated L45X). At approximately day 123, half the gilts within each genetic line were allocated to receive ad libitum (A) access to a corn-soybean meal diet or 75% of the ad libitum feed (energy) intake (R). During the developmental period, pigs were weighed, and ultrasound mea- surements of 10th-rib backfat (BF) and longissimus muscle area (LMA) were recorded every 14 days. In addition, feeders were weighed for the estimation of average daily feed intake for the A groups. Feed intake in the R groups was restricted to 74 to 76% of the A-group gilts. Restricting energy intake was effec- tive at reducing bodyweight gain and BF depth and LMA in both genetic lines. Subsequent analyses of sow productivity will be based in part on these fi ndings. This type of analysis will be important in evaluating potential gilt development strategies (based on a constant age or body weight) for prolifi c gilt lines similar to those used in this study.