Abstract
The objective of this study was to determine the effects of nutritional interventions for growth rate manipulation during gilt development on lifetime reproductive performance and survivability through parity 4. A total of 810 gilts (PIC Camborough L42, of 9 to 11 weeks of age, and initial BW of 27 ± 0.8 kg) were weighed and allotted to one of two dietary treatments, balanced by average pen weight and lot (birth week), with a total of 24 pens per treatment. Dietary treatments included Control and Slow-Growth and were fed in 3 diet phases (27 to 54 kg, 54 to 82 kg, and 82 to 113 kg BW). Control diets were formulated to meet or exceed the PIC recommendations for standardized ileal digestible lysine (SID Lys) and contained 10, 10, and 11% total dietary fiber content (TDF) in phases 1, 2, and 3; respectively. For Slow-Growth diets SID Lys was reduced by 6, 11, and 11%, dietary ME was reduced by 2.7, 4.6, and 4.7%, and TDF content increased to 15, 18, and 20% for phases 1, 2, and 3; respectively. Diets were corn-soybean meal based with wheat middlings. For Slow-Growth diets, corn germ was added as a fiber source. At the end of phase 3, gilts were individually weighed and selected. After selection, gilts were heat-checked and sent to 8 commercial sow farms, balanced by treatment, for breeding at their next recorded heat. Reproductive performance and retention data were recorded for each gilt through parity 4. Data were analyzed using generalized linear mixed models considering treatment as fixed effect, and lot as random effect. Gilts fed the Slow-Growth diets were 4.8 kg lighter (P< 0.05) than gilts fed Control diets. There was a tendency for higher retention of sows through parity 4 when they were fed the Slow-Growth diet during development (P=0.0531, 26.40 vs 32.96%, for Control and Slow-Growth, respectively). Feeding Slow-Growth diets to developing gilts reduced cull rate of sows through parity 4 (P=0.0467; 60.00 vs. 52.68% for Control and Slow-Growth, respectively). primarily due to fewer removals for reproductive reasons (No heat, not-in-pig, pregnancy-check-negative, abortion, returns to service). Total mortality (P=0.7733) and lifetime pigs born (P=0.4243) through parity 4 were not different between treatments. In summary, results from this study demonstrated that nutritional strategies targeted to reduce the growth rate of developing gilts increased their retention through parity 4 without negatively affecting reproductive performance.