Effects of Increasing Dietary Lipid Inclusion in Nursery Diets with or Without Sucrose on the Growth Performance of Weaned Pigs

The objective of this study was to determine the effects of increasing dietary lipids on the growth performance and morbidity of weaned pigs when fed diets with or without sucrose. A total of 480 pigs (BW = 5.08 ± .90 kg; PIC 1050 x PIC 337) were allotted across 48 pens equally balanced by gender. A 42d study was divided into 3 dietary phases based on a 2 and 7 kg/pig feed budget, phase 3 was fed until the end. Diets were mash form corn-soybean meal based, and formulated to meet or exceed amino acid and nutrient requirements with energy floating. Soybean oil was used as the lipid source. In a 2 x 4 factorial design, pens were randomly assigned diets containing Sucrose (with or without, 10% inclusion in phase 1 and 5% in phase 2) and 0%, 3%, 6%, or 9% lipid inclusion for phases 1 and 2. Pigs were fed a common diet for phase 3. Within phase and overall, pen body weights and feed disappearance were collected to determine ADG, ADFI, and G:F. Pig removals and mortalities were recorded. Data were analyzed using a complete randomized design. During phase 1, an interaction was found between sucrose and lipid inclusion for ADFI (P = 0.006). When sucrose was not fed, increasing lipid levels quadratically impacted ADFI (P = 0.016; 67.3, 97.2, 117.6, and 103.4 g/d for 0, 3, 6, and 9%, respectively). Pigs fed diets with sucrose had greater energy intake (P = 0.001, 0.434 Mcal ME/d) than those fed diets without sucrose (0.359 Mcal ME/d). Increasing lipid levels increased daily energy intake (linear P = 0.012, 0.355 0.369, 0.431, and 0.432 Mcal ME/d, respectively). Pigs fed diets containing sucrose in phase 1 had a greater ADG (P = 0.024, 93.7 g/d) than those fed without sucrose (69.1 g/d), resulting in heavier pigs at day 10 (P = 0.021, 6.08 vs 5.82 kg, respectively). During phase 2, pigs fed sucrose diets had higher ADFI than those fed without sucrose (P = 0.028, 0.457 vs 0.425 kg). Overall (day 0-42) ADFI, ADG, and end body weights did not differ by dietary treatment. However, a sucrose and fat inclusion interaction for overall G:F (P = 0.011) was observed. When sucrose was not included, increasing lipid levels quadratically impacted G:F (P = 0.003, 0.614, 0.695, 0.736, and 0.712, respectively). A sucrose and lipid interaction was also observed for pig removal (P = 0.096). When sucrose was not included in diets, increasing lipid levels reduced the removal probability of pigs (linear P = 0.040, 24.6, 15.5, 10.0, and 11.6%, respectively). In conclusion, although final body weight was not impacted, sucrose supplementation during the first phase post-weaning resulted in higher energy intake and greater body weight gain. Additionally, increasing lipid levels in early nursery diets without sucrose progressively decreased pig removals.