Effect of starter feeding program on growth performance and gains of body components from weaning to market weight in swine

Three experiments were conducted to test the hypothesis that different star ter feeding programs (High, high quality; Low, low quality) will affect gro wth performance and body composition of pigs from weaning to market weight and that this effect may be influenced by gender (barrows or gilts) and bre ed (F, Yorkshire-Duroc x Hampshire; P, PIC Camborough 15 x PIC line 405). I n Exp. 1, 21+/-4-d-weaned F pigs (n = 90) were used in a 2 (High or Low) x 2 (barrows or gilts) factorial design. In Exp. 2, 21 +/- 3-d-weaned pigs (n = 184) were used in a 2 (F or P) x 2 (High or Low) x 2 (barrows or gilts) factorial design. In Exp. 3, 21 F pigs from each gender and feeding program treatment were killed at d 0, 3, 7, 14, 42, 82, or 152 postweaning for eva luating body composition. Two starter feeding programs (High or Low) were a pplied to pigs for 6 wk postweaning. Pigs from both High and Low treatments were provided the same corn-soybean meal-based diets for the growing and f inishing periods. Although the ADG of all pigs receiving the High treatment during the early starter period were higher (P < .01) than those of the Lo w, the terminal BW of F barrows were similar between High and Low (Exp. 1 a nd 2) and those of gilts were similar between High and Low (Exp. 2) (P > .8 0). However, the BW of P pigs receiving the High treatment, regardless of g ender, tended to be heavier than those receiving the Low (Exp. 2) and F bar rows receiving the High treatment tended to be heavier than those receiving the Low (Exp. 1). For the first 7 d postweaning, the High-fed pigs gained more protein (P < .05) and lost less fat (P < .05) than Low-fed pigs. Durin g the growing-finishing period, the Low-fed pigs exhibited compensatory pro tein gain and achieved a body protein content similar (P < .60) to High-fed pigs by termination. Protein gains from weaning to termination between Hig h- and Low-fed pigs were not different in Exp. 2 and 3. The protein gain of gilts was higher (P < .05) than that of barrows. Similarly, fat gain withi n genders was not affected by starter feeding program. Fat gain of gilts, h owever, was lower (P < .08) than that of barrows in Exp. 3. In conclusion, the nutritional quality of the starter feeding program affected growth perf ormance immediately after weaning but did not affect protein gain over the entire production period.