Evaluation of Nursery Diet Complexity on Growth Performance and Carcass Traits of Pigs

The study was conducted to investigate the effect of nursery diet complexity on growth performance and carcass traits of pigs. A total of 126 piglets (initial BW 6.30 ± 0.68 kg and 18 d old) were blocked by body weight and randomly allotted to 1 of 3 treatments, with 7 pigs/pen and 6 pens/treatment. In the nursery period (week 1-2, 3-4, 5-6 as phases 1, 2, and 3 respectively), piglets were fed 1 of 3 experimental diets: (1) positive control (PC; with spray-dried porcine plasma, fishmeal, antibiotics, and zinc oxide), (2) PC without antibiotics (PC-AB), and (3) negative control (NC; without spray-dried porcine plasma, fishmeal, antibiotics, zinc oxide). During the growing-finishing period, pigs were fed common diets containing no animal proteins and antibiotics. Data were analyzed using mixed model of SAS, with treatment as fixed effect and block as random effect. Tukey test was used for multiple comparison. In phase 1, the NC group had lower (P < 0.05) ADG, ADFI than the other two groups and lower (P < 0.05) G:F compared with the PC group. The NC pigs ate less (P < 0.05) and tended (P < 0.10) to gain less than the PC-AB pigs in phase 2, Nevertheless, the NC group had higher (P < 0.05) G:F than the PC group in phases 2 and 3. During the entire nursery period, the NC group had lower (P < 0.05) ADG and ADFI than the PC-AB group, but no difference (P > 0.05) in G:F was observed among treatments. For the overall experimental period, the NC group ate less (P < 0.05) than the other two groups, and tended (P < 0.10) to have lower ADG relative to the PC group, but there were no effects (P > 0.05) of dietary treatments on feed efficiency. No difference (P > 0.05) on growth performance during the entire nursery phase and the whole experiment period was noticed between the PC and PC-AB groups. For the whole nursery period, ADG was 494, 532, 457 g/d, ADFI was 727, 763, 656 g/d, and G:F was 0.681, 0.698, 0.697 for the PC, PC-AB, and NC groups, respectively. Dietary treatments did not impact (P> 0.05) carcass characteristics. In conclusion, feeding simple nursery diets had negative impact on growth performance in the nursery period, which could be carried over to the growing-finishing period.

Key words: nursery diet complexity, growth performance, carcass traits, pigs