LAUSR

The objective of this experiment was to determine the effects of dietary functional proteins with or without antibiotics on the growth and health of nursery pigs. A total of 1,230 pigs weaned at 15–18 days (4.93 ± 0.02 kg BW; PIC 359 X 1050, Hendersonville, TN) were randomly assigned to 1 of 6 dietary treatments (10 pens/treatment) for a 42-d experiment. Treatments were arranged as a 2 X 3 factorial of in-feed antibiotics (no vs yes) and functional feed additive proteins [none (CON), spray-dried plasma proteins (SDPP; AP 920, APC Inc., Ankeny, IA), or dried egg protein with IgY (DEP; Globimax JS, EW Nutrition, Des Moines, IA)]. Diets were fed in 4 phases with phase 3–4 common across treatments. Proteins were fed in phases 1 (d 0–13; 3% SDPP or 0.2% DEP) and 2 (d 13–26; 2% SDPP or 0.1% DEP). Antibiotics were fed in phase 1–3 (662 mg chlortetracycline/kg, 28 mg carbadox/kg, 441 mg chlortetracycline/kg, respectively). Growth performance data were analyzed using PROC MIXED of SAS (9.4). Pen was the experimental unit; proteins and antibiotics and their interaction were considered fixed effects. In the absence of antibiotics, compared with CON, SDPP and DEP increased ADG (CON: 0.237 kg, SDPP: 0.254 kg, DEP: 0.257 kg/d; P = 0.036) and ADFI (CON: 0.360, SDPP: 0.378, DEP: 0.383 kg/d; P = 0.040). In the presence of antibiotics, SDPP increased ADG compared with DEP, but not CON, (CON: 0.258, SDPP: 0.268, DEP: 0.251 kg/d; P = 0.036) and ADFI (CON: 0.385, SDPP: 0.398, DEP: 0.381 kg/d; P = 0.040). Diet had no effect on feed efficiency (P > 0.10). SDPP and DEP decreased the number of medical treatments administered (P = 0.001). In conclusion, the functional proteins increased growth performance in the absence of antibiotics, but not when antibiotics were used. However, the functional proteins were effective in decreasing medical treatments regardless of antibiotic use.