Evaluation of Benzoic Acid As an Alternative to Antibiotic Growth Promoter in Weaned Pigs

Benzoic acid supplement (BA) was evaluated as an alternative to anti-microbial growth promoter in weaned pigs. A total of 96 piglets (6.2±.3 kg BW) were weaned at d 21 of age and placed in pens (4 piglets per pen) based on BW and gender and allocated to three diets to give 8 replicates. Diets included: control (C) corn-soybean meal diet, C + in-feed antibiotic (AB, 220mg/kg chlortetracycline hydrochloride and 31.2 mg/kg tiamulin) and C + 0.5% BA (BA). Pigs had free access to diets and water for six weeks. Feed intake and BW were taken weekly to calculate ADG, ADFI and FCR. Fecal scores were taken from d 8-14 post-weaning to assess incidence and severity of diarrhea and grab fecal samples taken for fecal DM content. The severity of diarrhea was assessed using a fecal consistency scoring (1, normal; 2, soft feces; 3, mild diarrhea; 4, severe diarrhea). In wk 2, pigs fed BA showed greater (P = 0.04) ADG than C fed pigs which in turn had similar ADG to AB fed pigs. However, in wk 4 and 5, pigs fed AB showed greater (P < 0.05) ADG than C whereas BA fed pigs had intermediate and similar (P > 0.10) ADG to C or AB fed pigs. The overall (wk 1-6) ADG and final BW were greater (P < 0.05) for AB and tended to be higher (P = 0.07) for BA fed pigs than for C fed pigs. However, ADG and final BW for pigs fed AB and BA was similar (P > 0.10). The overall ADG was 494, 533, 528 g/d for C, AB and BA, respectively and corresponding final BW was 26.9, 28.6 and 28.2 kg, respectively. There was no effect (P > 0.05) of diets on feed intake. In the overall, pigs fed AB (1.58) and BA (1.54) had better (P < 0.05) FCR compared to C (1.64) fed pigs. Treatment effects (P < 0.05) on fecal score was only observed on d 12 in which case pigs fed AB and BA showed lower score than C fed pigs. In the overall, the mean fecal score was 2.5, 2.2 and 2.3 for C, AB and BA, respectively. There was no diet effect (P > 0.05) on fecal DM content; the overall mean values were 22.3, 23.9 and 23.6%, respectively. In conclusion, benzoic acid supported piglet growth to the same extent as AB growth promoter.