Benzoic acid (BA) and essential oils (EOs) (thymol, 2-methoxyphenol, eugenol, piperine, and curcumin) are being studied to minimize the impairment of gastrointestinal functions in weanling piglets. This study evaluates the effects of combining BA and EO on the performance and intestinal health of piglets challenged with E. coli F4 (1 mL, 106 CFU/mL). In total, 270 weaned piglets were used in a randomized block design with six treatments: positive control, with 40 mg/kg colistin (PC); negative control, without the growth promoter (NC); negative control +5 g/kg benzoic acid (BA); negative control +2 g/kg combination of BA+EO (BA+EO2); negative control +3 g/kg combination of BA+EO (BA+EO3); negative control +4 g/kg combination of BA+EO (BA+EO4). BA+EO3 presented a greater average daily gain (ADG) (p = 0.0013) and better feed-to-gain ratio (p = 0.0138), compared to NC, from 21 to 35 days age. For the total period, BA, BA+EO3, and BA+EO4 were similar to PC and superior to NC for ADG (p = 0.0002) and final body weight (BW) (p = 0.0002). No difference (p > 0.05) was verified for diarrhea, microbial population, production of volatile fatty acids, pH, weight of organs, cellular proliferation, and cholecystokinin count. NC and BA+EO4 resulted in a higher villus height in the jejunum (p = 0.0120) compared to BA+EO3. The use of BA or the combination of BA and EO at 3 g/kg provides improved performance, aside from being an economically viable alternative to replace colistin.

The demand for animal protein is a fact of relevance for the production systems, especially pork, the most consumed animal protein source in the world. In this sense to ensure the efficient production during the pigs raising the use of Prophylactic Antibiotics (PA) is a common practice, but there is a great potential for the occurrence of resistance to antibiotics. However, the use of PA may not be necessary for certain groups of pigs for example with high sanitary status within the production system. The study lasted for 76 days. Seventy-two barrows at 63 days of age with initial weight of 26.11±3.55 kg were used. Two treatments were performed, without the use of prophylactic antibiotics or with the use for five days, being given at 63 days of age with Doxycycline and at 105 days of age with Tiamulin. PA use worsened ADG (p = 0.035) by 5.0% and body weight by 3.0% (p = 0.039) of pigs at 105 days of age when compared to pigs that did not receive Doxycycline. After the second use of PA the pigs at 117 days of age which received Tiamulin presented better ADG of 7.0% (p = 0.035) and a greater body weight of 1.2% (p = 0.038) compared to control group. The animals of the control group presented 6.0% greater loin depth (p = 0.023) than the animals that received the PA, however pigs of the PA group presented greater hot carcass weight of 0.6% (p = 0.005) and greater carcass compactness of 2.4% (p = 0.004) compared to the control group. The use of PA should be studied with caution and in a holistic way, considering the sanitary characteristics of management to verify if its use is really justified, as observed in the present study if used in inopportune moments its use can impair the performance of the pigs.