Oregano essential oil as food additive for piglets: antimicrobial and antioxidant potential

This study aimed to investigate the effect of dietary supplementation of oregano essential oil on the performance and on the occurrence of diarrhea in weanling pigs, as well as its antioxidant and antimicrobial activity evaluated in vitro. It was compared four treatments (diets): negative control; positive control, 0.5% ZnO (preventive diarrhea) + 0.05% zinc acitracin (growth promoter); or 0.003% of essential oil of oregano, combined or not with preventive of diarrhea. Weight gain, feed intake and feed conversion were evaluated from 27 (weaning) to 62 days of age of the animals, and the occurrence of diarrhea was evaluated on the first 14 days of the experiment. The positive control diet and the oregano oil + zinc oxide diet were the ones that provided the best zootechnical performance. The number of piglets with diarrhea, as well as the duration of diarrhea, were lower in animals fed positive control and oregano oil + zinc oxide diets. Oregano oil had in vitro bacteriostatic action on all the tested microorganisms and bactericidal action against four bacteria. The in vitro antioxidant activity of oregano oil was 98.88% through linoleic acid/β-carotene system methodology, and 174.17 mg/mL by the DPPH method, expressed as CE50. Oregano oil shows potent antioxidant effect and a strong antimicrobial activity, however, it does not improve the zootechnical performance neither it is efficient in preventing diarrhea in weanling pigs. Com este estudo objetivou-se verificar o efeito da suplementação dietética do óleo essencial de orégano no desempenho e na ocorrência de diarréia em leitões recém-desmamados, bem como suas atividades antimicrobiana e antioxidante avaliadas in vitro. Foram comparados quatro tratamentos (dietas): controle negativo; controle positivo, 0,5% ZnO (preventivo diarréia) + 0,05% bacitracina de zinco (promotor de crescimento); ou com 0,003% de óleo essencial de orégano, combinado ou não ao preventivo da diarreia. O ganho de peso, consumo de ração e conversão alimentar foram avaliados dos 27 (desmame) aos 62 dias de idade dos animais, e a ocorrência de diarréia foi avaliada nos primeiros 14 dias de experimento. A dieta controle positivo e aquela com óleo de orégano + óxido de zinco foram as que proporcionaram o melhor desempenho zootécnico. O número de leitões que apresentaram diarréia, assim como a duração da diarréia, foi menor nos animais que receberam as dietas controle positivo e óleo + óxido de zinco. O óleo de orégano teve ação bact