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-The objective of this work was to evaluate the performance of piglets in the nursery phase submitted to activation of immune system with vaccine against Haemophilus parasuis and to different levels of metabolizable energy in the diets. It was used 160 barrows and females at 30 days of age, weaned at 23 days of age, with initial weight of 7.97 ± 0.54 kg, distributed in 2 × 4 factorial arrangement (with vaccination and without vaccination with four levels of metabolizable energy -3,200; 3,300; 3,400 and 3,500 kcal/kg). Each combination was evaluated with five repetitions of four animals per experimental plot (two males and two females). Energy levels reduced linearly the intake, feed conversion and the total number of leukocytes in blood in the experimental period, regardless of the use of vaccine which in turn reduced daily average weight gain only in the first week after second application and it increased the number of limonocytes and spleen weight after three weeks. There was no difference in the C-reactive protein quantity in the blood in the periods when it was evaluated. The use of vaccine reduces performance immediatelly after its application but after it occurs recovery of performance with changes in the number of monocytes and spleen weight. Dietary energy levels do not smooth this reduction in the performance, but they influence intake, feed conversion and blood parameters in the total period of use.

-The objective of this work was to evaluate the use of vegetable extract based addictives associated or not to symbiotics as an alternative for antibiotic as growth promoters for piglets at initial phase. It was used 125 pigs of commercial genetic line with initial weight of 7.4 ± 1.1 kg, weaned at 20 days of age, during 50 days. The experimental design used was randomized blocks (initial weight), with five treatments and five replicates with five animals per experimental unit. The experimental diets were a basal diet, without additive, and other four diets, one diet containing antibiotic (colistin + zinc oxide); diet with 0.3% of a symbiotic mixture; diet with 0.3% of a symbiotic mixture plus 0.05% of herbal mix (plant extracts and microencapsulated essential oils); and another diet with 0.3% of symbiotic mixture plus 0.1% of herbal mixture. It was observed that the use of the symbiotic mixture associated to 0.05% of herbal mixture showed positive results, similar to the ones obtained with diets containing antibiotics for the final weight, average weight gain, average daily feed intake and pH of stomach and diarrhea incidence. The use of symbiotics promoted smaller vilous:depth crypt ratio, except when associated to 0.1% of herbal mixture, which was similar to the diet without addictives. There was no differences in the feed conversion, coliform and lactobacillus count in the jejune and in the cecum and in the pH of cecum. The use of herbal mixture associated to symbiotic is a viable alternative for replacing the use of antibiotics as growth promoters for piglets in the initial phase. However, the concentration of the herbal mixture is an important factor to be considered.Key Words: growth promoters, performance, prebiotic, probiotic, swineExtratos herbais e mistura simbiótica em substituição aos antibióticos para suínos na fase inicial RESUMO -O objetivo neste trabalho foi avaliar o uso de aditivos à base de extratos vegetais associados ou não ao uso de simbióticos como alternativa aos antibióticos como promotores de crescimento para suínos na fase inicial. Foram utilizados 125 leitões de genética comercial, com peso inicial de 7,4 ± 1,1 kg, desmamados aos 20 dias, durante 50 dias. O delineamento experimental foi o de blocos casualizados (peso inicial) com cinco tratamentos e cinco repetições com cinco animais por unidade experimental. As dietas experimentais foram uma ração basal, sem aditivo, e outras quatro, uma contendo antibiótico (colistina + óxido de zinco); outra com 0,3% de uma mistura simbiótica; outra com 0,3% da mistura simbiótica e 0,05% de uma mistura herbal (extrato de plantas e óleos essenciais microencapsulados) e outra com 0,3% da mistura simbiótica e 0,10% da mistura herbal. Foi observado que o uso da mistura simbiótica associada a 0,05% da mistura herbal teve resultados positivos e semelhantes aos obtidos com as dietas contendo antibióticos quanto ao peso final, ganho de peso, consumo médio diário, pH do estômago e incidência de diarreia. O uso de simbióticos promoveu menor relação...