Removal or substitution of in feed antimicrobials in swine production.

Antimicrobial substitutes are being used in pig production systems, to maintain the health of the animals without compromising their performance. The aim of this study is to evaluate the impact of either the removal of in feed antimicrobials or their substitution for feed additives, at the nursery and growing/finishing stages. At weaning, 1091 piglets were sexed, vaccinated, homogenized by weight and allocated to six treatments during the nursery stage (26-63 d): T1- feed with no antimicrobials nor additives; T2 - feed with antimicrobials; T3 - feed with prebiotic; T4 - feed with probiotic; T5 - feed with essential oils; T6 - feed with organic acids. The same treatments were applied to 840 pigs during the growing/finishing stages (64-167 d). There was no effect of the treatments on feed conversion at the nursery (P = 0.222) and the growing/finishing (P = 0.809) stages. The average daily gain did not differ across treatments in the nursery (P = 0.342) and in growing/finishing (P = 0.050). The cost of the interventions with injectable drugs was not different between the treatments neither at the nursery (P = 0.990) nor at the growing/finishing (P = 0.310). However, the pneumonia and pleurisy index for all treatments was equal or above 1.0, which indicates a respiratory challenge. There was an increase in the cost with antimicrobials or additives per kg of feed produced, which impacts the cost per kg of pig produced. In conclusion, the removal of antimicrobials in pig diets is financially feasible and their substitution by additives did not impact growing performance.