Metabolism and Nutrition: Vitamins and Minerals

Antibiotics have been common feed additives in poultry rations as growth promoters to improve performance via reducing burden of pathogens. However, it has been increasing pressure to reduce or even eliminate antibiotic usage in poultry feed due to the negative human health issues of antibiotic resistance. Safe broiler production without medication and vaccination was conducted at present study. The effect of vitamins and minerals deficiency was also investigated. One hundred eighty day-old male broilers were used on a randomized complete block design experiment with treatment consisting of 3 rep­ lication and 10 chicks per pen. The birds were housed in floor pens. The experiment was designed as following groups: 1) negative control (not receiving any drugs, growth promoters, vaccines, feed additives, extra vitamins or minerals); 2) basal diet + vaccines: IB, ND and IBD; 3) basal diet + multivitamins (2.5%) and multiminerals (2.5%) (Razak Co., Tehran, Iran); 4) basal diet + multiminerals (2.5%); 5) basal diet +multivitamins (2.5%); 6) positive control (basal diet + vaccines: IB, ND and IBD + multivitamins (2.%5) + multiminerals (2.5) + antibiotic (15 ppm virginiamycin). Vaccinated and unvaccinated groups were kept in separate rooms. The following parameters were measured: BW, FI, FCR, carcass yield, breast, thigh, liver, bursa of Fabricius, and abdominal fat relative weight. Immune response to SRBC in 27 and 42 d and toes ash percentage at 42 d of age was also measured. Analysis of results showed that, there was significant difference between treat ­ ments in BW, FI, FCR, carcass yield, breast, thigh, liver, spleen, bursa of Fabricius and abdominal fat relative weight. Antibiotic treatment had highest BW, lowest FCR and highest antibody titer against SRBC (P < 0.05). The result of this experiment showed that deficiency of minerals and vitamins or vitamins alone had a significant effect on performance parameters and SRBC antibody titer, while minerals deficiency alone did not show great effect on growth performance and antibody titer against SRBC. No significant differences were seen in performance parameters and SRBC antibody titer among vaccinated and no vaccinated groups.