Evaluation of Calendula officinalis L. (marigold) flower as a natural growth promoter in comparison with an antibiotic growth promoter on growth performance, carcass traits and humoral immune responses of broilers

The objective of this experiment was to investigate the effects of dried powder of Calendula officinalis L. (marigold) flower as an antibiotic growth promoter substitute on growth performance, organ weights, and immunological parameters in broilers. A total of 240 mixed sex broilers (Ross 308) at 1 d of age were individually weighed and randomly assigned to 4 treatments with 4 replicates of 15 birds for 6 wk. The dietary treatments were: 1) a basal diet (control); 2) control plus 4.5 mg flavophospholipol/kg of diet; 3) control plus 5 g marigold/kg of diet; 4) control plus 10 g marigold/kg of diet. Antibody responses against Newcastle (NDV), influenza (AI) viruses, and sheep red blood cells (SRBC) were measured. Supplementing 4.5 mg flavophospholipol/kg of diet enhanced body weight (BW) of broilers at 14 and 28 d of age (P < 0.05), but final BW at 42 d was not markedly affected. At 14 and 28 d of age, broilers fed diets supplemented with 10 g marigold/kg of diet had significantly lower BW compared with broilers fed the basal diet supplemented with antibiotic or 5 g marigold/kg of diet. During the starter period, broilers fed diets supplemented with antibiotic had significantly (P < 0.05) better FCR compared with broilers supplemented with 10 g marigold/kg of diet, but did not differ from broilers fed the basal diet or basal diet supplemented with 5 g marigold/kg of diet. There were no significant differences in FCR between treatments, during grower, finisher phases as well as for the whole experiment. Carcass yield was significantly (P < 0.05) higher in broilers supplemented with 5 g marigold/kg of diet compared with broilers in other groups. The treatments failed to induce any marked effect on immune parameters. In conclusion, the results of this experiment showed that supplementation of 5 and 10 g dried powder of marigold/kg of diet has no affirmative influence on growth performance of broilers.