Dietary Houttuynia Cordata/Fermented Red Koji Blends to Improve Duck Growth Performance and Alum Blends Addition to Reduce Litter Ammonia Concentration

| We investigated the effects of different formulations of the herb Houttuynia cordata (HC) mixed with fermented red koji (FRK) as feed additives on the growth performance of ducks and the effects of adding chemical blends (alum and AlCl3 ) on the pH and ammonia (NH3 ) concentration of duck litter. After a 2-week brooding period, 240 one-day-old Peking ducks (160 male and 80 female) were allocated to one of four dietary groups (control, 1% HC powder mixed with FRK, pelleted 1% HC/FRK, and coated pellets of 1% HC/FRK), each with four replicates of 15 birds, and four chemical blend litter treatments (control, 50 g alum+50 g AlCl3 , 100 g alum+100 g AlCl3 , and 150 g alum+150 g AlCl3 /kg duck litter) in the pens used for feeding trials. In terms of growth performance, we found that final body weight, weight gain, feed intake, and feed conversion ratio varied significantly among birds fed the different HC diets (P<0.05). Duck litter pH differed significantly during the experimental period (P<0.05), except during days 28. The additive blends had a strong influence (P<0.05) on NH3 throughout the experimental period (not on day 7). In conclusion, adding 1% HC (in pellets and coated-pellet form) with FRK to duck diets improved growth performance and the inclusion of chemical blends (a combination of 50 g alum and 50 g AlCl3 per kg litter as optimal rate) in duck litter in pens during the feeding trial decreased litter NH3 concentration and pH.