Nature and level of trace mineral premix supplementation on growth parameters and mineral excretion in commercial broiler rations.

Masters Degree. University of KwaZulu-Natal, Pietermaritzburg.

Commercial broiler premixes provide trace minerals (TM) such as Zinc (Zn), Manganese (Mn) and Copper (Cu) in excess of the birds’ requirements to maximize broiler performance (Untea et al., 2011). High inclusion levels of TM along with their low absorption in the GIT of the broiler, has led to increased levels of TM in their litter (Nicholson & Chambers, 2008; Manangi et al., 2012). Concerns have been raised about the accumulation of TM in the environment due to the high TM content of poultry litter. Two 35-day broiler trials were conducted at a broiler facility with 2880 day-old, Cobb 500 broiler males. Trial 1 evaluated whether decreasing inorganic trace minerals (ITM) levels (specifically Zn, Mn and Cu) in broiler diets would have a negative effect on broiler growth parameters such as body weight (BW), average daily gain (ADG), cumulative feed intake (Cum. FI) and feed conversion ratio (FCR). Zn, Mn and Cu were supplemented at 100%, 50%, 25% and 0% of the Cobb standards. Trial 2 tested whether broilers differed in their growth performance when supplemented with ITM, Organic (OTM) and Hydroxy (HTM) sources of TM (Zn, Mn and Cu) and which source would produce the least amount of TM in their excreta. No significant difference in Cum. FI and FCR was observed between the treatments in both trials for the first 21 days. On completion of Trial 1, no difference was observed in body weight between the PC, NC and 50% Cobb levels at day 35. In Trial 2 birds supplemented with HTM were 55g heavier (P<0.05) than those fed ITM at the same inclusion level at 35 days of age while those birds fed the PC, OTM and HTM showed no significant difference in their body weights. Providing broilers with HTM significantly reduced (P<0.05) Zn and Cu excretion at 35 days of age when compared to those diets containing ITM. From the study it was concluded that reducing TM levels or supplementing different sources of TM to broiler diets at lower levels showed no negative effect on broiler performance. The use of HTM significantly reduced TM mineral excretion of broilers. The results suggest that the use of HTM can maintain broiler performance while sustaining the environment.