Effect of Withdrawing Vitamin and/or Trace Mineral Premixes from Grower and Finisher Diets of Broilers

An experiment was conducted to evaluate the effect of withdrawing vitamin and/or trace mineral premixes from grower and finisher diets of broilers. A 2×4 factorial arrangement of treatments, consisting of four diets and two-removal times (from 28 to 49, and from 35 to 49 days of age) was utilized. The four diets consisted of control, supplemented with vitamin (VIT) and Trace Minerals (TM)(T1); TM with no VIT supplements (T2); VIT but no TM supplements (T3); neither VIT nor TM supplements (T4). Average Weight Gain (WG) and Feed Intake (FI) were not affected by treatments of 28 to 35 days of age (P>0.05). Feed intake for T2 was lower (P>0.05) than for T1 in the 35 to 42 days of age removal time. There were no significant (P>0.05) differences observed between T1 and other treatments for this trait. Feed intakes for T1 and T3 were greater (P>0.05) than those for the other treatments during the last week of age. Feed efficiency (FE) was greater (P<0.05) for T4 than for T3 during the removal time of 35 to 42 days of age, but differences were not significant (P>0.05) in comparison with the other treatments. No significant (P>0.05) differences were observed among T1, T2, and T3 for feed efficiency. During the second days of age period weight gain for T2 and T4 were lower (P>0.05) than those for T1 and T3 during the last two weeks of age. FI for T3 was greater (P>0.05) than that for the other treatments during the last week of age, but no significant (P>0.05) differences were observed between T1 and T4. FI for T1 was greater (P<0.05) than for T3 during this period. FE for T3 was lower (P<0.05) than those for the other treatments during the last two weeks of age while greater (P<0.05) than for T4, but no significant (P>0.05) differences were observed among T1, T2 and T3. Carcass characteristics, mortality and incidence of leg disorders were not affected by treatments in this experiment (P>0.05).