Effect of mixing periods of various feed ingredients on the performance of broilers

The effects of variable mixing periods (2.5, 5.0, 7.5, 10.0 and 12.5 min.) in a horizontal mixer having three quintal capacity on the homogeneity of a feed formulated from maize, soybean meal, fish meal, rice polish and mineral mixture were assessed by measuring coefficient of variation for ash, number of maize grains per kg of feed sample and weight gain by the broilers. Maize, soybean meal and fish meal were ground through a hammer mill using 5mm sieve. Two hundred day old broiler chicks were procured and offered starter ration from 0–3 weeks and finisher ration from 3–7 weeks of age. The percent CV for ash, number of maize grains/kg of sample, particle size (μ), particles/g and surface area (cm²) was minimum at 10 min. mixing time. The ash content of the different treatments ranged from 12.29–14.9% with CV values ranging from 13.59–19.55%. The average particle size was 1137, 1036, 1087, 1042 and 1075μ for treatments T₁, T₂, T₃, T₄ and T₅, 12345 respectively with CV variation of 7.60–11.15%. Average number of particles/g of sample ranged from 24119 to 80630 and CV from 78 to 53%. The effect of different treatments in all the phases of growth was significant (P<0.05). The average wt. gains (g/bird) were 890, 1130, 1144, 1132 and 1175 at 5 weeks of age, 1204, 1530, 1526, 1487 and 1501 at 6 weeks of age and 1541, 1823, 1967, 1907, and 1912 at 7 weeks of age for treatments T₁, T₂, T₃, T₄ and T₅, respectively. The body weight gain increased (P<0.05) with the increase of mixing time from 1541g in T₁ to 1967g in T₃ and thereafter decreased (P<0.05) to 1907g in T₄ and 1912 in T₅. The feed efficiency was best in T₄ (2.21 at 5 wks age, 2.31 at 6 wks age and 2.36 at 7 wks age) compared to other treatments indicating that 10 min. time was optimum for mixing. It may be concluded that 10 min time is optimum for uniform mixing.