Impact of Ideal Protein Concept on Low Crude Protein Diets Supplemented with LAAs for Broilers: Effects on Growth Performance, Nitrogen Digestibility and Economic Advantages
M. O. Adamolekun *
Department of Animal Sciences, Faculty of Agricultural Sciences, Ekiti State University, Ado-Ekiti, Nigeria.
A. O. Fasuyi *
Department of Animal Sciences, Faculty of Agricultural Sciences, Ekiti State University, Ado-Ekiti, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
This study aimed to investigate the effects of broiler chicken on low crude protein diets with supplementation of four limiting essential amino acids (LAAs): tryptophan, threonine, lysine and methionine, on growth performance, nitrogen utilization and economic benefits. One hundred and twenty (120) unsexed commercial day-old chicks of Arbor Acre strain were acquired and randomly distributed into five dietary treatments with three replicates of eight (8) chicks each. The five experimental diets were formulated with different dietary crude protein (CP) levels, such that there were 2% CP reductions from the control diet as indicated in diet 5. The %CP of the experimental diets were 24 (control), 22, 20, 18 and 16% for the starting period (Day 1-28) and 22, 20, 18, 16 and 14% CP for the finishing period (Day 29-56), respectively. The low-CP diets were supplemented with combined LAAs (threonine, tryptophan, lysine and methionine) to meet the respective levels of the amino acids requirement according to NRC 1994. Data were collected on growth parameters, nitrogen digestibility and economic analysis. Birds on diet 2 (22% CP) had the highest (P<0.05) final body weight, average daily weight gain, lowest feed intake and best and lowest feed conversion ratio while birds on diet 5 (16% CP) had the lowest (P<0.05) final body weight, average daily weight gain, highest feed intake and feed conversion ratio. The nitrogen intake had the highest similar values of 3.13±0.08gN and 3.06±0.01gN for birds on the control diet of 24% CP and diet 2 containing 22% CP. The nitrogen retention (NR) had the highest significant (P<0.05) value of 3.04±0.06gN for birds on control diets. The lowest significantly different (P<0.05) apparent nitrogen digestibility (AND) value of 52.45±0.16% was obtained for birds on diet 5 (16% CP) supplemented with LAAs. The economic analyses were better at diet 2 and diet 3. Dietary supplementation with LAAs to low-protein diets (22-20%CP) improved the economic returns of broiler chickens. LAAs supplemented ommercial broiler diets can be formulated with 4% CP reduction in both starter and finisher diets with economic benefits in broiler production without adverse health implication.
Keywords: Crude protein reduction, essential amino acids, low crude protein diets, broiler chicken