| Four experiments were conducted to investigate effects of ideal amino acid profile and week-feeding on broiler's production performance, carcass composition and nitrogen excretion. The most optimal protein-amino acid levels were tested too. In all experiments, male broiler chicks were fed a common corn-soybean meal (SBM) with different amino acid levels and chicks had ad libatum the isoenergetic diets (3000 kcal MEn/kg).Experimentâ… :Ideal amino acid profile, BAHA (Han and Baker, 1994) and BAHA week-feeding (WF) were tested to evaluate their efficacy compared with NRC 1994 recommendation for broiler chicks. 13 kinds of diets were fed from 0-49 days to 192 broiler chicks. All chicks were allotted to three treatments in a completely randomized design, every treatment has 8 replicates (8 chicks per pen).The results were: Fed ideal amino acid profile diets, lower the protein 1.45% in 1-3week, 1.39% in 4-6 week, there were no differences (P>0.05) in weight, weight gain, feed intake and feed efficiency to NRC diets. Fed ideal amino acid profile WF diets, lower the protein 2.61% in 3th week, 2.41% in 6th week, there were no differences (P>0.05) in weight, weight gain, feed intake and feed efficiency to NRC diets. These results indicated that WF supports maximum growth performance during the protein levels were reduced period. Economic analysis indicated that BAHA and WFwould reduce the cost per unit weight gain without sacrificing growth performance. For the blood sugar in artery and vein, BAHA and WF may increase its content (P<0.05).Experiment â…¡:Week-feeding (WF; Treatment 2) was tested relative to an BAHA regimen (Trearment 1) to evaluate the impact of WF on broilers' metabolism about the variance of uric acid content of serum, total protein content of serum, blood sugar content of serum and xanthine oxidase (XOD) in liver. 336 chicks were allotted to two treatments in a completely randomized design; every treatment had 3 replicates (14 chicks per pen). Every week, 4 chicks were let blood and be killed. Results were: The uric acid content of serum reduced (P<0.01) and blood sugar content of serum increased (P<0.05) among chicks fed WF diets. No difference (P>.05) in total protein content of serum in WF treatment. The content of xanthine oxidase (XOD) in liver reduced (P<0.05) among chicks fed WF diets. Experimentâ…¢:192 broiler chicks were allotted to six treatments (the treatments amino acid requirements predicted by 5% (WF 5), 10% (WF 10) and lowering the slope of the linear regression equations by 5% (WF -5), 10% (WF -10) and 15% (WF -15) in a completely randomized design; every treatment has 4 replicates (8 chicks per pen) to test the effect of WF on liver DNA, NRA content. Results indicated that no difference (P>0.05) in liver NRA content among treatments.Experimentâ…£:Six modified WF regimens were tested that involved increasing amino acid requirements predicted by 5% (WF 5), 10% (WF 10) and lowering the slope of the linear regression equations by 5% (WF -5), 10% (WF -10) and 15% (WF -15) to evaluate which treatment has the most efficacy on broiler's production performance, carcass compoision and nitrogen excretion. Experimental diets were fed from 0-49 day to 768 broilers. Results indicated that higher protein-amino acid level treatments have no effect (P>0.05) on improve the production of broilers, no differences (P>0.05) in percertage breast, leg, but abdominal fat was observed reduced (P<0.05). At 7 day, when reduce the protein from 22.4% to 19.1% and Met/Lys from 1.18 / 0.82 to 1.00 / 0.71, no differences (P>0.05) in weight, weight-gain, feed intake and feed efficiency. The lower protein-amino acid level treatment (WF -5) has no effect (P>0.05) on sacrifice production performance of broilers, no differences (P>0.05) in percertage breast, leg, and abdominal fat deposition. Intake of protein-amino acid level were decreased by WF -10, WF -15 relative to that of broilers fed the WF diet, no differences (P>0.05) in weight gain, feed intake and feed efficiency and no differences (P>0.05) in percerta...
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