| Three experiments were conducted to investigate the effects of enzymes, probiotic and low protein-supplemented amino acids diets on chickens' growth, nutritients utilization, laying performance and egg-shell quality. The objective of experiment one was to determine the influence of micro-phytase, compound enzymes, probiotic and low protein-supplemented amino acids diets on growth of 0～6 week-old chickens. One day 450 Lomman chickens were randomly distributed to five treatments with six replicates and seventeen per replicate. The five diets were as following: (1) Low phosphorus and amino acid diet+micro-phytase+ antibiotic(AB); (2) Basal diet(BD)+compound enzyme(CE)a+AB; (3) BD+CEb+AB; (4) BD+probiotic (PB); (5) Low protein-supplemented amino acids diet+PB. The primary component was cellulase in CEb, and CEa included amylase, protease , pectinase, cellulase and so on. The chickens were fed pelleted diets and raised in nets over the ground. Average daily gain (ADG), feed intake (FI) and feed efficiency (FE) were calculated at the end of the experiment.Effects of wheat bran phytase, micro-phytase and probiotic on growth and nutrients utilization in 6～12 week-old chickens were evaluated in experiment two. Forty five day-old 510 Lomman chickens were individed into five groups with six replicates receiving the following diets randomly: (1) Positive control diet (PD); (2) Negative control diet (ND) (supplemented 14.5%wheat bran, metabolizable energy, crude protein, lysine and methionine content lowered 10% than PD); (3) ND+0.02%micro-phytase (reducing total and available phosphorus content); (4) ND+0.15%protiotic; (5) PD+0.02%micro-phytase (reducing total and available phosphorus content). All chickens feeding powder diets were raised in cages at the same house. Parameters comprised ADG, FI and FE, and apparent metabolizability of dry matter (DM), crude protein (CP), calcium (Ca) and phosphorus (P). Two chickens per treatment were slaughtered and the length of their left tibia was measured after the feeding and metabolizing experiment.The effect of probiotics on laying performance and egg-shell quality was examined in experiment three. Four diets supplied for 48～52week-old 450 Lomman hens were designed: (1)Basal diet (BD); (2) BD+0.1%probiotic; (3) BD+0.1%enzyme-probiotic; (4) BD+0.1%probiotic+0.1%urea. The laying hens were fed powder diets.The results of experiment one showed that CEa enhanced chickens' live weight (LW) and ADG (P<0.05), and CEa and low protein-supplemented amino acids diets improved FE (P<0.05) than phytase diet. Probiotic raised FI comparing with CEb treatment (P=0.10).In experiment two, negative control treatment achieved the similer growth and higher content of DM (P<0.05) and Ca in manure (P<0.01) than the positive control. Reducing total and available phosphorus (TP and AP) and supplementing 0.02%micro-phytase in negative control diet lowered excrement of phosphorus (P<0.01), and enhanced FI (P<0.01), ADG and apparent metabolizability (AM) of CP and P (P>.05) and Ca in manure (P<0.05) comparing with PD. Probiotic did not improve the chickens growth and nutrients utilization except for feed intake (P<0.01). Phytase improved phosphorus AM (P=0.09) than PD treatment.Probiotic and urea improved the laying performance and egg shell quality of 48～52 week old hens at some degree in experiment three. Enzyme-probiotic and probiotic+urea treatments enhanced significantly egg production than the control treatment (P<0.05).The conclusions of this study could be summarized as following: (1) Micro-phytase could not be used in pelleted diet because of the high temperature in feed processing. Adding 0.02%micro-phytase to low phosphorus diet (ME 11.76MJ/kg, CP 16.00%, Ca 0.82%, Met 0.26%, Lys 0.70%, TP 0.50%, AP 0.26%) or high wheat bran (14.5%) diet (ME 10.88MJ/kg, CP 14.80%, Met 0.23%, Lys 0.63%) and bringing down the TP and AP content (TP0.55%,AP0.27%) had no influence on growth, but improved nitrogen and phosphorus utilizability and lowered their excretion, feed cost and pollution f...
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