| This thesis was designed to assess the influence of low protein AAs supplemented diet on theperformance, egg quality and egg components of laying hens in same SID AA pattern, and thecharacteristics of blood, N excretion and greenhouse gas emissions were also further contained withboth effects of dietary energy and crude protein considered.Experiment1. Effect of Dietary Crude Protein Level on the Performance, Egg Quality, BloodParameter and N balance in Laying Hens Under the Same SID AA PatternIn order to apply the standard ideal digestible (SID) amino acid (AA) diets to laying hen, anexperiment was conducted to evaluated the effect of dietary protein reduction on performance, bloodparameter, egg quality and N balance in laying hens. Hy-Line W36Breeds (n=540,20wk of age) wererandomly allotted to five dietary treatment groups (18.00%,17.50%,17.00%,16.50%,16.00%of CP)in the metabolic energy (ME) of11,82MJ/kg, with Met, Lys, Trp, Thr, Ile, Val supplemented under thesame AA pattern of standardized ileal digestible (SID) and Lys basis (estimated SID value at0.831%).Treatments were replicated with6pens with18birds per pen in6continuous cages. Hen-day EP (eggproduction), daily EM (egg mass), FI (feed intake) and FCR (egg/feed conversion ratio) were wellmaintained in low-protein groups. Egg weight and egg albumen weight (P<0.01), N excretion (P<0.01)and egg albumen height (P<0.01) got declined while egg yolk color (P<0.01) got enhanced, no othereffects (P>0.05) on BA (blood ammonia) and PUA (plasma uric acid) and other egg quality were found.It was shown that dietary reduction of EAA (essential AA) including Arg, Phe and Leu significantlycorrelated with the declined egg weight by Pearson Correlation and Pearson Partial Correlation analyses.In conclusion, both economic and environmental benefits could be obtained by applying low proteindiets to laying hens.Experiment2. Effects of Dietary Energy and Crude Protein Levels on the Performance, EggQuality, Blood Characteristics, N Excretion and Greenhouse Gas Emission in Laying HensA trial was conducted to assess the effects of ME (metabolic energy) and CP (crude protein) levelsin diets on the performance, egg quality, blood characteristics, N excretion and greenhouse gasemissions in laying hens. Six hundred and forty eight laying hens of20week-old were randomlydivided into six groups with six replications, in each replication which had eighteen laying hens. Eachgroup was fed from21to34weeks with diets containing CP17.00%, CP16.50%, CP16.00%in high MEat11.82MJ/kg and CP17.00%, CP16.50%, CP16.00%in low ME at11.00MJ/kg respectively. Researchresult showed that:1) Dietary protein reduction in the background of SID AA pattern had a significanteffect on declining (P <0.05) EW (egg weight) and a trend of increasing EP (egg production) and DEM(daily egg mass) in the early laying period of21~24w（P=0.11, P=0.06. Dietary ME concentrationaffect feed intake (P <0.05) while birds ME intake of total seldom affected (P>0.05). Birds in the lowdietary ME group had more (P <0.05) Feed intake and CP intake and a poor performance than that of birds in high dietary ME group, which seemed to be a waste of protein. Birds in the high dietary MEgroup had a higher EP, DEM and egg/feed ratio in the period of25~34w and a lighter EW in the periodof21~24w and and a lighter BWG (body weight gain) in the whole trial period (P=0.09).2) Birdsintake feed with dietary protein reduced perduced eggs with a strenthened color, lighter albumen weight,lower albumen height and yolk DM (dry material) percentage, while birds from high ME groupperduced eggs with lower albumen height in whole periods, higher HU (Haugh unit) in the early period(21~24w) and lower egg shell thickness and lower egg shell and yolk DM percentage in the laterperiod (29~34w).3) Dietary CP reduction had little effect on BA (blood ammonia), significant effect onN excretion reduction and a declined trend on PUA (plasma uric acid), total fresh weight and DM ofexcreta, while dietary high ME had a declined trend on total N excretion and lead a lower PUA, totalfresh weight and DM of excreta and a higher BA, moisture of excreta and N material percentage.4)Dietary ME concentration had greater effect on the greenhouse gas emission of CH4than that of dietaryprotein level, with the later one only a decline trend existed. Birds from high dietary ME groupperduced less CH4than that of birds from low dietary ME group, with163.97vs.219.23mg/day and258.82vs.351.90mg/day experssed on a per kilogram of BW and per bird basis. In conclusion, lowdietary ME (11.00MJ/kg) with CP declined from17.0%~16.0%still turn out to be a protein waste andagainst to the laying performance, N excretion and CH4emission reduction, and a dietary higher MEwith lower CP configuration should be applied in laying hens perduction for both economic andenvironmental benefits in the background of SID AA pattern. |
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