| The experiments were conducted to investigate the effects of corn particle sizes onnutrient metabolism, productive performance and egg quality of Lueyang black-bone hens(LBH) and to find out the most suitable corn particle sizes for LBH during the laying period.Exp.1: Fourty39-week-old LBH were randomly assigned to4groups with5replicatesper group and2birds per replicate. Four complete mash diets with identical botanical andchemical composition containing mash corn ground through a hammer mill with4.0-,6.0-,8.0-,10.0-mm screens, were formulated and fed to the birds, respectively. Metabolizableexperiments in which the preparation period last6days and the main period4days, wereconducted during39~40wk and47~48wk. All cereals were collected to test GE and CP andthen to calculate the energy and CP apparent metabolism. The results were showed as below:(1) Particle sizes of corn ground though4.0-,6.0-,8.0-,10.0-mm screens were736.07,865.11,962.09,974.83μm and the corresponding diets were662.14,715.69,743.80,851.39μm, respectively.(2) No significant differences in energy and CP apparent metabolism between groups ofdifferent corn particle sizes were found (P>0.05).Exp.2: Two hundred and twenty35-week-old LBH were randomly assigned to4groupswith5replicates per group and11birds per replicate. Corn particle sizes, composition andnutrient levels of experimental diets and feed treatment were the same as exp.1, absolutely.Feed remained in troughs after the diets were sufficiently consumed was collected to analyzeGMD, GE and CP content. Egg sample were collected during different periods to test eggquality and egg shape uniformity. Here followed the results:(1) Corn particle sizes varying from736.07μm to974.83μm did not significantlyaffected ADFI, ADEM, EP, AEW, ABWG and F/E of LBH from35to50wk of age (P>0.05),but in the F/E of LBH from39to46wk of age was affected very significantly (P<0.01)while EP of LBH from39to42wk of age was significantly affected (P<0.05) by the sizes.(2) The GMD and GE content of the remained feed in troughs were not significantlyaffected by the corn particle sizes varying from736.07μm to974.83μm (P>0.05), but CP content of the remained feed in736.07μm group was very significantly lower than that in962.09μm and974.83μm groups (P<0.01), and was not different from that in865.11μmgroup (P>0.05). The GMD differences between diet and the remainded feed increased withthe improvement of corn particle sizes very significantly(P<0.01). The difference in the974.83μm group was wilder than the othert three groups very significantly (P<0.01) whilethat in962.09group was wilder than736.07and865.11μm groups (P<0.01) and that in865.11μm group was wilder than736.07μm group (P<0.05).(3) ST, SBS, ESI, AH, YC, HU, YR and AR were not affected by corn particle sizesvarying from736.07μm to974.83μm significantly (P>0.05), but ECS in the962.09μmgroup was higher (P<0.05) while SR was lower (P<0.05) than that in both the736.07μm and865.11μm groups. CP content in eggs without shell (on the freeze-dried basis) in the974.83μm group was very significantly higher than that in the962.09μm group (P<0.01), while nosignificant effects were observed among736.07,865.11and974.83μm groups (P>0.05).(4) Corn particle sizes varying from736.07μm to974.83μm did not significantlyaffected the CV of EW, LD, SD and ESI of eggs (P>0.05).Conclusion: Particle sizes of corn ground though4.0-,6.0-,8.0-,10.0-mm screens were736.07,865.11,962.09,974.83μm respectively and the sizes had no significant effects onnutrient metabolism, productive performance and egg quality of LBH from35~50wk of age. |
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