| The new line of Gushi Chicken fostered by Institute of Poultry Science, Chinese Academy of Agricultural Sciences was used as test material in this study, the chickens were fed in floor model for the first five weeks, and then weighed, sampled and divided into several groups, 15 samples per group, one group per week was randomly increased for free range feeding from 7th week to 13th week for cocks and 16th week for hens respectively. The body weight, body measurements, slaughter performance, muscle quality and blood biochemical parameters were measured for cocks at 13-week-old and hens at 16-week-old. The breast component, fatty acid component and its related content were measured only for hens. The effect of different week-old free range feeding on the geowth, development, meat performance and muscle quality of Gushi chicken were studied in order to provide guide for production and meat quality improvement of quality chick. The main results of this study were as follows:(1) The body weight of 13-week-old cocks in 9 week-old free range feeding groups was significant lower than other experimental groups(P<0.05) but no significant difference in body weights and feed conversion rate of 13-week-old cocks and 16-week-old hens among different week-old free range feeding groups(P>0.05). The body lean length, breastbone length, comb length, comb height, comb color and breast angle of cocks were no significant difference among different week-old free range feeding groups(P>0.05) while the metatarsus length, metatarsus girth, metatarsus color and breast width of cocks were significant difference(P<0.05). The breastbone length and comb length of 16-week-old hens were no significant difference among different week-old free range feeding groups(P>0.05), the body lean length, metatarsus length, metatarsus girth, metatarsus color comb height, comb color and breast angle of hens were significant difference(P<0.05) but no clear rules were observed in the study.(2) Expect for semi-eviscerated ratio, eviscerated ratio, claw rate, alimentary canal weight and stomach rate, other slaughter performance of 13-week-old cocks were no significant difference among different week-old free range feeding groups(P>0.05). The semi-eviscerated ratio, eviscerated ratio, head rate, leg rate, liver rate, alimentary canal weight and stomach rate of 16-week-old hens were significant difference among different week-old free range feeding groups(P<0.05) while other other slaughter performance were no significant difference, the effects of different week-old free range feeding on slaughter performance showed no clear rules for hens and cocks.(3) The water losing rate, shear force, meat color of 13-week-old cocks were significant difference among different week-old free range feeding groups(P<0.05) while shank strength and PH were no significant difference(P>0.05). The water losing rate of 16-week-old hens were significant difference among different week-old free range feeding groups(P<0.05) while shear force, meat color, PH and shank strength were no significant difference(P>0.05).(4) The fatty acid contents of the hen breast muscle was no significant difference among different week-old free range feeding groups(P>0.05). The unsaturated fatty acid contents of the hen breast muscle ranged from 42.66% to 54.96%, which significant higher than saturated fatty acid contents(ranged from 29.16% to 32.71%), different week-old free range feeding showed effects on the different kinds of fatty acid contents to some degree, the contents of unsaturated fatty acid and essential fatty acid of of 7-week-old free range feeding group hens were significant higher than those of 11-week-old and 15-week-old free range feeding groups, the contents of unsaturated fatty acid and essential fatty acid of of 7-week-old free range feeding group hens were 54.96% and 23.03% respectively, which were the highest in all groups. The contents of linoleic acid and linolic acid of 7-week-old free range feeding group hens were higher than other groups to some degree.(5) The contents of RBC, HGB, MCH, T-CHOL and CLU, RDW, the activities of LDH, HBDH, MAO and MDH of 13-week-old cocks were significant difference among different week-old free range feeding groups(P<0.05) while MCHC, MCV, HCT, Ca, P, TG and the activities of other enzymes were no significant difference(P>0.05). RBC, MCHC, MCV, MCH and HCT of LDH, HBDH, MAO and MDH of 16-week-old hens were significant difference among different week-old free range feeding groups(P<0.05), to all hen groups, the blood indexes wavered violently without clear rule. For cocks and hens, HGB, RDW, P, TG, T-CHOL CLU, ALT, ADA, 5-NT and MAO were no significant difference among different week-old free range feeding groups(P>0.05). The activities of some enzyme were higher in. the hens feeded in relative short time free range, which perhaps caused by short stress time and violent waving of their metabolism.
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