Effects Of Stocking Density On Production Performance And Blood Biochemistry Of Layer

Stocking density is one of the important factors that affect the production performance and welfare status of layers.Stocking density affects directly the range of poultry activity space and affects indirectly the air quality of the poultry house and production performance of layers.Therefore,stocking density plays an important role in the production of layers.The study was divided into three experiments.The first experiment was conducted to investigate the effect of stocking density on growth performance and blood biochemical indexes of chickens during brooding and rearing period.The second experiment was conducted to estimate the effect of conducted density on growth and development and blood biochemical indexes of pullets during the rearing period.The third experiment was to investigate the effect of conducted density on egg production performance,blood biochemical indicators,and behavioral aspects of laying hens.Experiment I:1650 Hy-Line brown commercial laying hens at 14 days of age with similar body weight were randomly used and divided into 3 groups(A,B,and C group)with 5 replicates in each group.The cage floor area per hen in group A,B and C was 260 cm2,284 cm2 and 312 cm2 at 3-6 weeks of age,and 312 cm2,347 cm2 and 390 cm2 at 7-9 weeks of age,respectively.The experiment lasted 7 weeks.The results showed that,body weight gradually increased as the stocking density decreased.The chicken body weight at 3 to 5 week of age and 7 to 8 week of age ingroup A was significantly lower than that of group B and C(P<0.05).The body weight and shank length of chicken at 9 week of age in group A were significantly lower than those in group C(P<0.05),respectively.In group B,The contents of serum T-AOC,SOD,GSH-Px and ALP in group B were significantly higher than those in group A and C(P<0.05),however the plasma MDA content in group B was significantly lower than that in group A and C(P<0.05).The serum T3 content in group A was significantly lower than that in group B and C(P<0.05).The serum T4 content in group B was significantly higher than that in group A and C(P<0.05).The serum CORT content in group B was significantly higher than that in group A(P<0.05).Experiment II:1050 Hy-Line brown commercial laying hens at 13 week of age with similar body weight were randomly divided into 4 groups(A,B,C,and D groups)with 5 replicates in each group.in the cage floor area per henin group A,B,C,and D were 420 cm2,458 cm2,504 cm2,and 560 cm2,respectively.The experiment lasted 6 weeks.The results showed that,the body weight and shank length of pullets gradually increased with the decrease of rearing density(P>0.05).The uniformity of group D was higher than that of other groups at 15 to 17 week of age.The plasma T-AOC,SOD and ALP content in group C were significantly higher than those in other three groups(P<0.05),respectively,however the plasma MDA content was significantly lower than that in other three groups(P<0.05).The serum GSH-Px in group A was significantly higher than that in the other three groups(P<0.05).The plasma of T3 and T4 content in group A was significantly higher than those in group D.Experiment ?:600 Roman Pink commercial Laying hens at 60 week of age with similar body weight and plumage scores were selected and randomly divided into 3 groups(group A,B,and C).The cage floor area per hen in groups A,B,and C were 450 cm2,540 cm2,675 cm2,respcetively.The experiment lasted 8 weeks.The average daily feed consumption of the laying hens increased,as thestocking density of laying hens decreased,and the feed-to-egg ratio and the rate of broken eggs decreased during the experimental period.The eggshell color decreased with the decreasing of the stocking density.Blood biochemical parameters such as MDA,TGand ALT were not significantly affected(P>0.05).The probability of occurrence of fatty liver syndrome in group A was found higher than that in group B and C.The number of chickens fed simultaneously in group A and group B were significantly higher than that in group C(P<0.05).The number of feedings and fighting times in group A were significantly higher than those in group B and C(P<0.05),respcetively.The plumage scores of the back in group C was significantly higher than those in group A and B(P<0.05).The plumage scores of wings,chest,and abdominal feathers in group C were significantly higher than those in group A(P<0.05),respectively.The following conclusions were drawn from this experiment:(I)The stocking density was 284 cm2 per hen at 3 to 6 week of age,and 347 cm2 per hen at 7 to 9 week of age of Hy-Line brown commercial laying hens,which could significantly increase the body weight and shank length of pullets as well as anti-oxidation and anti-stress ability and improve the physique status of pullets and meet the demands for pullets.(?)The stocking density of 504 cm2 per hen were beneficail to the promotion of growth and antioxidant capacity of pullets,in according to improving the health breeding of pullets.(?)The stocking density had no significant effect on the production performance of laying hens at the late laying period of 61 to 66 week of age(P>0.05).The stocking density of 675 cm2 per hen could only increase the production performance and feed utilization performance of laying hens and meet the laying hens production standards at 67 to 68 week of age.The low density group facilitated the behavioral expression of laying hens and reduces feather damage.