| Cottonseed meal is a valuable source of protein,and it is very cheap.However,excessive add easy to cause the egg quality degradation,previous studies found that,after adding 30%cottonseed meal in laying hens fodder,eggs refrigerated after a certain time,egg yolk elasticity increased.Cottonseed meal increases in egg yolk elasticity in the specific mechanism is still controversial.Free gossypol and propylene fatty acid in cottonseed meal is considered to be the main cause of the phenomenon.But what exactly caused by what kind of material and egg yolk elasticity increase the specific mechanism is still unclear.In this study,the main anti-nutritional factors in cottonseed meal were investigated,the effects of FG and CPFA on production performance and egg quality of laying hens,and the toxic effects of FG on liver,and thus provide a theoretical basis for the rational application of cottonseed meal.A total of 270 healthy 42-week-old JINGFEN 2 laying hens were randomly divided into 3 groups with 3 replicates per group and 30 hens per replicates.Laying hens in 3 groups were fed the basal diet(group C),the basal diet supplemented with 400 mg/kg FG(group FG)and the basal diet supplemented with 400 mg/kg CPFA(group CPFA)respectively.Test laying hens adopts three ladder caged,feeding separately for each repetition,feeding and drinking for free,daily management and immune procedure according to routine.The experiment lasted for 6 weeks.The results showed as follows:The effects of FG and CPFA on production performance of laying hens.Recorded egg production,total egg weight,broken egg number every day,weighted hens at the beginning and end.Eggs were collected at 14,28,42 days of the experiment,and calculated laying rate,average egg weight,feed-egg ratio,weight gain rate,death and culling rate.The results showed as follows:The laying rate of FG group reduced with the increasing of the experiment time.At 4 and 6 weeks,compared to group C,the average egg weight of group FG was significantly decreased(P<0.01),and the feed-egg ratio was increased,while no significant difference on weight gain rate(P>0.05).The results suggest that FG can reduce the laying rate and average egg weight of laying hens,while CPFA has no effects on production performance of laying hens.2.The effects of FG and CPFA on egg quality of laying hens.Eggs were collected at 13,14,27,28,41,42 days,part of which were used for determination of regular egg quality(Egg yolk color,ha units,eggshell thickness,egg shape index,eggshell strength,egg yolk ratio,egg yolk pH,egg white pH and egg yolk moisture),triglyceride and cholesterol content in egg yolk,and content of calcium and iron in egg yolk and egg white on the day.The remaining were used for determination of egg yolk pH after 4 weeks of storage in 4?,and the changes in egg yolk elasticity after different weeks of storage in 4?,as well as the egg yolk granule and egg yolk membrane structure in each group.The results showed as follows:FG and CPFA have no significant influence to the egg quality of fresh eggs(P>0.05).Triglyceride content in egg yolk of group CPFA was decreased significantly after 6 weeks of storage.The Fe and Ca ion content in egg yolk of group CPFA were decreased significantly(P<0.05)at every experiment period,while the Ca ion content in serum was increased significantly(P<0.01)after 4 or 6 weeks of storage.After 4 weeks of storage in 4?,the egg yolk pH of group CPFA was obviously increased(P<0.01),while egg white pH decreased significantly(P<0.05).After storage,the egg yolk spring of group CPFA increased significantly(P<0.01),and showed time-and dose-dependence,and the yolk granules was taken placed by a sheet shape,with many holes appearing in the vitelline membrane.The results suggested that FG and CPFA have no significant influence to the egg quality of fresh eggs,but have a trend to decline the triglycerides in egg yolk.The exposure of CPFA alone can lead to the appearance of "rubber eggs",which is related to the influences of CPFA on the pH,Fe and Ca ions content in egg yolk and egg white,as well as the permeability of vitelline membrane.3.The effects of FG and CPFA on liver of laying hens.A random sample serum 15 laying hens was collected at 14,28,42 days of the experiment for determination of TG,GLU,CHOL,AST,ALT,TP,ALB and LDL-C.At the end of experiment,each group of randomly selected three layers and put to death,collect the liver to determine lipid peroxidation index,element,and the fatty acids,and made pathology and ultrathin sections.The results showed as follows:(1)FG and CPFA lead to the increase of ALT P<0.05)and the decrease of TP,TG P<0.05).At 4 and 6 weeks,the AST in serum was significantly increased(P<0.05),but the ALB was significantly decreased(P<0.05).At the 6week,CHOL of the FG group was significantly increased(P<0.05),but the CPFA group was significantly decreased(P<0.05).(2)Liver lipid peroxidation index SOD,GSH-Px and GSH decreased significantly(P<0.05)and MDA increased significantly(P<0.05).(3)A significant rise(P<0.05)in experimental liver Fe and Ca ions,Zn ions in FG group was increased,CPFA group increased significantly(P<0.05).(4)The oleic acid was not detected in in group H(P<0.01).(5)FG and CPFA leads to different degree of liver steatosis.(6)Liver cell mitochondria damage caused by FG.In conclusion,FG and CPFA will cause the damage of liver,liver steatosis.It will also affect the consist of fatty acid and ion in liver.These changes of laying hens may be related to the FG,ring CPFA complex with 2 valence ions in the liver,cause liver function abnormalities,fatty degeneration of liver cells and mitochondria damage. |
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