Effect Of Dietary Cottonseed Meal With And Without Iron On Laying Performance, Egg Quality And Residue Of Gossypol In Egg And Tissue Of Laying Hens

The purpose of this study is to investigate the effect of dietary ferrous sulfate on the laying performance, egg quality and the residue of gossypol in egg and tissue of laying hens, which could provide experimental basis and technical support for the safe production of eggs. One thousand and eighty Roman layers,34 weeks,were divided into 9 groups by the basis of laying rate. The control group was fed a corn-soybean meal basal diet,trial groups 2,3,4,5 were used 25%,50%,75%,100% cottonseed meal instead of soybean meal containing free gossypol 58mg/kg,116mg/kg、174mg/kg、232mg/kg.The trial groups 6,7,8,9 were used ferrous sulfate supplement Fe2+ on the conttonseed meal diet,and free gossypol to Fe2+ was the mass ration of 1:1. There were 8 replications in each group and 15 laying hens in one replication. The trial term lasted 12 weeks.The experimental results showed:1 Throughout the experimental period,the body weight,egg production,feed intake had no significant effect(P>0.05);Cottonseed meal replacement level had significant influence on egg weight (P<0.05), compared with the control group, the average egg weight in 75% and 100% cottonseed meal replacement were significantly decreased (P<0.05), the cottonseed meal replacement level had significant interaction with ferrous sulfate (P<0.05),added ferrous sulfate significantly increased the average egg weight in 75% and 100% cottonseed meal. Different levels of cottonseed meal had significant influence on feed-egg ration(P<0.05), the feed-egg ration was significantly increased with cottonseed meal level (P<0.05),added ferrous sulfate had no significant effect on the feed-egg ration(P>0.05).2 The cottonseed meal with or without ferrous sulfate had no significant impact on eggshell thickness, shell strength,albumen height,Haugh unit, yolk and shell ratio (P>0.05). After feeding 4wk,8wk,12wk,egg sensory evaluation results showed that increasing with cottonseed level,feeding time and storage time(4℃),the yolk color gradually intensified,the ratio of OBJ egg increased. Adding ferrous sulfate could be greatly reduced egg yolk discoloration and unacceptable proportions, but not completely.3 The glutamic pyruvic transminase (GPT) activity of 100 percent cottonseed meal replacement was significantly higher than in control group (P<0.05),added ferrous sulfate has reduced its activity a trend (P=0.097).Along wih cottonseed meal level increased, the white blood cells were significantly decreased (P<0.05), which 75 percent cottonseed meal replacement was the lowest, and adding ferrous sulfate had no significant effect on white blood cell levels. The hemoglobin levels of 100 percent cottonseed meal replacement was significantly lower than in control group (P<0.05), while adding ferrous sulfate did not affect the content of hemoglobin (P> 0.05).4 Compared with the control group, the cottonseed meal replacement group could significantly improve the content of total gossypol and free gossypol in liver (P<0.05), adding ferrous sulfate can significantly reduce the amount of residual total gossypol and free gossypol (P<0.05). Different levels of cottonseed meal replacement can significantly affect total gossypol content of egg yolk (P<0.05), and increased linearly with the replacement level, adding ferrous sulfate can significantly reduce the amount of residual yolk total gossypol (P<0.05).Conclusions:In the diet of laying hens which the cottonseed meal replacement ratio reached 75% and 100%, reduce egg weight and improve feed-egg and have some adverse effects on health of laying hens, increase egg yolk color and unacceptable proportions, and the gossypol residues in the liver and eggs of laying hens,the security risk is relatively small.