Effects of free gossypol level in diet and feeding period on free gossypol residue in eggs.

【Objective】The experiment studied the effects of free gossypol(FG)level in diet and feeding period on FG residue in eggs.【Method】480Brown laying hens at the age of 30weeks were assigned to 5treatments,with 6replicates per treatment.The preparation period lasted for 1week and the experimental period lasted for 24weeks.1control group fed with corn-soybean basal diet and 4experimental groups fed with diets containing 50,100,150and 200g/kg cotton seeds,respectively.The FG contents in diets of experimental groups were 43.15,86.30,129.45and 172.60mg/kg,respectively.During the experimental period,production performance,egg quality and FG residue in the eggs were measured.【Result】Feeding 129.45mg/kg FG for 24weeks to hens significantly decreased egg production,average egg weight and daily feed intake,while increased feed conversion ratio significantly.Eggshell strength and yolk color in the group fed with 172.60mg/kg FG for 24weeks were significantly lower(P0.05)than that of the control.On week 12,the FG residues were 20.64,31.86,39.13and 43.32mg/kg when the daily FG intakes per hen were 5.29,10.26,15.04and 19.09mg,respectively.On week 24,the FG residues were 27.38, 42.40,45.17and 53.44mg/kg when daily FG intakes per hen were 5.02,9.83,14.24and 17.55mg,respectively.【Conclusion】The cotton seed content in diet should not exceed 100g/kg to avoid the effects on productivity and eggs quality.FG residues in eggs increased significantly with the increase of FG level in diets and the extension of feeding period.