| The research was conducted to study the effect of dietary supplement with daidzein on the mating behavior, reproductive performance and serum tri-iodothronine(T3)and thyroxin(T4) level in broiler breeders exposed to heat stress. The study included three series: 1. The effect of daidzein on the mating behavior, laying performance and endocrinefunction in young laying hen under hot environmental conditions (summerseason).Ninety Lingnanhuang(Local breed) broiler breeders hens and nine roosters at 155 day of age were randomly assigned to three groups which were supplemented with daidzein at doses of 0, 3 and 6mg/kg diet (control, Exp I and II). The animals were raised on ground under natural environmental conditions of 22-33 C.The blood samples were collected on the -ld(22C),7d(23C),lld(30.5C),15d(32.3aC). The result was shown as follows: (1). High ambient temperature decreased the mating frequency. The diet supplemented with daidzein ameliorated the effect of heat stress on mating behavior in broiler breeders. (2). At the temperature of 30.5 C, the laying rate in the Exp I and II increased by 30.0% and 44.3% compared with the control. The egg weight decreased significantly in Exp I and increased in Exp II. When the temperature rose to 31.5-33C, the laying rate, fertility rate and egg weight in the groups supplemented with daidzein were higher than these of the control. At the temperature of 22-33 C ,the laying rate in Exp I and II increased by 23.53%(P<0.05) and 12.46%.The egg fertility rate was increased by 3.59% and 6.46%,respectively, and the egg weight also increased. The cracked egg rate in Exp I decreased by 37.35%, while it increased by 12.65% in Exp II. (3) Compared to the control, the serum T^ level in Exp I and II increased at the lid and ISd.The serum T4level in Exp I increased by 32.2%, while it decreased by 9.12% in Exp II at the lld.The serum T4 level in Exp I decreased by 15.17%, while it elevated by 47.9%(P<0.05).2. The effect of daidzein supplement on the performance in broiler breeder hen at later laying stage under high environmental temperature.666 42-wk-old broiler breeder hens and 66 roosters were randomly divided into three groups that were supplemented with daidzein at doses of 0, 3 and 6mg/kg diet (control, Exp I and II). The eggs were collected to evaluate the fertility and hatchability. The egg quality was determined at the end of the experiment. The result showed that the laying rate increased and the egg shell thickness decreased significantly in Exp I, but there were no significant difference in Exp II. Daidzein supplement had no significant effect on egg weight, cracked-egg rate, fertility rate, hatchability, egg shell strength and egg shape index hi broiler breeder hens at later laying stage.3.The effect of diet supplemented with daidzein on the testicle development, sperm quality and endocrine function in acute heat-stressed roosters18 Lingnanhuang(Local breed) roosters at 32 week of age were divided equally into three groups which were supplemented with daidzein at doses of 0, 3 and 6mg/kg diet (control, Exp I and II). For a ten-day treatment period, all birds were subjected to 39C(2h) and 40C(2h) acute heat stress treatment. The blood samples obtained at the Ih before acute heat stress, 4h after heat stress and 2 days after heat stress were used to assay the serum TS and T4 level. Semen samples were taken for analysis of sperm concentration, rate of live sperm. The birds were slaughtered and testis was collected at the end of the experiment. The results indicated that the rate of live sperm in rooster exposed to acute heat-stress was decreased dramatically, while the sperm concentration was only slightly decreased. Serum T4 level in the roosters after exposure to acute heat-stress was elevated. Daidzein supplement significantly increased the testicular seminiferous tubule diameter, but had no significant effect on sperm quality, the development of germ cells and testis weight, and level of serum TS and T?in roosters.In conclusion,...
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