Effects Of Forced Molting And Dietary Supplementation Of Isolfavone On Performance Of Laying Hens

The depression of ovary function of laying hen leads to a slowdown in development anddifferentiation of follicular, resulting in the decreased egg production and the shortened layingpeak period. The inner regulatory factors, such as FSH, LH, E2and P4, could play importantrole in ovary function of laying hens. Moreover, the change external environment, such asclimate and diet, also affect the ovary function. In the present study, three trials wereperformed to investigate the effect of external environment on performance of laying hens.In trial1,120Hy-line Brown layers (82wk of age) with similar body weight, wererandomly divided into8groups. When the molting program was carried out, water waswithdrawn for the first three days and the feed was removed on Day1that lasted for14days,which resulted in an approximate30%reduction in the average body weight, and then fullfeed was provided at85weeks of age. The sample were collected at the three stages, thebeginning of molt (at83weeks of age, BM), during molt (at85weeks of age, DM) andpostmolt (at89weeks of age, PM). At the BM and PM,6eggs were sampled for the eggquality. Two hens of each replicate were weighed from each treatment, and then blood wasdrawn from a wing vein and centrifugated. After hens were killed, the numbers ofpreponderant follicles were recorded, and preponderant follicles and small yellow follicle(SYF) were harvested and weighed. The preponderant follicle members was sampled, cooleddown in liquid nitrogen immediately and stored at-80℃until analysis. The results showedthat at PM, the laying rate was increased from70%to93%; The shell thickness, egg proteinheight, yolk color, haugh unit, shell ratio and index was significantly increased; the VLDLlevel of plasma was significantly increased, and the level of E2, P4, FSH, and LH wassignificantly changed; the expression of ESR, Occludin mRNA level of the follicle membranewas significantly decreased, and the expression of VLDLR, CYP17A1, CYP19A1, PGR,FSHR, LHR mRNA was significantly increased. It was suggested that forced molting causedthe regression of ovary function of laying hen, and some hormones and VLDLR and Occludinmight be involved in. In trial2,432Hy-line Brown layers (33wk of age) with similar egg production wererandomly divided into following two groups: Treatment (corn-soybean diet+isoflavone), andcontrol (corn-soybean diet). The volume of isoflavone in diet was6mg/kg, and the purity ofisoflavone extract was40%. The trial lasted for28weeks. Egg production and egg weightwere recorded every day, and feed intake were recorded every week. The results showed that,long-term supplement of low level isoflavone not significant affected the laying rate, FI,feed:egg ratio and egg production.In trial3,192Hy-line Brown layers (25wk of age) with similar egg production, wererandomly divided into following two groups: Treatment (corn-miscellaneous diet+isoflavone), and control group (corn-miscellaneous diet). The diet contained8%soybean,10%virus-free cottonseed and3.16%corn gluten meal, in order to decrease the isoflavone ofsoybean in diet. The volume of isoflavone in diet was80mg/kg, and the purity of isoflavoneextract was40%. The trial lasted for50weeks. Egg production, egg weight and were recordedevery day, and feed intake were recorded every week. Every5weeks during the trial,3eggsin each replicates were sampled for testing egg quality. At the peak period and the end of thetrial,9hens were weighed for each group，blood was drawn from a wing vein. The resultsshowed that long-term supplement of high level isoflavone did not affect the layingperformance of hens, as well as the laying rate, FI, feed:egg ratio, egg production and eggquality. At the peak period of egg production, the level of E2, P4, FSH, and LH of plasmawas not significantly changed. At the end of trial, the VLDL level of plasma was increasedsignificantly. All the period of trial, the level of UA, GLU, TG was not significantly changed.The rejuvenation in reproductive performance following molt may be medicated by anincreased sensitivity of ovary. Long-term supplement of isoflavone did not affect the layingperformance of hens.