| Safety evaluation of genetically modified corn(Bt corn)in hens was investigated in a series of studies.The effect of long-term and multigenerational feeding Bt corn on growth and health of third generational laying hens and roosters were studied,and to provide data reference for the establishment of the safety evaluation system and the government standard of genetically modified feeds.The objective of Exp.1 was to determine the nutrient and energy values of the non-transgenic nearisoline control corn(CTC),Bt corn(BTC),and commercially available reference corn(RFC),and three corresponding diets using an in vitro digestion method.Nutrient concentration was similar between the BTC and CTC corn ingredients and diets.The in vitro gross energy digestibility of BTC were less than that in CTC(83.68 vs 84.54%,P=0.02),the corresponding variation of coefficient(CV)was 0.72%,less than the variation coefficient of feed ingredients determined using the SDS-II in vitro method(CV?1.64%).The EHGE of BTC diet was greater than the EHGE of CTC diet(10.81 vs 10.55 MJ/kg,P=0.04,CV=1.62%).The other nutrient values of BTC corn has no difference with those of CTC corn and diet.The objective of Exp.2 was to investigate the effect of long-term and multigenerational feeding BTC on growth and production performance of the third generational laying hens and roosters.Compared with CTC,feeding BTC diet increased the feed:weight gain value of laying hens in the 17-28 week period(P<0.05).However,the dressing rate,half-eviscerated rate,eviscerated rate,thigh meat rate,and so on of laying hens were not affected by BTC corn.In roosters study,there was no difference in the performance of roosters fed BTC diet compared with CTC diet.Compared with CTC diet,the laying hens feeding BTC diet had higher yolk color value(P<0.05)and there was no difference in other egg production performance and egg quality index for laying hens feeding BTC and CTC diet.The objective of Exp.3 was to investigate the effect of long-term and multigenerational feeding BTC on blood biochemistry,organ health and reproductive performance of the third generational laying hens and roosters.Compared with CTC diet,feeding BTC diet increased the creatinine level(6.53 vs 5.88 ?mol/L,P<0.05),and decreased the concentration of total protein(32.50 vs 37.67 g/L),globulin(14.58 vs 18.83 g/L),glutamyltranspeptidase(23.00 vs 25.67 U/L),and blood Ca(2.34 vs 2.42 mmol/L,P<0.05).However,the ranges for these values were narrow,and all these indexes were within the normal physiological values of healthy poultry.Compared with CTC diet,feeding BTC diet increased the whiskers length of roosters(P<0.05),but had no difference in sex hormone,testicle health,and semen quality.There was no difference in the liver,spleen,and kidney health between BTC corn group with CTC corn group.The objective of Exp.4 was to investigate the effect of long-term and multigenerational feeding BTC diet on the intestinal structure and cecal microbes of the third generational laying hens and roosters.Compared with CTC diet,feeding BTC diet improved the villus height of jejunum of laying hen(P<0.05),and the crypt depth of duodenum and jejunum of roosters(P<0.05).All these indexes had no negative effect on intestinal health of laying hens and roosters.Compared with CTC diet,feeding BTC diet couldn't affect the diversity,abundance,and COG function of cecal microbes in laying hens and roosters.None of above differences was repeatable in two batches of laying hens or roosters studies,and the differences might also be attributed to the machine precision,the difference of animal,the experiment operation,or other factors.All in all,the Bt corn had similar nutrient content and energy value with nontransgenic near-isoline control corn.Long-term and multigenerational feeding Bt transgenic corn has no negative effect on the growth,production performance,and health of third generational laying hens and roosters. |
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