日粮氟水平对雏鸡免疫影响的研究

EFFECTS OF DIETARY FLUORINE ON IMMUNE PROFILE IN CHICKS

研究了日粮氟水平对雏鸡免疫的影响。试验将１５０只１天龄海兰雏公鸡随机分成空白对照、免疫对照、试验Ⅰ～Ⅳ组等共６组，每组２５只，在隔离器内饲养６周，从１天龄起，空白对照组和免疫对照组喂以基础日粮，试验Ⅰ～Ⅳ组分别饲喂氟含量为２５０、５００、１０００和２０００ｍｇ／ｋｇ的日粮。１４天龄时除空白对照组外，其余各组用ＮＤ＋ＩＢＤ双价油剂灭活苗进行免疫，每周定期采血，用ＥＬＩＳＡ法检测ＩＢＤ和ＮＤ抗体水平，试验结束时测定囊重、囊体比、囊指数等，并对法氏囊进行组织学切片检查，结果表明：（１）日粮中氟含量达５００ｍｇ／ｋｇ以上时法氏囊生长发育受阻，当氟含量达２０００ｍｇ／ｋｇ时，严重影响法氏囊的生长发育，囊指数仅为０７。且囊重、囊体比及囊指数均明显低于其余各组（Ｐ＜００１）。（２）当饲料中氟含量达到５００ｍｇ／ｋｇ以上时，对法氏囊有毒害作用，主要引起小血管扩张、充血和出血，法氏囊局部粘膜上皮皱缩和脱落。在氟含量达２０００ｍｇ／ｋｇ时还见法氏囊部分淋巴小结髓质坏死、部份上皮基底细胞增生。（３）高氟日粮（含氟５００ｍｇ／ｋｇ以上）会导致ＩＢＤ和ＮＤ母源抗体的消失加快，并对免疫抗体的产生有抑制作用，而适量的氟对免疫抗体的产?

his paper studied the effects of levels of dietary fluorine on immune profile in Hy-Line cockerels.One hundred and fifty Hy-Line cockerels of 1-day old were randomly divided into 6 groups (n=25)as the non-treated controls,immunized controls,and the treated groups Ⅰ to Ⅳ.The birds were transferred into isolators from first day of age for 6 weeks.The non-treated and immunized control groups were fed with a basic ration,whereas the treated groups Ⅰ to Ⅳ were offered diets containing fluorine at concentrations of 250 ,500 ,1 000 and 2 000 mg/kg,respectively.On day 14,all groups were immunized with ND+IBD inactivated vaccines in mineral oil adjuvant.Sera were collected weekly and antibody titres against IBD and ND were measured by ELISA,At the end of trial,bursa of Fabrica were recovered,their weights and relative weights determined and bursa indexes calculated.It was revealed that development of bursa of Fabrica was retarded when dietary levels of fluorine exceeded 500mg/kg ,such phenomenon was especially prominent in Group Ⅳ which was fed with the diet containing 2 000 mg/kg fluorine,which produced a bursa index of 0.7,and substantially (P<001)lower bursa weights,relative bursa weights and bursa index compared with other groups.Histological examination of bursa of Fabrica showed that dietary levels of fluorine exceeding 500 mg/kg was toxic to bursa of Fabrica,leading to swelling,congestion,haemorrage of capillary vessels,shrinkage and detachment of epithelia of partial membrane of the bursa.Necrosis of medullar of lymphnoduli in the bursa was observed with part of basal epithelia hyperplastic.Diets containing high levels of fluorine over 500 mg/kg also accelerated depletion of maternal antibodies against IBD and ND,and also inhibitive to production of antibody.However moderate levels of dietary fluorine was beneficial towards production of antibody.