脂多糖应激对添加不同锌源蛋鸡免疫反应和组织锌代谢的影响

Effects of Lipopolysaccharide Challenge on the Performance, Immune Responses and Zinc Metabolism of Laying Hens Fed Two Zinc Sources

36只海兰褐壳蛋鸡按2×3因子进行试验,饲喂3种日粮(分别为基础日粮、基础日粮中添加60 mg/kg硫酸盐和氨基酸络合形式的锌),每组随机选取半数腹腔注射脂多糖(LPS),另一半注射同样剂量的生理盐水,研究LPS应激对饲喂不同锌源蛋鸡产蛋性能、直肠温度、血清IL 1β以及肝脏和脾脏组织MT和锌含量的影响。结果表明,日粮锌源以及锌源与LPS互作对蛋鸡的产蛋率、蛋重和破蛋率均没有显著影响(P> 0.05),LPS攻毒显著降低产蛋率(P< 0.05)并增加破蛋率(P< 0.05),其中添加氨基酸络合锌(ZnAA)蛋鸡的产蛋率显著(P< 0.01)低于基础日粮组;饲喂ZnAA的蛋鸡LPS攻毒后直肠温度峰值出现以及发热消退的时间均早于添加ZnSO4和不添加锌的蛋鸡。饲喂ZnAA的蛋鸡注射LPS 3 h后血清IL 1β的水平显著高于饲喂ZnSO4 的蛋鸡,而注射LPS 12 h后血清IL 1的水平则显著低于硫酸锌组(P< 0.05)。与ZnSO4 相比,添加ZnAA具有提高注射LPS后肝脏和脾脏组织锌浓度的趋势(P< 0.09)。锌源和LPS应激以及两者的互作显著影响组织金属硫因(MT)的含量(P< 0.001),在LPS应激蛋鸡中,添加ZnAA的蛋鸡肝脏和脾脏MT的水平显著高于添加ZnSO4 的蛋鸡(P< 0 001):与饲喂基础日粮的蛋鸡相比,添加ZnAA蛋鸡肝脏和脾脏MT浓度分别提高266%和225%,而添加ZnSO4仅提高158%和151%。

The current study was conducted to determine the effects of Salmonella Typhimurium lipopolysaccharide (LPS) challenge on egg production performance, inflammatory response, tissues metallothionein (MT) synthesis and tissue zinc distribution in laying hens fed two zinc sources. The experimental Hyline brown hens were fed with three different diets (a corn-soybean meal based diet without additional zinc supplementation and basal diet supplemented 60 mg/kg zinc from ZnSO_4 or ZnAA) respectively from 3-week old. At the age of 58-week-old, twelve hens of each dietary treatment were selected and randomly allotted in a 2×3 factorial design. On day 1, 3, 5, 7 of 58-week, six hens of each dietary treatment were injected intraperitoneally with Salmonella Typhimurium LPS or an equivalent amount of sterile saline. There was neither zinc source×immune challenge interaction nor zinc source effect on egg production, egg weight and percentage of cracked eggs during 7 d study period (P>0.05). However, LPS-challenged birds have decreased egg production (P<0.05) and increased percentage of cracked eggs (P<0.01) compared to saline treated birds. When challenged with LPS, the fever response of hens fed ZnAA peaked and subsidized early relative to those fed ZnSO_4 or basal diet. Among LPS-challenged birds, serum IL-1β was higher in hens fed ZnAA than those fed ZnSO_4 at 3 h post-injection (P<0.01), however, birds fed ZnAA had the lowest serum IL-1β concentration among dietary treatments at 12 h post-challenge with LPS (P<0.001). Among saline-treated birds, serum IL-1β was higher in hens fed ZnAA diet than those fed the basal diet at 3 h post-challenge(P<0.01). Zinc concentration of liver and spleen tended to be higher in LPS-challenged hens fed ZnAA than those fed ZnSO_4 (P<0.09). MT concentration in liver of birds fed ZnAA diet was higher than those fed ZnSO_4 diet (P<0.05). When challenged with LPS, birds fed ZnAA diet have a higher concentration of MT in both liver and spleen than those fed ZnSO_4 (P<0.05). Supplementation of ZnAA increased MT concentration by 266% and 225% in liver and spleen respectively, whereas supplementation of ZnSO_4 increased MT concentration only by 158% and 151% in liver and spleen respectively. The results suggested that supplementation of zinc from ZnAA may increase tissue MT synthesis and zinc sequester in liver and spleen, then elevated the sensitivity to LPS challenge and shortened acute phase response which may be beneficial to immune defense.