锌对5—15周龄鹅免疫、抗氧化功能、金属硫蛋白-Ⅰ基因表达量的影响及变量相关性分析

【目的】研究不同水平锌对5—15周龄鹅免疫抗氧化功能与金属硫蛋白-Ⅰ(MT-I)m RNA表达量的影响及相互关系,以科学地确定鹅饲粮中锌的需要量。【方法】试验随机选用29日龄体重相近的青农灰鹅360只(P0.05),设计6个处理,每处理6次重复,每重复10只(公母各半);各处理饲粮中锌水平分别为:27.46(Ⅰ组)、77.46(Ⅱ组)、127.46(Ⅲ组)、177.46(Ⅳ组)、227.46(Ⅴ组)、277.46(Ⅵ组)mg·kg-1(基础饲粮中含锌),试验进行11周。【结果】(1)胸腺指数、脾脏指数和法氏囊指数受饲粮中锌水平的影响,随锌水平的升高呈现先升高后降低趋势;当锌水平为127.46 mg·kg-1时,胸腺指数最高(P0.05);当锌水平为77.46 mg·kg-1时,脾脏指数、法氏囊指数最高(P0.05)。(2)饲粮锌水平为177.46 mg·kg-1时,鹅副黏病毒疫苗免疫后7日的抗体滴度最高(P0.05);饲粮锌水平为157.41 mg·kg-1时,鹅副黏病毒疫苗免疫后14日的抗体滴度最高(P0.05)。(3)当饲粮锌水平为153.84 mg·kg-1时,鹅血清和肝脏总抗氧化能力(T-AOC)活性最高(P0.01);当饲粮中含锌127.46 mg·kg-1时,血清和肝脏过氧化氢酶(CAT)活性最高(P0.01);当饲粮锌水平为148.33 mg·kg-1时,鹅血清和肝脏谷胱甘肽过氧化物酶(GSH-Px)活性最高(P0.05);当饲粮中含锌148.33 mg·kg-1时,血清和肝脏铜锌超氧化物歧化酶(Cu Zn-SOD)活性最高(P0.01);当饲粮中锌水平为177.46 mg·kg-1时,血清和肝脏中丙二醛(MDA)最低(P0.05)。(4)饲粮中锌能显著提高MT-I m RNA表达量(P0.05),当饲粮中锌水平为177.46 mg·kg-1时,肝脏MT-I m RNA表达量最高(P0.01)。(5)肝脏中MT-I m RNA表达量与肝脏中T-AOC(r=0.94)、Cu Zn-SOD(=r 0.97)活性指标呈极显著性正相关(P0.01),与CAT(r=0.85)、GSH-Px(r=0.89)活性呈显著正相关(P0.05),与MDA呈负相关(r=-0.70,P0.05);肝脏中MT-I m RNA表达量与血清中T-AOC(r=0.99)、CAT(r=0.92)和Cu Zn-SOD(r=0.94)活性均呈极显著正相关(P0.01),与GSH-Px呈正相关(r=0.81,P0.05),与MDA呈负相关(r=-0.39,P0.05)。【结论】(1)饲粮中适宜水平锌能够促进鹅免疫器官发育,增强T-AOC、CAT、GSH-Px、Cu Zn-SOD抗氧化酶活性,降低MDA水平。(2)饲粮中锌能够干预肝脏MT-I m RNA表达量,从而调节机体抗氧化能力。(3)鹅饲粮中锌水平在77—150 mg·kg-1范围内机体处于高位免疫和抗氧化状态。

Effects of Dietary Zinc on Immunity,Antioxidant Capacity and MT-I mRNA Gene Expression Level and Their Factor Correlation Analysis of 5-15 Weeks Old Goose

【Objective】 This experiment was conducted to determine the required level of zinc in goose feed. The effects of different levels of dietary zinc on immunity, antioxidant capacity and metallothionein (MT-I) mRNA gene expression to 5-15-week-old Qing-Nong-Hui geese were evaluated. 【Method】 Three hundred and sixty 29-day-old Qing-Nong-Hui geese were randomly selected and divided into six treatment groups with six replicates for each group, and each replicate contained ten geese (5♂+5♀). The content of added dietary zinc in each group was 27.46 (GroupⅠ, control), 77.46 (GroupⅡ), 127.46 (Group Ⅲ), 177.46 (Group Ⅳ), 227.46 (Group Ⅴ), and 277.46 (Group Ⅵ) mg·kg^-1, respectively. The geese were fed for 11 weeks. 【Result】The results were as follows: Index of thymus, spleen and bursa of fabricius showed an increase and downward trend with the effect of zinc level in feed. The thymus index obtained the highest (P＜0.05) level when the added zinc in feed was 127.46 mg·kg^-1, while the spleen index and the fabricius bursa index reached the highest level (P＜0.05) when the added zinc in feed was 77.46 mg·kg^-1. The index of immune organs decreased as long as the dietary zinc in feed was out of the range of 77.46-127.46 mg·kg^-1. The antibody titer reached the highest (P＜0.05) after the geese were immunized by goose paramyxovirus vaccine for 14 days when the zinc level in feed was 157.41 mg·kg^-1. The activity level of total antioxidant capacity (T-AOC) for the goose serum and liver reached the highest (P＜0.01) when the zinc level in feed was 153.84 mg·kg^-1. The activity level of both catalase (CAT) and glutathione peroxidase (GSH-Px) for the serum and liver of goose was the highest (P＜0.01) when the zinc level in feed was 148.33 mg·kg^-1. The activity level of superoxide dismutase (CuZn-SOD) was the highest (P＜0.01) in the goose’s serum and liver when the zinc level in feed was 148.33 mg·kg^-1. On the other hand, when the zinc level in feed was 177.46 mg·kg^-1, the malonaldehyde (MDA) in the serum and liver had the lowest level (P＜0.05); With the increase of the zinc level in feed, the expression quantity of MT-I mRNA was significantly increased (P＜0.05). And when the zinc level in the feed was 177.46 mg·kg^-1, the expression quantity of MT-I mRNA of liver was the highest. It was highly significant that the expression quantity of MT-I mRNA in goose liver was positively correlated with the activity level of T-AOC (r= 0.94, P＜0.01) and CuZn-SOD (r= 0.97, P＜0.01). The MT-I mRNA expression level in goose liver was also positively correlated with the activity level of CAT (r=0.85, P＜0.05), GSH-Px (r=0.89, P＜0.05), and negatively correlated with MDA (r=-0.70, P＞0.05). The expression level of MT-I mRNA in goose liver was significantly positively correlated with activity levels of T-AOC (r=0.99, P＜0.01), CAT (r=0.92, P＜0.01) and CuZn-SOD (r=0.94, P＜0.01) in serum. It was also positively correlated with GSH-Px (r=0.81, P＞0.05) and negatively correlated with MDA (r=-0.39, P＞0.05).【Conclusion】 Appropriate additional level of dietary zinc promoted the immune organs development and antioxidant capacity of goose. Dietary zinc also intervened the MT-I mRNA expression level, which was closely related with the body’s antioxidant capacity. Feed zinc levels in the 77-150 mg·kg^-1 range can keep the body in high immunity and antioxidant capacity level of the 5-15 weeks old geese.