用外翻肠囊法研究有机锰在肉仔鸡小肠中的吸收特点

In vitro Study on Absorption of Manganese as Different Manganese Sources by Everted Gut Sacs of Broilers

用外翻肠囊法研究肉仔鸡十二指肠、空肠和回肠对无机锰和有机锰的吸收特点。共包括2个试验,试验1是以硫酸锰为锰源,根据单位时间锰的吸收率与外翻肠囊培养时间的曲线关系确定最佳培养时间,试验2是在此培养时间下比较不同形态锰在肉仔鸡小肠中的吸收特点。2个试验均采用单因子完全随机设计。试验1培养时间分别为20、40、60和80min4个处理组,将48只28日龄商品代AA肉公鸡随机分到4个处理组,每组6个重复,每个重复2只鸡(为了扣除内源影响,其中1只鸡作为零添加锰水平处理),每只鸡的十二指肠、空肠和回肠分别用作相应部位肠段外翻肠囊的1个重复。在试验2中共设8个处理组,分别为:硫酸锰、甘氨酸锰螯合物、蛋氨酸锰螯合物、弱络合强度的蛋氨酸锰(Mn-MetE)、中等络合强度的氨基酸锰(Mn-AAA)和强络合强度的氨基酸锰(Mn-AAB)、硫酸锰与甘氨酸混合物及硫酸锰与蛋氨酸混合物的处理组。为了扣除内源影响,另设1组作为零添加锰水平处理。用于试验1中日龄相同的AA肉公鸡72只,随机分到9个处理组,每组8个重复,每个重复1只鸡,每只鸡的十二指肠、空肠和回肠分别用作相应部位肠段外翻肠囊的1个重复。结果表明:(1)锰的吸收率和培养时间在40min内呈线性关系,因此选择30min为试验2的培养时间;(2)体外培养回肠肠囊对无机锰的吸收率?

Two in vitro experiments were conducted to investigate the absorption differences between organic and inorganic Mn by incubating everted intestinal sacs of broilers in media containing Mn as different sources. Trial 1 was conducted to determine an optimum incubation time for trial 2, according to the change of Mn absorption as incubation time varied. Trial 2 was conducted to compare the absorption of organic Mn with that of inorganic Mn in the intestines of the animals at the optimum incubation time. The incubation time of four treatments in trial 1 was 20, 40, 60 and 80 min, respectively. 48 male broilers at the age of 28 day-old were randomly assigned to one of the four treatments for six replicates of two birds each. In each replicate, the intestinal sacs of one bird were incubated in media without adding Mn to it to deduct the endogenous Mn, while the intestinal sacs of the other incubated in media containing 120 μg/mL Mn as MnSO_4·7H_2O. The duodenum, jejunum and ileum of each animal were used to produce the everted sacs of corresponding intestinal segments. In trial 2, there were eight treatments of different Mn sources, which were MnSO_4·7H_2O, Mn-Gly chelate, Mn-Met chelate, Mn methionine complex with the weak complex strength (Mn-Met E, Q_f 3.2, Mn 8.27%), Mn amino acid complex with the moderate complex strength (Mn-AA A, Q_f 45.3, Mn (6.48)%), Mn amino acid complex with the strong complex strength (Mn-AA B, Q_f 115.4, Mn 7.86%), the mixture of MnSO4 and glycine, the mixture of MnSO_4 and methionine, respectively. Mn-Met E, Mn-AA A and Mn-AA B were three organic Mn sources which had been used in our previous study of bioavailabilities of different forms of Mn. An additional group without adding Mn to the media was set up to deduct the endogenous Mn. In the treatment groups of different Mn sources, 120 μg/mL Mn was added to the media. The incubation time of all the everted sacs was 30 min. 72 male broilers at the age of 28 day-old were randomly allotted to one of the nine treatments for eight replicates of one chick each. The duodenum, jejunum and ileum of each bird were used as one replicate of the everted sacs of corresponding intestinal segments. The results showed that: (1) The relationship between Mn absorption and the incubation time was linear within 40 min. The incubation time of 30 min was chosen as an optimum time for comparison of the absorption of Mn as different forms to obtain the most sensitive response in trial 2.(2) The absorption percentage of Mn in everted ileal sacs was about 2～6 times that in duodenal or jejunal sacs. (3) Significant differences were found in Mn absorption by incubating ileal sacs in the solutions of different forms of Mn. The absorption of Mn as Mn-Met chelate was significantly higher than inorganic Mn and Mn-Gly chelate. The absorption of Mn as Mn-AA A and Mn-AA B were significantly higher than inorganic Mn and Mn-Gly chelate. The results suggest that when incubated in simple buffer solutions in vitro, ileum is the main site of Mn absorption for broilers. The absorption of Mn as 'complexed' or 'chelated' organic Mn is higher than inorganic Mn in broilers' everted intestinal sacs. As a ligand, methionine is more effective in facilitating Mn absorption than glycine.