奶山羊不同锌源的消化吸收规律及适宜添加量

Appropriate additive level of different zinc sources and its digestion in dairy goats

明确奶山羊日粮中不同锌源的适宜添加量及消化吸收率,为配制饲料选择合适的锌源提供指导。本研究以安装消化道三位点瘘管的关中奶山羊为试验对象,采用连续灌注的方法,从瘤胃分别灌注不同梯度的硫酸锌(ZnSO4)溶液和复合氨基酸螯合锌(Zn-AA)溶液,分别采集十二指肠食糜、回肠食糜、粪和血清样品,检测锌含量,计算奶山羊肠道的消化率,确定不同锌源的适宜添加水平。结果表明:1)奶山羊对2种锌源的消化率表现为先升高后降低的变化趋势,Zn-AA的全肠道消化率高于ZnSO4,分别为(70.01±1.8)%和(65.41±8.2)%;2)奶山羊对锌的主要吸收部位在小肠,大肠也有一定的吸收能力,血清锌与食糜锌水平的消化率变化同步,而与不同锌源的消化率呈负相关;3)ZnSO4的适宜添加水平为40mg/kg(RM)(瘤胃内容物),选择添加范围为40～60mg/kg(RM);Zn-AA的适宜添加水平为60mg/kg(RM),选择添加范围为40～80mg/kg(RM)。奶山羊小肠和大肠对2种锌源均可消化吸收,相同水平下奶山羊对Zn-AA的消化率高于ZnSO4,血清锌水平与添加的锌水平和锌源有关,消化道对Zn-AA有更高的耐受量。

In order to determine the appropriate additive level of different zinc sources,help feeders make correct choice between zinc sulfate（ZnSO4） and zinc amino acid chelate（Zn-AA）.Twelve 2.5-3.0 year old,40-45 kg body weight Guanzhong dairy goats,with three site permanent fistulas in rumen,duodenum and ileum were selected and randomly assigned to two groups.The goats were feeding with non zinc additive dietary,zinc level were provided by infusion two form of zinc solution,ZnSO4 and Zn-AA at zinc levels of 0,20,40,60,80,100 and 200 mg/kg of RM（rumen mass）,respectively.Samples of duodenum chyme,ileum chyme,dung and serum were collected discontinously to detect zinc content,and small intestinal and whole intestinal zinc digestive rate were calculated.The results showed that,1） Zn-AA had a higher digestion rate than ZnSO4 overall,small intestine is the main absorption part in dairy goats,but large intestine were manifested also had strong absorbency to the two zinc source.2） Serum zinc level was not rise with the high digestion rate of Zn-AA,but follow zinc levels of ZnSO4 and Zn-AA respectively.3） Optimum ZnSO4 level in dairy goat was 40 mg/kg RM,it＇s optional concentration range was 40-60 mg/kg of RM.Optimum Zn-AA level in dairy goat dietary was 60 mg/kg of RM,it＇s optional concentration range was and 40-80 mg/kg of RM.It can be concluded that ZnSO4 and Zn-AA could be absorbed in small intestine as well as in large intestine,Zn-AA in general had a higher digestion rate and stronger tolerant than ZnSO4.Serum zinc level depends on the zinc source and levels due to different absorptive mechanism of two zinc forms.