| Trace elements closely relate to animal’s health and performance,in order to master the variation of trace elements in grazing sheep of Zhaosu pastoral areas,the following investigations were carried out:(1)The pasture and grazing sheep tissues(the wool,serum,myocardium,liver,spleen,kidney,skeletal muscle and bone)were collected at four seasons,and the samples’ trace elements were detected;(2)Trace element Supplementary feeding test was carried out according grazing sheep’s trace element surplus and deficit,the effect of the supplement trace element on feed intake,daily gain and nutrient digestibility,blood physiological and biochemical indices of the grazing sheep were determined.Experiment 1 Analysing and evaluating nutrition status of trace element on grazing sheep(1)Pasture: compared with nutrient requirements of sheep(NRC,1985),pasture iron exceeded the normal level in each season;copper、zinc、manganese and cobalt in the pasture could meet the sheep need in all year;the pasture was an acute shortage of selenium in all year,there was less than 0.1 mg Se/kg in the each season and the sheep couldn’t obtain enough selenium for their nutrient requirements.(2)Wool: contents of iron and zinc were in the normal level,and the contents of copper,cobalt and selenium were lower than normal level.The concentration of manganese in woof of the adult ewe and the autumn growing ewe were below the normal level.(3)Serum: the content of iron,copper and cobalt in serum were in normal range;but the concentration of zinc and selenium were below normal value in the adult ewe and the growing ewe;serum manganese of adult ewewas below the normal level in autmn and winter,and growing ewe was below the normal level in the all year.(4)Liver: the cobalt and selenium content of liver in adult ewe and the growing ewe were below the normal level;the liver copper content in growing ewe was below normal level in all year.(5)Heart,kidney,spleen,muscle and bones: the concentration of iron,copper,manganese,zinc,selenium in heart,kidney were on the normal level;the selenium in the spleen of growing ewe was below the normal level in the autumn and winter;the bone of the adult ewe and the growing ewe had a low level at the concentration of copper,manganese,slenium,and the cobalt in growing was at the critical level.At the comprehensive evaluation,the grazing sheep of Zhaosu area was in the state of lack cobalt and selenium,it was advised that composite additive that cotain cobalt and selenium trace elements be supplementary.Experiment 2 Effect of supplemental trace elements feeding on growing sheepAccroding to the surplus and deficiency of trace elements in ewes during autumn grazing,and comparing the nutrient requirement of trace elements on sheep of NRC(1985),a experiment though licking brick to supplement trac element(manganese,copper,zinc,selenium,cobalt)to growing ewe was carried out,and we studyed the effect of supplement of trace element on the feed intake,daily gain,nutrientdigestibility of pasture and Serum biochemical indexes.The result showed that,compared to control group,experimental group didn’t have a significant difference(P>0.05)on feed intake,but average daily gain was significanny increased(P<0.05).The digestibility of dry matter,crude protein,neutral detergent fiber and acid detergent fiber in experimental group were significantly(P<0.05)higher than the control group.The content of serum manganese and zinc in the growing ewes serum were improved(P<0.05),and the content of serum selenium was improved extremely significant(P<0.01).The activity of GSH-Px and SOD in the experimental group were increased significantly(P<0.05);the level of MDA in the experimental group was lower than the control group(P<0.05).The content of serum IgG in experimental group was significantly higher(P<0.05)than control group’s. |
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