Effect Of Zinc Lactate On Performance,Serum Biochemical Indexes And Intestinal Morphology Of Yellow-feathered Broilers

Zinc is an essential trace element in animal organisms.Under the condition of modern intensive feeding,the environmental pollution caused by the excessive addition of trace element zinc,which can not be absorbed by excrement,has aroused widespread concern.Therefore,exploring a new type of zinc source is one of the hot spots in the research of trace element nutrition.Experiment 1:The present study aimed to investigate the effects of zinc lactate on growth performance,serum biochemical indexes,immune,intestinal morphology and hepatic metallothionein?MT?gene expression in the yellow-feathered broilers.At 19days of age,2 250 yellow-feathered broilers were randomly allocated to 5 dietary groups with 3 replicates per group and 150 birds in each replicate.The control group of broilers was fed with basal diet,the treatment groups of broilers were fed with basal diets supplemented dietary supplementation of 40,60,80 mg Zn Kg^-1as reagent grade Zinc lactate groups,and 80 mg Zn Kg^-1from zinc sulfate group.As a result:?1?The dietary zinc treatments had no significant effect on the growth performance up to61 days of age,regardless of the zinc source and dosage.?2?Dietary supplementation of 60 mg/kg zinc lactate significantly increased the levels of the serum total protein and albumin at 44 days of age indicating an improved protein metabolism of birds as compared with both Zn SO₄ and control birds.?3?60 mg/kg zinc lactate supplementation significantly increased the serum GSH-Px levels at 62 days of age compared with the Zn SO₄ and the control groups,demonstrating an enhanced antioxidant ability of these birds.?4?In addition,60 mg/kg zinc lactate supplementation significantly up-regulated the hepatic expression of MT m RNA likely due to the higher zinc uptake.?5?Moreover,dietary supplementation of 40mg/kg zinc lactate significantly increased the villi height while decreased the crypt depth of ileum,exhibiting an improved intestinal morphology of the yellow-feathered broilers.The results showed that the optimal zinc level in yellow broiler chick was 60mg/kg.Experiment 2:The objective of this study was to evaluate the effects of different zinc sources on growth performance,intestinal morphology,serum biochemical indexes,carcass traits,tibia zinc content,zinc apparent metabolic rate and hepatic metallothionein?MT?gene expression in the slow-growing broilers?female?.The experiment was designed to compare the effects of four kinds of organic zinc on broiler chickens,to provide a scientific basis for the selection and application of broiler zinc additives.A total of 1 080 18-day-old healthy yellow-feathered broilers were randomly divided into 6 groups:basal diet+?zinc lactate,zinc sulfate,zinc methionine,zinc glycine,zinc methionine,zinc glycine,protein zinc 60 mg/kg?and basal diet group?excluding additional zinc sources?,with 6 replicates per group and30 birds in each replicate.As a result:?1?Adding 60 mg/kg Gly-Zn,zinc lactate and Gly-Zn to corn-soybean meal basal diet could increase the production performance of yellow feather broilers.?2?The level of serum TP,ALB was increased in zinc-supplemented group,and it was significantly higher in Gly-Zn group than that in control group;At the age of 59 days,the serum total protein of zinc lactate group was significantly higher than that of the control group.?3?The effects of Gly-Zn and zinc methionine on GSH-Px activity were better than those of other zinc sources,and significantly higher than that in zinc sulfate group and control group.There was a significant difference between the 39-day-old organic zinc addition group and zinc sulfate group and control group in serum MDA content.?4?Zinc addition group had the tendency of increasing villus height and decreasing recess depth.The ratio of duodenum villous crypt to zinc glycine group was significantly higher than that of control group.Zinc glycine and zinc methionine in the ileum were significantly higher than those in the control group,indicating that the addition of organic zinc had a certain effect on the intestinal morphology.?5?In addition,zinc lactate,Met-Zn and Gly-Zn were more effective in the absorption of zinc according to the expression of zinc-associated transporter MT.?6?Groups treated with Gly-Zn,zinc methionine and zinc lactate had higher tibia zinc content than groups with Zn SO₄ and control.?7?The effect of different dietary zinc sources on the apparent metabolic rate of zinc in yellow feather broilers was significant.Zinc lactate,glycine zinc and zinc methionine were significantly higher than those in zinc sulfate group.The results showed that the best dietary zinc source for yellow-feather broilers were zinc lactate,Met-Zn and Gly-Zn.In conclusion,the optimal zinc level in yellow broiler chick was 60mg/kg.The best dietary zinc sources for yellow feather broilers are glycine zinc,zinc lactate and zinc methionine.