Study On Suitable Amount Of Zinc For Growing Rex Rabbits In 3-5months Old

The purpose of this subject was to study the effects of different zinc levels on the production performance,muscle quality,fur quality,hair follicle development,fat metabolism and nitrogen metabolism of 3-5 months Rex rabbits by single factor experiment.In this experiment,a total of 160 3-months-old healthy rabbits with a similar number of males and females were randomly divided into 4 groups,each group of 40 replicates and 1 rabbit per replicate.Experimental diets were fed separately,which supplemented with 0,40,80 and 120mg/kg zinc(zinc sulfate)at the basic diet level.After the preliminary test for 7d,the experiment lasted for 49 d.Maintain suitable appropriate ventilation and light during the test.The results are as follows:(1)Effects of dietary zinc supplementation on production performance and muscle quality: under the premise of that the initial body weight(IBW)has no significant difference(P > 0.05),the zinc supplemented level has no significant effects on the final body weight(FBW),the average daily gain weight(ADG),the average daily intake(ADFI)and the weight ratio(F/G)(P > 0.05).Dietary zinc supplemental level has no significant influences on eviscerated ratio,back lumbar muscle ratio and muscle quality indices including p H and meat color(L* and a*values)(P >0.05);has significant influences on front leg muscle ratio b*(P < 0.05),has extremely significant influences on hind leg muscle ratio and drip loss(P < 0.01)and the lowest appeared in 120 mg/kg group of all the four indexes.(2)Effects of dietary zinc supplementation on fur quality and hair follicle development:dietary zinc supplemental level has no significant influence on fur weight(P > 0.05);has extremely significant influence on fur area(P < 0.01)and the highest appeared in 80 mg/kg group;has significant influences on fur thickness and fur length(P < 0.05),in which thelowest of the fur thickness appeared in 120 mg/kg group,the fur length first increased and then decreased followed by the increase of zinc supplementation and the highest appeared in40 mg/kg group.Dietary zinc supplemental level has extremely significant influence on hair follicle density(P <.0001)and the 40 mg/kg and 80 mg/kg group are higher than the others.(3)Effects of dietary zinc supplementation on nitrogen metabolism: dietary zinc supplemental level has significant influences on nitrogen deposition(RN)and nitrogen utilization efficiency(NUR)(P < 0.05),similarly the 40 mg/kg and 120 mg/kg group are higher than the other two groups;has significant influence on urine nitrogen(UN)(P < 0.05)and the lowest appeared in 120 mg/kg group;has significant influence on biological titer(NBV)(P < 0.05)and the highest appeared in 120 mg/kg.Dietary zinc supplemental level has no significant influences on nitrogen intake(NI),fecal nitrogen(FN),digestible nitrogen(DN)and nitrogen apparent digestibility(NAD)(P > 0.05).(4)Effects of dietary zinc supplementation on fat deposition: dietary zinc supplemental level has no significant influences on the shoulder fat and the renal weekly fat(P > 0.05).(5)Effects of dietary zinc supplementation on the gene expression of rabbit hair follicle development: dietary zinc supplemental level has extremely significant influence on the Noggin m RNA expression quantity(P < 0.01)and the highest appeared in 40 mg/kg group;has extremely significant influence on the BMP4 m RNA expression quantity(P < 0.01)and the lowest appeared in 40 mg/kg group.To the genes of Ver,ALP,HGF,BMP2 and IGF-1,m RNA expressions were not significant(P > 0.05).(6)Effects of dietary zinc supplementation on the gene expression of rabbit fat metabolism: dietary zinc supplemental level has significant influence on the shoulder fat PPARα m RNA expression quantity(P < 0.05)and the lowest appeared in 40 mg/kg group;has significant influence on the FABP m RNA expression quantity(P < 0.05)and the highest appeared in 40 mg/kg group;has extremely significant influence on the CPT1 m RNA expression quantity(P < 0.01)and the highest appeared in 80 mg/kg group;has extremely significant influence on the HSL m RNA expression quantity(P < 0.01)and the highest appeared in 120 mg/kg;has significant influence on the LPL m RNA expression quantity(P <0.05)and the lowest appeared in 40 mg/kg group,while there were no significant influences on m RNA expression of PPARγ,FATP,FAS and ACC(P > 0.05).Dietary zinc supplemental level has extremely significant influence on the renal weekly fat CPT1 m RNA expression quantity(P < 0.01)and the highest appeared in 120 mg/kg group;has significant influence on the HSL m RNA expression quantity(P < 0.05)and the highest appeared in 120 mg/kg group;has significant influence on the LPL m RNA expression quantity(P < 0.05),while there were no significant influences on m RNA expression of PPARα,PPARγ,FATP,FABP,FAS and ACC(P > 0.05).In conclusion,the appropriate dietary zinc supplemental level of 3-5 months growth rabbits was 40 mg/kg(the measured value of zinc in the diet of that group was 49.4 mg/kg).