Study On Protein And Methionine Levels Of Cage-Rearing Laying Ducks In Earlier Period Of Laying

The experiment was conducted to study the requirements of dietary protein and methionine for cage-feeding Jin-ding ducks from 19-28 weeks. In the experiment, the 216 Jin-ding ducks of commercial strain(19 weeks of ages) were assigned to six groups randomly with three replicates of 12 ducks per group. Each group was fed with the crude protein(CP) contents of 15%, 17%, 19% and methionine(Met) contents of 0.30%,0.36% diets contained 11.55MJ/kg metabolizable energy(ME) respectively, n 3+2 factorial arrangements.The results of rearing experiment showed that in the stage from nineteen to twenty-eight weeks, ducks receiving CP level 17% and Met level 0.36% diets had a higher laying rate than all other groups, while no significant difference from the high protein groups(P>0.05). In this trials, the feed conversion rate of group IV was the lowest among all groups. There was no significant effect on the feed conversion rate and broken egg rate(P>0.05).The interaction of dietary CP and Met levels had no significant effect on the laying rate, egg production and feed conversion rate(P>0.05),but significant on the average egg weight and broken egg rate(P<0.05). The laying rate and egg production increased with the growth of CP levels, and the laying rate decreased when dietary CP level 19%. The average egg weight had no significant difference among groups(P>0.05), the feed conversion ratio of the group receiving CP level 17% and Met level 0.36% was the lowest. The laying rate and egg production of ducks increase and the feed conversion rate decrease with the growth of the dietary Met level.The results of metabolic trial revealed that retention of nitrogen of group IV was significantly higher than other groups(P<0.05) in the earlier stage of laying ducks. The availability of dietary EF of group IV was insignificantly different from the high dietary CP level groups(P>0.05),and tended to increase while aging. The dietary EE, Ca, P availability of group IV were significantly higher than all other groups(P<0.05),but dietary energy and organic matter tended to decrease from group I to group IV .The availability of dietary Na and K of groupIV was significantly higher than groupVI(P<0.05),and insignificantly different from group V(P>0.05).The availability of dietary Mn and Fe of groupIV were insignificantly different from the high dietary CP level groups(P>0.05).The interaction effect of dietary CP and Met levels had significant influence on retention of nitrogen, the availability of dietary Na, and great influence on the availability of K, EF, EE, Ca, Mg and Mn(P<0.01)while insignificant on the availability dietary energy, organic matter, P and Fe(P>0.05).The measure trial of serum biochemical indexes was indicated that serum BUN and CRE contents of groupIV were significantly lower than all other groups, serum uric acid contentssignificantly lower than high protein groups(P<0.05).The content of serum total protein of group IV had an insignificant difference from the high dietary CP groups(P>0.05).The interaction of the dietary CP and Met levels had significant greatly influence on serum creatinine and serum uric acid(P<0.01),and insignificant on BUN and serum total protein(P>0.05).Master candidate: Song Chunling Major: Animal Nutrition and Feed ScienceSupervisor: Prof. Wang An...