Effect Of Dietary Protein On Growth Performance, Feed Conversion Efficiency, Nitrogen Balance And Carcass Composition In Cherry Valley Ducks

Three hundred Cherry Valley meat line ducklings with average birth living weight 56 gram were used in the feeding,metabolisable and slaughter trial to investigate the effect of dietary protein on the growth performance,:feed conversion efficiency, nitrogen balance and carcass composition to gain optimum level of dietary protein for Cherry Valley meat line ducks of feeding in Yulman Provine.The ducklings were randomly divided into five groups of sixty and were housed in individual metabolism cages.The experiment was conducted over 2 periods as follows:PeriodⅠ:days 0-10.All ducklings were offered diet with five levels of dietary protein of 23.0%,21.0%,19.0%,17.0%and 15.0%in TreatmentⅠ,Ⅱ,Ⅲ,ⅣandⅤrespectively.At the end of this period 30 randomly selected ducks from each Treatment were slaughtered.PeriodⅡ:days 10-30.The remaining 30 ducks from each Treatment were received diet with five levels of dietary protein of 21.0%,19.0%,17.0%,15.0%,13.0%in the TreatmentⅠ,Ⅱ,Ⅲ,ⅣandⅤrespectively.At the end of this period all remaining ducks were slaughtered.The experimental results are as follow:Liveweight:Initial liveweight was highest for the ducklings in TreatmentⅠand the lowest for the ducklings in TreatmentⅤ;it has been shown that initial liveweight was significantly higher for the ducklings in TreatmentⅠthan in TreatmentⅡ;in TreatmentⅡthan in TreatmentⅢ;in TreatmentⅢthan in TreatmentⅣand in TreatmentⅣthan in TreatmentⅣ(all showed P＜0.05).Similar results were observed for the finial liveweight(P＜0.01).Liveweight gain per day(g/d):Live weight gain increased with increasing of dietary protein.There were significant differences for liveweight gain among the Treatments in PeriodsⅠandⅡ(P＜0.05).During PeriodⅠ,liveweight gain were significantly greater for those ducks in TreatmentⅠthan in TreatmentsⅡ,Ⅲ,ⅣandⅤrespectively (P＜0.05).During PeriodⅡ,liveweight gain were significantly greater for the ducks in TreatmentsⅠandⅡthan in TreatmentsⅢ,ⅣandⅣ(P＜0.05);There were no significant difference between the TreatmentⅠandⅡ(P＞0.05).Duck livability(%):Dietary protein levels significantly affected duckling livability in PeriodⅠ.It was shown that ducking livability were markedly higher(95%)in TreatmentsⅠandⅡand there was a decrease tendency as decreasing of dietary protein. It has been observed that there was a positive relation between the dietary protein and duckling livability in PeriodⅠ.Duck livability was 100%in TreatmentⅠand it showed 100%other Treatments in PeriodⅡ.Feed conversion efficiency:During PeriodⅠ,the feed cost was the lowest for those ducks in TreatmentⅠ(3.01 Yuan RMB per kg live weight gain)and the highest for those ducks in TreatmentⅤ(4.47 Yuan RMB per kg liveweight gain)among the Treatments.The feed cost for those ducks in TreatmentⅠdecreased by 2.9%,4.14%,28.5%,32.66%compare to those ducks in TreatmentsⅡ,Ⅲ,ⅣandⅤrespectively.In PeriodⅡ,the feed cost was the lowest for those ducks in TreatmentⅡ(4.05 Yuan RMB per kg liveweight gain)and the highest for those ducks in TreatmentⅤ(4.90 Yuan RMB per kg liveweight gain)among the Treatments.For the economic profit,it has been shown the highest for those ducks in TreatmentⅡ;as second for those ducks in TreatmentⅠand the lowest for those in TreatmentⅤamong the Treatments.It was shown a decrease tendency of the economic profit of the ducks from TreatmentⅡtoⅢ,ⅣandⅤ.Nitrogen balance:Nitrogen retention(%)of ducks increased with increasing of dietary protein.It has been shown that nitrogen retention had somewhat higher for those ducks in TreatmentⅠthan for other Treatments,but there were no significant differences (P＞0.05).Serum urea concentrations were the lowest for those ducks in TreatmentⅠand the highest for those ducks in TreatmentⅤ;there was an increase tendency of serum urea of ducks from TreatmentⅠtoⅡ,Ⅲ,ⅣandⅤin PeriodⅠ.In PeriodⅡ,it was shown that serum urea concentrations were the lowest for those ducks in TreatmentⅠand the highest for those ducks in TreatmentⅣ.Significant differences were observed for those ducks between TreatmentⅠand TreatmentsⅡ,Ⅲ,ⅣandⅤrespectively(P＜0.01).Carcass composition:Dressing percentage was the highest for those ducks in TreatmentⅠand showed a decrease tendency from TreatmentⅠto PeriodsⅡ,Ⅲ,ⅣandⅤ.Water content of carcass was the highest for those ducks in TreatmentⅢand the lowest for those ducks in TreatmentⅤamong the Treatments.There was significant difference for water content of carcass between TreatmentsⅠandⅢ(P＜0.05).No significant differences were observed for water content of carcass in TreatmentⅠandⅢandⅣ(all showed P＞0.05)and TreatmentⅠandⅤ(P＞0.05). Crude protein content of carcass was the highest for those in TreatmentⅢand the lowest for those in TreatmentⅤamong Treatments;as second was for those in Treatment;there was no significant difference for crude protein content of carcass between the TreatmentsⅠandⅢ(P＞0.05);significant differences(all showed P＜0.05) were observed for crude protein content of carcass between the TreatmentⅢand TreatmentsⅡ,ⅣandⅤrespectively.For the crude fat content of carcass,the ducks in TreatmentⅠwas the lowest and the highest for the ducks in TreatmentⅤ.Significant differences for crude fat content of carcass were observed between the TreatmentⅠand TreatmentsⅡ,Ⅲ,ⅣandⅣrespectively(all showed P＜0.05).