| Laying performance of egg-type ducks is affected by many factors,including breed,nutrition and management.In recent years,the extension and application of net-rared system has increased the extent of intensification and scale in egg-type ducks breeding,among which population scale is a key factor influencing animal health and welfare.However,the majority of studies about the impaction of population scale are concentrate on lay chickens,its influence on egg-type ducks still unclear.In this experiment,Jin Ding Duck was used as experimental object to preliminarily discuss the influence on egg-type ducks by comparing the growth performance(body weight,body measurement index)and laying performance(laying rate,feed egg ratio and egg quality)of egg-type ducks in different feeding groups,The main obtained results were as follows:(1)At 14 weeks of age,the difference of body weight between 60/group,40/group and 120/group ducks were significant(p<0.01);on the body size,the keel length of the60/group of ducks(10.95 cm)was significant longer than that in 90/group(10.55 cm)(p<0.01).Besides,the difference observed in circumference between the 60/group of ducks(3.67 cm)and the 40/group and 90/group of ducks(3.55 cm)was also extremely significant(p<0.01).In the mortality,among 40/group,60/group,120/group and 90/group ducks,it also exist significant difference(p<0.01).These results indicate that the size of different populations will affect the body weight,body size and death rate of the ducks during the breeding period.Combining all the results,we conclude that,under net-rared system,the 60/group feeding population has the best growth performanceand highest survival rate.(2)At 14 to 19 weeks of age,the body weight of 60/group of ducks was about 235 g higher than that of 40/group,90/group and 120/group ducks(p<0.01).The 19-week-old egg production rate of60/group,40/group,90/group and 120/group was 20.63%,18.8%,13.46% and 10.37%,respectively.There was a significant difference in egg production rates between each group.Based on the above results,it was found that the population of60 groups/group had the best early production performance.(3)During the whole period of 21 to 35 weeks,the egg production rates of 20/group,30/group,60/group and 90/group were 42.00%,71.05%,54.78% and 49.97%,respectively.The egg production rate of the 30/group ducks was significantly higher than the other three groups.At the same time,the feed egg ratio from low to high successively was 30/group(4.22),60/group(4.96),90/group(5.29)and 20/group(6.77).The test results showed that30/group of eggs had the best laying performance during laying period.(4)At 25 weeks of age,the egg weight,egg shape index,eggshell strength,protein height,color of egg yolk among 20/group,30/group,60/group and 90/group were significantly different(p<0.05).At 28 weeks of age,there also existing significantly difference on egg weight,egg shape index and egg yolk ratio among 20/group,30/group,60/groupand 90/group(p<0.01).Forthermore,30/group was best laying performance,lowest feed egg ratio and better egg quality.In summary,the growth performance,laying performance and egg quality of ducks can be affected by group size.Furthermore,the result suggested that,under net-raring system,ducks belong to 60/group feeding populations had the best growth performance and the highest survival rate during breeding period.While during the laying period,30/group ducks had the best egg production performance,the lowest feed egg ratio and the better egg quality. |
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