Effects of Dietary Calcium Formate Supplementation on Production Performance and Egg Quality of Elderly Laying Hens
[Objective]As an organic calcium source with small molecular weight,calcium formate has a good application potential in improving the production of laying hens.The purpose of this study was to reveal the effect of dietary calcium formate supplementation on the production performance,blood indexes and egg quality of elderly laying hens,and the appropriate level of supplementation.[Method]A total of 360 62-week-old healthy Hy-Line Brown laying hens were randomly divided into 4 treatment groups,with 6 replicates and 15 chickens per replicate.The hens in control group were fed a basal diet,and the hens in three experimental groups were fed 0.5％,1.0％and 2.0％calcium formate to partially replace the basal diet of stone powder,respectively,and the calcium level of each group was same.The formal feeding period was 12 weeks.The egg production was recorded every day,and the feed weekly.At weeks 2,4,6 and 8,egg quality was determined.At the end of the feeding,one layer per replicate was selected for blood samples collection,and blood routine and serum biochemical indexes were measured,and organ index and tibial mass were determined after slaughter.[Result]Compared with control group,calcium formate supplementation had no effects on the performance of laying hens and the egg quality at the second and fourth weeks(P＞0.05),but increased the eggshell ratio,eggshell thickness and eggshell strength at the eighth and twelfth weeks(P＜0.05),and the 0.5％addition level had the best effect.Calcium formate supplementation reduced the content of mononuclear leukocytes,basophils and neutrophils in the blood of laying hens(P＜0.05),and increased the content of hemoglobin and hematocrit(P＜0.05).Calcium formate supplementation decreased the serum total protein,globulin,albumin and creatinine contents(P＜0.05),and increased the total bilirubin content(P＜0.05).The pancreas,spleen,leg muscles and shinbone index of laying hens were not affected by calcium formate supplementation(P＞0.05),but the work required for shinbone fracture increased(0.05＜P＜0.1).[Conclusion]Dietary addition of calcium formate to partially replace stone powder did not affect the production performance of elderly laying hens,while could improve the health of the body and the quality of eggshells,and the recommended addition level was 0.5％.
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