논문 ; 산란계에 대한 칼슘 공급제의 사료가치 비교시험 ; 1 . 패분 ( 貝粉 ) , 석회석 , 방해석 ( 方解石 )의 사료가치 비교시험

This experiment was conducted to compare the nutritive values of limestone, calcitic limestone, and oystershell with a total of 1200 White Leghorn layers. The results obtained during 22 weeks of experimental period are summarized as follows. 1. The calcium contents of oystershell, limestone and calcitic limistone used in this experiment were analyzed to be 29.46%, 34.87% and 38.46%, respectively. 2. Different source of calcium in laying hen diets had no apparent effects on the egg production rate, average egg weight and feed efficiency. 3. The eggshell thickness w-as significantly (p$lt;0.05) different among groups fed different calcium supplements. The eggshell thickness of oystershell, limestone and calcitic limestone fed group was 0.359㎜, 0.346㎜ and 0.339㎜, respectively. The ratios of eggshell weight to egg weight were also significantly (p$lt;0.05) different among treatments in the same trend as the eggshell thickness. 4. There were no significant differences among treatments in contents of calcium and phosphorus of tibia and in the nutrient utilizability of experimental diets. The results obtained from the present experiment showed that the nutritive values of limestone and calcitic limestone were not much different from that of oystershell except in egg shell qualities. It is suggested that all three calcium supplements could he used as good calcium sources in laying hen diet.