INTERACTION OF CALCIUM, PHOSPHORUS AND PROTEIN IN BROILERS

다국어 초록 (Multilingual Abstract)

In order to study the interrelationships of calcium (0.45 vs. 0.90%), phosphorus (0.40 vs. 0.70%) and protein (17, 20, 23%), $2{\times}2{\times}3$ factorial design was employed. A total of 480 broilers (Hisex-Hibro) aged 3 days were fed the experimental diets for a period of 28 days. Body weight gain, daily feed intake and feed efficiency were investigated for the simple effects, first order interaction and second order interaction of the dietary factors. These effects were also applied to bone ash retention, percent Ca in bone & ash, percent P in bone & ash, and protein utilizability. Results were as follows. 1) For body weight gain, simple effects of dietary levels of Ca, P, CP were found to be significant (p<0.05). Body weight gain at 0.90% Ca level was improved as the dietary CP levels increased. For the feed intake, single effects of dietary levels of both P and CP were found (p<0.05). Feed efficiency was improved as the dietary CP and P levels increased. Ca $\times$ P interaction was found to be significant for body weight gain, feed intake and feed efficiency (p<0.05), however, Ca $\times$ P $\times$ CP interaction effect was not found. 2) Protein utilizability decreased as the dietary CP level increased (p<0.01). 3) 0.90% Ca in diet showed less bone ash retention than 0.45% Ca level. And, increasing the dietary P level resulted in increased bone ash retention. Increasing the dietary P level resulted in increased bone Ca retention (p<0.01) and increased bone P retention (p<0.05). Dietary CP levels had significant (p<0.01) effect on bone Ca retention except for 23% CP level. Increasing the dietary Ca level resulted in wider Ca:P ratio of bone, but increasing the dietary P level resulted in narrower Ca:P ratio of bone. 4. Ca $\times$ P interaction effects were found to be significant (p<0.01) for bone ash, bone Ca & P, ash P content, and bone Ca:P ratio. Ca $\times$ P $\times$ CP interaction effects were found for bone ash (p<0.01), bone Ca (p<0.05) and bone P content (p<0.01).