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Effects of dietary calcium concentrations on the apparent total tract digestibility and the balance of calcium, phosphorus, and nitrogen in growing pigs
Y. She, X. S. Piao, L. Liu, and D. F. Li
State Key Laboratory of Animal Nutrition, Ministry of Agriculture Feed Industry Centre, China Agricultural University, Beijing 100193, China
Abstract Text: This study was conducted to determine the total endogenous Ca output and to determine the effects of dietary Ca concentrations on endogenous Ca outputs, the true total tract digestibility (TTTD), and balance of Ca, P, and N in growing pigs. Thirty-six growing barrows (initial BW: 42.2 ± 2.0 kg) were placed in metabolism crates and allotted to a randomized complete block design with 6 diets and 6 pigs per diet. Diets were based on cornstarch and casein, and were formulated to provide the following levels of total Ca: 0.13, 0.31, 0.50, 0.68, 0.87, and 1.05%, and the analyzed ratio of total Ca to total P was between 1.16:1 and 1.23:1. Calcitic limestone and monosodium phosphate provided the majority of the Ca and P in the diets. Feces and urine samples were collected from d 8 to d 12. Total endogenous Ca and P outputs and values for TTTD of Ca and P were determined using the regression procedure. Results indicate that the estimated total endogenous Ca and P outputs were 0.508 and 0.428 g/kg DMI, respectively. The TTTD of Ca in calcitic limestone was estimated at 76.8% and the TTTD of P in monosodium phosphate was estimated at 88.8%. It is concluded that the dietary concentration of Ca affects the retention of P significantly (P<0.01), but does not affect the retention of Ca or N.
Keywords: calcium, endogenous losses, phosphorus