Phytase and cholecalciferol supplementation of low-calcium and low-phosphorus diets for pigs

The effects of different levels of calcium, phytase, and cholecalciferol in low-phosphorus diets were studied in individually-penned 20-kg pigs for 28 d. The positive control diet, used in all three experiments, was formulate d to contain 6 g Ca and 5.4 g P kg(-1). In the first experiment, four barro ws and four gilts received one of seven diets arranged as a positive contro l plus 2 x 3 factorial of phytase (0 or 1, 600 units kg(-1)) and calcium (3 , 4.5 or 6 g kg(-1)) containing phosphorus at 3.4 g kg(-1). Phytase additio n increased (P < 0.05) plasma phosphorus concentration, weight gain and gai n:feed ratio. Plasma phosphorus, weight gain and gain:feed ratio were linea rly reduced (P < 0.05) as dietary calcium level increased in the low-phosph orus diets but not in the phytase-supplemented low-phosphorus diets. The se cond experiment was similar to the first experiment, except that phytase wa s reduced to 800 units kg(-1) and dietary calcium levels were 2.5, 3, or 3. 5 g kg(-1). Phytase addition increased (P < 0.05) weight gain, gain:feed ra tio, plasma phosphorus and calcium. A low-calcium (3.5 g kg(-1)), low-phosp horus (3.4 g kg(-1)) diet was supplemented with phytase (0 or 800 units kg( -1)) and cholecalciferol (0 or 800 ug kg(-1)) in a 2 x 2 factorial arrangem ent plus a positive control in the third experiment. Growth performance was similar (P > 0.1) among pigs that received the positive control and the ph ytase- or cholecalciferol-supplemented low-calcium, low-phosphorus diets. T hese results demonstrate that high dietary calcium in a low-phosphorus diet depresses pig performance and that phytase or cholecalciferol supplementat ion of a low-calcium (3.5 g kg(-1)), low-phosphorus (3.4 g kg(-1)) diet pro duces similar growth performance as a diet with adequate calcium (6 g kg(-1 )) and phosphorus (5.4 g kg(-1)) when fed to 20-kg pigs.