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

Abstract

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 formulated to contain 6 g Ca and 5.4 g P kg−1. In the first experiment, four barrows and four gilts received one of seven diets arranged as a positive control plus 2 × 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 addition increased (P < 0.05) plasma phosphorus concentration, weight gain and gain:feed ratio. Plasma phosphorus, weight gain and gain:feed ratio were linearly reduced (P < 0.05) as dietary calcium level increased in the low-phosphorus diets but not in the phytase-supplemented low-phosphorus diets. The second experiment was similar to the first experiment, except that phytase was 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 ratio, plasma phosphorus and calcium. A low-calcium (3.5 g kg−1), low-phosphorus (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 × 2 factorial arrangement plus a positive control in the third experiment. Growth performance was similar (P > 0.1) among pigs that received the positive control and the phytase- or cholecalciferol-supplemented low-calcium, low-phosphorus diets. These results demonstrate that high dietary calcium in a low-phosphorus diet depresses pig performance and that phytase or cholecalciferol supplementation of a low-calcium (3.5 g kg−1), low-phosphorus (3.4 g kg−1) diet produces 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. Key words: Pigs, phytase, cholecalciferol, phosphorus, calcium