Effects of omitting vitamin and trace mineral premixes and(or) reducing inorganic phosphorus additions on growth performance, carcass characteristics, and muscle quality in finishing pigs

Three experiments were conducted to determine the effects of omitting vitam in and trace mineral premixes and(or) reducing inorganic phosphorus additio ns to finishing diets on growth performance, carcass characteristics, and m uscle quality in pigs. In Exp. 1, a corn-soybean meal-based diet (.70% lysi ne, .65% Ca, and .55% P) was used as the control. Pigs (n = 128; average in itial BW of 85.7 kg) were fed the control diet or the control diet without 1) the vitamin premix, 2) the trace mineral premix, or 3) both premixes. Om itting the premixes had no effect on ADG (P > .39); gain/ feed (P > .17); c arcass backfat thickness (P > .42); and marbling, color, and firmness of th e longissimus muscle (P > .11). In Exp. 2, pigs (n = 128; average initial B W of 86.2 kg) were fed the control diet (.65% Ca and .53% P) used in Exp. 1 and the control diet without 1/3 (.56%Ca and .46% P), 2/3 (.51% Ca and .40 % P), or all (.47% Ca and .31% P) of the added monocalcium phosphate (MCP). Omitting up to 2/3 of the MCP increased ADG (quadratic effect, P < .02) an d had no effect on meat quality (P < .12), but backfat thickness increased slightly (quadratic effect, P < .02). In Exp. 3, pigs (n = 160; average ini tial BW of 86.6 kg) were fed the control diet used in Exp. 1 or the control without 1) the vitamin and trace mineral premixes, 2) 2/3 of the MCP, or 3 ) the premixes and 2/3 of the MCP. Treatment had no effects on ADG (P > .23 ), gain/feed (P > .94), stomach lesions (P > .37), or serum gamma globulins (P > .08). In conclusion, vitamin and trace mineral premixes and up to 2/3 of the supplemental MCP can be omitted during late finishing (i.e., approx imately the final 30 d) to reduce nutrient excesses that increase cost of f eeding and nutrients excreted in waste material.