Abstract
Manganese and magnesium were supplemented to a corn-soybean meal base diet fed to pigs in confinement and on pasture at the following rates in ppm: 0/0, 50/0, 100/0, 0/100, 50/100 and 100/100. Average daily gain was significantly reduced when 50 ppm Mn was supplemented to the diet. Supplementing Mg at 100 ppm to pigs on pasture also reduced gains compared to pigs in confinement. A location x Mg interaction for gain and feed intake was observed. Pigs in confinement grew faster and ate more feed when 100 ppm Mg was added to the diet in confinement but both were reduced when this level was fed on pasture. Feed/gain was not significantly affected by any of the treatments. Percent bone ash was significantly increased when pigs were grown on pasture and when 100 ppm Mg was added to the diet when averaged across both locations. Breaking strength of the fourth metatarsal bone of pigs grown on pasture was almost twice that of pigs raised in confinement with the difference being highly significant. The quadratic component of the effect of levels of Mn on breaking strength was significant with diets containing 50 ppm producing bones with the lowest strength. The location x Mg interaction was significant. Thus, adding 100 ppm Mn in confinement reduced bone strength but increased it when this level was supplemented on pasture. Supplementing Mg in confinement increased bone Mg levels, but the reverse occurred for pigs on pasture. Supplementing 100 ppm Mg reduced serum Mg levels in both environments. Pigs raised in confinement also had significantly lower serum Mg levels than pigs reared on pasture. A location x Mn interaction was observed for serum Mg with 50 ppm Mn in confinement producing the highest serum Mg levels and the lowest on pasture. The pronounced difference in breaking strength of the metatarsals of pigs raised in confinement and on pasture is unexplained at this time. Copyright © 1969. American Society of Animal Science . Copyright 1969 by American Society of Animal Science