The Effects of a Manganese Deficiency upon the Growth, Development, and Reproduction of Swine

Four experiments were conducted to determine the effect of low-manganese rations on growth, fattening, and reproduction in swine. No difference in rate of gain or feed efficiency was observed in pigs fed from a starting weight of from 9.5 to 43 lb. to a final weight of from 185 to 246 lb. on semi-purified rations containing from 0.5 to 40 p.p.m. manganese. Second generation boars from gilts raised on rations containing either 1.0 or 3.4 p.p.m. manganese grew normally and showed normal spermatogenesis when raised on a ration containing 3.3 p.p.m. manganese. A study was made of the absorption, excretion; and tissue distribution of orally administered Mn54 by these boars. The prolonged feeding of rations containing 0.5 to 3.5 p.p.m. manganese resulted in a tissue manganese depletion of from 2 to 10 times that of the controls receiving approximately 40 p.p.m. manganese. The greatest depletion was in the livers of the Experiment-IV gilts. When female pigs were weaned at three weeks of age and at an average weight of 9.4 lb. and were fed throughout the growing, gestation, and lactation period on a ration containing either 0.S p.p.m. or 40 p.p.m. manganese the following deficiency symptoms developed in the 0.5 p.p.m. manganese group: (a) reduced skeletal growth and an accompanying skeletal or muscular weakness; (b) increased fatness as shown by a statistically significant greater back fat thickness at an average weight of 164 lb.; (c) irregular estrual cycles; (d) complete absence of estrus in some animals and absence of marked signs of estrus in others; (e) resorption of fetuses or birth of small, weak pigs which could neither stand nor walk properly, with tissues containing approximately 33% as much total manganese as did those of the control pigs; (f) poor udder development and almost complete absence of milk production and secretion, the colostrum and milk containing approximately 33% less manganese than similar samples from a control gilt; and (g) a reduction in the tissue manganese in the first-generation gilts to from 10 to 20% of the controls.