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The sequence of ceruloplasmin development and limiting factors controlling this process in neonatal piglets was studied in a randomized block design. Guided by the change in serum ceruloplasmin levels, the liver copper concentrations of piglets fed copper-deficient and copper-supplemented diets were compared in three different periods. The plasma of piglets was devoid of both apo- and holo-ceruloplasmin at birth. The system responsible for the synthesis of apoceruloplasmin developed shortly after birth as indicated by a steady increase in serum ceruloplasmin activity during the first week without being affected by the diet. Copper apparently was not the limiting factor at this stage since very high concentrations of copper were found in the livers of newborn piglets. However, the liver copper was depleted quickly within 1 to 2 weeks and became the limiting factor if the diet was deficient in copper. The livers of these piglets were fractionated by differential centrifugation to compare the liver copper distribution in the two dietary groups with and without copper supplementation. The treatments did not affect the copper distribution on a percentage of total liver copper basis. However, fractionation study revealed that, unlike adult pig livers, about 70% to 80% of copper was present in the heavier particle fractions of piglet livers.

Colostrum-free newborn pigs were raised artificially to investigate the appearance of ceruloplasmin in the serum of piglets. The sensitivity of the p-phenylenediamine oxidase activity assay, commonly used as a measure of ceruloplasmin, has been increased 10-fold. Based on this activity, no evidence was found that this copper protein was present in the serum of baby pigs at birth, although some evidence was obtained that the protein moiety (apoceruloplasmin) was present. Holoceruloplasmin usually became detectable in the serum 10-15 hours after birth. Its concentration increased slowly at first and then at an accelerated rate. The ceruloplasmin in the sera of 2-3-day-old piglets was isolated and compared with that isolated from the serum of adults. Contrary to a previous report, the physical and chemical properties of ceruloplasmin synthesized during the first 3 days of life of the piglet showed no significant difference from that synthesized by the adult.

Purified diets containing sodium sulfate and DL-methionine as sole dietary sources of sulfur were fed to fistulated sheep. The effect of dietary sodium molybdate (50 ppm Mo) on the capacity of the rumen microorganisms to produce sulfide from either sulfate or methionine was assayed in the two sulfur diets. Dietary molybdenum significantly inhibited the production of sulfide from sulfate but enhanced significantly the production of sulfide from methionine. The inhibitory effect of molybdenum on sulfide production in vitro and the number of sulfide-producing bacteria present in the rumen of these sheep are discussed in considering the mechanism of the molybdate effect on sulfide production.