Sex-related differences of hepatic microsomal mixed function oxidase system and antibody production in broilers implanted with corticosterone and/or fed ascorbic acid.

1. Most of the components of the mixed function oxidase (MFO) in hepatic microsomes were reduced by corticosterone implants, and the degree of the reduction in females and at an older age was greater than those in males and at a younger age. 2. Ascorbic acid (AA) prevented the reduction in the MFO caused by corticosterone implants. 3. The activities of aniline hydroxylase and aminopyrine N-demethylase were enhanced by corticosterone implants regardless of AA supplementation. 4. The activity of NADPH-cytochrome c reductase in male broiler was greater than that in females under normal conditions. 5. Corticosterone implants and dietary AA had less influence on the antibody production, especially to T-cell dependent antigen.

Effect of an antithyroid agent (propylthiouracil) and L-ascorbic acid on mixed-function oxidase and drug metabolism in hepatic microsomes of chickens.

1. The experiments were undertaken to determine if an antithyroid agent (propylthiouracil, PTU) and/or ascorbic acid (AA) affect mixed-function oxidase (MFO) in hepatic microsomes of male broiler chicks. 2. Feeding PTU increased the MFO activity in a dose-related manner. Addition of AA to the PTU-containing diet further increased the content of cytochromes P-450 and b5, but not the activities of NADPH-cytochrome c and NADH-cytochrome b5 reductase, and the drug-metabolizing enzymes. 3. Supplemental AA induced cytochrome b5 rather than cytochrome P-450.

Effects of supplemental ascorbic acid on performance, organ weight and plasma cholesterol concentration in broilers treated with propylthiouracil.

1. Four experiments were conducted to determine if dietary ascorbic acid (AA) affects body weight gain, food intake, organ weights, plasma cholesterol concentration, and ascorbic acid concentration in the plasma and liver of growing male broilers treated with an antithyroidal agent, propylthiouracil (PTU). 2. In the first experiment, 15 mg AA was administered daily into the crop of chicks fed on a diet supplemented with or without PTU (500 mg/kg). Administration of AA reduced plasma cholesterol concentrations in the PTU-treated chicks. 3. In the other three experiments, chicks were given the basal diet or an AA-containing (3 g/kg) diet supplemented with or without PTU (250 mg or 500 mg/kg). Feeding AA partly prevented the decreases in body weight gain, gain:food ratio and weights of the bursa of Fabricius and thymus in chicks fed on the 250 mg/kg PTU diet, and also prevented the increase in plasma cholesterol concentrations in chicks fed on the PTU diet. 4. These results suggest that AA improves the performance of chicks with experimentally induced hypothyroidism.

Nutritional Interdependence Among Rumen Bacteria, Bacteroides amylophilus, Megasphaera elsdenii, and Ruminococcus albus.

Nutritional interdependence among three representatives of rumen bacteria, Bacteroides amylophilus, Megasphaera elsdenii, and Ruminococcus albus, was studied with a basal medium consisting of minerals, vitamins, cysteine hydrochloride, and NH(4). B. amylophilus grew well in the basal medium supplemented with starch and produced branched-chain amino acids after growth ceased. When cocultured with B. amylophilus in the basal medium supplemented with starch and glucose, amino acid-dependent M. elsdenii produced an appreciable amount of branched-chain fatty acids, which are essential growth factors for cellulolytic R. albus. A small addition of starch (0.1 to 0.3%) to the basal medium containing glucose and cellobiose brought about successive growth of the three species in the order of B. amylophilus, M. elsdenii, and R. albus, and successive growth was substantiated by the formation of branched-chain amino acids and fatty acids in the culture. Supplementation with 0.5% starch, however, failed to support the growth of R. albus. On the basis of these results, the effects of supplementary starch or branched-chain fatty acids on cellulose digestion in the rumen was discussed.