Uptake of zinc from zinc sulfate and zinc proteinate by ovine ruminal and omasal epithelia

Uptake and transport of Zn from (65)Zn-labeled ZnSO(4) and Zn proteinate (ZnProt) by ruminal and omasal epithelia were examined by using a parabiotic chamber system. Uptake was measured during a 4-h incubation with 10, 20, or 200 microM Zn as ZnSO(4) or ZnProt in the mucosal buffer (pH 6.0, Krebs-Ringer phosphate). Zinc uptake and transport were also evaluated after simulated ruminal digestion. Buffered ruminal fluid contained a feed substrate and 10 or 200 microM added Zn as ZnSO(4) or ZnProt. In a preliminary experiment, uptake of Zn by omasal tissue was low; thus, the remaining experiments were conducted solely with ruminal epithelium. Incubations to determine the effect of time on Zn uptake from mucosal buffer containing 20 microM added Zn as ZnSO(4) or ZnProt resulted in increased (P < 0.01) Zn uptake as incubation time increased from 30 to 240 min. Zinc uptake was also greater (P = 0.02) from mucosal buffer containing ZnProt compared with ZnSO(4). Zinc uptake from incubations containing 10 or 200 microM was affected by source x concentration (P = 0.05) and concentration x time (P < 0.01) interactions. With 10 microM Zn, uptake was not influenced by Zn source, whereas when 200 microM Zn was added, Zn uptake from ZnProt was greater than from ZnSO(4). Increasing incubation time resulted in increased Zn uptake with 200 microM Zn in the mucosal buffer; however, with 10 microM Zn, uptake did not change after 30 min. After simulated ruminal fermentation, the proportion of Zn in a soluble form was influenced by a source x concentration interaction (P = 0.03). After 18 h of incubation, the proportion of Zn that was soluble was not different between ZnProt and ZnSO(4) in buffered ruminal fluid that contained 10 microM added Zn, but was greater for ZnProt compared with ZnSO(4) with 200 microM Zn in the incubation. Zinc uptake from the aqueous fractions of simulated ruminal digestions containing 200 microM added Zn was greater (P < 0.01) than from those containing 10 microM added Zn. Zinc transport, based on detection of (65)Zn in serosal buffer, did not occur in any of the experiments. The results of the current experiments suggest that absorption of Zn into the bloodstream does not occur from the ruminant foresto-mach; however, Zn uptake occurs in ruminal tissue and is greater from ZnProt than from ZnSO(4).     

Board-invited review: Peptide absorption and utilization: Implications for animal nutrition and health

Over the last 50 yr, the study of intestinal peptide transport has rapidly evolved into a field with exciting nutritional and biomedical applications. In this review, we describe from a historical and current perspective intestinal peptide transport, the importance of peptides to whole-body nutrition, and the cloning and characterization of the intestinal peptide transporter, PepT1. We focus on the nutritional significance of peptide transport and relate these findings to livestock and poultry. Amino acids are transported into the enterocyte as free AA by a variety of AA transporters that vary in substrate specificity or as di- and tripeptides by the peptide transporter, PepT1. Expression of PepT1 is largely restricted to the small intestine in most species; however, in ruminants, peptide transport and activity is observed in the rumen and omasum. The extent to which peptides are absorbed and utilized is still unclear. In ruminants, peptides make a contribution to the portal-drained visceral flux of total AA and are detected in circulating plasma. Peptides can be utilized by the mammary gland for milk protein synthesis and by a variety of other tissues. We discuss the factors known to regulate expression of PepT1 including development, diet, hormones, diurnal rhythm, and disease. Expression of PepT1 is detected during embryological stages in both birds and mammals and increases with age, a strategic event that allows for the immediate uptake of nutrients after hatch or birth. Both increasing levels of protein in the diet and dietary protein deficiencies are found to upregulate the peptide transporter. We also include in this review a discussion of the use of dietary peptides and potential alternate routes of nutrient delivery to the cell. Our goal is to impart to the reader the nutritional implications of peptide transport and dietary peptides and share discoveries that shed light on various biological processes, including rapid establishment of intestinal function in early neonates and maintenance of intestinal function during fasting, starvation, and disease states.     

Effects of an oral superoxide dismutase enzyme supplementation on indices of oxidative stress, proviral load, and CD4:CD8 ratios in asymptomatic FIV-infected cats

This study was designed to test the effect of antioxidant supplementation on feline immunodeficiency virus (FIV)-infected felines. Six acutely FIV-infected cats (> or =16 weeks post-inoculation) were given a propriety oral superoxide dismutase (SOD) supplement (Oxstrin; Nutramax Laboratories) for 30 days. Following supplementation, the erythrocyte SOD enzyme concentration was significantly greater in the supplemented FIV-infected group than the uninfected control group or the unsupplemented FIV-infected group. The CD4+ to CD8+ ratio increased significantly (0.66-0.88) in the SOD supplemented FIV-infected cats but not in the unsupplemented FIV-infected cats. Proviral load and reduced glutathione (GSH) levels in leukocyte cell types did not change significantly following supplementation. Antioxidant supplementation resulted in an increase in SOD levels, confirming the oral bioavailability of the compound in FIV-infected cats. This result warrants further investigation with trials of antioxidant therapy in FIV-infected cats that are showing clinical manifestations of their disease, as well as in other feline patients where oxidative stress likely contributes to disease pathogenesis, such as diabetes mellitus and chronic renal failure.     

ZINC,MANGANESE AND PHOSPHORUS INTERRELATIONSHIPS AND THEIR EFFECTS ON IRON AND COPPER IN CHELATOR-BUFFERED SOLUTION GROWN RUSSET BURBANK POTATO

Three hydroponic experiments were conducted with Russet Burbank potato to elucidate zinc (Zn) and manganese (Mn) relationships and associated interactions with other nutrients at different levels of phosphorus (P). Except when P was optimal, root Mn concentration was reduced at optimal solution Zn relative to deficient or excessive Zn levels. Shoot Mn generally increased with augmented solution Zn. As solution Zn increased, root P declined while shoot P and copper (Cu) and root iron (Fe) and Cu increased. Increasing solution Mn generally decreased Zn in all plant tissues—especially in roots. The Mn influence on plant P, Cu, and Fe concentrations was nearly opposite the Zn impact, indicating that Zn and Mn have counter effects. Partitioning between root and shoot micronutrient concentrations occurred when available P was either deficient or excessive, which may also help explain poor plant health and adverse micronutrient relationships in potato when available P is not optimally maintained.     

Ectopic spleen presenting with anemia and an abdominal mass in a dog

An 11.5-year-old, neutered male, golden retriever dog that had previously had a splenectomy for benign disease 2 years prior to presentation was diagnosed with anemia and a large abdominal mass. Necropsy and histopathology identified the abdominal mass as ectopic splenic tissue.