W. E. Huff

Aflatoxicosis alters avian renal function, calcium, and vitamin d metabolism

Experiments were designed to determine the effects of aflatoxicosis on avian renal function, calcium (CA), inorganic phosphorous (Pi), and vitamin D metabolism, and to determine if the effects of aflatoxin are reversible upon discontinuation of toxin administration. Three-week-old male broiler chickens (n = 12 per treatment) received aflatoxin (AF; 2 mg/kg po) or an equal volume of corn oil, the AF carrier vehicle, for 10 consecutive days. After 10 d of treatment, half of the birds from each treatment group were anesthetized and prepared for renal function analysis, which included a 2-h phosphate loading period. Ten days after discontinuation of AF treatment, the remaining birds in each treatment group were anesthetized and prepared for renal function analysis. AF decreased plasma 25-hydroxy vitamin D [25(OH)D] and 1,25-dihydroxy vitamin D [1,25(OH)2D] levels after 5 d of treatment. After 10 d of treatment, urine flow rate (V), fractional sodium excretion (FENa), and fractional potassium excretion (FEK) were lower in AF-treated birds. In addition, total plasma Ca tended to be lower (p = .10) and fractional Ca excretion (FECa) tended to be higher (p = .10) in the AF-treated birds. Intravenous phosphate loading produced a sharp increase in urine hydrogen ion concentration ([H+]) in the AF-treated birds. Glomerular filtration rate (GFR) was reduced and plasma osmolality was increased in AF-treated birds 10 d after discontinuation of toxin administration. The results indicate that AF directly or indirectly affects Ca and Pi metabolism in avians. At the present time, the effects may be related to altered vitamin D and parathyroid hormone (PTH) metabolism. Aflatoxicosis may decrease endogenous PTH synthesis and the renal sensitivity to PTH. The AF-related increase in urine [H+] during phosphate loading is probably due to increased Na+/H+ counterport, suggesting that AF stimulates sodium reabsorption. Also, the decrease in GFR exhibited 10 d after toxin removal indicates that AF may cause prolonged alteration in renal function.

Effects of Escherichia coli Challenge and Transport Stress on Hematology and Serum Chemistry Values of Three Genetic Lines of Turkeys

Three lines of turkeys were compared for response to an Escherichia coli challenge followed by transport stress (transport). The turkey lines were a slow-growing line selected for increased egg production (egg line), a fast-growing line selected for increased 16-wk BW (F line), and a commercial line (Comm line). Birds were challenged at 14 wk of age with an air sac injection of 5,000 to 10,000 cfu of E. coli. At 8 d postchallenge, birds were subjected to a transport stress procedure that included 12 h of holding time in a transport vehicle. The following morning all birds (n = 10 to 19 birds/line) were bled. Whole blood was analyzed using the Cell-Dyn 3500 blood analysis system (Abbott Diagnostics), and serum chemistry was measured using the Express Plus analyzer (Ciba-Corning Diagnostics Corp.). Transport significantly decreased the levels of hematocrit, hemoglobin, mean cell volume, mean corpuscular hemoglobin, glucose, triglycerides, cholesterol, phosphorus, iron, albumin, and alkaline phosphatase (AP) and increased the levels of uric acid, blood urea nitrogen, alanine aminotransferase, aspartate aminotransferase, and creatine kinase. Line differences were variable, but the levels of both iron and AP were least in the fastest-growing Comm line birds and greatest in the slowest-growing egg-line birds with intermediate values in the F line. Iron and AP were also the only parameters influenced by sex, with males having greater levels of both compared with females. The creatine kinase levels were more than 6-fold greater in transported Comm line birds, and iron levels of transported Comm males were 3-fold less than controls. Previously, the growth rate of these lines was positively correlated with increased heterophil to lymphocyte ratios and susceptibility to colibacillosis. The differences seen in the Comm line for these commonly measured blood parameters suggest that they may be useful for profiling flocks to determine their response to transport stress and feed withdrawal.

Aflatoxin exposure produces serum alphafetoprotein elevations and marked oval cell proliferation in young male Pekin ducklings

Summary Feeding of aflatoxin to ducks produces extensive oval cell proliferation in the liver associated with a prolonged elevation of serum alphafetoprotein (AFP). Short term feeding of 0.075–0.6 μg/g of aflatoxin to young male Pekin ducks results in rapid and massive dose-related proliferation of “oval” cells, which extend from the portal zone across the hepatic lobule within three to five weeks. Longer term feeding of 0.15 μg/g and 0.3 μg/g results in prolonged elevations of serum AFP. Prolonged elevation of serum AFP serves as a marker of oval cell proliferation proceding hepatocellular carcinoma (HCC) development. These results confirm that ducks are sensitive to low amounts of aflatoxin and develop early lesions that have been shown in other studies to be associated with hepatocarcinogenesis. These findings in ducks support the likelihood that aflatoxin exposure contributes to the risk for development of HCC in humans.Abbreviations: AFB1, aflatoxin B1; AFP, alphafetoprotein; CCA, cholangiocarcinoma, DHBV, duck hepatitis B virus; HCC, hepatocellular carcinoma.

Effect of thiram on chick chondrocytes in culture

The effect of thiram, a fungicide that increases the incidence of tibial dyschondroplasia (TD) in poultry, was studied in vitro using growth plate chondrocyte culture. Thiram caused a significant reduction in alkaline phosphatase, acid phosphatase, and lactate dehydrogenase (LDH) activities at concentrations of 5 microM and above. It was highly cytotoxic to chondrocytes at and above this concentration as determined by their ability to reduce 3(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (triazolyl blue, MTT), a marker of cellular viability. An increase in the leakage of LDH into culture media was evident at concentration as low as 1 microM. Very few differences were noticed in the electrophoretic migration profiles of cell-extract proteins at any treatment level relative to control. The cytotoxic effect of thiram is possibly due to its damaging effect on the cell membrane, which may be responsible for chondrocyte death.

Aflatoxin and glutathione in domestic fowl (Gallus domesticus)—II. Effects on hepatic blood flow

1. The effect of aflatoxin on plasma aspartate aminotransferase (AST), protein, and hepatic glutathione (GSH) and hepatic blood flow (perfusion), were determined in 3-week-old male chickens. 2. Daily aflatoxin gavage (2 mg/kg body wt, in corn oil) for 5 and 10 days elevated plasma AST and hepatic GSH, and depressed plasma protein and hepatic perfusion. Also, renal GSH was elevated after 10 days of aflatoxin treatment. 3. Birds given aflatoxin for 10 days followed by a 10-day recovery period exhibited tissue GSH, plasma AST and protein levels that were not different from control, but hepatic perfusion remained depressed.