Three trials were conducted with recently weaned pigs (n = 198) to determine the effects of feeding different types of clay in conjunction with aflatoxin-contaminated diets. In Trial 1, pigs (n = 54; trial length 4 wk) were assigned to either an uncontaminated treatment (NC), 800 ppb of aflatoxin from contaminated corn (AC), or AC with one of four clays. In Trial 2 (n = 81; trial length 5 wk), pigs were assigned to NC, AC (500 ppb of aflatoxin from rice starch), or AC with one of seven types of clay. In both trials, pigs fed AC had decreased ADG and gain:feed ratios (P < .05) compared with controls. The clays differed in their ability to produce gains similar to those of controls. The clays did reduce changes in the serum measurements normally affected by aflatoxin, including albumin, total protein, gamma glutamyltransferase (GGT), and alkaline phosphatase (ALP) levels, in a manner similar to their effect on ADG. In Trial 3, pigs (n = 63) were assigned to one of seven diets for 4 wk: NC, AC (800 ppb of aflatoxin) with no clay, AC with one of four levels of a treated Ca bentonite (.25, .5, 1, and 2%), or AC and .5% hydrated sodium calcium aluminosilicate. The addition of treated Ca bentonite to AC improved ADG (P < .05) and ADFI (P < .01) linearly. Gain:feed ratios were not affected by treatments. The inclusion of treated Ca bentonite to the AC diet linearly decreased aspartate aminotransferase (AST) levels and quadratically decreased ALP and GGT levels (P < .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Three trials using 207 crossbred pigs were conducted to evaluate the effects of aflatoxin-contaminated corn on young pigs and to determine whether several nutritional and nonnutritional dietary amendments would benefit performance or health in situations of aflatoxin B1 contamination. In Trial 1 using 90 pigs in a 49-d trial, linear (P < .01) and quadratic (P < .05) decreases in ADG were observed with increasing (0, 420, 840 ppb) dietary aflatoxin level. This growth decrease was associated with linear reductions (P < .01) in ADFI and decreases in gain/feed. Serum indicators of protein synthetic capabilities and of liver damage were also adversely affected. Improvements in growth rate for the total trial period in the presence of 840 ppb of aflatoxin were obtained with the addition of the 2 ppm of folic acid (P < .05) or .5% hydrated sodium calcium aluminosilicate (HSCA) (P < .01); the magnitude of improvement was greater for the HSCA. The addition of HSCA to the contaminated diet also restored the serum clinical chemistry profile to that exhibited by pigs fed the diet without contaminated corn. The addition of .6 ppm of Se to a basal diet containing .3 ppm of Se was generally without effect. In Trial 2, 63 pigs were used in a 42-d trial to further assess the effectiveness of both folic acid and HSCA, as well as of two sodium bentonites, in reducing the effects of aflatoxin from naturally contaminated diets (800 ppb of aflatoxin). Folic acid had no positive effect in this trial, but HSCA improved ADG (P < .01) and all clinical chemistry indicators that had been negatively affected by the contaminated diet (P < .05).(ABSTRACT TRUNCATED AT 250 WORDS)

In three experiments, mice from lines selected for resistance (R) or susceptibility (S) to growth depression from endophyte-infected fescue seed in the diet were fed diets containing infected (E+) or non-infected (E-) seed. Activities of liver enzymes known to participate in oxidation, reduction, or hydrolysis or in conjugation of xenobiotics were measured in these mice. In all experiments, E+ caused greater reduction in initial ADG of S than of R mice. In Exp. 1, liver cytochromes P450 and b5 activities were not affected by line, diet, or their interaction. These enzymes were not evaluated in subsequent experiments. In all experiments, glutathione-S-transferase (GST) and uridine diphosphate glucuronosyltransferase (GRT) activities differed between lines. Resistant mice had significantly higher GST activity on both diets in Exp. 1, on E- in Exp. 2, and on E+ in Exp. 3. Resistant mice had higher GRT activities on E+ in Exp. 1, on E- in Exp. 2, but after 4 wk on either diet in Exp. 3. Before test diets were imposed in Exp. 3, GST and GRT activities were higher in R-line mice. Divergent selection created lines that differed in response to tall fescue in the diet. Postweaning growth of resistant mice was less severely depressed by E+, although susceptible mice later expressed compensatory gain. Activities of two detoxification enzymes generally were higher in livers from R-line mice, suggesting a biochemical mechanism for the difference. Using such traits, it may be possible to select ruminants for resistance to fescue toxicosis.

Ninety-six crossbred weanling pigs (36 d of age, initial weight of 8.8 kg) were used in a three-phase study to determine the effects of feeding an aflatoxin-contaminated corn (AC) diet (922 ppb of aflatoxin B1) with and without sodium bentonite (clay) on performance, liver function, and mineral metabolism. In the nursery phase, control corn (NC) or AC was fed in corn-soybean meal diets with and without 1% clay for 6 wk. Compared with NC, AC decreased ADFI and ADG (P < .01) and increased serum activities of gamma-glutamyltransferase (P < .01) and alkaline phosphatase (P < .05). In the growing phase, 48 pigs from the nursery phase were fed NC but continued on their respective clay treatments for 5 wk. Pigs previously fed AC had higher (P < .01) ADFI and lower (P < .05) gain/feed, serum Ca, K, and glucose; ADG, other serum values, and liver minerals were not affected by treatments. In the metabolism phase, 24 barrows from the nursery phase were continued on the same corn and clay treatments for two 4-d total collections of urine and feces. Feeding AC increased (P < .05) P and Na absorption. The addition of clay lowered Mg and Na absorption (P < .01) for both AC and NC. Significant interactions for many minerals indicated that the effects on mineral metabolism were more pronounced when AC was fed. Serum and liver mineral concentrations were generally unaffected by the treatments in all phases. Feeding clay with AC results in partial restoration of performance and liver function without greatly influencing mineral metabolism.

Gossypol, a pigment of cotton, is a hepatic toxin for chickens. Thus, despite its high protein content, inclusion of cottonseed meal in poultry diets is problematic. Silymarin, an extract from milk thistle, has hepatoprotective qualities and could potentially serve as a feed additive to offset the toxicity of gossypol. The objective of this study was to determine if silymarin could counteract gossypol toxicosis. Cockerels (n = 144) from lines divergently selected for humoral immunity were used. Three individuals from each line were randomly assigned to a cage and fed a corn-soybean meal (control) diet for 14 d. Six cages per line were then randomly assigned 1 of 4 dietary treatments (1,000 mg/kg of gossypol, 1,000 mg/kg of silymarin, 1,000 mg/kg of both gossypol and silymarin, or a control diet). Body weight and feed intake data were collected for 21 d, with chickens bled weekly to collect plasma and determine hematocrits. Chickens were then killed, and livers were collected for subsequent histology and enzymatic activity analyses. Endpoints measured weekly were analyzed with repeated measures and regression methodologies. Plasma and liver enzyme activities, and histological measures, were analyzed using ANOVA. No significant interactions between diets and lines were observed. Chickens assigned to the gossypol and gossypol-silymarin diets stopped gaining weight at d 14 (P < 0.001) and lost weight by d 21 (P < 0.001). Gamma glutamyltransferase was also elevated in these chickens at d 14; activities increased further by d 21 (P < 0.001). Histological examination of liver slices indicated substantial lipidosis (P < 0.001). Furthermore, quinone reductase activity was higher in gossypol- and gossypol-silymarin-treated chickens than in control and silymarin-treated chickens (P < 0.001). Silymarin did not alleviate any clinical effects of gossypol toxicosis.

(ABSTRACT)Ten polymethylmethacrylate (PMMA) beads containing metronidazole (3 concentrations); gentamicin sulfate; or metronidazole and gentamicin sulfate were immersed in 5 ml of phosphate buffered saline in triplicate. Eluent was replaced at specified time intervals for 1 day (1, 3, 6, 12 and 24 hours), daily, or weekly for 21 days.Antibiotic concentrations were measured by High Performance Liquid Chromatography.Changes in antibiotic bioactivity attributable to polymerization or co-polymerization of the antibiotics with PMMA, ethylene oxide sterilization, and storage of antibioticimpregnated PMMA (AIPMMA) beads containing metronidazole were evaluated.Antibiotic elution patterns were similar for all groups. Day-1 elution for groups containing either metronidazole (3 concentrations) or gentamicin represented a mean 63% to 66% and 79% respectively of the 21-day total elution. Approximately 50% of the day-1 elution occurred during the first hour. The elution of metronidazole was dosedependent. There was no significant difference in the total amount of antibiotic eluted from groups that had the saline changed daily versus weekly. The elution of metronidazole (day 3-21) and gentamicin (all days) was significantly greater when metronidazole and gentamicin were combined (p<0.05). Polymerization of PMMA was delayed in groups containing metronidazole.Neither polymerization nor copolymerization of metronidazole and gentamicin with PMMA, gas-sterilization, or 2-month storage of beads containing metronidazole significantly affected antimicrobial bioactivity.Metronidazole elutes from PMMA. The frequency at which the saline was changed did not affect the rate of antibiotic elution.

Weanling crossbred pigs (n = 216, 6.9 kg initially) were used in three 5-wk trials to evaluate the effect of supplemental biotin (0, 220, 440 and 880 ppb) and Cu (0, 200 and 400 ppm) on performance, hemoglobin concentrations, serum and liver Cu levels and immune response (humoral and cell-mediated). Feeding 200 ppm Cu increased growth rate (P less than .01) and feed intake (P less than .01) during the 5-wk trials; 400 ppm Cu depressed growth and feed intake after wk 2. Efficiency of feed utilization, however, was improved (P less than .05) when either 200 or 400 ppm Cu diets were fed. Whereas supplemental biotin generally did not affect pig performance, an interaction (P less than .01) during the first 2 wk was detected; ADG and feed intake were highest for 200 and 400 ppm Cu dietary levels in combination with the 440 and 880 ppb biotin levels. Hemoglobin concentration was depressed (P less than .01) when 400 ppm Cu was fed, and liver Cu levels were increased (P less than .01) 8- and 35-fold for pigs fed 200 and 400 ppm supplemental Cu, respectively. Although the magnitude of the immune response was small and inconsistent, diets containing 220 and 440 ppb biotin seemed to increase the immune response to sheep red blood cells, but 880 ppb biotin appeared to depress the response; there was no effect of biotin level on lysozyme titers. Addition of Cu to the diet tended to depress the immune response to lysozyme and phytohemagglutinin but did not affect sheep red blood cells.

Liver enzymes are essential to xenobiotic metabolism. Expression of these enzymes is dependent upon factors such as age and sex. The objective of this study was to determine basal liver enzyme levels in male and female White Leghorn chickens to provide reference values for future studies. Chickens from 2 lines divergently selected for 35 generations for high antibody and low antibody immune response to SRBC were used. Six male and 6 female chickens from each line were killed at each of 4, 8, 12, and 20 wk of age. Livers were collected and used for enzyme analyses. Liver tissue was analyzed for quinone reductase, glutathione-S-transferase, and cytochrome P450 3A4 activity. All data were analyzed using ANOVA. There were no consistent differences in enzyme activity between high- and low-antibody lines at any age. Cytochrome P450 3A4 activity was substantially greater in 4- and 8-wk than in 12- and 20-wk-old chickens (P < 0.001). This study provides insights into enzyme activities of liver enzymes; however, except for cytochrome P450 3A4, no clear trends across ages were observed.