Liver enzymes in White Leghorns selected for the sheep red blood cell immune response.

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.

Effects of silymarin on gossypol toxicosis in divergent lines of chickens.

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.

Influence of endophyte consumption and heat stress on intravaginal temperatures, plasma lipid oxidation, blood selenium, and glutathione redox of mononuclear cells in heifers grazing tall fescue.

A grazing experiment was conducted to assess the effects of wild-type endophyte-infected (E+) tall fescue consumption and elevated ambient temperatures on intravaginal temperatures, plasma lipid peroxidation, and glutathione redox of peripheral blood mononuclear cells. Angus heifers (n = 34) were allotted by BW to 4 blocks consisting of E+ and endophyte-free (E-) fescue pastures. Monthly, in June, July, and August, temperature loggers were fixed into blank controlled internal drug releasers and inserted into a subsample of heifers (n = 16) for 2 d. After 48 h, heifers were weighed, and blood (30 mL) was collected via jugular venipuncture. Peripheral blood mononuclear cells were isolated for analysis of glutathione peroxidase activity, glutathione reductase activity, and reduced:oxidized glutathione. Plasma malondialdehyde was evaluated as a marker of lipid peroxidation, and whole blood Se concentration was determined. Serum prolactin was assayed after the grazing period. Heifer ADG was greatest in August and least in July (P < 0.001). In August, heifers grazing E+ fescue exhibited greater (P < 0.05) afternoon intravaginal temperatures and temperature fluctuations than heifers grazing E- fescue. In July and August, all heifers had greater afternoon temperatures (P < 0.02) and less reduced:oxidized glutathione (P < 0.0001) than in June. Glutathione reductase activity of all heifers was greater in June (P = 0.03) than in July. Similarly, all heifers exhibited decreased glutathione peroxidase activity (P < 0.0008) in July, whereas whole blood Se was reduced (P < 0.0001) in July and August. No treatment or date effects were detected for malondialdehyde, but serum prolactin was reduced at the end of the grazing period (P = 0.008) in heifers stocked on E+ fescue. Using these markers, differences in oxidative stress were not detected between heifers consuming E+ fescue and those consuming E- fescue. Date effects indicating altered glutathione redox and enzyme activity may have been related to heat stress and nutritional limitations.

Applications of laser-based ultrasonics to the characterization of the internal structure of teeth.

Dental health care and research workers require a means of imaging the structures within teeth in vivo. For example, there is a need to image the margins of a restoration for the detection of poor bonding or voids between the restorative material and the dentin. In addition, a high-resolution imaging modality is needed to detect tooth decay in its early stages. If decay can be detected early enough, the process can be monitored and interventional procedures, such as fluoride washes and controlled diet, can be initiated to help remineralize the tooth. Currently employed x-ray imaging is limited in its ability to visualize interfaces and incapable of detecting decay at a stage early enough to avoid invasive cavity preparation followed by a restoration. To this end, nondestructive and noncontact in vitro measurements on "as-is" extracted sections of human incisors and molars using laser-based ultrasonics are presented. Broadband ultrasonic waves are excited in the extracted sections by using a pulsed carbon-dioxide (CO2) laser operating in a region of high optical absorption in the dental hard tissues. Optical interferometric detection of the ultrasonic wave surface displacements is accomplished with a path-stabilized Michelson-type interferometer. Laser ultrasonics is found effective in characterizing the anisotropic and inhomogeneous nature of dentin. In addition, time-of-flight analysis of the measured bulk transmission waveforms allows for detection of dentino-enamel and carious dentin-dentin junctions. These results are compared to those obtained for specially prepared tooth phantoms that mimic the mechanical properties of dental hard tissues.

Fatal unintentional occupational poisonings by hydrofluoric acid in the U.S.

BACKGROUND: Case reports have identified hydrofluoric acid (HF) as causing fatal work injury, and HF has both local and systemic toxicity. Surveillance for HF-related mortality is problematic because of the lack of unique coding for this acid in hospital records and vital statistics. METHODS: We identified HF-related fatal work injuries investigated by the Occupational Safety and Health Administration (OSHA) for 1984-94 from coding of Hazardous Substance 1460 (HF) and requested case investigation files under the Freedom of Information Act. We attempted to identify HF-related deaths in the US for the same period through literature case reports, the Consumer Product Safety Commission, and the American Association of Poison Control Centers (AAPCC). RESULTS: For the 11 year period, OSHA investigated nine deaths in eight incidents which involved HF. Four deaths were from skin contact with concentrated HF, and five deaths involved both skin contact and inhalation of vapor. Unsafe work practices were factors in all of the deaths. Calcium chloride or gluconate was noted to have been administered to five of the nine victims. Calcium was administered 90 min after exposure to two victims, and more than 6 h after exposure to a third. We were able to establish that the regional poison control center had been contacted in regard to only one victim. For the period 1984-94, we were able to identify no additional deaths from CPSC reports, one additional death from AAPCC annual reports, and four other deaths from case reports in the medical literature. CONCLUSIONS: For the period of this study, OSHA records identified the greatest number of HF-related fatalities. The limited information in the records suggest that some victims did not receive appropriate medical care, nor was the regional poison center contacted regarding care. The full extent of health problems related to HF could be better quantified if usual surveillance sources, such as vital records, included unique coding for this acid.

Fescue toxicosis.

Most of the tall fescue pastures in the United States are infected by an endophyte, N. coenophialum. The fungus derives nutrients from the plant while supplying the plant with toxins for defense. The most detrimental toxins for animals in tall fescue are ergopeptine alkaloids, especially ergovaline. Ergovaline functions as a dopamine D2 agonist and alters prolactin and several other hormones in the body. Pregnant mares are most susceptible during their last month of gestation. Clinical signs include prolonged gestation, dystocia, retained placentas, agalactia, and dysmature foals that are either stillborn or weak.

Sporidesmin-induced mortality and histological lesions in mouse lines divergently selected for response to toxins in endophyte-infected fescue.

For eight generations, mouse lines were selected for smaller or larger reduction in postweaning gain from endophyte-infected fescue seed in the diet. After five generations in which there was no further selection for divergence in response to fescue toxicosis, the current experiment was conducted to determine whether resistant (R) and susceptible (S) lines differed in response to the mycotoxin sporidesmin (SPD). At approximately 8 wk of age, R and S mice that had never consumed endophyte-infected fescue seed were randomly assigned (five to seven per line x sex x SPD dose subclass) to receive dimethyl sulfoxide (DMSO) carrier or 10, 20, 30, or 40 mg/kg SPD by oral gavage. At death or euthanasia 14 d after treatment, livers and kidneys were collected for histological examination. Mice receiving 40 mg/kg SPD died sooner than mice receiving 30 mg/kg (63 vs 134 h; P = .02), but there was no line or line x dose interaction effect for time to death. Within those mice, neither line, dose, nor their interaction influenced liver weight or liver weight as a proportion of body weight. The R mice were more resistant to SPD than S mice; LD50 values were 23.6 and 31.8 mg/kg for the S and R lines, respectively (P < .05). Sporidesmin caused dose-related liver and kidney lesions in both lines. Selection lines did not differ significantly in the incidence of infarcts of hepatic lobules. However, at 30 and 40 mg/kg SPD doses, severity of this lesion was higher in affected S than in affected R mice. At the higher SPD doses, there also was a greater incidence of hepatic subacute cholangitis in S mice than in R mice. Foci of acute tubular necrosis were found in kidneys of mice receiving 20, 30, or 40 mg/kg SPD, with no protection against these lesions in the R line. Foci of tubular basophilia (indicative of tubular regeneration) were present in all line x dose subgroups, but incidence was not SPD dose-dependent in either line. In summary, divergent selection for weight gain response to ingestion of endophyte-infected fescue seed resulted in a favorable correlated response in survival following exposure to a chemically distinct toxin. It may be possible therefore, to select livestock populations for simultaneous resistance to a variety of toxins.

Impacts of an endophyte-infected fescue seed diet on traits of mouse lines divergently selected for response to that same diet.

In previous work, mouse lines were selected for eight generations for resistance (R) or susceptibility (S) to endophyte-infected fescue toxicosis using depression in postweaning gain caused by a toxin-containing diet as the selection criterion. Characterizing biological changes associated with resistance or susceptibility in those mice might suggest genetic or therapeutic approaches to alleviate fescue toxicosis in cattle. The first objective of the current experiment was to determine whether the toxin-containing diet depressed reproduction and mature size more severely in S than in R mice. The second was to investigate line and diet effects on hepatic glutathione-S-epoxytransferase (GST) and uridine diphosphate glucuronosyl-transferase (UDPGT) activities and to relate enzyme activities to reproduction within line by diet groups. Twenty-eight pairs per line (S or R) x diet (toxin-containing [+] or toxin-absent [-]) group cohabitated for 36 wk. The + diet depressed the number of pups born and weaned and litter weight weaned (P < .01) within the first two litters produced. Diet effects were greatest early in the experiment. Percentage changes in reproduction caused by the + diet for R and S pairs, respectively, were -13 and -28 for total pups born, -10 and -25 for total pups weaned, -13 and -14 for total litters produced, and -30 and -42 for total litter weight weaned. The S line mice were heavier than R line mice on both diets, but the + diet had a larger depressing effect on mature size of S line than of R line males (line x diet interaction, P = .09) and females (interaction not significant). Averaged across diets, GST activity was higher in R than in S dams (P = .05) at 44 wk of age but was not affected by diet or line x diet. Activity of GST was correlated with number of pups born (-.50), number of litters produced (-.44), and survival percentage (.40) within the R- group; in the R+ group, GST activity was correlated only with survival percentage (.37). In the S- and S+ groups, GST activity was not correlated with any reproductive trait. Line, diet, and their interaction did not affect UDPGT activity, and UDPGT activity was not correlated with any reproductive trait in any line x diet group. Selected lines differed in response to a toxin-containing diet as measured by its effect on reproduction and mature size. The R and S mice also differed in GST activity, but GST activity was correlated with reproductive traits only in R-line mice.

Suspected citrus pulp toxicosis in dairy cattle.

Thirteen lactating dairy cows from a herd of 650 died over a 6-week period. Most animals were down in milk production at 1 milking and were found dead at the next milking. Two cows had elevated heart rate and enlarged mandibular lymph nodes. Two others had azotemia, elevated heart rate, hyperglycemia, and weight loss. Necropsy of 10 cows revealed hemorrhages on the intestinal serosa and epicardium, lymphadenopathy, interstitial nephritis, small intestinal hemorrhage, and interstitial pneumonia. Histopathology showed lymphocytic to lymphogranulomatous inflammation in the heart, spleen, kidney, lymph nodes, liver, lung, pancreas, and adrenal gland. Phlebitis was present in 2 livers. The lesions resembled those of hairy vetch toxicosis, but no vetch was being fed. Similar lesions have been reported with the feeding of citrus pulp. Citrus pulp was being fed to the lactating cows and had been added to the diet 6 weeks before the first death. The syndrome resolved with elimination of citrus pulp from the diet.

Comparison of oxime-initiated reactivation of organophosphorous-inhibited acetylcholinesterase in brains of avian embryos.

Organophosphorous (OP) insecticide-induced inhibition and oxime reactivation of acetylcholinesterase (AChE) was determined in whole-brain homogenates prepared from 15-d-old chick embryos. Doses of chlorpyrifos, parathion, acephate, and trichlorfon that inhibited AChE >70% were administered to the embryos. Following insecticide exposure, an in vitro system compared the capability of the oximes pralidoxime (2-PAM), obidoxime, TMB-4, and HI-6 to reactivate the OP-inhibited AChE. Concentration-related increases in AChE activities were noted in embryo brains reactivated with 2-PAM, TMB, and HI-6. 2-PAM was the most effective reactivator of trichlorfon-inhibited AChE; 2-PAM and obidoxime were relatively similar in effectiveness for reactivation of AChE inhibited with the other OP insecticides used as test agents. All oximes were similarly effective against acephate, but HI-6 was the least effective reactivator of AChE in chick embryo brain homogenates inhibited by the other OP insecticides. These results suggest that both the OP insecticide inhibiting AChE and the oxime reactivating this enzyme can contribute to the effectiveness of the avian brain AChE reactivation.

Evaluation of physiologic indices in mice vaccinated with protein-ergotamine conjugates and fed an endophyte-infected fescue diet.

OBJECTIVES: To assess effects of vaccination against fescue toxicosis on weight gain, serum prolactin and cholesterol concentrations, and alkaline phosphatase (ALP) activity in mice fed an endophyte-infected (EI) or endophyte-free (EF) fescue diet. ANIMALS: 50 six-week-old male BALB/c mice. PROCEDURE: Mice were randomly allocated to the following 5 groups: 1, vaccinated intraperitoneally with a bovine serum albumin-ergotamine (EG) conjugate and fed an EI fescue diet; 2, orally vaccinated with cholera toxin (CT) subunit B-EG conjugate mixed with free CT and fed an EI fescue diet; 3, not vaccinated and fed an EI fescue diet; 4, passively vaccinated with monoclonal antibodies specific for ergovaline (EV) and fed an EI fescue diet; and 5, not vaccinated and fed an EF fescue diet. RESULTS: Antibodies against EG and EV were in serum of mice of groups 1 and 4, respectively. Secretory IgA and IgG coproantibodies against EG were induced in mice of group 2. Weight increased in groups 1 and 2 and tended to be increased in group 4 versus group 3. Prolactin concentration was similar in all groups; cholesterol concentration was decreased in groups 1, 3, and 4, compared with group 5. Compared with that in group 5, serum ALP activity decreased in groups 1 and 4 and was further decreased in group 1, compared with that in groups 2 and 3; it was negatively correlated with anti-EG titer. CONCLUSIONS AND CLINICAL RELEVANCE: Induction of anti-EG antibodies and administration of EV monoclonal antibodies tended to increase short-term weight gain in this murine model of fescue toxicosis. However, systemic IgG antibodies against EG or EV antibodies were not protective against decreases in serum ALP activity and cholesterol concentrations. Clinical significance of decreased ALP activity associated with vaccination is unknown, but represents a worsening of a response often associated with fescue toxicosis in cattle.

Oral and parenteral vaccination of mice with protein-ergotamine conjugates and evaluation of protection against fescue toxicosis.

Acremonium coenophialum produces ergopeptide alkaloids in tall fescue (Festuca arundinacea Schreb.). These ergot alkaloids decrease serum alkaline phosphatase (ALP) activity, serum cholesterol and prolactin concentrations, as well as average daily gains (ADG) in cattle. The objective of this study was to evaluate the protection of anti-ergotamine antibodies induced by either oral or parenteral vaccination with protein-ergotamine conjugates or passive vaccination with anti-ergovaline, monoclonal antibodies in a murine model of fescue toxicosis. Ergotamine (EG) was conjugated to bovine serum albumin (BSA) and cholera toxin subunit B (CTB) by the Mannich reaction. Mice were blocked based on weight and randomly allocated into five groups of 10 mice each. Treatment groups were as follows: (1) group vaccinated intraperitoneally (ip) with a BSA-EG conjugate and fed an endophyte-infected (EI) fescue diet (BSA-EG group); (2) group orally vaccinated with a CTB-EG conjugate mixed with free cholera toxin (CT) and fed an EI fescue diet (CTB-EG group); (3) nonvaccinated group fed an EI fescue diet (EI group); (4) group passively vaccinated with anti-ergovaline, monoclonal antibodies and fed an EI fescue diet (MoAB group); and (5) nonvaccinated group fed an endophyte-free (EF) fescue diet (EF group). The EI diet contained 1.5 ppm of Ergovaline (EV), whereas no EV was detected in the EF diet.Respective diets were similar upon nutritional analysis. Unvaccinated mice in the EI group exhibited features of fescue toxicosis as indicated by decreased serum ALP activity and cholesterol, and decreased weight gain as compared to mice in the EF group. Antibodies against EG and EV were present in sera of mice in the BSA-EG and MoAB groups, respectively. Mice orally vaccinated with the CTB-EG conjugate developed secretory IgA (sIgA) antibodies and short-lived, systemic IgG responses against EG. Weight gains were increased in the BSA-EG and CTB-EG groups and tended to be increased in the MoAB group vs. the unvaccinated EI group. Serum ALP activity was decreased in the BSA-EG and MoAB groups as compared to the EF group. Serum ALP activity was further decreased in the BSA-EG vaccinated group as compared to the EI group. Cholesterol concentrations were decreased in the EI, BSA-EG and MoAB groups as compared to the EF group. Prolactin concentrations were similar in all groups.

Inbreeding and reproduction in mice divergently selected for response to a dietary toxin.

This study was conducted to determine whether inbreeding coefficients of selected parents or of progeny differed between lines of mice selected for increased or decreased responsiveness to a nutritional toxicosis. A second objective was to determine whether the influence of inbreeding of parents and/or progeny on reproductive traits differed between those lines. Mice were selected divergently for 8 generations for the effect on post-weaning growth of endophyte-infected fescue seed in their diet. Forty pairs (or in Generation 7, 20 pairs) were selected and mated per generation in each line. Inbreeding increased 0.5 to 0.6% per generation in both lines, a rate close to that predicted from genetic theory. Inbreeding coefficients of selected parents were not higher in the susceptible than in the resistant line. A difference would have been expected if the inbreeding coefficient had been correlated with susceptibility to toxicosis. The magnitudes of inbreeding depression for reproductive traits did not differ significantly between lines. The average inbreeding coefficient of the potential litter tended to be higher in nonfertile than fertile matings (P = 0.10), but inbreeding coefficients of sires and dams did not differ between successful and unsuccessful matings. Inbred litters tended to be born earlier than noninbred litters (P = 0.10). Inbred dams produced smaller litters than noninbred dams (main effect P < 0.05) but only when the litter also was inbred (interaction P < 0.01). Sex ratio was not influenced by inbreeding of sire, dam or litter, but there was a higher proportion of male progeny in the susceptible than in the resistant line (P = 0.01). To avoid reduced reproductive fitness, laboratory animal populations should be managed to minimize inbreeding of progeny and dam.

Growth and physiological responses to toxicosis in lines of mice selected for resistance or susceptibility to endophyte-infected tall fescue in the diet.

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.

Evaluation of humoral immune responses in cattle grazing endophyte-infected or endophyte-free fescue.

Anecdotal reports suggest cattle with fescue toxicosis may not respond to vaccination and thus, experience increased incidence of Bovine Respiratory Disease Complex (BRDC) when shipped to feedlots. Fescue toxicosis causes hypoprolactemia in cattle. Hypoprolactemia decreases humoral immune responses in mice. Therefore, a study was conducted to compare the magnitude of primary and secondary humoral immune responses against specific antigens in cattle grazing endophyte-infected or endophyte-free fescue. Angus steers were blocked by weight and allocated into four groups. Two groups grazed endophyte-infected (EI) fescue and the other two groups grazed endophyte-free (EF) fescue. All steers were injected IM on d 0 and 21 with lysozyme without adjuvant and concanavalin. A (Con A) with sheep red blood cells (SRBC) in incomplete adjuvant of Freund. Steers were bled on days 0, 21 and 35 post-vaccination. Average daily gains (ADG), alkaline phosphatase (ALP) activity, cholesterol concentrations, rectal temperatures, and serum prolactin concentrations were measured to confirm fescue toxicosis in steers grazing EI fescue. Antibodies to Con A and SRBC were determined by ELISA and hemagglutination assay, respectively. The ADG were decreased for the EI group during the first month. Rectal temperature were elevated and serum prolactin concentrations were decreased in the EI group. Cholesterol and ALP concentrations also were decreased in the EI group. Primary and secondary immune responses against Con A tended to be increased and were increased against SRBC in the EI group. Antibodies against lysozyme were not induced in either group. In conclusion, cattle grazing EI fescue mounted similar humoral immune responses to vaccination, despite hypoprolactemia, as cattle grazing EF fescue. Increases in bovine respiratory disease in cattle maintained on EI fescue probably is not associated with lack of humoral immune response to vaccination protocols as a result of fescue toxicosis.

Lithium toxicosis in a cow.

A case of lithium toxicosis is described in a cow that had consumed grease. Clinical signs included increased salivation, ataxia, reduced consciousness, seizures and diarrhea. No treatment was instituted. The grease did not contain high concentrations of other heavy metals or minerals.

Effect of selenium supplementation on colostral IgG concentration in cows grazing selenium-deficient pastures and on postsuckle serum IgG concentration in their calves.

Effects of selenium (Se) deficiency and supplementation on production of colostral immunoglobulins by beef cows and transfer of antigen-specific and nonspecific immunoglobulins to their calves were examined. Eight beef cows, with marginal to deficient Se status (blood Se concentration, 50 micrograms/L), were allotted by breed and age to 1 of 4 Se treatment groups (n = 20/group): no supplemental Se; parenteral administration of 0.1 mg of Se and 1 mg of vitamin E/kg of body weight; ad libitum consumption of 120 mg of Se/kg of salt-mineral mix (SMM); and parenteral administration of 0.1 mg of Se and 1 mg of vitamin E/kg plus ad libitum consumption of 120 mg of Se/kg of SMM. All cows were inoculated IM with lysozyme. Cows consumed Se-deficient pastures or hay (21 to 62 micrograms/kg) during the study that began at mid-gestation and ended at postpartum hour 24. Although the concentration of specific lysozyme antibodies was not affected, cows given 120 mg of Se/kg of SMM (treatments 3 and 4) had higher colostral IgG concentration (P < 0.002) than did Se-deficient cows (treatments 1 and 2). Calves from cows in treatments 3 and 4 had higher postsuckle serum concentrations of IgG (P < 0.01) than did calves from cows in treatments 1 and 2. Colostral IgM and calf serum IgM concentrations did not differ among treatments.

Effect of copper and iron on neutrophil function and humoral immunity of gestating beef cattle.

Eighty gestating beef cattle were used to determine the effect of trace mineral salt mixtures containing copper (Cu) and iron (Fe) on selected immune functions and factors affecting copper bioavailability. Pastured cattle were randomly assigned to receive one of the following combinations of Cu and Fe in the free-choice trace mineral salt: (1) 0 mg of Cu/0 mg of Fe/kg of trace mineral salt, (2) 1,600 mg of Cu (CuSO4)/3,000 mg of Fe/kg of trace mineral salt, (3) 1,600 mg of Cu (CuSO4)/0 mg of Fe/kg of trace mineral salt, and (4) 1,600 mg of Cu (CuCO3)/3,000 mg of Fe/kg of trace mineral salt. Total Cu/Fe consumption (from trace mineral salt) was 2/678, 193/1,050, 162/553, and 202/1,140 mg/head/d, respectively, for the 4 groups. After a 1-month period of acclimation and also on day 28 of the 36-day study, copper concentrations in serum were significantly (P < 0.05) lower in group 1 than in groups 3 and 4. Serum copper concentrations did not increase with time for any group, whereas hepatic copper concentrations increased significantly (P < 0.05) with time for all groups except group 1. Hepatic iron concentrations were similar among groups at the time of the initial and final hepatic biopsies on days 0 and 28, respectively. Hepatic iron concentrations increased significantly (P < 0.05) with time in groups 3 and 4. Humoral response to chicken gamma-globulin was high but did not differ among groups on any of the days analyzed.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of feeding aflatoxin-contaminated diets with and without clay to weanling and growing pigs on performance, liver function, and mineral metabolism.

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.