Direct evidence linking alkaloids found in endophyte-infected tall fescue forage with the livestock disorder known as fescue toxicosis is lacking. Physiologic effects of fescue toxicosis include reduced serum prolactin concentration in cattle. A monoclonal antibody specific to the lysergic moiety of ergot alkaloids was developed in mice after creating an immunogen by linking lysergol to human serum albumin. The antibody was specific to the lysergic moiety and, therefore, it cross-reacted with ergot alkaloids, lysergic acid, and lysergol. The antibody did not cross-react with alkaloid derivatives that had bromated or hydrogenated lysergic ring moieties. Fescue toxicosis conditions were elicited in yearling Angus steers by permitting them to graze endophyte-infected tall fescue containing > 650 Kg/kg of ergovaline for 60 days. Passive immunization of steers by infusion of the monoclonal antibody increased serum prolactin concentration by 7 ng/ml, beginning immediately after infusion. Control steers did not respond to treatment with bovine serum albumin. Active immunization of yearling Angus heifers with immunogens containing lysergol or ergonovine linked to human serum albumin resulted in an antibody response.

We evaluated the effectiveness of 2 dopamine antagonists as treatments for fescue toxicosis in horses. Sixteen gravid mares were assigned by breed and expected foaling date to 1 of 3 treatment groups: endophyte-infested control 1.1 mg of domperidone/kg of body weight/d; and 3.3 mg of sulpiride/kg/d. Mares were pastured on endophyte-infected fescue and received 0.454 kg of a corn and dried molasses carrier containing the drug treatment. Treatment started 30 days prior to expected foaling date and continued until parturition. Blood samples were collected, and mammary gland scores were recorded every 5 days. Body weight and body condition scores were obtained every 28 days. Serum was analyzed for prolactin, progesterone, and estradiol-17beta concentrations. Domperidone-treated mares had shorter (P = 0.09) gestation duration and foaled closer (P = 0.07) to their expected parturition date than did control mares. Mammary gland scores were higher (P < 0.05) for domperidone-treated mares than for control mares. By 4 and 9 days after the start of treatment, serum prolactin concentration was higher P < 0.05) in domperidone-treated mares and sulpiride-treated mares, respectively, than in control mares. Domperidone- and and sulpiride-treated mares had higher (P < 0.05) serum progesterone and lower (P < 0.01) estradiol-17beta concentrations than did control mares. These results indicate that domperidone may offer considerable potential as a treatment for fescue toxicosis in horses.

Sixteen IgA-deficient German Shepherd Dogs with small intestinal bacterial overgrowth were randomized into 2 groups. One group was fed a chicken-based kibble diet; the other was fed the same diet, but with 1% fructo-oligosaccharides supplemented at the expense of cornstarch. After being exposed to the diets for 46 to 51 days, the group that ate the supplemented diet had significantly (P = 0.04) fewer aerobic/facultative anaerobic bacterial colony-forming units in fluid from the duodenum/proximal part of the jejunum, as well as in the duodenal mucosa. We could not detect significant differences in the species of bacteria found in the intestine of these 2 groups of dogs. We conclude that at least some dietary carbohydrates can affect small intestinal bacterial populations in dogs with small intestinal bacterial overgrowth.

Drug-metabolizing enzyme activities were measured in livers from calves fed commercial milk replacer (nonfunctioning rumen [veal]), and those fed milk replacer supplemented with whole grain and hay from the first week of age (functioning rumen [ruminating calves]). After birth, cytochrome P450 and its NADPH-dependent reductase activities remained unchanged in veal calves; in ruminating calves they increased almost 50%. Cytochrome P450-mediated reactions, such as aniline hydroxylase activity, tripled in ruminating calves, but remained unchanged in veal calves. In both groups of calves, coumarin hydroxylase and 7-ethoxycoumarin 0-deethylase activities increased after birth, but maturation rates and activity values in ruminating calves were considerably greater than those of veal calves. The aminopyrine N-demethylase activity for veal calves was equal to that of calves with functioning rumen. Uridine diphosphoglucuronic acid glucuronyl transferase and glutathione-S-transferase activities also were higher in calves with functioning rumen than in veal calves. This increased activity in calves with functioning rumen probably represents a response to environmental exposure to xenobiotics. Compared with rumen-functional calves, bob veal (0 to 3 weeks old) and fancy veal (15 to 19 weeks old) calves fed commercial milk replacer have a significantly (P = 0.05) diminished capacity for metabolizing drugs and other xenobiotics. From a regulatory perspective, the variance in drug-metabolizing enzyme activities within these different market classes of calves suggests that specific studies designed to determine drug residue-depletion times in veal calves may be needed.

Effects of dietary aflatoxin (AF) and supplemental vitamin E (d-alpha-tocopherol) were evaluated in growing crossbred pigs. Nine barrows (3 replicates of 3 each, mean body weight, 14.0 kg) per group were assigned to 1 of 4 treatment groups (for a total of 36 barrows): 0 IU of supplemental vitamin E and 0 mg of AF/kg of feed (control); 2,400 IU of vitamin E divided into equal doses and administered IM on days 1 and 16; 2.5 mg of AF/kg of feed; or 2.5 mg of AF/kg of feed plus 2,400 IU of vitamin E administered similarly to treatment 2. Barrows were administered their respective treatment for 32 days. Evaluations were made for group production performance and for serum biochemical, immunologic, hematologic, pathologic, serum and tissue tocopherol, and serum retinol variables. Body weight was reduced by AF-alone and AF plus vitamin E treatments, compared with control and vitamin E-alone treatments. Liver weight was increased for the AF alone-treated and the AF plus vitamin E-treated barrows, compared with control barrows. The AF alone-treated barrows had alterations in: serum values of alkaline phosphatase, gamma-glutamyltransferase, albumin, glucose, phosphorus, calcium, cholesterol, total iron, unsaturated iron-binding capacity, total iron-binding capacity, and urea nitrogen; RBC numbers, hematocrit, hemoglobin concentration, and prothrombin time; and mitogen-induced lymphoblastogenic responses. With the exception of some slight ameliorating effects on hematologic measurements, supplemental treatment with vitamin E did not prove beneficial against the toxicosis-associated AF treatment. The AF alone-treated barrows had decreased serum tocopherol and retinol concentrations, compared with control and pretest values, and decreased tocopherol concentration in cardiac tissue. High parenterally administered doses of vitamin E did not have sparing effect on Af-induced reductions of serum tocopherol or retinol concentration; however, compared with pretest values, serum tocopherol concentration was increased by vitamin E-alone treatment. Tocopherol concentration in cardiac tissue of the AF plus vitamin E-treated barrows was increased over that of the AF alone-treated barrows, indicating an ameliorating effect on AF-induced tissue concentrations reductions. These data indicate that vitamin E may not have a sparing effect on AF-induced toxicosis and that AF may reduce serum retinol and serum and tissue tocopherol concentrations.

Observations were made on development of diarrhea in special-fed calves (n = 460) on 8 commercial facilities during 2 successive 16-week production cycles at weeks 0, 2, 4, 8, 12, and 16. A total of 23% were affected, with peak number of calves with diarrhea observed at week 0. Suspected enteropathogens were identified in 86% of these calves, most commonly cryptosporidia, coronavirus, and rotavirus. Identified potential zoonotic pathogens included Giardia and Salmonella spp and verotoxigenic Escherichia coli. Noncytopathic bovine viral diarrhea virus was isolated from 6 calves that had repeated bouts of illness. Only 22% of calves entering the veal facilities had adequate transfer of passive immunity. At week 0, serum IgG concentration in calves that subsequently died or had diarrhea was lower (P < 0.001) than that in healthy calves. All calves that died (n = 6) during the first 4 weeks of production had complete failure of transfer of passive immunity.

Consumption of chlortetracycline (CTC) at concentration of 220 mg/kg of feed for 4 weeks in experiment 1 and at concentrations of 110 and 220 mg/kg for 3 weeks and 440 mg/kg for 2 weeks in experiment 2 failed to eliminate streptococci-induced lymphadenitis from swine referred to as principals. Abscesses, mostly in the head and neck, developed in at least a third of all swine in the various groups fed these CTC concentrations. Feeding of 220 mg of CTC/kg of feed in experiment 1 began 12 weeks after exposure of principals to an untypeable group E streptococci (GES; isolate 3X29A). In experiment 2, feeding of 110 and 220 mg of CTC/kg of feed began 5 weeks after exposure of principals to GES and feeding of 440 mg of CTC/kg of feed began 6 weeks after exposure. One or more cohabitating sentinel swine of experiment 1 and one or more sentinels in all groups of principals of experiment 2, except group 2, developed abscesses that were mostly in the head and neck. In experiment 2, correlation between serum GES antibody titer and development of one or more abscesses in the principals was highly significant (P < 0.01); however, correlation between antibody titer and abscesses in the sentinels only approached significance (P < 0.10).