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.

Polymyxin B and an antiserum against an Re mutant Salmonella typhimurium were evaluated for protective effect in an equine model of endotoxemia. Six 3- to 5-month-old foals were given endotoxin (0.25 micrograms/kg of body weight) IV after no pretreatment, or pretreatment with polymyxin B (6,000 U/kg, IV) or S typhimurium antiserum (1.5 ml/kg, IV). When given without pretreatment, endotoxin caused transient recumbency and increases in rectal temperature, and heart and respiratory rates. In addition, leukopenia and increases in circulating tumor necrosis factor (TNF) and interleukin 6 (IL-6) activities were detected. Compared with results obtained when endotoxin was given alone, pretreatment with polymyxin B resulted in significantly (P < 0.05) lower maximal plasma TNF and IL-6 activities, and significantly lower rectal temperature and respiratory rate. In contrast, compared with effects of endotoxin given without pretreatment, use of antiserum was associated with significantly (P < 0.05) higher respiratory rate, maximal plasma IL-6 activity, and total TNF response (as determined by areas under curves of plasma TNF vs time). These results indicate that polymyxin B may have potential as a treatment for equine endotoxemia. Salmonella typhimurium antiserum had no positive effect in this model, and, under certain conditions, may exacerbate the actions of endotoxin.

Liposomes and immunostimulating complexes (ISCOM) are adjuvants that have been known to potentiate the immune response to membrane proteins. Adjuvanted outer membrane proteins (OMP) from Salmonella enteritidis were evaluated for their protective efficacy against S enteritidis infection in turkeys. The adjuvanted vaccines prepared for evaluation were: positive or negatively charged liposomes, lipid-conjugated ISCOM, and mineral oil vaccines. These preparations were compared with that of a whole cell bacterin and protein alone. After vaccination, turkeys were challenge-exposed with a nalidixic acid-resistant strain of S enteritidis. They were monitored for clinical signs of disease, antibody response, bacterial shedding pattern, and clearance of the challenge S enteritidis from internal organs. Results indicated a significantly (P < 0.05) higher antibody response to the positively charged liposomal OMP vaccine, compared with the whole cell bacterin. The antibody response to positively charged liposomal OMP vaccine was greater when a booster dose of this preparation was given. Shedding of S enteritidis was decreased in all vaccinated and challenge-exposed turkeys (P < 0.001). The tissues from a high percentage (90 to 100%) of birds that received a booster vaccination of the liposomal (+ or -) and ISCOM vaccine were culture-negative for S enteritidis.

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.

The usefulness of tidal breathing flow-volume loops (TBFVL) to evaluate pulmonary function was investigated in 6 Standardbreds during treadmill exercise. Tidal breathing flow-volume loops are a graphic representation of airflow rate vs tidal volume for each individual breath. These TBFVL were obtained from horses exercising it speeds corresponding to 75 and 100% of maximum heart rate. Measurements were recorded in each horse before and after ovalbumininduced allergic lung disease. Moderate obstructive lung disease, characterized by a significant increase in pulmonary resistance, was observed while the horses were at rest. We found that in horses with airway obstruction exercising at 75 or 100% of maximum heart rate, the quantitative indices describing TBFVL shape and size were not markedly different from those in clinically normal horses exercising at similar speeds.