Tansy ragwort (Senecio jacobaea ) was evaluated for animal and human health hazard using the Salmonella/mammalian-microsome mutagenicity test. An acetone extract of tansy ragwort (TR) produced a negative mutagenic response for bacterial tester strains TA1535 and TA100 and a toxic response in tester strains TA1537 and TA98. Assay of this extract in the presence of mammalian liver microsomes (S-9) resulted in positive mutagenic responses in tester strains TA1535, TA1537, TA98 and TA100. Species differences were evaluated by use of liver microsome preparations from induced rat and uninduced sheep, beef, hamster, trout and rat. Only a slight species difference was demonstrated. A mixture of pyrrolizidine alkaloids (PA), extracted from TR flowers, produced a negative response in tester strains TA1535, TA1537, TA98 and TA100. A negative response was also demonstrated when the TR flower PA mixture was assayed with the Salmonella tester strains and induced rat liver microsomes ( IRLM ). A mixture of PA extracted from Senecio longilobus also produced a negative response. The major PA present in TR, jacobine , produced a negative response without and with IRLM exposure in tester strains TA1535, TA1537, TA98 and TA100. Another similar PA, monocrotaline, found in various Crotalaria species also gave a negative response. Milk from TR-fed goats was evaluated for mutagenic response. Milk from goats not receiving TR and from goats receiving TR at a level of 1% of their body weight/day via rumen cannula produced a negative response without liver microsomes present. Milk from TR-fed goats, however, yielded both negative and marginally positive responses for different combinations of tester strains and liver microsome preparations.

Concerns have been expressed by the American Society of Animal Science (ASAS) leadership about the declining membership in ASAS. I present the viewpoint that the history of the Poultry Science Association (PSA) membership and the elimination of poultry science departments from many land grant universities could be an indication of what the future holds for animal science. I suggest that the industrialization of poultry production has led to a decline in the demand for traditionally trained poultry scientists. Industrialization of swine production is proceeding rapidly, with other animal-based industries showing the same trend. If maintaining a large ASAS membership is indeed a priority, new opportunities must be developed. Equine and companion animal programs offer such possibilities, tapping into a high level of student interest.

The effect of prolonged phenobarbital (PB) administration on the toxicity of Senecio jacobaea (SJ) was studied in sheep. Hepatic microsomal mixed function oxidase (MFO) activity was monitored. Pentobarbital sleeping times were decreased after 17 d of treatment, indicating initial induction of MFO. At 105 d of treatment, hepatic microsomal aminopyrine N-demethylase activity and cytochrome P-450 levels were increased (P less than .05) as a result of PB administration. No differences (P greater than .05) were observed in activity of microsomal epoxide hydrolase, glutathione S-transferase or liver glutathione as a result of SJ and (or) PB. Epoxide hydrolase activity in control sheep was about fivefold higher than values previously reported for rats. Liver Cu concentration was increased (P less than .05) in sheep receiving PB and SJ when compared with controls, but no differences (P greater than .05) were observed in the hepatic intracellular distribution of Cu as a result of PB and(or) SJ. Histopathological examination of liver revealed greater incidence and severity of lesions in animals receiving SJ, but PB did not appear to potentiate SJ intoxication. The results suggest that MFO induction by PB does not increase the susceptibility of sheep to SJ intoxication. Sheep possess a high activity of hepatic microsomal epoxide hydrolase which could account for their resistance to SJ intoxication.

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