vitro test for mimosine and DHP degradation using ruminal conteBts taken from TARC Note in the Selangor area, Malaysia was conducted. Three Kedah Kelantan (KK) steers and two water buffalos kept at the Faculty of Absence of Detoxification of DHP Veterinary Medicine and Animal Sciences, Universiti Pertanian Malaysia (UPl\iI), Se­ by Rumen Microorganisms from langor, were freely fed Guinea grass. Rumen Malaysian , Water Buffalos samples were obtained from rumen fistula and Sheep for three consecutive days. In addition, four nimen-fistulated KK steers and one male water Leiwaenri is widely grown in tropical and buffalo kept in the Malaysian Agl'icultural sub-tropical countries. The plant is potentially -aesearch and Development Institute (MARDI) a source of crude protein and is regarded as were used for the study. They were feel a promising forage species. However, its use Guinea grass. Inocula were taken from six for feed has been limited because it contains groups of sheep (Dorset x local crossbred) mimosine, {1 - [N-(3-hydroxy-4-pyridone) J-a­ fed different diets. Namely group 1 fed aminopropionic acid, a toxic substance that Guinea grass (98%), group 2 fed palm kernei causes low weight gains, poor health condition cake (83 %) + bran (15%), group 3 fed palm and hair loss in both ruminants and non­ kernel cake (97%) + urea (0.5%), group 4 ruminants0> . Mimosine is readily hydrolyzed fed palm kernel cake (97 %) + urea (1%), in the rumen of ruminants by microbial de­ group 5 feel palm kernel cake (82%) + Guinea gradation to 3-hydroxy-4-(lH)-pyridone, and grass (15%) + urea (0.5%), and group 6 sometimes to 2-hydroxy-3- (lH) -pyridone fed palm kernel cake (82 %) + Guinea grass (DHP)*, a potent goitrogen•>. Mimosine (15%) + urea (1 %) . Each group was made toxicity is more acute in nonruminants owing of two animals except group 6 (one animal) . to the absence of endogenous microorganisms All animals received 2 to 2.5 % mineral supple­ capable of enzymatic detoxification. Kudo et ments. Rumen samples of them were taken al. demonstrated a potential detoxification of through a stomach tube (0.8 cm in internal mimosine in Canadian domestic ruminantsti> diameter) 1 hour after the morning feeding. and in voles• 0 >: rate of mimosine and DHP Mimosine (Sigma Chemical Co. ) and 2,3- degradation was enhanced by microbiota from dihyclroxy pyridine (DHP, Aldrich Chemicals animals fed on concentrate diets, but inocula Co.) were dissolved in distilled water by heat­ from animals 011 hay diets were relatively in­ ing and stirring. Experimental procedures active. Workers in , USA•.~> , Inclo­ and estimation of mimosine and DHP were nesia8> and the Bahamas'"' reported no ad­ described previousJyn> . Mimosine and DHP verse effects of Leiwaena feel to beef and dairy concentrations were measured at 0, 5 and 24 hr cattle, and sheep. The absence of toxi­ (occasionally, 48 and 72 hr) after incubations. city in ruminants in these areas was attri­ Rumen contents taken from seven KK cattle, buted to the microbiaJ degradation of DHP three water buft'alos and eleven sheep showed in the rumen5,r.>. Mimosine toxicity prevents only a little activity of mimosine degradation intensive use of Leucaena as forage in Aus­ (mean 5.3%, range 0-9.2%) in 24 hr. Two tralia, Papua New Guinea and probably in KK cattle of UPM and one KK cattle of , but it has not been reported from MARDI showed no indication of degradation much of Asia or tropical America:1• An in of mimosine and DHP. In the colorimetric assay, a decrease in absorbance of > 10% at 535 nm indicated disruption of the 3-hydroxy- * Known as 3,4-dihydl'Oxy pyridine (3,4 DHP), 4-keto moiety of the pyl'idine ring and t he1·e­ and 2,3-dihydroxy pyridine (2,3 DHP). fore removal of toxic activity in animals~> but 79

0 O ability from other countries whe1:e such micro­ organfami, exist. Development of the viable bacterial preparation that degrades and de­ toxifies mimosine and DHP is desired. H. Kudo, one of the authors, was assigned to the Malaysia-Japan Agriculture Research (J" ~c:J" Cooperative Work and stationed at UPM dur­ c 11,-c11 -coo 11 11 I ing a period from September 12 to 29, 1988. Nll1, Further and detailed studies will be reported Mimosinc 3-Hydroxy I\ \ 1H) --pyridone \011 1') by the same authors from T ARC and UPM in the fu tnre. The authors are grateful to the Malaysian a decrease in absorbance of < 10 % could be Agricultura.J Research and Development Insti­ solely attributed to the hydrolysis of mimosine tute, Serdang, fo1· permission to use ani ma.ls. to DI-IP ~ml the l'esultant change in molar extinction coefficient' 1>. Therefore, all the 31 1) Hegarty, M. P., Schinckcl, P. G. & Court, samples from 21 animals showed no disruption R. D.: Reaction of sheep to the consumption of the active site on the r ing. of [,1m.ccu11ui glmwa Benth. and to its toxic The lower rates of disappearance of mimo­ principle mimosine. A11st. J . A11r. Res., 15, 153- 167 (1964). sine measured by the colorimetric method 2) Hegarty, M. P. et al.: Mimosine .in Len­ with inocula from the animals fed Guinea caena. leucocephalci is metabolir.ed to a goitro­ grass suggest an absence of an effective com­ gen in ruminants. Aiist. Vet. J., 52, 490 bination of microorganisms capable of mimo­ (1976) . sine and DHP detoxification. This was con­ 3) Hegarty, M. P.: Toxic amino acids of plant origin. In Effects of poisonous plants on firmed with an in vit1·0 DI-IP degradation test livestock. eds. Keeler, R. F., Kampen, K. R. using the same samples. None of them showed van & James, L. F., Academic Press, New obvious disruption of the active site on the York, 575-585 (1978) . ring ( < 2-%) . As there is no difference in 4) Henke, L. A. : Value of Leu.ca.enci glmwa as mimosine degradation rate between 5 and a feed for cattle. In Proc. 8th Congt·. Pacif. Sci., Manila, 46, 591 (1958). 24 hr samples, conversion of mimosine to 5) Jones, R. J.: Does rnminal metabolism of DHP seems to occur within 5 hr after incuba­ mimosine and DHP explain the absence of tion. Even after 72 hr there was no indication Leiwaena, toxicity in Hawaii? Aiist. Vet ../., of any degradation. The result that both 57, 55 (1981). mimosine and 2,3-dihyclroxy pyridine were 6) Jones, R. J. & Mcgarrity, R. G.: Compara­ tive toxicity responses of goats fed Le1icaenct not detoxified indicates that 3-4-dihydroxy lencocevlwla in and Hawaii. Aust. pyridine was also not detoxified. ,J, Ayr. Res., 3,1, 781-790 (1983). From these results it is obvious that the 7) Jones, R. J. & Megarrity, R. G.: Successful tested Mala.ysim1 ruminants may be able to transfer of DHP-degrading· bacte 1·ia from convert mimosine to DHP. But they were Hawaiian goats to Australian ruminants to unable to degrade DHP, although roughage ove1·come toxicity of Leiwaena. Aitst. Vet. J., 63, 259- 262 (1986) . diets might have account for the lower activity 8) Kranevelcl, F. C. & Djaenoedin, R.: Haaruit­ to some extent. A concentrate diet may in­ val bij dieren na voeclering; met lamto1·0 crease the detoxification and serve to alleviate ( Leiwcum a g/au ca). H emerci Zoa, 54, 170- mimosine poisoning. Selection and breeding 184 (1947) . of Leucaena for low mimosine content may be 9) Kudo, H. et al.: Degradation of mimosine in 1·umen fluid from cattle and sheep in a solution. However, it seems that the more Canada. Cwn. .}. Anim1.. Sci., 64, 937- 942 practical method to overcome the toxicity (1984). problem is to transfer specific rumen micro­ 10) Kudo, H. et al.: 1n v-itro degracla.tion of organisms which have high detoxification mimosine by microorganisms from the eso- 80 JARQ Vol. 23, No. 1, 1989

phageal sac of voles (Microt1tS cw·vctlis). Hiroshi KUDO Can. J. Anim,. Sci., 66, 547-551 (1986). Eco-physiology Research Division, Tropical 11) Megarrity, R. G.: An automated colorimet­ Agriculture Research Center (Tsukuba, Iba­ ric method for mim.osine in Letteaena leaves. ral

(Received for publication, Dec. 26, 1988)