Biodegradation of mimosine and 3-hydroxy-4 (1H) pyridone in Karan fries crossbred (Holstein Friesian × Tharparkar) cattle.

Three rumen fistulated Karan Fries crossbred (Holstein Friesian × Tharparkar) calves were fed increasing dry matter (DM) levels of 25, 50, 75 and 100% through leucaena leaf meal (LLM) starting in week 1, 2, 3, and 6, respectively. The mimosine, 3, 4 DHP and 2, 3 DHP levels were determined in strained rumen liquor (SRL) at 0, 2, 4, 8, 12 and 24 h post feeding on days 1, 8, 15, 22 and 42 and in serum samples at 0, 4, 8h post feeding on days 1, 8, 15, 22 and 45. LLM was incubated for 24 h with SRL in vitro on days 0, 7, 14, 21, 42 and 98 to study mimosine and dihydroxy pyridone (DHP) biodegradation. DM intake was 2.29, 2.14, 1.83, 1.51, 1.46 and 0.71% of live weight through 1st to 6th weeks, respectively. Both in vitro and in vivo studies showed degradation of mimosine to 3, 4 DHP and 2, 3 DHP from 1st day of LLM feeding, but from 2, 3 DHP to further degradation to nontoxic compound was limited. The overall in vitro DHP degradation was 33.11, 48.65, 39.37, 57.93 and 31.94% on day zero, 7th, 14th, 21st and 42nd of LLM feeding. The appearance of mimosine, 3, 4 DHP and 2, 3 DHP in blood indicated their absorption from gastrointestinal tract. The faecal and urinary excretion of mimosine, 3, 4 DHP and 2, 3 DHP as per cent of mimosine intake declined from first week (40.09±1.63) to 6th week (27.44±2.22).