Influence of feeding increasing levels of leucaena leaf meal on the performance of milch goats and metabolism of mimosine and 3-hydroxy-4 (1H) pyridone

Four crossbred (Alpine x Beetal) milch goats (24 months; 30 kg live weight) in early lactation received during 31 days increasing levels of Leucaena leucocephala leaf meal (LLM): 25, 50, 75 and 100% of dietary DM during first, second, third and fourth week onwards, respectively. Remaining dietary DM was supplied through green berseem and a concentrate mixture which constituted the whole diet after the 31 days feeding on LLM. Mimosine and 3-hydroxy-4 (1H) pyridone (3,4 DHP) contents of the LLM were 1.88 and 0.78% respectively. Daily average mimosine, 3,4 DHP and total toxin intake was 196, 82 and 278; 339, 141 and 480; 553, 230 and 783; and 648, 269 and 971 g kg(-1) live weight (W) during first, second, third and from fourth week onwards, respectively. DM intake on sole feeding of LLM was 65.9 g kg(-1) W-0.75. NO clinical toxicity symptoms were noted. Milk yield started declining from Day 27 onwards and reached the lowest level on Day 33 though LLM was discontinued from Day 31 onwards. Milk yield started improving from Day 37 and reached a peak by Day 49. The milk samples were free of mimosine and DHP, possibly due to some kind of barrier between blood and udder. Mimosine was not detectable in blood serum samples. The 3,4 DHP concentration in the blood serum, however, ranged from 97 on Day 8 to 402 mu g ml(-1) on Day 29 and disappeared completely by Day 36 when animals were on conventional diet. During metabolism trial faecal excretion of mimosine and 3,4 DHP was 4.43 and 17.9% of total toxin intake, respectively. Urinary excretion of mimosine was 1.59% while that of 3,4 DHP and 2,3 DHP through farces and urine was 52.17% of total toxin consumed. DCP and TDN values of LLM in goats were 16.03 and 61.58%, respectively. Goats were in positive N balance. The T-3 and T-4 levels declined but DM intake was not affected. The SGOT and SGPT values were in the normal range. The study indicated that LLM could form a substantial portion of milch goat ration and milk of such goats being free of mimosine and DHP should be fit for human consumption. (C) 1999 Elsevier Science B.V. All rights reserved.