Leucaena leaf meal in the diet of growing rabbits: Evaluation and effect of a low-mimosine treatment

Abstract

Leucaena leaf meal (LLM), prepared with the mimosine content unmodified or with the mimosine largely converted to 3-hydroxy-4(IH)-pyridone (DHP), was given to rabbits at levels of 20, 40 and 60% of the diet. Liveweight gain and feed intake were measured for a 6-week period. Digestibility of protein and energy was determined for the 60% LLM diets using chromium oxide as marker. After 4 weeks of feeding, mimosine and DHP were measured in feed, faeces and urine. At the end of the trial, carcass percentage and relative organ weights were determined. No acute toxicity attributable to mimosine was observed with any treatment, and mimosine appeared to be largely degraded to DHP in the digestive tract. There was no evidence of degradation of DHP, but the expected clinical effects of DHP, depressed plasma thyroxine and depressed feed intake, were not observed. All diets containing leucaena gave lower growth rates than the control diet, on which rabbits gained 166 g week −1, and those with 60% LLM were severely depressed. Treatment to convert mimosine to DHP did not improve growth performance, but rather had an adverse effect. Protein and energy digestibility for the diets containing 60% LLM were much lower than for the control diet and it was probable that this largely accounted for the relative weight gains. Although the proximate composition of dry leucaena leaf suggests it could make a useful contribution to intensive rabbit production in the tropics, these results indicate that its use would be uneconomic in most circumstances.