EFFECT OF REPLACING RICE BRAN OR FISH MEAL BY FRESH OR DRIED MULBERRY LEAVES ON DIGESTIBILITY AND NITROGEN RETENTION OF PIGS

Abstract

Two experiments were conducted to study the effect of replacing rice bran or fishmeal by fresh or dried mulberry leaves on digestibility and nitrogen retention of pigs. Inexperiment 1, a double 4x4 Latin square design in a 2x4 factorial arrangement was used tostudy the effect of graded levels of mulberry leaf meal (0, 15, 30 and 50% on a dry basis,respectively) in diets based on rice brans and broken rice on the N balance of eight youngcastrate male Mong Cai pigs with a mean weight of 15 kg. Mulberry leaf meal (MLM)contained DM 30.4% and in the dry matter: ash 16.9, crude fibre 20.1 and crude protein(Nx6.25) 25.4%, respectively. Feed intake was calculated to be 50 g DM/kg body weight.Although not significant, DM and organic matter digestibility appeared to increase withincreasing levels of dietary MLM. Organic matter digestibility was significantly better(P<0.05); N balance indices improved with the inclusion of MLM in the diet, and this effectwas significant for N retention (P<0.05) when expressed as proportion of the digested N. Inexperiment 2, six Large White castrate male pigs, weighing on average 15 kg, wereallocated according to a balanced change-over design, to two diets where mulberry leaves,either in milled of sun-dried or chopped off fresh, contributed about 45% of the total dailyN intake in iso-nitrogenous diets (Nx6.25, 13.7% on a dry basis). There were no significanteffects of treatment on DM, organic matter and N digestibility but dry leaves wereassociated with slightly lower digestibility values. N balance tended to be better in pigs fedwith fresh mulberry leaves compared to mulberry leaf meal. It can be concluded that inrice-based diets, it is possible to use mulberry leaves as the main protein source.Keywords: Digestibility, leaves, mulberry, pigs, protein.