PHYSICAL TREATMENT OF RICE STRAW FOR GOATS AND SHEEP AND THE RESPONSE TO SUBSTITUTION WITH VARIABLE LEVELS OF CASSAVA (MANIHOT ESCULENTA CRANTZ), LEUCAENA (LEUC0AENA LEUCOCEPHALA) AND GLIRICIDIA (GLIRICIDIA MACULATA) FORAGES

C. DEVENDRA

SUMMARY

The results of five balance studies are presented concerning the utilisation of untreated rice straw with physicalt reatment and substitution with either cassava leaves (Manihot esculenta Crantz), leucaena leaves (Leucaena leucocephala, leucaena leaves plus stems plus pods (L. leucocephala) or gliricidia (Gliricidia maculata). Feeding freshlyo cllected versus stored older rice straw to goats and sheep increased DMI with olderstraw (46.3- 55.2g /^0.75kg) comparedto the fresh feed (40.5- 41.0g /W^0.75 kg). Goats significantly consumed more DMI than sheep (P<0.05), and the digestibility of crude fibre and ash were significantly better utilized in the older straw (P<0.05). Wetting the straw at 1 kg/litre of water reduced DMI (59.9 vs 51.6 g/W^0.75kg) and dry matter digestibility significantly (P<0.05). Feeding chopped straw was a sociated with increased crude protein digestibility and N retention compared to long straw. The ME content of fresh (chopped), stored (chopped) or long rice straw were 6.09 - 6.19, 5 .38 - 6.04 and 6.39 MJ/kg respectively. The effect of substituting rice straw with 33 - 34 per cent cassava leaves was to significantly (P<0.05) increase DMI by 34 to 37 per cent and also improve the digestibility of organic matter (OM), crude protein (CP), crude fibre (CF), ether extract (EE) and nitrogen-free extract (NFE), (P<.05). Substituting rice straw with 10 to 60 per cent leucaena leaves was to increase DMI, and the apparent digestibility of crude protein and nitrogen-free extract significantly (P<0.05); this improvement was linear and statistically significant (P<0.01). The highest DMI and crude protein digestibility was recorded for the 50 per cent level of substitution. Substituting rice straw with 30 per cent of either cassava or leucaena leaves, leucaena leaves plus stems plus pods or gliricidia leaves gave no differences in DMI, however, there were significant differences in OM, CP, EE and NFE digestibility (P<0.05). Dietary energy supply, nitrogen and mineral balance indicated that in all instances, the effect of the substitution was to increase dietary ME, N and also mineral supply (Ca, P and Mg). The results emphasise the feeding value of especiallv cassava and leucaena leaves for improving the dietary quality of basal roughage diets for ruminants

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