Three experiments were carrried out.in the research farm
of the
Department of Livestock and Fisheries, Faculty of Agriculture
National University of Laos, Vientiane Capital, Lao PDR.
Experiment 1. Four growing male goats fed ad-libitum Tithonia diversifolia hay were allocated in a 4*4 Latin square design to supplements of cassava chips (1% of BW), fresh mulberry leaves (1% of BW as DM), both cassava chips and mulberry leaves (0.5% BW of each on DM basis) or no supplement.
Supplementation did not affect the intake of the Tithonia hay thus total DM intake was higher on all the supplement treatments. Crude protein intake was highest for the treatment of mulberry leaves. N intake was lowest in the goats given Tithonia and Tithonia with cassava chips. Lowest N retention was on the Tithonia diet expressed as absolute amounts or as percentages of N intake or N digested. N intake on the diet with cassava chips was low, but the efficiency with which the N was retained was higher than on all the other diets. Live weight changes were in the same order as those for N retention with highest value on the diet with supplements of both cassava chips and mulberry leaves.
Experiment 2. Four growing male goats were assigned to a 2*2 factorial design in a 4*4 Latin square. The factors were: ad-libitum fresh tithonia foliage or tithonia hay; and supplementation with cassava root chips + mulberry leaves (1% BW of each on DM basis). Total DM intake for goats fed fresh Tithonia foliage was higher than when the Tithonia hay (plus jackfruit leaves) was fed. Supplementation with mulberry leaves and cassava chips increased DM intake compared with no supplement, reaching 46.5 g/kg live weight. Coefficients of apparent digestibility for DM, organic matter, crude protein and NDF were lowest when the Tithonia was fed as hay. Supplementation improved the coefficients on Tithonia hay but not on fresh Tithonia. Urine volume was much higher on fresh Tithonia than on sun-dried Tithonia. When the diets were supplemented the urine volume was decreased on the fresh Tithonia but not on the sun-dried Tithonia. N retention did not differ between fresh and sun-dried Tithonia but was increased when the Tithonia was supplemented with cassava chips and mulberry leaves.
Experiment 3. Four growing goats were assigned in a 4*4 Latin square to evaluate four sources of bypass protein (banana leaves, jackfruit leaves, erythrina leaves and mulberry leaves) at levels of 2% BW (DM basis) with a basal diet of ad libitum fresh Tithonia foliage. Urine volumes were highest on the banana and erythrina diets and reflected the rates of excretion of N in the urine. N retention was highest on the mulberry-supplemented diet which was not different from the diet with jackfruit. The lowest value was on the diet with banana leaves. N retention on the erythrina supplemented diet appeared to be only slightly less than on the diet with jackfruit. The weight gains broadly followed the values for N retention being much less on the Tithonia supplemented with banana leaves.
The findings of these three experiments support the hypothesis that, in goats fed tree foliages as the basal diet, digestibility indicates nutritive potential of the diet but actual performance is dependent on appropriate supplementation to increase the amino acids absorbed by the animal.
Keywords: Banana leaves, bypass protein, digestibility, DM intake, dried cassava root, Erythrina, Jackfruit, Mulberry leaves, N retention, Tithonia diversifolia.