Abstract
Studies were conducted for inventory of tree fodders available in four regions of Bangladesh named Mymensingh, Chittagong, Khulna and Rajshahi districts, their evaluation, production practice and feeding effect on growth of animals. A survey was conducted in these regions using prepared questionnaire. About 22 different types of fodder trees were identified that were being used as livestock feed at varying degrees. The number of Artocarpus heterophyllus and Mangifera indica were found highest followed by Psidium guajava, Ficus auriculata, Tamarindus indica and Bambusa species, Erythrina orientalis, Garuga pinnata and Morus alba were also popular. Nutritional analyses of fodder samples showed that digestible crude protein (DCP) content was the highest in Leucaena leucocephala and lowest in the Mangifera indica. Among the tree forages Leucaena leucocephala, Sesbania grandiflora, Morus alba and Erythrina orientalis had relatively higher DCP and metabolisable energy (ME) contents. Field trial for production of four selected tree forages showed that there were significant (p<0.01) effect of species on the development of vegetative buds. Early winter had significantly (p<0.01) positive effect on branch development and number of leaves per branch followed by late winter and rainy season. L. leucocephala had the highest number of new branches followed by S. grandiflora, M. alba, and E. Orientalis. The highest survival percentage of the E. Orientalis was 75.30 in early winter followed by 61.72 in late winter and 56.66 in rainy season. Survival percentage of S. grandiflora was too low in all three seasons and only 20.98% in early winter. Among three seasons and four fodder species the highest fodder yield of E. Orientalis was obtained in early winter and its yield (ton/ha./cut) at 1st, 2nd, 3rd and 4th harvest were 16.51, 32.10, 33.84 and 37.37, respectively, in late winter were 11.07, 21.05, 21.05, 28.46 and in rainy season these were 10.15, 19.35, 21.80 and 23.74. The second highest production was in L. leucocephala followed by M. alba and then S. grandiflora having the similar seasonal effect. Fodder production was linearly increased from 1st to 4th harvest. Animal experiment with 25 growing goats (in 5 groups) were fed above four different tree forage based diets (along with green grass based diet termed as control diet) showed that there were significant (p≤0.05) differences among the animal groups in terms of total DM, ME and DCP intake. Although there were no significant differences in the digestibility of DM, OM, CP and ADF, digestible intake of these nutrients were significantly (p<0.05) different among the treatments. There were no significant differences in the digestibility of diets having different forages but they were significantly higher than that of grass based control diet. Feeding of tree forages had significant (p<0.05) effect on live weight gain of goats. Animals fed with tree forage based diets significantly increased weight gain (60.03, 59.10, 57.75 and 55.57 g/d for S. grandiflora, L. leucocephala, E. orientalis and M. alba, respectively) compared to that (39.25 g/d) of control group fed with green grass. However, there were no significant differences in weight gain of the animals fed with different tree forage based diets. Feed conversion efficiency (kg feed/kg gain) also showed that animals fed with tree forage based diets were having significantly (p<0.01) higher efficiency (11.74, 12.05, 12.21 and 12.02 for L. leucocephala, E. orientalis, S. grandiflora and M. alba, respectively) compared to that (16.00) of animals fed with control diet. Nitrogen balance trial showed that there were significant (p<0.05) differences among the mean values in terms of total N intake (g/d), nitrogen retention (%) and nitrogen balance (g/d). It may be concluded that in the four regions of the country 22 fodder trees were found to be used as animal feeds of which some of the species were found to have high nutritive values. Early winter was the best season for growing fodder trees. Supplementation of diets with tree forages. resulted in better weight gain, digestibility and nitrogen balance compared to green grass. So, the diets of goats may be supplemented with tree forages for improved growth performance.