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Ajebu Nurfeta disputerte 2. oktober 2008
Ane Gro Siri SkjelfjordEvaluation of the nutritive value of Enset (Ensete ventricosum) as livestock feed in southern Ethiopia
English language abstract
Enset (Ensete ventricosum), also known as 'false banana', is a perennial herbaceous monocarpic plant, which is grown in southern and south-western parts of Ethiopia for human consumption and animal feed. Apart from some studies conducted to determine the chemical composition and degradability on 3 enset varieties and intake study, there were no comprehensive studies conducted to evaluate the nutritive value of enset. Therefore, the main objectives of this study were to investigate the chemical composition and degradability of different morphological fractions of enset and the nutritive value of enset fractions fed as sole diets or supplemented to the basal diet of wheat straw.
Samples of enset were collected from 5-to-6-year-old 10 selected enset varieties and fractionated into leaf lamina, leaf midrib, pseudostem and corm. Samples were analysed for chemical composition (including minerals) and in sacco degradability studies were performed. Fractions of enset (leaf, pseudostem, corm and their mixture), urea-and-calcium oxide (CaO or lime)-treated wheat straw and Desmodium intortum (Desmodium) hay were fed as sole diet to evaluate the intake, digestibility and nitrogen utilization. We have evaluated also the supplementary value of enset fractions to the basal diet of wheat straw and Desmodium hay. In another experiment, three levels of enset leaf: low (215) medium (417) and high (594 g DM per day), were supplemented to the basal diet of untreated or urea-and CaO-treated wheat straw in sheep feeding.
Significant variation was observed in the content of dry matter (DM), ash, neutral detergent fiber (NDF), acid detergent fiber (ADF), crude protein (CP) and metabolizable energy (ME), in sacco degradability, macro and trace mineral content among morphological fractions and varieties of enset. The DM content of leaf midrib and pseudostem was low compared with other fractions. The NDF content was higher in leaf lamina and pseudostem relative to other fractions. Leaf midrib had the highest ADF content and the lowest was in corm. The DM degradability and ME content ranked in the following order: corm > pseudostem > leaf midrib > leaf lamina.
Most enset fractions were rich sources of major minerals such as phosphorus, potassium, magnesium and calcium (Ca) except corm which is poor in Ca. The sodium content was very low in all fractions. Most fractions were rich in iron and manganese, but deficient in copper, except leaf lamina. The zinc content was high in corm, but low in other fractions.
When fed as sole diet, daily DM and CP intake was higher in sheep fed Desmodium hay than those fed pseudostem. The DM intake of enset fractions ranks in the following order for enset fractions: whole enset ≥ leaf > corm > pseudostem. Organic matter (OM) digestibility was highest for corm and whole enset and lowest for Desmodium hay and untreated wheat straw. The CP digestibility ranged from 0.636 in Desmodium hay to -0.408 in corm. The nitrogen (N) balance was highest for Desmodium hay and lowest for corm.
In an experiment where enset fractions were supplemented to the basal diet of wheat straw and Desmodium hay, no differences was found in total DM or OM intake between diets supplemented with pseudostem, corm and enset mixture. The N intake in sheep supplemented with enset mixture was higher than in those supplemented with corm and pseudostem. The apparent digestibility of DM was highest for sheep supplemented with pseudostem followed by corm and enset mixture. Organic matter digestibility was highest for pseudostem and corm supplemented sheep than for those supplemented with enset mixture. There was no difference in N digestibility between treatments. The digestibility of NDF was higher for pseudostem and corm supplemented sheep than for those supplemented with enset mixture. The N retention was higher for sheep fed pseudostem and corm than for those fed enset mixture. There was no difference in gain per day between sheep fed pseudostem, corm or enset mixture.
When different levels of enset leaf were supplemented to the basal diet of untreated or calcium oxide treated straw, the mean DM and OM intake was higher (P<0.00l) at medium and high levels of supplementation than at low level. Intake of total DM, OM and N was higher (P<0.05) for treated than for untreated straw. Sheep fed medium and high levels of enset leaf supplementation had similar weight gain but higher than those supplemented at low level. The digestibility of DM, OM and NDF was highest at medium level of supplementation and the digestibility values declined as the level of supplementation increased to high level. The digestibility of N was lower (P<0.05) for treated than untreated straw. The N retention was similar between treated and untreated straw. The highest mean N retention was at medium level of supplementation. The rumen ammonia N declined (P<0.001) with increasing levels of enset leaf to both untreated and treated straw. Sheep fed untreated straw had higher (P<0.05) total purine derivatives excretion, absorbed microbial purines and microbial N supply than those fed treated straw. It can be concluded that there is no major beneficial effect above medium level of enset leaf supplementation to both treated and untreated straw.
Key words / ISI database key words: Ensete ventricosum, morphological fractions, chemical composition, degradability, enset varieties, enset fractions, mineral content, Ethiopia, wheat straw, urea/lime treatment, digestibility, nitrogen balance, sheep, dry season feeding, nitrogen retention, enset leaf, urea, calcium oxide, purine derivatives
Address as of October 2008: Hawassa University, College of Agriculture, P.O.Box 5, Hawassa, Ethiopia
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Publisert: 10.10.08
Oppdatert: 29.06.09
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