Evaluation of Nutritional Composition and Fermentation Characteristics of Different Lablab Accessions
Abstract
Livestock productivity in Uganda is still very low due to inadequate protein supplementation, among other factors. Lablab purpureus is a leguminous forage plant which can be used as a cheap and quality protein supplement by farmers who can’t easily afford commercial protein supplements. The objective of the study was to evaluate the nutritional composition of ten Lablab Purpureus accessions (T1, T5, T6, T8, T10, T12, T14, T16, T17 and T20) for supplementary feeding. Dry matter, CP, EE, NDF, ADF and total ash were determined for all the accessions. The study also evaluated the fermentation characteristics of the accession that had the highest crude protein content using four inclusion levels of molasses (0, 2, 4, and 6%).Volatile fatty acids namely; lactic, acetic and butyric acids and the pH in the resultant silages from the four treatments were determined. Considering nutritional composition, the different lablab accessions differed significantly (P<0.05) in all the parameters that were assessed. Dry matter content ranged from 23.1 – 26.7%. Accession T8 had the highest DM content while accession T17 had the lowest but its DM content did not differ from that of accessions T1, T5, T10, T14, T16 and T20. Crude Protein content ranged from 16.4 - 26.7%. Accession T6 had the highest CP content though its level wasn’t significantly different from that of accession T10. Accession T1 had the lowest CP. Regarding neutral detergent fibre, the content ranged from 35.7 – 55.2% while the ADF content range was from 22.3 – 30.1%. Accessions T10 and T1 had the highest NDF and ADF content respectively, while accession T17 and accessions (T6 and T14) had the lowest NDF and ADF content respectively. Considering total ash whose content ranged from 8.6 – 10.8%, accessions T10 and T14 had the highest levels while accessions T16, T5 and T17 had the lowest levels. With regards to ether extract levels, the content ranged from 0.73 – 1.42% with accession T12 having the lowest EE content and accessions (T17 and T5) having the lowest. Regarding fermentation characteristics, the different levels of molasses led to significant differences in the pH and the concentrations of the different volatile fatty acids. Lactic, acetic, and butyric acids concentrations had ranges of 1.68 – 2.76%, 0.24 – 0.97% and 0.04 – 0.47% respectively while pH ranged from 4.3 – 4.7. The treatment with the 4% level of molasses had the highest lactic acid content (2.76%) and the lowest pH (4.3) while the 0% level of molasses had the lowest lactic acid content (1.68%) and the highest pH (4.7). Lactic acid was the dominant VFA in all the treatments. Accessions T6, T10 and T14 were identified as the best since they
were highest in CP and lowest in ADF, indicating highly digestible protein as compared to the rest. These accessions should therefore be promoted to farmers. With the ensiling of accession T6, the 4% level of molasses inclusion was identified as the optimum for the best quality silage because it had the highest lactic acid content and the lowest pH. Therefore, the best accessions can be conserved as silage at 4% inclusion of molasses for prolonged and quality protein supplementation.