Feed intake, digestion kinetics and rumen volatile fatty acids in Menz rams supplemented with Lablab purpureus or graded levels of Leucaena pallida 14203 and Sesbania sesban 1198

Abstract

35 Menz rams weighing 19.3 ± 0.87 kg (mean ± S.D.) were used in a randomized block design experiment that was conducted for 35 days at Debre Zeit Research Station of the International Livestock Research Institute, Ethiopia. The objectives of the study were to determine feed intake, apparent digestibility, passage rate and level of rumen volatile fatty acids (VFA) in Menz rams fed tef ( Eragrostis tef) straw. The basal diet was supplemented daily on DM basis with dried foliage of Lablab purpureus, LAB – (230 g) or graded levels of Leucaena pallida 14203, namely, LP1 – (170 g), LP2 – (230 g), LP3 – (290 g), and Sesbania sesban 1198, namely, SS1 – (170 g), SS2 – (230 g), and SS3 – (290 g). The nitrogen (N) content of the supplement feeds was over 28.8 g kg −1 DM, whereas it was only 8.5 g kg −1 DM in the basal feed. High contents of NDF (747.6 g kg −1 DM) and ADF (419.5 g kg −1 DM) were determined in tef straw compared to the supplement feeds. Among the supplement feeds, L. purpureus had relatively high NDF (454 g kg −1 DM) and ADF (346.2 g kg −1 DM) content. L. pallida 14203 contained relatively high levels of the anti-nutritive factors, namely, condensed tannins (82.7 Abs g −1 NDF) and soluble phenolics (27.9 g kg −1 DM). Basal feed DM intake ( P < 0.05) reduced with an increase in the level of L. pallida 14203 supplementation. The apparent digestibility of N, ADF and ADL was lower ( P < 0.001) in L. pallida 14203 than in L. purpureus or S. sesban 1198 supplemented rams. L. pallida 14203 promoted lower ( P < 0.05) fractional outflow rate of particulate matter from the rumen and longer rumen mean retention time than L. purpureus and S. sesban 1198. Higher levels of total VFA ( P < 0.001) were observed in S. sesban 1198 than in L. pallida 14203 supplemented rams. It was concluded that the anti-nutritive factors in L. pallida 14203 have a major impact on fractional outflow rate of particulate matter from the rumen, and the digestibility of nutrients, with particular limitations on N digestibility. Increasing levels of S. sesban 1198 supplementation reduced nutrient digestibility due to increased passage rate, and thus supplementation of animals with the lowest level of the fodder tree appears to be more appropriate. The relatively high fiber content of L. purpureus reduced intake and apparent digestibility of feed on a limited scale.