Digestibility and feeding value of improved tropical grasses and Leucaena leucocephala cultivars for goat nutrition in Vietnam
Abstract
This study evaluated the nutritive value and digestibility of five tropical grass cultivars, including Ruzi (Brachiaria ruziziensis), Mulato II (Brachiaria ruziziensis × B. decumbens × B. brizantha), and three Panicum maximum cultivars (Purple, Mombasa and Mun River), together with five Leucaena leucocephala cultivars (Tarramba, Peru, Cunningham, KU15 and KU56). In vitro digestibility was determined using ANKOM DAISYII incubator system, and an in vivo feeding trial evaluated the effects of increasing dietary inclusion of Tarramba leaves (0, 10, 20 and 30% of dietary dry matter) in Mombasa-based diets on nutrient intake and apparent digestibility in goats. Grass cultivars differed significantly (P < 0.05) in dry matter and fibre digestibility. No significant differences were detected among grass cultivars for in vitro dry matter, neutral detergent fibre or acid detergent fibre digestibility, although numerical differences were observed. Similarly, digestibility did not differ significantly among the five Leucaena cultivars, whereas Leucaena cultivars had substantially higher crude protein concentrations than the grasses. Increasing Tarramba inclusion resulted in a linear increase in crude protein intake and apparent crude protein digestibility while apparent dry matter and organic matter digestibility remained unaffected. Dry matter and organic matter intake showed quadratic responses to increasing Tarramba inclusion, whereas ADF digestibility decreased linearly and NDF digestibility showed a numerical decline. Under the conditions of the short-term digestibility trial, inclusion of Tarramba leaves up to 30% of dietary dry matter did not adversely affect apparent dry matter and organic matter digestibility. These findings indicate that improved tropical grasses and Leucaena can provide complementary forage resources for improving the nutritional quality of grass-based diets for goats.