Chemical composition and in vitro dry matter digestibility of local landraces of sweet sorghum in Botswana

Abstract

Sweet sorghum is a variant of grain sorghum (Sorghum bicolour (L) Moench, grown in Botswana for edible juicy sweet stem instead of grain. Suitability of sweet sorghum as forage for livestock was investigated by evaluating twelve local landraces for chemical composition and in vitro dry matter digestibility (IVDMD). The samples were collected from a randomised complete block design trial that had three replicates. Samples of whole plant and parts (leaf and, stalk and panicle) were analysed for crude protein, calcium, phosphorus, neutral detergent fibre (NDF), acid detergent fibre (ADF), acid detergent lignin (ADL), neutral detergent bound nitrogen (NDF-N), IVDMD and ash.

The different landraces had similar chemical composition and in vitro dry matter digestibility. Neutral detergent fibre was significantly different among the landraces and was highest in Moitshopari (645 g/kg) and lowest in Botala landrace (550 g/kg). IVDMD averaged 78% and was not significantly different among landraces. Leaf had significantly higher calcium, ADF, NDF, NDF-N, Ash and phosphorus. Crude protein tended to be different between plant parts. There was a significant interaction between landrace and plant parts for phosphorus only.

The results showed that local sweet sorghum landraces might provide a viable energy resource for ruminants due to high IVDMD. It is necessary to screen these local landraces for biomass production and nutritional evaluation through animal trials.