Forage quality of browseable fractions of Chamaecystisus palmensis pasture (Poster)

Pastures of Chamaecystisus palmensis , (Tree Lucerne (TL)) are resilient to drought and provide high dietary proteins during extended dry spells. The forage is low in tannins and both leafy and woody components can be browsed. Tree Lucerne is not a common forage utilized in Southern Africa, although utilized widely in East Africa and Oceania. With increasing mortalities of ruminant livestock during summer dry spells caused by El Nino weather, Tree Lucerne could be a viable strategy to mitigate nutritional deficiencies. Preliminary research has been done on nutrition of edible components of TL in semi-arid areas. The aim of the study was to determine fiber fractions of edible leafy and woody components of TL and in vitro degradation of fresh and air-dried materials in a pre-bloom pasture. Samples of TL leaves, petioles + twigs (3 mm) and stems (6 mm) were harvested from a planted pasture in Limpopo. Coppicing was done at 1.2 m and plant material samples (fresh and air-dried) were analysed for fibre content, crude protein content and in vitro rumen dry matter disappearance (DMD) at 12 h and 18 h incubation. Air-dried samples were milled through a 2 mm screen and particle size of fresh leaves was reduced by chopping using a sharp knife to achieve 2-3 mm diameter. Dry matter (DM) of edible freshly harvested petioles + twigs and stems ranged from 618 to 653 g/kg. Crude protein content of fresh and air-dried leaves were 220 and 250 g/kg DM, respectively; and averaged 90 g/kg DM in petioles + twigs and stems with no differences between treatments. Fresh and air-dried leaves differed in neutral detergent fibre (NDF) content (134 g/kg DM vs . 272 g/kg DM; P<0.01) and acid detergent lignin (ADL) content (85 vs . 100 g/kg DM) was similar. Edible stems and petioles + twigs resulted in a NDF content of 544 g/kg and 363 g/kg DM, respectively, and did not differ between fresh and air-dried samples. The woody components had an acid detergent fibre (ADF) content of 200 to 307 g/kg DM and an ADL content of 100 to 137 g/kg DM, with higher proportions in the air-dried fractions. There were no differences in DMD of petioles+twigs and stems. Asymptote was reached at 18 h incubation with a mean disappearance of 660 g/kg DM in fresh and air-dried woody components vs . 550 g/kg DM in both fresh and air-dried leafy materials. The lower DMD of air-dried TL leaves relative to fresh leaves was related to high ADF and ADL contents. The lower DMD of leafy components compared to woody fractions was not expected, some leaf flavonoids could have inhibited rumen bacteria. Preservation by air drying tended to lower nutritional quality. Both woody and leafy components of TL can be harvested during early bloom to increase forage biomass and nutrient supply for ruminant livestock.