Browse silage as potential feed for captive wild ungulates in southern Africa: A review

Abstract

The objective of the review was to assess the potential of indigenous browse trees as sustainable feed supplement in the form of silage for captive wild ungulates. Several attempts to use silage as feed in zoos in temperate regions have been conducted with success. Information on silage from the indigenous browse trees preferred by wild ungulates in southern Africa is scanty. The use of silage from the browse trees is of interest as it has potential to reduce or replace expensive feed sources (pellets, fruits and farm produce) currently offered in southern African zoos, game farms and reserves, especially during the cold-dry season. Considerable leaf biomass from the indigenous browse trees can be produced for silage making. High nutrient content and minerals from indigenous browsable trees are highly recognised. Indigenous browse trees have low water-soluble carbohydrates (WSC) that render them undesirable for fermentation. Techniques such as wilting browse leaves, mixing cereal crops with browse leaves, and use of additives such as urea and enzymes have been studied extensively to increase WSC of silage from the indigenous browse trees. Anti-nutritional factors from the indigenous browse preferred by the wild ungulates have also been studied extensively. Indigenous browse silages are a potential feed resource for the captive wild ungulates. If the browse trees are used to make silage, they are likely to improve performance of wild ungulates in captivity, especially during the cold-dry season when browse is scarce. Research is needed to assess the feasibility of sustainable production and the effective use of silage from indigenous browse trees in southern Africa. Improving intake and nutrient utilisation and reducing the concentrations of anti-nutritional compounds in silage from the indigenous browse trees of southern Africa should be the focus for animal nutrition research that need further investigation.

Keywords: Anti-nutritional factors; Indigenous browsable trees; Nutritive value; Silage; Ungulates.

Fig. 1

Effects of rainfall patterns on consumable biomass production per hectare for sample area of ridge-top acacia regeneration woodland. Source: Pellew (1980).

Fig. 2

Bipedal stance by antelope to reach consumable biomass.

Fig. 3

Daily silage intake (SI) and dry matter intake (DMI) of reindeer fed silage with high (- - -) or low (^___) dry matter content. Vertical lines indicate the slaughter occasions. Adopted from Nilsson et al. (1996).