In vitro fermentation of commonly fed herbivorous feedstuffs using African elephant (Loxodonta africana) faecal inoculum

Gastrointestinal issues and elevated body condition scores are concerns for human-managed African elephants Loxodonta africana. Thus, research to formulate appropriate feeding programmes is paramount. Fermentability of seven commonly fed types of forage were studied in-vitro using faeces from human-managed African elephants as an inoculum source. Air-dried plant samples (0.5 g) from various harvest seasons [timothy hay (n=4 seasons), N&S grass (n=2), alfalfa hay (n=3), tulip poplar (n=2), thorny elaeagnus (n=3), sweet gum (n=3) and willow oak (n=3)] were incubated with buffered faecal inoculum (n=4 elephants). Gas production was measured over 72 hr and concentration of short-chain fatty acids (SCFA) and ammonia at 72 hr. The fermentation parameters varied widely among plant species (P<0.001) with grass and legume species being more fermentable than browse species. Gas production ranged from 22 ml/g organic matter (OM) for willow oak to 140 ml/g OM for alfalfa hay and SCFA from 1.38 (willow oak) to 5.43 (alfalfa hay) mmol/g OM. Within forage, differences in fermentability (P<0.05) were found between harvest seasons for timothy hay, N&S grass and alfalfa hay (for total SCFA 7 to 23% deviation from the average) but this effect was limited or absent for the browse species. Total SCFA correlated with dietary fibre (R2=0.477, P<0.001), lignin (R2=0.432, P=0.002) and with non-starch polysaccharide + lignin (R2=0.637, P<0.001). It is recommended to consider fermentative capacity of evaluated forage species and also harvest season for the grass and legume species in African elephant feeding management programmes to assure elephant body condition and nutritional health.IntroductionThe health and welfare of African elephants Loxodonta africana in zoological institutions is promoted by feeding strategies that meet their behavioural and nutritional requirements. Common nutrition-related health and welfare problems include being overweight and obesity (Morfeld et al. 2014; Edwards et al. 2019), which are caused by an energy intake that exceeds expenditure and is associated with foot problems, reproductive difficulties and insulin resistance (Greco et al. 2016; Morfeld and Brown 2016). Overconsumption of highly digestible forage and lack of activity may underlie obesity in elephants managed in human care (Dierenfeld 2006). The forage commonly used to feed elephants in human care may contrast with their natural foraging ecology. Free-ranging African elephants forage for 48–63% of daylight hours with approximately 56% of the time spent manipulating browse and 45% grazing (Dougall and Sheldrick 1964; Tchamba and Seme 1993; Chiaki 1996). However, time spent feeding does not directly correlate to intake of mass, as browsing requires more manipulation and processing prior to ingestion than does grazing. Furthermore, they also have profound seasonal changes and habitat-attributed differences in browse and grass consumption with higher browse consumption in the dry season and higher grass consumption in long-grass regions as compared to thicket areas (Laws 1970; Barnes 1982). When available, grasses, creepers and herbs are the predominant consumed forage and are preferred over browse. The consumption of browse in the dry season is related to the decreased availability of grasses, creepers and herbs in this season (Bax and Sheldrick 1963). Natural diets are