Provisioning polyethylene glycol (PEG) to large herbivores in nutrient poor savannas can break food limitation

Abstract

Reproduction and survival of herbivores in nutrient poor savannas is low due to low nutrient and energy availability, partly caused by high levels of tannins. Polyethylene glycol (PEG) increases the availability of proteins for herbivores by binding tannins. The effect of PEG on the diet of free-roaming herbivores has not been tested. Our hypothesis was deploying lick blocks with the addition of PEG in a nutrient poor savanna, will result in a broadening of the diet of free-roaming herbivores with higher percentages of browse species and higher utilisation per browse species, with higher tannin levels. We further hypothesised that the mineral content in the faeces, once exposed to PEG would increase. We collected faecal samples of five herbivore species with various feeding methods (grazers, browsers or mixed feeders). The study used a Before-After-Control-Impact (BACI) design. The results show that the addition of PEG promotes a change in the browse dietary choices of four of the five herbivore species, and are expressed as a broader choice of diet, coupled with higher numbers of browse species with low edibility and higher tannin levels. The addition of PEG had no noteworthy effect on the concentration of minerals found in the faeces.