Estimation of grazing by herbivores from analysis of dung

Abstract

Two phenolic acids, p-coumaric and ferulic acid, can be liberated from grass material by mild alkaline hydrolysis and resolved by thin layer chromatography (TLC). The two acids can also be recovered from the dung of various herbivores and their presence can be used as evidence of grazing by animals such as cattle, hippopotamus and warthogs. The reduced presence of these compounds in the dung of goats supports the fact that goats both graze and browse. Analysis of the dung of typical browsers such as kudu, black rhinoceros and giraffe suggests that kudu and black rhinoceros may occasionally graze when grass is available. p-Coumaric and ferulic acid are not readily detectable by this method in extracts of the major tree species browsed by goats in the area studied. The yield of these two compounds in the dung of goats gives a reasonable estimate of the extent to which goats are known to graze in this area. The simplicity and uniqueness of this approach in obtaining a rough estimate of the extent of grazing by browsing animals is particularly attractive as it is more practical than field observations and invasive techniques studying gut contents.