The white rhinoceros and the Indian rhinoceros are partially selective roughage herbivores. White rhinos feed mostly on short, sweet, and appetizing grasses and do not ruminate because they are monogastric.
White rhinos are dependent on water and drink up to 50 liters at a time with average water consumption of 12 liters per day. The white rhino’s preferred diet varies seasonally, and during the hot and humid summer season they prefer the 5 to 12 cm of tall grass, mostly dry, in winter Panicum season, they consume plants 12 to 35cm long.
The diet of the white rhinoceros is generally composed of 99% grass, the rhino chews its food thoroughly 23 times. The daily food ration of an adult white rhinoceros in the wild is 50 to 65 kg and when confined to a perch, 35 to 40 kg. Strictly pasture, with herbaceous plants which normally make up no more than about 1% of the diet.
Occasional reported cases of white rhinos chewing on woody stems, otherwise no slipping is observed. In Hluhluwe–iMfolozi Park, they favor short grass areas where species of Panicum, Urochloa, Digitaria, Sporobolus, and Cynodon dominate. These species can constitute more than 50% of the diet during the rainy season.
Since some of these grass species grow elsewhere in a bushy form, a prostrate growth form appears to be cultivated by white rhino grazing pressure. Much of the foraging occurs around termite mounds, ancient human settlement sites, and other areas where nutritious short grasses prevail.
During the dry season, the white rhinoceros transfers its pastures mainly to higher herbaceous species, Particolare in The latter species can constitute up to half of the diet at this time of the year. In extreme conditions, they may extend their search for food upward where there are reserves of tall grass.
Apart from lawn-forming species like Cynodon dactylon and Dactyloctenium australe growing under shade canopies, fibrous grasses growing in sandy soil areas are eaten little. Grasses such as Cymbopogon spp. are rejected, although Bothriochloa is eaten when short.
The grazing impact of white rhinos promotes the formation of a mosaic interspersion of short and tall grasslands. White rhinos of the northern subspecies have been observed feeding on medium-sized grasses Hyparrhenia, Panicum, Chloris, Heteropogon, and Brachiaria in the Garamba N.P., Loudetia arundinacea was only grazed by white rhinos when the grass was below 0.5 m in height.
During the subsequent rainy season, their diet was largely limited to medium-sized grasses, genera Brachiaria, Pennisetum, Sporobolus, Cynodon, etc. White rhinos are typically active for about 50% of the 24-h cycle, distributed equally between day and night, with most of this time spent foraging. Peak grazing occurs in the early morning and late afternoon, extending well into the night, avoiding the peak heat of the day.
However, when food is plentiful, daytime foraging activity is reduced. Foraging time tends to decrease during the dry season, possibly to save energy when only poor-quality grass is available. Peak daytime activity occurs during the new grass growth period at the start of the rainy season, and frequent splashing indicates that animals are under much thermal stress at this time of the year.