Malnutrition is a major contributing factor to wildebeest mortality. Its effects can fluctuate widely depending on rainfall and thus the availability and quality of grazing in the dry season.
The majority of wildebeest that die of malnutrition do so late in the dry season, usually between August and October. The protein content of many grasses fall below the level required by the wildebeest for adequate nutrition. Green grass has about an eight percent protein content, but the level declines as the grass matures. Dry dead vegetation may have only two percent protein.
The wildebeest needs to eat nearly seven pounds of dry grass per day to maintain a healthy condition. Like other ruminants, it can lose up to 30 percent of its body weight and still survive, but becomes highly susceptible to disease after 20 percent loss. Apart from starvation, malnutrition also makes it more susceptible to parasites and predation.
Because of the abundant supply of grass on the plains, malnutrition is only a factor in the wet season for calves which become separated from their mothers. No cow will accept the calf of another, even if she has lost her own and still has milk.
