Ecological Biochemistry of Secondary Plant Compounds in Herbivore Nutrition

There are over 24,000 known secondary plant compounds including the alkaloids, non-protein amino acids, cyanogenic glycosides, terpenoids, saponins and flavonoids. Research has concentrated on toxicity and nutritional limitations of plants that result from the presence of secondary compounds. Secondary plant compounds have both anti-nutritional and toxic effects on mammalian herbivores. They also affect methods for determining the nutritive value. Plants seldom contain a single class of secondary plant compound and interactions between two or more compounds in the same plant are possible. Dominant range plants contain high amounts of these compounds and manipulating vegetation so that dominant plants contain less inhibitory compounds is a challenge to range and grassland management. More research is required to take advantage of the beneficial effects of secondary plant compounds in plant protection and animal health while minimizing their potentially toxic or antinutritional effects.