ANN 111: Principles of Animal Nutrition and Feed Technology (2+1)

Nutrients in the pasture

NUTRIENTS IN PASTURE

The nutrient composition is extremely variable; for example, the crude protein may range from 3 per cent in very mature herbage to 30 per cent in young heavily fertilised grass. The crude fibre content is inversely related to crude protein content and may range from 20 in young grass to as much as 40 per cent in very mature grass. Consequently the digestibility declines as the plant matures. In early stages of growth, moisture content is high about 75 to 85% and as the plant mature, it falls to about 60 per cent. The pasture lipid content rarely exceeds 4 per cent of the dry matter. Based on the stage of growth, soil type, amount of fertiliser applied etc the mineral content varies with species. Green herbage is exceptionally rich in carotene, the precursor of vitamin A and quantities as high as 55 mg per 100 grams of dry matter of young green crops. The nutritive value of temperate grass varies from tropical grass. Temperate species of grass belong to (C3) three carbon compound phosphogylcerate as important intermediate in photosynthethetic fixation of carbon dioxide, where as tropical grasses have (C4) pathway of photosynthesis in which carbon dioxide is fixed in four carbon compound – Oxaloacetate. Hence the tropical grass species contain low protein content compared to temperate grasses. Legumes belong to leguminosea and have ability to grow in a symbiotic relationship with nitrogen fixing bacteria. Example – cowpea, bersem, lucerne etc,. Legumes are superior to grasses in protein and mineral content, particularly calcium, phosphorus, magnesium, copper and cobalt.

C.P: 3-30% C F: 20-40% Fat: 4% Legumes have ability to grow in a symbiotic relationship with nitrogen fixing bacteria. Legumes are superior to grasses in protein and mineral content.