35 ref.

The growth rate and milk production of cattle grazing solely on tropical pastures is usually lower than that found when grazing temperate pastures. This lower production is mainly caused by the poorer feeding value of the tropical pastures since high levels of animal production can be achieved in the tropics if grain supplements are fed. The main factor controlling the growth rate and milk production of cattle is the quantity of net energy (NE) absorbed each day. Three factors control the intake of net energy, the quantity of food energy eaten (I), the proportion of each unit of feed that is digested (D) and the efficiency of utilization of the products of digestion (E). Thus, NE = I x D x E. The three parameters of feeding value, I, D and E, will depend on the chemical and physical composition of the pasture which in turn is related to soil conditions, climate, pasture species, stage of growth and the part of the plant being eaten. In this chapter tropical and temperate pasture will be compared in terms of the three parameters of feeding value, I, D and E