For the purposes of this symposium in vitro techniques for the evaluation of ruminant feeds are defined as laboratory methods in which the availability of nutrients in the feed to the digestive process in the ruminant animal is estimated by the incubation of the feed with micrwrganisms or semi-purified enzyme preparations, or both. Ewart (1974) reviewed for the Society recent developments in co...

1. Total body energy retention (ER) and metabolizable energy intake (MEI) values from experiments with 231 lambs (Suffolk male x (Border Leicester male x Cheviot female) female) housed indoors and given thirteen forage diets were used to estimate the metabolizable energy (ME) required for maintenance. 2. ER was measured using the comparative slaughter technique, and the lambs were fed at severa...