HEIFER DEVELOPMENT ON A WESTERN RANGE ENVIRONMENT .1. SYNCHRONIZATIONOF GROWTH AND ESTRUS

A total of 167 head of crossbred heifers (average bodyweight of 195 kg ) grazed native range and daily received 4.5 kg of alfalfa hay (13.75% N) from November 15, 1990, until December 15, 1990, after which heife rs received 5.8 kg . head(-1) . d(-1) of alfalfa hay until the breedin g season began on April 15, 1991. Additionally, heifers received 1.8 k g . head(-1) . d(-1) of a corn-based supplement from February 15, 1998 , until April 15, 1991,to provide additional energy and supply melenge strol acetate (MGA) for an MGA plus prostaglandin synchronization prog ram. Heifers were weighed, body condition scored (BCS), and reproducti ve tract scored (RTS) on February 4, 1991, and March 12, 1991, to asse ss reproductive status. Results indicate that new technologies and/or management techniques can be incorporated into an extensive western ra nge operation.