STRONG demand at today's Warwick Cattle Sale has seen prices hit new highs, with strong demand for young cattle.   Numbers increased by 18%  and a full panel of export buyers was present and operating along with the usual feed and trade buyers plus restockers.   Young cattle continued to receive very strong demand from all sections of the market, with some well-bred light weight calves and vealer steers selling to a new high.   Vealer heifers to the trade averaged 11c dearer and yearling steers and heifers to feed improved 6c to 10c/kg.   Heavy grown steers and bullocks sold to solid demand.   Plain condition cows averaged 15c dearer, pushed on by stronger support from restockers as well as export processors.   Calves returning to the paddock averaged close to 340c, with special sales to 397.2c/kg.   The occasional vealer steer with show ring potential made to 408.2c/kg.   Vealer heifers to the trade mostly sold around 304c with some to 308.2c/kg.   Light weight yearling steers returning to the paddock averaged 320c and made to 349.2c/kg.   The largest number of medium weights to feed averaged 310c while the better classes averaged 330c and made to 332c/kg.   A couple of heavy weights to the trade made to 333.2c, with most around 319c/kg.   Most of the light weight yearling heifers averaged in the mid-to high 280c range with a few well-bred classes to 309.2c/kg.   Medium weights to feed averaged 292c and made to 315.2c while a small selection to the trade averaged 301c and made to 313.2c/kg.   Heavy grown steers to export slaughter averaged 306c and bullocks averaged 315c and made to 319.2c/kg.   A fair sample of medium weight 2 score cows averaged 236c and made to 243.2c/kg.   Good heavy cows made to 277.2c to average 265c/kg.   Heavy bulls made to 290c/kg.