Effects of 1[Alpha]-Hydroxycholecalciferol and Phytase on Growth Performance, Tibia Parameter and Meat Quality of 1- to 21-D-Old Broilers (Report‪)‬

INTRODUCTION In 1973, Haussler first reported that 1[alpha]-hydroxycholecalciferol (1[alpha]-OH [D.sub.3]) could replace vitamin [D.sub.3] in chicken diets and further studies showed that the activity of the former is about 8 times of vitamin [D.sub.3] based on tibia ash (Boris et al., 1977; Edwards et al., 2002). Holick et al. (1976) and Edelstein et al. (1978) have found that 1[alpha]-OH [D.sub.3] metabolized quickly to 1,25-(OH)2[D.sub.3] in intestinal membrane of chicks, and the latter is the active form of vitamin [D.sub.3]. As the analog of vitamin [D.sub.3], 1[alpha]-OH [D.sub.3] has similar effect to facilitate growth and phytate phosphorus utilization of broilers (Biehl et al., 1995; Biehl and Baker, 1997a, b; Edwards, 2002; Snow et al., 2004). Whether 1[alpha]-OH [D.sub.3] has positive effect on meat quality of broilers is not known, although vitamin [D.sub.3] improved meat quality of swine and cattle (Swanek et al., 1999; Montgomery et al., 2000; Karges et al., 2001; Wiegand et al., 2002; Wilborn et al., 2004).