Abstract
This experiment was conducted to investigate the effects of interaction between la-hydroxycholecalciferol (la-OH D 3 ) and phytase on growth performance, parameters of tibia and plasma, and meat quality of 1- to 21-d-old broilers. Two hundred and forty male, 1-d-old Arbor Acres broilers were randomly assigned to 20 cages, with 12 chicks per cage. Five treatments were designed, with four cages each. A 2x2 factorial experiment was designed to test 0 and 5 μg/kg of la-OH D 3 in combination with 0 and 500 U/kg of phytase. A basal diet was formulated to contain 2.9 g/kg of non-phytate phosphorus (NPP), and the control diet was formulated to contain a normal level of NPP (4.5 g/kg). Results showed that la-OH D 3 alone increased tibia ash, contents of calcium and phosphate, breaking strength, concentrations of plasma calcium and phosphate, and water-holding capacity of breast and thigh meat, while it decreased growth of broilers. Phytase alone improved performance and tibia quality. Although growth of broilers was lower than that of the positive control when the diet was supplemented with la-OH D3 and phytase, tibia quality was significantly improved by the addition of la-OH D 3 and phytase. These data suggest that interaction between la-OH D 3 and phytase at 2.9 g/kg of dietary NPP could significantly increase bone quality of 1- to 21-d-old broilers, while not improving growth performance.
Highlights
In 1973, Haussler first reported that 1αhydroxycholecalciferol (1α-OH D3) could replace vitamin D3 in chicken diets and further studies showed that the activity of the former is about 8 times of vitamin D3 based on tibia ash (Boris et al, 1977; Edwards et al, 2002)
Growth performance Addition of 1α-OH D3 to the basal diet had negative effects on body weight gain (BWG) and feed intake (FI) in this experiment, which indicated that 1α-OH D3 could not improve growth performance of broiler chicks when basal dietary non-phytate phosphorus (NPP) is up to 2.9 g/kg and vitamin D3 is abundant
When vitamin D3 was enough (Biehl et al, 1997c) or dietary NPP reached 3.0 g/kg (Edwards, 2002), growth of broilers was not improved by 1α-OH D3 addition
Summary
In 1973, Haussler first reported that 1αhydroxycholecalciferol (1α-OH D3) could replace vitamin D3 in chicken diets and further studies showed that the activity of the former is about 8 times of vitamin D3 based on tibia ash (Boris et al, 1977; Edwards et al, 2002). Holick et al (1976) and Edelstein et al (1978) have found that 1α-OH D3 metabolized quickly to 1,25-(OH)2D3 in intestinal membrane of chicks, and the latter is the active form of vitamin D3. As the analog of vitamin D3, 1α-OH D3 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). Previous studies have shown that dietary phytase improved growth performance, tibia ash, and phytate phosphorus (PP) utilization of broiler chicks (Lim et al, 2001; Guo et al, 2003; Shirley and Edwards, 2003; Singh et al, 2003; Selle et al, 2007). In the study of Driver et al (2005b), tibia ash content was significantly lower than those of broilers fed normal NPP diet, BWG was equivalent to the control group when 1α-OH D3 and phytase were supplemented together
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