Phosphorus Availability

Abstract

Four experiments were conducted with 0 to 3-and 4 to 7-week-old broiler chicks to study the effects of age and vitamin D form on the phosphorus availability in several samples of defluorinated phosphate (DFP). All birds were housed in raised, wire floored cages. A corn-soybean meal ration was used as the basal diet throughout the experiment. Monobasic sodium phosphate was used as the standard (assumed to be 100% available) and the calcium/phosphorus ratio was maintained at 1.25 to 1. The youngest age group (0 to 3 weeks) appeared to utilize the phosphorus from DFP virtually 100%, but the older birds could utilize only 82-90% of this phosphorus. Approximate calculations indicate that 25-OH-D 3 and 1 a-OH-D, are 2 to 2.5 and 4.5 times as active as pure D 3 (cholecalciferol) on a weight basis, respectively. The values obtained for phosphorus availability were relatively consistent whether the assessment was based on growth, toe ash, or biological index, although toe ash was generally the most reproducible parameter used. Phosphorus availability from most current commercial sources of DFP is quite high even though feed grade sources for poultry vary considerably in particle size.

The effects of dietary cholecalciferol and 1α-hydroxycholecalciferol levels in a calcium- and phosphorus-deficient diet on growth performance and tibia quality of growing broilers

“…Using body weight, plasma Ca, tibia ash weight and percentage, and incidence of rickets as criteria, Edwards et al (2002) reported that the relative biological values of 1α-OH D 3 to vitamin D 3 were 10.08, 9.50, 11.26, 4.48, and 4.50, respectively. The relative potency of 1α-OH D 3 to vitamin D 3 on body weight in our study was similar to the results of Soares et al (1978) and lower in BWG and plasma Ca, whereas higher in tibia ash weight and content, than those reported by Edwards et al (2002). The differences may have been caused by the age and sex of the birds and the dietary Ca and P contents.…”

“…Previous research has shown that 1α-OH D 3 is 4.5 times more active than vitamin D 3 in respect to the BWG of broiler chickens (Soares et al, 1978), 8.6 times in respect to tibia ash increase (Boris et al, 1977), and at least 10 times in terms of mobilizing bone calcium and raising plasma calcium concentrations in Leghorn cockerels (Haussler et al, 1973). Using body weight, plasma Ca, tibia ash weight and percentage, and incidence of rickets as criteria, Edwards et al (2002) reported that the relative biological values of 1α-OH D 3 to vitamin D 3 were 10.08, 9.50, 11.26, 4.48, and 4.50, respectively.…”