Biological Values of Phosphorus from Various Sources for Young Turkeys

Abstract

Two experiments, each utilizing 540 turkeys, were conducted to determine the biological value of phosphorus from 13 different sources when compared with that from dicalcium phosphate (dihydrate, purified) as a standard. Each phosphorus source was added to a basal diet composed of 44% ground yellow corn and 52% dehulled soybean meal to supply .09, .18, .27, or .45% inorganic phosphorus. Each of 60 diets, which included duplicates of the standard source, was fed to a pen of 9 male poults from 1 day to 3 weeks of age in each experiment. Body weight and toe ash measurements of poults collected at 3 weeks of age were used in nonlinear (exponential) bioassays to obtain relative biological values of phosphorus from various sources. With the dicalcium phosphate standard set at 100%, the average relative biological values of three samples from each of commercial monocalcium phosphate (21% P), dicalcium phosphate (18.5% P), and defluorinated phosphate were 93, 81, and 70%, respectively. Four samples of experimental defluorinated phosphate averaged 75%. Differences of about 5% between values were required for statistical significance, indicating significant differences among these biological values of phosphorus from the various phosphate sources in diets of young turkeys.

The Relative Biological Value of Feed Phosphates for Chicks

“…It contained approximately 20% more available phosphorus for chicks than reagentgrade, anhydrous DCP (Nelson and Walker, 1964;Nelson et al, 1965). Therefore, increasing the BV reported by Potchanakorn and Potter (1987) by 20% would result in the BV of the phosphorus in DCP being similar to that obtained in the present experiment for chicks. But even with that adjustment, the BV of the phosphorus in DFP for turkeys was still less than that obtained for chicks in the present experiment.…”

“…The BV of DCP and DFP were similar when tested at different times, indicating that for the materials tested, the BV of the phosphorus in current phosphates had not changed. Using turkeys, Waibel et al (1984) as well as Potchanakorn and Potter (1987) obtained lower BV for DFP than those found in the current study.…”

“…Potchanakorn and Potter (1987) used reagentgrade, hydrous DCP as the reference phosphate. It contained approximately 20% more available phosphorus for chicks than reagentgrade, anhydrous DCP (Nelson and Walker, 1964;Nelson et al, 1965).…”

“…Therefore, the feed phosphates produced today can differ from their counterparts of 20 to 30 yr ago. More recently, greater differences have been reported between the BV Published with the approval of the Director, Arkansas Agricultural Experiment Station, Fayetteville, AR 72701. determined with turkeys for DCP and for monobasic calcium phosphate (MCP) (Waibel et al, 1984;Potchanakorn and Potter, 1987). In subsequent work, Potter (1988) reported that the BV for DCP and DFP with turkeys were similar.…”

Phosphorus Bioavailability: A Key Aspect for Conserving this Critical Animal Feed Resource with Reference to Broiler Nutrition

“…In the 1980s and '90s, the bioavailability of P was routinely estimated by non-linear bioassays (asymptotic or sigmoidal curves) of body weight and tibia bone or toe ash, using a graded range of P supplements [37][38][39][40][41]. Others [42,43] determined P bioavailability using responses in bone ash content, bone breaking strength, body weight gain or blood inorganic P concentration of birds fed a test P source compared with the response of birds to a standard reference P source.…”