PHOSPHORUS AND FLUORINE INTERRELATIONSHIPS IN POULTRY

Three experiments were conducted to evaluate the influence of phosphorus sources and level, Ca:P ratio, fluorine and heat stress on performance of turkey poults and broiler chicks. Two additional experiments were conducted primarily to measure the bioavailability of fluorine in different phosphate products. Large White (Nicholas strain) poults were used in the first experiment which involved a 2 x 3 x 3 factorial arrangement of variables with feed grade dicalcium phosphate (DCP) and concentrated triple superphosphate (CTSP, a fertilizer) as P sources. There were three levels of added P (.2, .3, and .4%) from each source and three levels of added F (200, 400, and 600 ppm) provided by NaF. A second experiment conducted with broiler chicks involved a 2 x 4 x 2 factorial arrangement of variables with DCP and CTSP, four levels of added P (.1, .15, .2 and .3%) and two levels of added F (400 and 800 ppm). A third experiment also conducted with broiler chicks and involved a 2 x 2 x 2 x 2 factorial arrangement of variables with DCP and raw rock phosphate (RRP), two levels of added P (.2 and .4%), two levels of added F (0 and 500 ppm) and two ratios of Ca:P (1.25:1 and 2,50:1). Basal diets used in these experiments were composed largely of ground yellow corn and soybean meal. Results of these experiments indicated that CTSP and RRP were inferior to DCP. Body weight gain of birds increased linearly with P level, but decreased linearly with F level, which was reflected by an interaction between P and F level (P \u3c .05). Increasing P level resulted in increased body weight gain and bone ash percentage, but decreased mortality rate and F content of bone ash (P \u3c .05). Increasing the F level resulted in decreased body weight gain and bone ash percentage, but increased mortality rate and F content of bone ash (P \u3c .05). Responses to heat stress in relation to dietary treatments were inconclusive. The percent bioavailabilities of F from CTSP-1, CTSP-2, and RRP were 64.1, 59.7, and 35.2, respectively, when F content of tibia ash from 3-week old turkeys was used as the response criterion and dietary P level was as recommended. The percent bioavailabilities of F from CTSP-1, CTSP-2, double-float uncalcined rock (DFUR), and double-float calcined rock (DFCR) were 63.7, 57.7, and 24.0, respectively, when the F content of eggshell ash after 2 weeks feeding (layers) was used as the response criterion