Ileal Digestibility and Total Tract Retention of Phosphorus in Inorganic Phosphates Fed to Broiler Chickens Using the Direct Method

Abstract

The objective of this study was to determine and compare the phosphorus (P) utilization of inorganic phosphates fed to broiler chickens using the direct method. On day 15 of age, six hundred forty 15-day-old male Ross 308 broiler chickens (initial body weight = 399 ± 38 g) were assigned to five experimental diets with 16 birds per cage in a randomized complete block design. The experimental diets consisted of four semi-purified diets containing monocalcium phosphate, monodicalcium phosphate, dicalcium phosphate, and tricalcium phosphate as the sole P sources. Additionally, a P-free diet was prepared to measure basal endogenous P loss. Chromic oxide was added to the experimental diets as an indigestible index. Excreta were collected per cage on days 17 to 18 of age, and all birds were asphyxiated with carbon dioxide on day 19 of age for ileal digesta collection. The cage was an experimental unit, and the number of replications per each treatment was eight except for the tricalcium phosphate treatment (n = 4). There was no interaction observed between the P source and the collection site (ileal digestibility vs. total tract retention). Phosphorus utilization differed (p < 0.05) among inorganic phosphates and the ileal digestibility of P was greater (p < 0.05) than the total tract retention. In conclusion, the standardized ileal digestibility of P in inorganic phosphates ranged from 56.7% to 89.8% and ileal digestibility was greater than the total tract retention.

Evaluation of Phosphorus Digestibility from Monocalcium and Dicalcium Phosphate Sources and Comparison between Total Tract and Prececal Digestibility Standard Methods in Broilers

“…Furthermore, differences between the ATTDP and pc-DP methods could be related with compensation mechanisms when broilers are fed P-deficient diets. An et al [ 8 ] outlined that, when Ca and P intake is low, the mobilization of Ca and P from bone can be promoted to maintain homeostasis, and thus, a portion of mobilized P can be found in the excreta, resulting in low ATTDP values. This would lead to the underestimation of ATTDP (either tc or m method) calculated via excreta compared with pc-DP.…”

“…Recently, alternative quantitative approaches to the WPSA protocol [ 6 ] have been assayed to evaluate P digestibility from mineral phosphates, plant and animal sources: the direct method [ 7 , 8 ] and the precision-fed chick assay [ 9 ]. The direct method requires a semi-purified P-free diet and thus can be considered impractical because semi-purified diets (based on corn starch and sucrose) can alter feed intake.…”

“…Previous studies performed at a marginal P level of supply to avoid endogenous excretion have shown that there were no significant differences between ATTDP-tc and pc-DP approaches for a given inorganic phosphate source with the regression technique [ 12 ]. An et al [ 8 ] and Munoz et al [ 9 ], however, found pc-DP exhibited higher results compared with ATTDP for meat and bone meal and various phosphates, including MCP and DCP.…”

Effect of Feeding a High Calcium: Phosphorus Ratio, Phosphorous Deficient Diet on Hypophosphatemic Rickets Onset in Broilers

“…The rapidity of impact reflected the greater impact of a Ca:P imbalanced diet on tibia bone mineral density and ash content, and therefore, bone-breaking strength, compared with a Ca:P balanced, P-deficient diet [26]. This may be because a high dietary Ca:AP ratio causes the formation of insoluble Ca-P complexes in the intestines [27], reducing the true digestibility of Ca [17], increasing Ca excretion, and decreasing plasma P concentration [16], thus leading to poor tibial mineralization [10,11]. In our study, no consistent difference was observed in lesions of visceral organs (heart, liver, spleen, kidney, bursal, gizzard, gut, thymus, and abdominal fat) between healthy chicks and lame chicks.…”

Evaluation of the ileal digestibility and excreta retention of phosphorus for feed phosphates in broiler chickens and in Pekin ducks

“…However, the regression method requires a basal diet and diets supplemented with at least two concentrations of a test P source, making it more expensive and laborious and the values of the ileal P digestibility ( iPD ) or the excreta P retention ( ePR ) can be affected by dietary nPP levels. An et al (2020) used the direct method to determine the iPD and ePR of commercial feed phosphates in broilers and recommended that the direct method has some advantages in comparison with the regression method. The semi-purified diets, however, are used in the direct method are less practical and cause an abnormal growth or physiology for poultry.…”