Effects of dietary total phosphorus concentration and casein supplementation on the determination of true phosphorus digestibility for broiler chickens

Abstract

A study was conducted to compare the regression-driven estimates of true precaecal digestibility (TPD) of phosphorus (P) in soybean meal (SBM) for broiler chickens fed diets with or without casein supplementation at moderate or low total P concentration. A total of 768 male Ross 308 broilers were allocated to 12 diets in a 2 Â 2 Â 3 factorial arrangement of two total P concentration (moderate-P or low-P), two diet types (with or without casein) and three SBM levels (low, medium or high). There were 8 chicks per cage and 8 replicate cages per treatment group in a randomised complete block design. The birds were fed experimental diets form d 14 to 21 posthatching. Chromic dioxide was used as an indigestible marker. The results showed that dietary casein supplementation improved body weight (BW) gain, feed intake and feed efficiency of broilers (p < .01). Broilers fed the moderate-P diets had greater dietary total P intake, precaecal flow and total tract output of P, precaecal digested P, and total tract retained P compared with birds fed the low-P diets (p < .01). Dietary casein supplementation increased precaecal digested P, total tract retained P, apparent precaecal digestibility (APD) and total tract retention (TTR) of P (p < .01). Broilers fed the moderate-P diets had a linear decrease in the APD and TTR of P with increasing SBM levels (p < .01). Precaecal digested P and total tract retained P increased with graded inclusion of SBM levels (linear, p < .01). Regression of precaecal digested P against dietary P intake showed that chicks fed the moderate-P diets had lower estimates of TPD of P in SBM than that for chicks fed the low-P diets (p < .05), while dietary casein supplementation had no effects on the determined values of TPD of P. In conclusion, the regression-driven true phosphorus digestibility in assay feed ingredients for broiler chickens was affected by dietary total P concentration.

Comparison of different protein sources on the phosphorus digestibility of soybean meal for broiler chickens determined using the regression method

“…The digestibility of P in soybean meal determined in diets where SBM provided all the protein or with the addition of casein or PPI were found to be similar when comparing the respective confidence intervals of each regression ( Table 4 ). This result is consistent with previous findings of Abbasi et al (2018) and Liu et al (2014) , that found that adding casein at 50 g/kg did not impact the regression-derived P digestibility of SBM. Thus, indicating that the inclusion of ingredients with highly digestible protein content in the basal diet does not affect the P digestibility of test ingredients.…”

Relationship between true digestibility of dietary phosphorus and gastrointestinal bacteria of goats

“…These are the main requirements of using the DLT to determine TDP. The average TDP of this study was 83.28%, which was higher as compared to pigs [31] or chickens [32]. Compared with https://doi.org/10.1371/journal.pone.0225018.g004…”

Relationship between True Digestibility of dietary Phosphorus and Gastrointestinal Bacteria of Goats

“…These are the main requirements of using the DLT to determine TDP. The average TDP of this study was 83.28%, which was higher compare to values described in pigs [30] and in chickens [31]. Compared with monogastric animals, the digestibility of feed phosphorus was higher in ruminants, mainly because ruminants have more abundant gastrointestinal microorganisms that can secrete phytase to hydrolyze phytic acid to release phosphorus, thereby promoting the digestion of feed phosphorus [32].…”