Phytase supplementation effects on amino acid digestibility depend on the protein source in the diet but are not related to InsP6 degradation in broiler chickens

Abstract

The objective was to determine phytase effects on prececal amino acid ( AA ) digestibility and phytate (InsP 6 ) breakdown when different oilseed meals were used in broiler chicken diets. The study included 14 diets: a corn-soybean meal ( SBM ) basal diet and 6 diets that contained SBM, rapeseed meal ( RSM ), and sunflower meal ( SFM ) with 2 inclusion levels at the expense of corn starch (150 and 300 g/kg SBM or SFM, or 100 and 200 g/kg RSM). Each diet was mixed with or without a phytase supplement of 1,500 FTU/kg. Diets were provided to broilers for 5 D. Digesta from the posterior half of the ileum were collected on day 21. The average essential AA digestibility, calculated by a regression approach, without and with phytase was 84 and 85% (SBM), 74 and 77% (SFM), and 66 and 73% (RSM), respectively. In the diets, phytase effects on AA digestibility were lower owing to other protein sources also present in the diet, but significant. Prececal InsP 6 disappearance was significantly affected by interactions between oilseed meal, inclusion level, and phytase supplementation. Overall, prececal InsP 6 disappearance was higher in SBM diets (52%) than in SFM diets (38%) and intermediate in RSM diets (43%). Across diets, phytase supplementation effects on prececal InsP 6 degradation linearly increased with the InsP 6 concentration of the diet up to 12 g/kg DM. The only exception from linearity was the diet with the high inclusion of SFM, which contained 15.9 g InsP 6 /kg DM. In the ileal content, the concentration of myo -inositol was significantly increased by phytase supplementation, and this effect was highest in the diets that contained SBM as the only oilseed meal. Concentrations of lower inositol phosphates were increased by phytase supplementation, and this effect was most remarkable for Ins(1,2,3,4)P 4 and inositol tetrakisphosphates. The study showed that phytase effects on AA digestibility varied among the 3 tested oilseed meals, but these differences were not detectable in the diets containing these meals. Although phytase effects on ileal content of InsP 6 and its degradation products were substantial, they were not related to the effects on AA digestibility.

Amino acid digestibility and metabolisable energy of spring and winter faba beans grown on two sites and effects of dehulling in caecectomised laying hens

“…maize 45 . Such negative correlations might have been caused by phytate–protein complexes 46 . Supplementing the phytate‐degrading enzyme phytase to diets can verify whether phytate are causative for the low AA digestibility of faba beans rich in phytate.…”

“…45 Such negative correlations might have been caused by phytate-protein complexes. 46 Supplementing the phytate-degrading enzyme phytase to diets can verify whether phytate are causative for the low AA digestibility of faba beans rich in phytate. In contrast to AA digestibility, no relation between phytate and ME N was determined while a previous study described phytate to be negatively correlated with ME N and starch digestibility in broiler chickens.…”

Low-calcium diets increase duodenal mRNA expression of calcium and phosphorus transporters and claudins but compromise growth performance irrespective of microbial phytase inclusion in broilers

“…Numerous studies have been published (e.g., Bello et al (2019) , Krieg et al. (2020) , and Ajuwon et al.…”

Effects of a novel consensus bacterial 6-phytase variant on the apparent ileal digestibility of amino acids, total tract phosphorus retention, and tibia ash in young broilers

“…Responses of individual AA to phytase are not equal ( Ravindran et al, 1999 ; Cowieson et al, 2006 ), appear to differ in male and female broilers ( Sebastian et al, 1997 ), with bird strain and age ( Li et al, 2015 ), and can vary among different phytases even when tested under the same conditions at equivalent dose-level ( Dersjant-Li and Kwakernaak, 2019 ). The AA response to phytase may also be influenced by a range of dietary related factors including the inherent AA and protein digestibility of feedstuffs in the diet ( Ravindran et al, 1999 ; Krieg et al, 2020 ), phytate content ( Cabahug et al, 1999 ; Walk and Rao, 2020 ), and Ca content or ratio to digestible P ( Sebastian et al, 1997 ; Amerah et al, 2014 ). A key step in understanding the effects of a new phytase on AA nutrition is to evaluate and characterize the dose-response of AA digestibility under controlled conditions using diet compositions relevant to commercial practice.…”