Abstract
Phytate forms insoluble precipitates with various cations that are recalcitrant to digestion in poultry. Dietary supplementation with exogenous phytase has been shown to improve phytate solubility and digestibility and, in turn, improve animal growth performance. Although the kinetics of phytate hydrolysis by exogenous phytase are well described in vitro, the progression of the reaction in vivo is still not well defined. The aim of the present study was, therefore, to monitor the kinetic variation of myo-inositol (myo-Ins) levels in both circulation and feather following exogenous phytase supplementation. In experiment 1, 4 week-old male broilers were individually housed with ad libitum access to water and a standard commercial diet. Birds were maintained under environmental temperature of 24°C and 30% RH. Birds were cannulated in the cutaneous ulnar vein on the right wing and remained untouched for 3 days. On the day of the experiment, birds were randomly divided into three body weight-matched groups and fed either the control diet, the control diet-supplemented with myo-Ins or Ronozyme HiPhos (0.06%, DSM Nutritional Products, Switzerland) for 10 h. In the experiment 2, birds were fed only HiPhos for 30 h. Growing feathers and blood were collected at baseline and then every 2 h for 10 h (experiment 1) and 30 h (experiment 2) post-prandially. Plasma and feather myo-Ins levels were determined by UHPLC-MS/MS. The relative expression of inositol polyphosphate-1-phosphatase (INPP1), inositol hexakisphosphate kinase 1-3 (IP6K1-3), inositol-3-phosphate synthase (ISYNA), and multiple inositol-polyphosphate phosphatase 1 (MNPP1) genes in blood and feathers was determined by real-time qPCR using 2–ΔΔCt method. Plasma and feather myo-Ins levels were significantly increased by HiPhos at 6 h to 8 h post-prandial. The mRNA abundances of INPP1, IP6K1, and ISYNA in the circulation were significantly down regulated at all periods compared to the baseline levels. IP6K2, IP6K3, and MINPP1 gene expression, however, was up regulated at 8 h post-prandial and then returned to the baseline levels. In feathers, the expression of INPP1 was induced at 8 h post-prandial and remained higher compared to the baseline. The expression of IP6K2, IP6K3, and MINPP1 was down regulated during the first 10 h and then returned to baseline levels for the rest of the post-prandial period. Taken together, our data show that phytase modulates the expression of genes associated with myo-Ins metabolism and generates release of myo-Ins in both circulation and feather at 6–10 h post-feeding. Feather myo-Ins concentration could be used as a non-invasive method to monitor phytate hydrolysis in practice.
Highlights
IntroductionA large proportion of the phosphorous (P) is bound in the form of phytate, the mixed salt of phytic acid (myoinositol hexakisphosphate; InsP6) (Plimmer and Page, 1913; Maga, 1982; Eeckhout and De Paepe, 1994; Viveros et al, 2000)
In plants, a large proportion of the phosphorous (P) is bound in the form of phytate, the mixed salt of phytic acid (Plimmer and Page, 1913; Maga, 1982; Eeckhout and De Paepe, 1994; Viveros et al, 2000)
As myo-Ins has been shown to be involved in hirsutism treatment (Minozzi et al, 2008), and as feathers have been demonstrated to be a new biomonitoring tool (Jaspers et al, 2011), we extended our analysis to growing feathers
Summary
A large proportion of the phosphorous (P) is bound in the form of phytate, the mixed salt of phytic acid (myoinositol hexakisphosphate; InsP6) (Plimmer and Page, 1913; Maga, 1982; Eeckhout and De Paepe, 1994; Viveros et al, 2000). The majority of commercial poultry diets have been supplemented with exogenous phytase (Bedford, 2000) to improve the use and absorption of phytate-P, but to decrease the anti-nutritive effects of this compound (Mullaney et al, 2000; Selle and Ravindran, 2007). This supplementation has beneficial effects on broiler performance, including increased body weight gain, feed efficiency (Dilger et al, 2004; Dos Santos et al, 2013), and nutrient utilization (Liu et al, 2014). As myo-Ins has been shown to be involved in hirsutism treatment (Minozzi et al, 2008), and as feathers have been demonstrated to be a new biomonitoring tool (Jaspers et al, 2011), we extended our analysis to growing feathers
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