Dietary muramidase increases ileal amino acid digestibility of wheat and corn-based broiler diets without affecting endogenous amino acid losses.

The objective of these studies was to evaluate the impact of dietary muramidase (MUR) on endogenous amino acids (AA) losses and digestibility of nutrients in wheat and corn-based broiler diets. In experiment 1, the effect of dietary MUR on the flow of endogenous AA (EAA) at the jejunum and terminal ileum of broilers were assessed using either the nitrogen (N) free diet method (NFD) or the highly digestible protein diet method (HDP; 100 g casein/kg diet). Sialic acid and muramic acid concentrations were measured in the jejunal content. In experiment 2, a 2x2x2 factorial arrangement of treatments with 2 base grains (wheat or corn), with low or high metabolizable energy (ME) levels, and without or with MUR supplementation was implemented. All diets contained phytase, xylanase, and cellulase. Apparent ileal digestibility (AID) of dry matter (DM), protein (CP), amino acids (AA), crude fat, and energy, as well as the apparent total tract metabolizability (ATTM) of DM, CP, and gross energy (GE) were determined. The standardized ileal digestibility (SID) of AA was obtained by correcting AID values for basal ileal EAA obtained from chicks fed with NFD or HDP in experiment 1, jejunal EAA flow of all AA was higher (P < 0.001) compared to the ileum, but this effect was method dependent. Jejunal, but not ileal, EAA flow measured with HDP was higher compared to NFD, as well as sialic acid (P < 0.001) and muramic acid (P < 0.004) concentrations. Muramidase inclusion had no effect on basal EAA flow, independently of the segment and the method used. In experiment 2, dietary MUR supplementation increased the AID of CP (P < 0.05), all AA, and tended (P = 0.07) to increase the AID of GE, independently of the cereal type used. However, ATTM of DM and GE, but not CP, increased with MUR inclusion compared with the control treatments, especially in wheat and low ME diets (P < 0.05). In conclusion, MUR supplementation improved AID of CP and AA without affecting EAA losses and increases energy utilization.

Research Note: Formulating broiler diets using digestible calcium significantly improved growth performance but reduced apparent ileal digestibility of calcium and phosphorus.

An experiment was conducted to compare the use of a total and digestible Ca formulation system in broilers from hatch to d 37 post-hatch. Ross 308 (n = 288) male broilers were obtained and allocated to one of 2 dietary treatments in floor pens. There were 18 birds per pen and 8 replicate pens per diet. One diet was formulated using ingredient and nutrient recommendations for total Ca and the second diet was formulated using ingredient and nutrient recommendations for standardized ileal digestible (SID) Ca. All diets were formulated to be nutrient adequate using a 2-phase feeding program and including 0.19% available P (avP) and 0.209% total Ca or 0.073% digestible Ca from 1,000 FYT/kg of phytase. On d 17 and 37, tibias and ileal contents were obtained. From hatch to d 37, birds fed diets formulated using digestible Ca gained (P < 0.05) more and were more efficient (P < 0.05) compared with birds fed diets formulated using total Ca. There was no impact of formulation system on tibia ash or minerals. Litter pH (P < 0.05) was greater and litter dry matter (P < 0.05) was lower in birds fed the diets formulated using digestible Ca compared with those fed diets formulated using total Ca. Apparent ileal digestibility (AID) of Ca (P < 0.05), AID of P (P < 0.05) and digestible P intake (P < 0.05) were lower in birds fed diets formulated using digestible Ca compared with those formulated using total Ca at d 17 or 37. However, apparent ileal digested Ca and digestible Ca intake were not different between the experimental diets on d 17 or 37. In conclusion, formulating diets using digestible Ca improved weight gain and feed conversion ratio, but reduced the AID of Ca and P compared with birds fed diets formulated using total Ca. These findings might be reflective of the higher total Ca concentration in the diets formulated using digestible Ca compared with those formulated using total Ca.

Evaluation of the efficacy of a novel phytase in short-term digestibility and long-term egg production studies with laying hens.

Three independent trials were conducted to evaluate the efficacy of a novel phytase in laying hens. Trial 1 used a total of 90 laying hens (Lohmann Brown, 33-wk-old) fed either a negative control (NC) diet with 0.09% non-phytate P (NPP) or NC supplemented with 187.5 or 375 FYT phytase/kg feed for 4 d before collection of excreta and ileal digesta to measure ileal digestibility and retention of Ca and P. In trial 2 and 3, a total of 108 laying hens (Hy Line Brown, 25-wk-old) and 360 hens (Lohman Brown, 25-wk-old) were used, respectively. In both trials, the hens were randomly assigned to 3 dietary treatments: NC with 0.1% NPP, positive control (PC) and NC plus 187.5 FYT phytase/kg feed, the experimental diets were fed for 12 wk, and egg production and bone mineralization were measured. The results showed that the ileal digestibility of P increased both linearly (P = 0.012) and quadratically (P = 0.01) with increasing supplementation of phytase in trial 1. In trial 2, phytase supplementation significantly improved egg production, egg weight, and feed conversion ratio and reduced the percentage of broken eggs during the overall trial duration compared with NC. In trial 3, phytase significantly improved egg production, egg weight, and feed intake and reduced the percentage of broken eggs during the entire trial duration. In addition, percentage and weight of bone Ca and P increased significantly with added phytase. In trial 2 and 3, there was no significant difference between PC and the phytase treatment. In conclusion, the novel phytase significantly increased the ileal digestibility of P in a short-term digestibility study and improved egg production and bone mineralization in a 12-wk laying cycle. Ileal digestibility of P rather than P retention in short-term digestibility studies as well as egg production and whole tibia mineralization in long-term studies should be measured to demonstrate the efficacy of phytase in laying hens.

Exploratory transcriptomic analysis in muscle tissue of broilers fed a phytase-supplemented diet.

The effect of phytase on phosphorus retention, broiler (Gallus gallus) performance and bone mineralization in diets with reduced inorganic phosphate concentration is well documented. Furthermore, so-called 'extra-phosphoric' effects of phytase have been described in the literature that may be associated with changes in mineral and amino acid partitioning and requirements per se. In particular, the role of myo-inositol in phytase responses is implied but not well elucidated. It was the purpose of the experiment reported herein to explore the effect of phytase on broiler growth, nutrient digestibility, blood biochemistry and gene expression. A 5-week broiler floor pen trial was conducted to evaluate the effect of supplementation of a moderately phosphorus-deficient diet with 1000 U/kg of a 6-microbial phytase. Parameters measured were growth performance, phosphorus (P), calcium (Ca) and myo-inositol plasma concentrations, apparent ileal P digestibility, bone mineralization, breast meat weight and Pectoralis major muscle transcriptome. Supplementation of the diet with phytase improved weight gain during the starter period (18%) and the whole period (24%) compared with animals that received the control diet (p < 0.05). Improved feed conversion ratio, increased myo-inositol plasma concentration, tibia ash contents and breast meat weight were also observed in animals fed phytase. The transcriptomic analysis revealed that some differentially expressed genes (DEG) in broilers, receiving phytase in comparison with animals fed reduced phosphorus diet without phytase, were part of pathways involved in muscle development, via calmodulin/calcineurin and insulin-like growth factor. Microarray data confirmation was performed on six genes by quantitative PCR (qPCR): PI3K regulatory and catalytic subunit, Phospholipase C beta, Myocyte Enhancer Factors 2A and 2C, and calcineurin A. The results suggested that dietary supplementation with this phytase could generate low molecular weight phytate esters and indirectly myo-inositol, and could help us to understand how muscle metabolism may be affected at a gene level.

Use of near infrared reflectance spectroscopy to predict phytate phosphorus, total phosphorus, and crude protein of common poultry feed ingredients.

The purpose of the study that is presented herein was to develop near-infrared reflectance spectroscopy (NIRS) calibrations to predict total phosphorus (P), phytate-P, and protein concentrations of feed ingredients commonly used in monogastric feed formulation. Samples representing 14 vegetable ingredients (cereals, cereal by-products, and oilseed meals) were collected worldwide throughout 2013. The samples were assayed by standard wet chemical techniques for total P, phytate-P, and protein content. There was substantial variability in protein, phytate-P, and total P within and between ingredients used in the calibration set. Protein content varied from 76 to 487 g/kg. Total P ranged from 2.09 and 22.5 g/kg and phytate-P ranged from 0.99 and 13.8 g/kg. Within these broad ranges, NIRS values were highly correlated for determination of protein, total P, and phytate-P with a standard error of prediction equal to 9.06 g/kg, 0.80 g/kg, and 0.66 g/kg, respectively. The wide diversity and heterogeneity of the mix of feed ingredients allowed the development of NIRS calibrations of sufficient accuracy to help nutritionists control the nutritional composition of their feed.