Effect of feeding broilers diets differing in susceptible phytate content

Abstract

Measurements of total phytate phosphorus content of diets may be deceptive as they do not indicate substrate availability for phytase; it may be that measurements of phytate susceptible to phytase effects are a more accurate measure of phosphorus (P) availability to the bird. To verify this hypothesis, an experiment was conducted to compare diets formulated to contain either high or low susceptible phytate, supplemented with either 0 or 500 FTU/kg phytase. Susceptible phytate was determined by exposing the feed samples to conditions that mimicked the average pH of the proximal gastrointestinal tract (pH 4.5) and the optimum temperature for phytase activity (37 °C) and then measuring phytate dissolved. Ross 308 birds (n = 240) were fed one of 4 dietary treatments in a 2 × 2 factorial design; 2 diets with high (8.54 g/kg, 57.90% of total phytate) or low (5.77 g/kg, 46.33% of total phytate) susceptible phytate, containing 0 or 500 FTU/kg phytase. Diets were fed to broilers (12 replicate pens of 5 birds per pen) from d 0 to 28 post hatch. Birds fed diets high in susceptible phytate had greater phytate hydrolysis in the gizzard (P < 0.001), jejunum (P < 0.001) and ileum (P < 0.001) and resulting greater body weight gain (BWG) (P = 0.015) and lower FCR (P = 0.003) than birds fed the low susceptible phytate diets, irrespective of phytase presence. Birds fed the high susceptible diets also had greater P solubility in the gizzard and Ca and P solubility in the jejunum and ileum (P < 0.05) and resulting greater tibia and femur Ca and P (P < 0.05) content than those fed the low susceptible diets. All the susceptible phytate was fully degraded in the tract in the absence of added phytase, suggesting the assay used in this study was able to successfully estimate the amount of total dietary phytate that was susceptible to the effects of phytase when used at standard levels. No interactions were observed between susceptible phytate and phytase on phytate hydrolysis. Hydrolysis of phytate was greater (P < 0.05) in the gizzard of birds fed the diets supplemented with phytase, regardless of the concentration of susceptible phytate in the diet. Phytase supplementation resulted in improved BWG (P < 0.001) and FCR (P = 0.001), increased P solubility (P < 0.001) in the gizzard, Ca and P solubility (P < 0.001) in the jejunum and ileum and Ca and P concentration (P < 0.001) and strength (P < 0.001) in the tibia and femur. Pepsin activity was higher in birds fed the diets supplemented with phytase (P < 0.001) and was greater (P = 0.031) in birds fed the high susceptible phytate diets compared with the low susceptible phytate diets. Findings from this study suggest that there may be a measure more meaningful to animal nutritionists than measurements of total phytate.

Influence of phytate and phytase on performance, bone, and blood parameters of broilers at 42 days old

“…The phytate content in the diets did not influence broiler performance variables, probably because the phytate concentration among diets was not large enough to show statistical differences. In a study by Morgan et al (2016), there was an improvement in WG and FCR of broilers fed diets with highly degradable phytate compared with those fed diets with a lower level of degradable phytate, suggesting the occurrence of higher phytate hydrolysis in broilers fed the highly susceptible diet. The degradable phytate fraction was indicated to interfere in the digestion process and the higher level of hydrolysis of this fraction may be correlated with better performance.…”

“…In phytate-rich diets, higher phytate hydrolysis occurs along the gastrointestinal tract, regardless of the presence or absence of phytase. Other factors, such as the ingredients of the diet, mineral and protein concentrations, phytate solubility, and gastrointestinal pH, can influence phytate degradation (Morgan et al, 2016).…”

Stimulatory effect of medium components on phytase production by Aspergillus niger and biotechnological application as a poultry feed additive

“…This phytic acid phosphorous is not usually accessible to the birds fed on plant-based diets due to insufficiency or lack of endogenous enzyme activity (Marchal et al, 2021), and is excreted without being digested (Kumar et al, 2012;Lalpanmawia et al, 2014) and absorbed in the digestive tract of monogastric animals. Due to the anti-nutritional effect, phytate has a negative effect on the digestion of other nutrients and thus reduces the poultry growth performance (Woyengo et al, 2013;Morgan et al, 2016).…”

Effect of Bacterial or Fungal Phytase Supplementation on the Performance, Egg Quality, Plasma Biochemical Parameters, and Reproductive Morphology of Laying Hens

“…Nevertheless, two-thirds of the total phosphate content in plant seeds is stored as phytate P and excreted without being digested [ 1 , 2 ]. Phosphorus phytate is poorly absorbed in the gastrointestinal tract of monogastric animals and can additionally negatively affect the digestibility of other nutrients and poultry performance due to its anti-nutritional impact [ 3 , 4 ]. Although sources of inorganic P, such as dicalcium phosphate, can be added to poultry diets, this will increase the amount of released P in the manure.…”