Interaction of calcium and phytate in broiler diets. 2. Effects on total and soluble phosphorus excretion

Synthesis of Carbon Nanotubes (CNTs) from Poultry Litter for Removal of Chromium (Cr (VI)) from Wastewater

Pakistan, an agricultural country, raises 146.5 million commercial and domestic poultry birds, which generate around 544,831 tons of waste per year. This waste finds its final disposal in agricultural land as soil fertilizer or disposal site amendment. The usage of poultry litter for this purpose is uncontrolled, which results in environmental degradation such as emission of greenhouse gases, e.g., methane. However, alternative options such as thermochemical conversion of poultry litter can offer better solutions where this waste can be used as a low-cost carbon source for the synthesis of Multiwalled Carbon Nanotubes (MWCNTs). In this study, efforts were made to utilize this cheap and plentiful carbon source for the synthesis of CNTs in the presence of Ni/Mo/MgO as a catalyst, through pyrolysis. For a better yield of carbon product, the optimum ratio for the catalysts (Ni/Mo/MgO) was found to be 4:0.2:1. Furthermore, the process parameters were also optimized for better carbon yield. A good yield of CNTs resulted from a pyrolysis time of 12 min, a temperature of 825 °C, and a catalyst weight of 100 mg. The structure and morphology of the produced nanotubes were confirmed through X-ray Diffractometer (X-RD) and Scanning Electron Microscopy (SEM). The environmental application of the nanotubes was tested in a synthetic chromium solution in the lab using a batch experiment. Different experimental conditions (pH, adsorbent dosage, and contact time) were optimized to improve the adsorption of Cr (VI) by carbon nanotubes and a UV-Visible spectrophotometer was used at 540 nm to measure the absorbance of Cr (VI). The results showed that up to 81.83% of Cr (VI) removal was achieved by using 8 mg of CNTs at pH 3 with 400 rpm at 180 min of contact time. Thus, it was concluded that poultry litter can be a useful source for the synthesis of MWCNTs and thereby removal of Cr (VI) from industrial tanneries' wastewater.

Effect of feeding broilers diets differing in susceptible phytate content

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.

Contribution of intestinal- and cereal-derived phytase activity on phytate degradation in young broilers

There is little consensus as to the capability of poultry to utilize dietary phytate without supplemental phytase. Therefore, an experiment was conducted to examine the extent to which endogenous phytase of intestinal and cereal origin contributes to phytate degradation in birds aged 0 to 14 d posthatch. Ross 308 broilers (n = 720) were fed one of 4 experimental diets with differing dietary ingredient combinations and approximate total phytate levels of 10 g/kg, dietary phytase activity analyzed at 460 U/kg, dietary calcium (Ca) levels of 11 g/kg, and nonphytate-phosphorus (P) levels of 4 g/kg. Broiler performance, gizzard, duodenum, jejunum and ileum pH, Ca and P digestibility and solubility, amount of dietary phytate hydrolyzed in the gizzard, jejunum, and ileal digesta phytase activity were analyzed at d 4, 6, 8, 10, 12, and 14 posthatch. Intestinal endogenous phytase activity increased significantly (P < 0.001) between d 4 and 6, resulting in increased phytate hydrolysis in the gizzard (P = 0.003), jejunum (P < 0.001), and ileum (P < 0.001). Phytase activity and phytate hydrolysis continued to increase with age, with a greater phytase activity and associated increase in phytate hydrolysis and mineral utilization between d 10 and 12. Gizzard and jejunum Ca and P solubility and ileal Ca and P digestibility increased significantly (P < 0.001), and gastrointestinal pH decreased significantly (P < 0.001) between d 4 and 6. By d 14, phytase activity recovered in the ileum was approximately 45 U/kg. There were strong correlations between phytase activity measured in the ileum and phytate hydrolyzed in the gizzard (r = 0.905, P < 0.001), jejunum (r = 0.901, P = 0.023), and ileum (r = 0.938, P = 0.042). This study shows intestinal- and dietary-derived endogenous phytase activity is responsible for phytate-P hydrolysis in broilers.

In vitro versus in situ evaluation of the effect of phytase supplementation on calcium and phosphorus solubility in soya bean and rapeseed meal broiler diets

1. In vitro assays provide a rapid and economical tool to evaluate dietary effects, but have limitations. In this study, the effect of phytase supplementation on solubility, and presumed availability, of calcium (Ca) and phosphorus (P) in soya bean meal (SBM) and rapeseed meal (RSM) based diets were evaluated both in situ and by a two-step in vitro digestion assay that simulated the gastric and small intestine (SI) phases of digestion. 2. Comparison of the in vitro findings to in situ findings was used to evaluate the in vitro assay. Ross 308 broilers (n = 192) were fed on one of 6 SBM or RSM diets supplemented with 0, 500 or 5000 FTU/kg phytase from 0 to 28 d post hatch. The 6 diets and raw SBM and RSM were exposed to a two-step in vitro assay. Ca and P solubility and pH in the gizzard and jejunal digesta and in the gastric and SI phase of in vitro digestion were measured. 3. Both in vitro and in situ analyses detected that Ca solubility was lowest when diets were supplemented with 500 FTU/kg phytase, compared to the control diets and diets supplemented with 5000 FTU/kg phytase. Phosphorus solubility increased with increasing phytase level. Both methods also identified that mineral solubility plateaus in the gastric phase. 4. Overall relationship of the two methods was strong for both determination of gastric phase Ca and P solubility (r = 0.96 and 0.92, respectively) and also SI phase Ca and P solubility (r = 0.71 and 0.82, respectively). However, mineral solubility and pH were higher when measured in vitro than in situ, and the in situ assay identified an interaction among the effects of phase, protein source and phytase inclusion level on Ca solubility that the in vitro assay did not detect. 5. This two-step in vitro assay successfully predicted phytase efficacy, but to determine detailed response effects in the animal, in situ data is still required.

Effect of feeding diets containing a probiotic or antibiotic on broiler performance, intestinal mucosa-associated avian pathogenic E. coli and litter water-soluble phosphorus

The aim of the present experiment was to examine the influence of feeding diets containing a probiotic containing three Bacillus subtilis strains or zinc bacitracin (BMD) on bird performance, intestinal mucosa-associated avian pathogenic Escherichia coli (APEC), intestinal morphology and litter water-soluble phosphorus (WSP) of broilers fed corn-based diets. Three treatments were employed, either a control diet; the control diet supplemented with probiotic at 7.5 × 104 colony forming units (cfu) /g of feed or the supplemented with BMD (50g/tonne feed). Broiler starter and finisher diets, based on corn and soybean meal, were formulated and fed ad libitum to seven pens of 50 male broilers per treatment from days 1 to 42. During the 1-35 d periods, feed intake and weight gain were not influenced (P > 0.05) by dietary treatments, but probiotic supplementation improved (P < 0.05) 35-d FCR compared to the control and BMD-supplemented diets (1.395, 1.447 and 1.484, respectively). During the 1-42d period, feed intake and weight gain were not influenced (P > 0.05) by dietary treatments. However, probiotic improved (P = 0.05) and BMD tended (P = 0.07) to improve FCR compared to control diet. Villus height and crypt depth in the duodenum and jejunum were not influenced (P > 0.05) by dietary treatment. The number of mucosa-associated APEC was not influenced (P > 0.05) by dietary treatments. Probiotic and BMD supplementation had no effect (P > 0.05) on litter total phosphorus. However, BMD reduced (P < 0.05) litter WSP compared to control and probiotic supplemented diet. In conclusion, probiotic supplementation had no effect on intestinal morphology or WSP but improved broiler performance and can be used as an alternative to antibiotic growth promoters.