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The effects of sodium hydroxide treatment and other factors on the utilization of DPW by the chicks Kwok, Ming Cheung


Broiler performance was studied with diets containing 10, 15 and 20% dried poultry waste (DPW) or sodium hydroxide treated DPW. Feeding trials in evaluating the utilization of non-protein nitrogen in the DPW, the supplemental energy requirement, the effects of amino acid supplementation, and antibiotic supplementation on the utilization of nutrients in the diets containing DPW were carried out. Metabolism studies were conducted to determine the availability of protein and minerals in DPW. Studies showed that DPW when added to the broiler diet at levels between 10-20% would support growth related to the dietary energy. Inclusion of DPW in the diet did not affect growth but lowered the feed efficiency when compared to the control diets containing similar energy and protein contents. Alkali treatment at various concentrations markedly improved the growth and feed efficiency of diets containing various levels of DPW. The metabolizable energy values of untreated DPW or DPW treated with 2, 3 or 5% sodium hydroxide were determined to be 827, 1155, 1245 and 1205 kcal/kg dry matter respectively. Supplementing the basal diets which were suboptimal in protein level with uric acid, urea, diammonium citrate or from the NPN in the DPW did not improve the growth of chicks. Nitrogen retention was reduced by the supplementation and uric acid excretion was increased indicating that these nitrogen sources would not be utilized for growth by chicks. The availability of total nitrogen and true protein of untreated DPW, DPW treated with 2, 3 or 5% sodium hydroxide were 63.6 and 50.5%; 83.2 and 66.1%; 83.3 and 70.2%; and 90.4 and 72.2% respectively. The availability of calcium and phosphorus in untreated DPW was 53.8 and 19.8% respectively. The calcium and phosphorus availabilities were not significantly affected by the alkali treatments. The sodium availability of untreated DPW was 84.4%, which was decreased to 41.8%-48.3% by the alkali treatments. Supplementing the basal diets with 0.2% methionine significantly improved the growth of chicks fed the control diet but did not affect those fed the DPW diets (untreated or alkali treated). Growth of chicks fed the DPW diets were better than that of the control (without supplementation). These indicated that the amino acids in DPW could be utilized for growth. Increasing the energy level of the diets by adding 2% fat improved the growth and nitrogen utilization of chicks indicating the poorer performance of chicks fed DPW diets was related to its energy dilution effect. In the absence of antibiotics, the dietary fat (tallow) utilization was impaired with the inclusion of DPW in the diet. The metabolizable energy of the diets was directly related to fat utilization. Antibiotics addition completely ameliorated the adverse effect of DPW on fat utilization and markedly increased the M.E. of the diets and improved the growth and feed efficiency. Antibiotics supplementation had. no effect on the nitrogen and minerals retention of the diets.

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