Effect of level of acidification by phosphoric acid, storage temperature, and length of storage on the chemical and biological stability of ground poultry mortality carcasses

Two experiments were conducted to evaluate the addition of feed-grade H3PO4 in comparison to lactic acid fermentation as a means of preserving ground poultry mortality carcasses. Mortality silage quality in both experiments w as evaluated by measuring the rise in pH after initial acidification (Delta pH) and the content of nonprotein N (NPN), volatile nitrogen (VN), NH3-N, and fecal coliform bacteria in the silage treatments. Preliminary work in E xperiment 1 evaluated the preservative effects of six initial levels of aci dification with H3PO4 (pH 2.0, 2.5, 3.0, 4.0, or 5.0) at two storage temper atures (21 and 45 C). Experiment 2 compared silages preserved with differen t levels of feed-grade 74.5% H3PO4 (4.13, 5.52, 6.90, and 8.28% wt/wt, conc entrated acid basis) to silages made by lactic acid fermentation. Based on the evaluations in Experiment 1, acidification with H3PO4 to pH less than o r equal to 3.0, when incubated at 45 C, or pH less than or equal to 2.0, wh en incubated at ambient temperatures, produced the most biologically favora ble poultry mortality silage for subsequent use as a feed ingredient. In Ex periment 2, mortality silages containing 8.28% H3PO4 (wt/wt, concentrated a cid basis) contained significantly (P < 0.05) lower levels of the protein d egradation by-products VN and NH3-N than silages prepared by lactic acid fe rmentation. Therefore, feedstuffs manufactured from mortality silages prepa red using 8.28% H3PO4 would be expected to result in improved animal perfor mance vs. feedstuffs manufactured using silages prepared by lactic acid fer mentation.