Effect of Select Tannin Sources on Pathogen Control and Microbial Nitrogen Metabolism in Composted Poultry Litter Intended for Use as a Ruminant Crude Protein Feedstuff

Abstract

Poultry litter is a good crude protein supplement for ruminants but must be treated to kill pathogens before feeding. Composting effectively kills pathogens but risks loss of ammonia due to uric acid degradation. The objectives of this study were to test the ability of tannins to reduce pathogens and preserve uric acid during poultry litter composting. In two experiments, poultry litter was mixed with phosphate buffer and distributed to 50-ml tubes (three tubes/treatment per sample day) amended with 1 ml buffer alone or buffer containing pine bark, quebracho, chestnut, or mimosa tannins. Treatments achieved 0.63% (wt/wt) quebracho, chestnut, or mimosa tannins in experiment 1, or 4.5% pine bark or 9% quebracho, chestnut, or mimosa tannins in experiment 2. Tubes were inoculated with a novobiocin- and nalidixic acid-resistant Salmonella typhimurium, closed with caps, and incubated at successive 3-day increments at 22, 37, and 42°C, respectively. In experiment 1, bacterial counts in contents collected on days 0, 6, and 9 revealed a treatment by day effect (p < 0.03), with the Salmonella challenge being 1.3 log10 CFU/g higher in quebracho-treated composts than in untreated controls after 6 days of composting. After 9 days of composting, Salmonella, wildtype Escherichia coli, and total aerobes in untreated and all tannin-treated composts were decreased by about 2.0 log10 CFU/g compared to day 0 numbers (3.06, 3.75, and 7.77 log10 CFU/g, respectively). Urea and ammonia concentrations tended (p < 0.10) to be increased in chestnut-treated composts compared to controls and concentrations of uric acid, urea, and ammonia were higher (p < 0.05) after 9 days of composting than on day 0. Despite higher tannin application in experiment 2, antibacterial effects of treatment or day of composting were not observed (p > 0.05). However, treatment by time of composting interactions was observed (p < 0.05), with quebracho- and chestnut-treated composts accumulating more uric acid after 24 h and 9 days of composting and chestnut-, mimosa- or quebracho-treated composts accumulating less ammonia than untreated composts. Results demonstrate that composting may effectively control pathogens and that tannin treatment can help preserve the crude protein quality of composting poultry litter.

Effects of Neem (Azadirachta indica) Leaf Powder Supplementation on Rumen Fermentation, Feed Intake, Apparent Digestibility and Performance in Omani Sheep

“…The binding mechanism of phenolic compounds with dietary CP [ 40 ] has been shown to hinder CP degradability in the rumen, thereby increasing ruminal escape protein [ 55 , 56 ]. Reduced ruminal NH 3 -N concentration is related to the presence of phytochemical secondary compounds that are able to suppress the hyper-ammonia-producing bacteria population in the rumen [ 57 ].…”

Effects of Hops Treatment on Nitrogen Retention, Volatile Fatty Acid Accumulations, and Select Microbial Populations of Composting Poultry Litter Intended for Use as a Ruminant Feedstuff

“…The packed centrifugation residue from Experiment 1 samples were analyzed for potential treatment effects on microbial community diversity using denaturing gradient gel electrophoresis, as described earlier [19]. The sequences of the bacteria-specific PCR primers used for amplification were 5 -ATTACCGCGGCTGCTGG-3 and 5 -CGCCCGCCGCGCGC-GGCGGGCGGGGCGGGGGCACGGGGGGCCTACGGGAGGCAGCAG-3 ).…”

“…However, increased retention of ammonia in amino acids due to decreased microbial degradation or increased microbial synthesis of amino acids cannot be ruled out. However, the effects of the tannin-or nitro-treatments on urea accumulations have been inconsistent, possibly due to the role of urea as an intermediate between uric acid degradation and ammonia production [17,19], which currently limits their application in practice.…”