Castillo-Castillo Yamicela, Arzola-Alvarez Claudio, Fonseca Mozart, Salinas-Chavira Jaime, Ontiveros-Magadan Marina, Hume Michael E, Anderson Robin C, Flythe Michael D, Byrd James Allen, Ruiz-Barrera Oscar
Facultad de Zootecnia y Ecología, Universidad Autónoma de Chihuahua, Chihuahua 31453, Mexico.
Department of Agriculture, Veterinary & Rangleland Sciences, University of Nevada, Reno, NV 89154, USA.
Microorganisms. 2023 Mar 25;11(4):839. doi: 10.3390/microorganisms11040839.
Poultry litter is a valuable crude protein feedstuff for ruminants, but it must be treated to kill pathogens before feeding. Composting effectively kills pathogens, but it risks losing ammonia to volatilization or leaching during degradation of uric acid and urea. Hops bitter acids also exert antimicrobial activity against certain pathogenic and nitrogen-degrading microbes. Consequently, the present studies were conducted to test if adding bitter acid-rich hop preparations to simulated poultry litter composts may improve nitrogen retention while simultaneously improving pathogen killing. Results from an initial study, testing doses of Chinook or Galena hops preparations designed to each deliver 79 ppm hops β-acid, revealed that, after nine days simulated composting of wood chip litter, ammonia concentrations were 14% lower ( < 0.05) in Chinook-treated composts than untreated composts (13.4 ± 1.06 µmol/g). Conversely, urea concentrations were 55% lower ( < 0.05) in Galena-treated than untreated composts (6.2 ± 1.72 µmol/g). Uric acid accumulations were unaffected by hops treatments in this study but were higher ( < 0.05) after three days than after zero, six, or nine days of composting. In follow-up studies, Chinook or Galena hops treatments (delivering 2042 or 6126 ppm of β-acid, respectively) for simulated composts (14 days) of wood chip litter alone or mixed 3:1 with ground Bluestem hay () revealed that these higher dosages had little effect on ammonia, urea, or uric acid accumulations when compared to untreated composts. Volatile fatty acid accumulations measured in these later studies were affected by the hops treatments, with butyrate accumulations being lower after 14 days in hops-treated composts than in untreated compost. In all studies, beneficial effects of Galena or Chinook hops treatments were not observed on the antimicrobial activity of the simulated composts, with composting by itself decreasing ( < 0.05) counts of select microbial populations by more than 2.5 log colony forming units/g compost dry matter. Thus, while hops treatments had little effect on pathogen control or nitrogen retention within the composted litter, they did lessen accumulations of butyrate, which may prevent adverse effects of this fatty acid on palatability of litter fed to ruminants.
家禽粪便对反刍动物来说是一种有价值的粗蛋白饲料，但在喂食前必须进行处理以杀灭病原体。堆肥能有效杀灭病原体，但在尿酸和尿素降解过程中，存在氨挥发或淋失的风险。啤酒花苦味酸对某些致病微生物和氮降解微生物也具有抗菌活性。因此，本研究旨在测试向模拟家禽粪便堆肥中添加富含苦味酸的啤酒花制剂是否可以提高氮保留率，同时提高病原体杀灭效果。一项初步研究的结果表明，在对木屑粪便进行九天的模拟堆肥后，测试了旨在分别提供79 ppm啤酒花β-酸剂量的奇努克或方铅矿啤酒花制剂，结果显示，奇努克处理的堆肥中的氨浓度比未处理的堆肥低14%（P<0.05）（13.4±1.06 µmol/g）。相反，方铅矿处理的堆肥中的尿素浓度比未处理的堆肥低55%（P<0.05）（6.2±1.72 µmol/g）。在本研究中，尿酸积累不受啤酒花处理的影响，但在堆肥三天后的积累量高于零天、六天或九天后的积累量（P<0.05）。在后续研究中，对单独的木屑粪便或与磨碎的须芒草干草按3:1混合的模拟堆肥（14天）进行奇努克或方铅矿啤酒花处理（分别提供2042或6126 ppm的β-酸），结果显示，与未处理的堆肥相比，这些较高剂量对氨、尿素或尿酸积累几乎没有影响。在这些后期研究中测量的挥发性脂肪酸积累受啤酒花处理的影响，啤酒花处理的堆肥在14天后的丁酸盐积累量低于未处理的堆肥。在所有研究中，未观察到方铅矿或奇努克啤酒花处理对模拟堆肥的抗菌活性有有益影响，堆肥本身使选定微生物种群的数量减少（P<0.05）超过2.5个对数菌落形成单位/克堆肥干物质。因此，虽然啤酒花处理对堆肥粪便中的病原体控制或氮保留影响不大，但它们确实减少了丁酸盐的积累，这可能会防止这种脂肪酸对喂给反刍动物的粪便适口性产生不利影响。
