Jean Bonhotal

REDUCTION OF SELECTED PATHOGENS IN ANAEROBIC DIGESTION

Anaerobic digesters are becoming a popular waste treatment option in New York State. These systems generate energy for on-farm use and sale while providing significant odor reduction. Research has shown that mesophilic systems (T=100oF) have the potential to reduce pathogens entering the environment. A plug flow digester was monitored for 14 months starting in May 2001. Samples taken from the digester influent and effluent were tested for the fecal coliform group of indicator organisms and Mycobacterium avium subspecies paratuberculosis (Map). M. avium paratuberculosis is the microorganism responsible for Johne’s disease in dairy cattle and other ruminants. Results show almost a 3-log reduction in fecal coliforms and slightly more than a 2-log reduction in Map. This paper describes an anaerobic digester and shows the comparative results of testing between a farm with a digester and a farm without a digester. Since both farms in this study compost and sell excess solids, analyses were done on the composted manure as well.

Effectiveness of Composting Road-Killed Deer In New York State

Composting of deer carcasses was effective in reducing pathogen levels, decomposing the carcasses and producing a useable end product after 12 months. The composting process used in this project involved enveloping the carcasses of road-killed deer in woodchips and allowing those piles with natural air circulation to sit undisturbed. Temperatures were measured and samples from the piles were analyzed periodically for pathogens and for compost parameters. While significant pathogen reduction occurred in several months, it took 12 months for all of the measured pathogens to decline to low levels in all of the 6 piles studied. Samples taken at other sites in New York State that have been composting road-killed deer for over a year also had low pathogen content. We thus suggest a composting duration of 12 months before use. In the interest of being cautious, we also recommend that the end product be used in low public contact settings such as highway rights-of-way.

Quantification of Sodium Pentobarbital Residues from Equine Mortality Compost Piles

Sodium pentobarbital, a euthanasia drug, can persist in animal carcasses following euthanasia and can cause secondary toxicosis to animals that consume the remains. This experiment was conducted to observe the effects of composting on euthanized horse carcass degradation and sodium pentobarbital residues in compost material up to 367 d. Six separate compost bins were constructed on pastureland. Three bins served as the control while 3 served as the treatment. The carbonaceous material, or bulking agent, consisted of hardwood chips mixed with yard waste wetted to approximately 50% moisture content. Bulking agent was added to each bin at a depth of 0.46 m, creating the pad. A licensed veterinarian provided 6 horse carcasses for use in the experiment. These horses had required euthanasia for health reasons. All horses were weighed and then sedated with an intravenous injection of 8 mL of xylazine. After sedation the 3 horses in the treatment group were euthanized by intravenous injection of 60 mL of sodium pentobarbital. The 3 control group horses were anesthetized by intravenous injection of 15 mL of ketamine hydrochloride and then humanely euthanized by precise gunshot to the temporal lobe. Following euthanasia, each carcass was placed on the center of the pad and surrounded with 0.6 m of additional bulking agent. Serum and liver samples were obtained immediately following death. Compost samples were obtained on d 7, 14, 28, 56, 84, 129, 233, and 367 while soil samples were obtained on d -1 and 367. Each sample was analyzed for sodium pentobarbital concentration. Compost pile and ambient temperatures were also recorded. Composting successfully degraded soft tissue with only large bones remaining. Data illustrate that sodium pentobarbital was detectable up to 367 d in compost piles with no clear trend of concentration reduction. Drug residues were detected in soil samples indicating that sodium pentobarbital leached from the carcass and through the pad. These findings confirm the persistence of sodium pentobarbital from equine mortality compost piles and emphasize the importance of proper carcass management of animals euthanized with a barbiturate to reduce environmental impact and secondary toxicosis.

Compost Sampling for Nutrient and Quality Parameters: Variability of Sampler, Timing and Pile Depth

In order to establish analysis-based quality guidelines for composts, it is necessary to have information about the variability of these traits as dependent on sampling methods. Composts exhibit significant spatial, site and time-related variability. In a preliminary survey of commercial and home users of compost in New York State, respondents indicated strong interest in test quality of purchased composts. However, little work has been done examining the consistency of reported values in composts sampled and shipped to laboratories. We evaluated within-farm and between-sampler variability of test traits at 7 farm compost sites. In one study we compared farmer and extension agents as separate samplers of the same compost piles. In the next study we examined repeated sampling by same sampler visiting the site a second time. Finally, we compared depth-based sampling variability at 3 selected farm compost sites. Analysis of variance was employed to distinguish effects of samplers, sampling timing and farms. The data showed very small differences in test values due to samplers for all parameters except weed seed and fecal coliforms. Geometric mean transformation eliminated fecal counts as a source of significant variability. Repeated sampling after two weeks of matured compost indicated no appreciable differences between points of time except for weed seeds. The sampling-depth study revealed significant variation of several selected test parameters attributed to pile stratification, and the variables most affected were moisture, potassium and weed seeds. Weed seed testing may not be useful for a quality parameter unless methodological variance is better understood. Overall, biological parameters varied less than chemical traits. The study underscores that prior to establishing numerical quality guidelines the preferred compost pile sampling protocol should be very carefully described.

How Mycobacterium avium paratuberculosis is affected by the composting process

Since its discovery in 1926, the virus of Newcastle disease (NDV) has been well described by several authors. But the control of this disease remains today a topical issue. It causes economic losses in industrialized and developing countries. The clinical manifestation of NDV differs from one species to another. This article places a state of clinical manifestation of the virus of Newcastle disease in traditional avian population, raised in the same breeding conditions. That avian population has been made up of chickens, ducks, guinea fowl and pigeons. The clinical manifestation of NDV has been observed by species, age and in epidemiological units (EpUn). The choice of EpUn has been done randomly. A total of 372 EpUn with a workforce of 13608 volatile have been observed. Young people aged at least 6 months have been 51.5% , 5.6%, 0.4% and 1.3% of the total, for chickens, ducks, guinea fowl and pigeons respectively. According to this order, adults over 6 months represented 28%, 5.4%, 4.8% and 3%. The clinical manifestation of the NDV has been observed in all domestic poultry species. Mortality varied between 26 and 99% in chickens; 17 and 75% in ducks; 8 and 100% in guinea fowls, and 11 and 100% among pigeons. Young volatiles have been more sensitive to NDV than adults. Mortality varied between 33 and 99% in young chickens, 21 and 75% in young ducks; 22 and 100% in young guinea fowl; 18 and 100% among young pigeons. In adults the rate varied respectively between 26 and 78%; 17 and 47%; 8 and 26%, 11 and 73% in the same species. Among this population of young volatiles, ducklings have been less sensitive than other young. Maternal antibodies seem to persist beyond a month and a half, while the chicks aged a month could present the clinical manifestations of the disease. Animal concentration, climatic changes, socio-economic activities of man and other emergence of ND factors seem to play an important role in the clinical manifestation of NDV from traditional domestic poultry. Knowledge of the clinical manifestation of this disease among the traditional bird population is one of the essential elements of its control.