Effects of Dietary Modification on Laying Hens in High-Rise Houses: Part I – Emissions of Ammonia, Hydrogen Sulfide and Carbon Dioxide
Dietary manipulation can substantially lower ammonia (NH3) emissions from laying-hen houses or manure storage. Recent lab studies showed a reduction of 40–60% in ammonia emissions for an experimental (EcoCalTM) diet as compared the standard or control diet. However, adoption of a mitigation technology at commercial production level should be preceded by substantial field verification tests to document not only NH3 emission reduction, but also impact of the strategy on production performance of the hens and cash returns. A study to assess the effects of feeding diets containing EcoCal on NH3, hydrogen sulfide (H2S), and carbon dioxide (CO2) emissions, laying-hen production performance, and economic returns was conducted at a commercial laying-hen farm in central Iowa. Two houses (256,000 or 262,000 hens per house) were used for the study. Hens in one house were fed the EcoCal diet while hens in the other house were fed a standard or control diet containing no EcoCal. A state-of-the-art mobile air emissions monitoring unit (MAEMU) and the associated sampling system were used to continuously monitor the gaseous concentrations, ventilation rate and environmental conditions. Comparative data collected from December 2006 to May 2007 are presented in this paper. Data from this period showed that the EcoCal diet led to NH3 emission reduction by up to 23.2% (0.86±0.04 and 1.12±0.03 g/d·hen for EcoCal and Control diet, respectively), at the same time, H2S emission increased by up to 134% (4.38±0.20 and 1.82±0.07 mg/d·hen for EcoCal and Control diet, respectively), although the magnitude of H2S emission is rather small for both dietary regimens. Data on the hen production performance are reported in a companion paper (Roberts et al., 2008).
Environmental toxicology of hydrogen sulfide.
The passenger-carrying paddle steamer Princess Alice was sunk in a collision on the River Thames in 1878 with the loss of over 640 lives and, curiously, may represent one of the largest mass poisoning episodes in history [1, 2]. Raw discharge from the London sewers had been released into the Thames (standard practice at the time) and some survivors reported the unusually foul nature of the water. The extraordinarily high death toll of the Princess Alice accident (> 80%) is in stark contrast to the similarly violent sinking of the pleasure craft Marchioness on the Thames a century later in 1989, where only 51 of 130 people on board were lost (< 40% fatalities) [3, 4]. The Board of Trade inquiry and the Coroner’s inquest at the time of the Princess Alice disaster were primarily concerned with establishing blame for the collision and determining if there were any criminal charges to be filed. That there may have been significant deaths caused by hydrogen sulfide (H2S) inhalation, possibly accelerated by the victims thrashing at the surface, was not given much serious consideration [1, 2]. Nevertheless, it was only nine years after the Princess Alice disaster occurred that the necessary investment was made to treat and separate the sewage before releasing it into the Thames [5]. It has since become entrenched in sanitary engineering lore that many of the Princess Alice deaths were due to poisoning, probably by H2S [6]. 
 
While it is now widely accepted that H2S acts as a signaling molecule and exhibits some potentially beneficial therapeutic effects [7–15] at elevated levels H2S is highly toxic. Gaseous H2S continues to be one of the most common hazardous substances attributed to acute poisoning deaths in occupational settings [16]. However, there are still facets of H2S toxicity that remain elusive – including, but not necessarily limited to, a comprehensive estimate of the prevalence of this poisonous gas emitted into the environment and any effects associated with such exposures, the mechanism(s) of its cellular toxicity, and lack of effective antidotes. Herein, we consider some of the knowledge gaps associated with H2S in the environment and its toxic effects on the human body when inhaled.
Die Populationsdynamik Von Canthocampt Us Staphylinus (Jurine) (Copepoda, Harpacticoida) Im Litoral Des Bodensees
The population dynamics of Canthocamptus staphylinus in the littoral zone of Lake Constance are described (fig. 2). Adult animals aestivate as cysts. The main part of the population emerges from the cysts in autumn. During the resting stage and the first spell after emerging, mortality is very low (fig. 3). Reproduction, expressed as numbers of ovigerous females, begins in November and reaches its maximum in January. The new generation becomes adult in May/June and encysts without previous reproduction. According to Sarvala (1979) it may be possible, that in littoral populations dormancy is induced by long day periods and temperatures of over 12° C (figs. 1, 2). In the profundal zone C. staphylinus also forms cysts, however, both light and temperature are not likely to induce this stage in depths of over 60 m.