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Dietary manipulation can substantially lower ammonia (NH3) emissions from laying-hen houses or manure storage. Recent lab studies showed a NH3 emission reduction for experimental diets with EcoCal™ and corn dried distiller’s grain with solubles (DDGS) as compared to the standard or control diet. The study reported here was a field verification test about the effects of diets containing DDGS and EcoCal™ on air emissions, hen production performance, and the economic returns for a commercial high-rise layer operation in Iowa. Comparative data were collected during December 2007 to Dec 2009. Feeding EcoCal diet at 7% inclusion rate and DDGS diet at 10% inclusion rate to laying hens in the high-rise houses showed 39% and 14% overall reduction in NH3 emissions, respectively. There were few differences in egg production, egg weight or egg mass (output) for hens fed the EcoCal or DDGS diet as compared to hens fed the control diet. Compared with the control and DDGS hens, the EcoCal hens consumed more feed and had a lower mortality rate, and had a similar feed conversion. The EcoCal hens also tended to have a greater body weight. Egg production was slightly lower for hens fed the DDGS diet (424 eggs hen-1 or 58.5 lb hen-1) than that of the Control (435 eggs hen-1 or 59.2 lb hen-1M) and EcoCal (447 eggs hen-1 or 61.9 lb hen-1) hens. The lower egg production by the DDGS hens (during the first cycle) could have resulted from learning management of the new strain birds during the first cycle. The cash returns (revenue – total cost) of each hen were, respectively, $11.88, $11.18 and $12.35 for Control, DDGS and EcoCal regimens over the 91-wk production period.

Dietary manipulation can substantially lower ammonia emissions from laying hen manure. However, such dietary changes would be of little value if the changes cause inferior egg production and hen performance. Therefore, the objective of this study was to evaluate the effect of a diet containing EcoCalTM (gypsum and zeolite), which has been shown to lower ammonia emission in laboratory-scale testing, on hen production performance in commercial high-rise laying hen houses. A companion paper describes the effect of the EcoCal diet on ammonia, hydrogen sulfide, and carbon dioxide emissions. Two high-rise houses, each containing approximately 255,000 hens, were used for the study. Hens in one house were fed a diet containing 3.5% EcoCal, whereas hens in the other house were fed an EcoCal-free, control diet. The cooperating farm provided the production records. The comparative production data have been collected since October 2006 and the study is scheduled to continue for another 2 years (i.e., through 2009). The period was broken into 2-wk increments for data analyses. Feed consumption was higher for the EcoCal-fed hens from 100 to 105 weeks of age. Egg production was transiently lower for the EcoCal-fed hens during the 92 to 93 wk-of-age period and egg weight was lower during the 96 to 97 wk-of-age period. Consequently, egg mass was lower during both the 92 to 93 and 96 to 97 wk-of-age periods. Feed conversion was more favorable for the control-fed hens from 100 to 103 wk of age. Mortality was lower for the EcoCal-fed hens from 92 to 93 and 100 to 105 wk of age. Results from December 2006 through May 2007 presented in this paper show mostly transient differences in production parameters between the dietary regimens. Future analyses will help better determine or affirm the effects of the EcoCal diet.

Dietary manipulation can substantially lower ammonia (NH3) emissions from laying-hen houses or manure storage. Recent lab studies showed a NH3 emission reduction of 40– 60% for an experimental (EcoCal TM ) diet as compared to the standard or control diet. The study reported here was a field verification test about the effects of EcoCal diet on NH3, hydrogen sulfide (H2S) and carbon dioxide (CO2) emissions, hen production performance, and the economic returns for a commercial high-rise layer operation in Iowa. Comparative data were collected during December 2006 to May 2007. The results showed that the EcoCal diet led to NH3 emission reduction by up to 23.2% (0.86±0.04 vs. 1.12±0.03 g NH3 d -1 hen -1 for EcoCal vs. Control diet, respectively) while H2S emission increased by up to 134% (4.38±0.20 vs. 1.82±0.07 mg d -1 hen -1 for EcoCal vs. Control, respectively). However, H2S emissions were small for both dietary regimens.

The goal of this project was to develop a system that identified magnesium demand for struvite formation by monitoring conductivity changes during continuous injection of magnesium chloride in several different manure slurries. The conductivity of six manure slurries was monitored to identify the response due to magnesium chloride injection and struvite precipitation. Struvite precipitation is a technically feasible treatment method for phosphorus removal and recovery from manure slurries (Bowers and Westerman, 2005a; Burns et al., 2000). Swine manure slurries typically require the addition of magnesium (Mg) to force struvite precipitation. The quantity of Mg required for maximized phosphorus removal is generally determined through laboratory tests. Optimized struvite precipitation in a field setting would require a real-time method to determine Mg addition rates for the duration of a land application event. This paper will discuss the requirements of a feasible automated control system which monitors and controls the injection of Mg to force struvite precipitation, accounting for real-time variations of magnesium demand. Theoretical predictions and pure solution tests provided information capable of determining the magnesium demand for struvite precipitations. After testing six different manures in