Abatement of particulate matter emission from experimental aviary housings for laying hens by spraying rapeseed oil.

In alternative systems for laying hens, concentrations and emission rates of particulate matter (PM) give reason for concern with regard to working conditions, bird health and productivity, and health of residents living near farms. Previously, we found that spraying a film of rapeseed oil onto the litter of broilers could substantially reduce PM concentrations and emissions. The objective of this study was to establish dose-response effects of oil spraying in aviaries on concentrations and emission rates of PM with aerodynamic diameters less than 10 µm (PM10) and 2.5 µm (PM2.5), on stockmen's exposure to PM10, on egg production, exterior quality and behavior of the hens, and on the litter. An experiment was carried out with 4 treatments: 0 (control), 15, 30, and 45 mL/m2 per d (oil treatments). Each treatment was applied in 2 rooms with different aviary systems (8 rooms in total). The experiment was repeated during a second period, both lasting 35 days. From d 11 to d 35, oil was applied daily using a spraying gun. Applying 15, 30, or 45 mL/m2 per d significantly reduced emission rates of PM10 by 27, 62, and 82%, and emission rates of PM2.5 by 71, 83, and 94%, respectively. No significant effects of oil spraying were found on mortality, egg production, dust bathing behavior, scratching behavior, plumage soiling, DM content of the litter, or friability of the litter. A significant worsening of the plumage condition was found only for the body spot back/wings/tail (not for: throat/neck, chest/breast, or legs) in the 45 mL/m2 per d treatment. Egg quality shifted significantly towards more second-class eggs in the oil treatments (1.9% versus 1.4%; P = 0.004). Remarkably, foot soiling decreased with increasing oil application. In conclusion, PM concentrations and emission rates in aviaries can be effectively reduced by spraying 15 to 30 mL/m2 per d with minor side effects within a 25 d application period.

The effect of two ammonia-emission-reducing pig housing systems on odour emission.

Odour nuisance from agricultural activities is increasing in densely populated countries like the Netherlands. To develop adequate regulations, a large-scale, government-financed monitoring programme was started in the mid-1990s to establish odour emission levels for both conventional and low ammonia emission housing systems for cattle, pigs and poultry. The results indicate that high- and low-odour emission housing are difficult to distinguish because of the large variation within housing systems. Measurements on different farm locations within the same housing system show both a large variation between locations and within one location (in time). The latter, however, is significantly smaller, which suggests that farm management is an important determinant in odour emission that interferes with the effects of housing systems. The current research was aimed at determining the effect of two common ammonia-reducing pig-housing systems on odour emissions compared to conventional housing systems under similar management conditions. The respective reduction principles of these systems are reducing the emitting surface of the manure pit and cooling of manure in the manure pit (both pits beneath slatted floor). Five farms that combined conventional housing with one low-ammonia system (three reduced emitting surface and two manure cooling) were selected for a direct, pair-wise comparison of (olfactometric) odour emission measurements. The results show a highly significant effect (p < 0.01) for two of the three reduced emitting surface systems and for one of the two manure cooling system. The average odour reduction percentages of these systems are 35% (from 24.9 to 16.0 OUE/s per animal) and 23% (from 30.1 to 24.0 OUE/s per animal) respectively. Although odour emission reduction through the type of housing system is possible, management factors interact with the system and thereby determine whether the system reduces odour emission or not.

Effects of dietary crude protein level on odour from pig manure.

The objective of this study was to determine the effects of dietary crude protein (CP) level on odour emission, odour intensity, hedonic tone, and ammonia emission from pig manure and on manure composition (pH, total nitrogen, ammonium, volatile fatty acids, indolic, phenolic and sulphur-containing compounds). An experiment was conducted with growing pigs (n = 18) in a randomised complete-block design with three treatments in six blocks. Treatment groups were 12%, 15% and 18% CP diets. Barley was exchanged for soya-bean meal. Crystalline amino acids (AA) were included in the 12% CP diet up to the level of pigs' requirement; the same amount of AA was added to the 15% and 18% CP diets. Pigs with an initial body weight (BW) of 36.5 ± 3.4 kg (mean ± s.d.) were individually penned in partly slatted floor pens and offered a daily feed allowance of 2.8 × maintenance requirement for net energy (NE: 293 kJ/kg BW0.75). Feed was mixed with water, 1/2.5 (w/w). Faeces and urine of each pig were accumulated together in a separate manure pit under the slatted floor. After an adaptation period of 2 weeks, the manure pits were cleaned and manure was collected. In the 5th week of the collection period, air samples for odour and ammonia analyses, and manure samples were collected directly from each manure pit. Air samples were analysed for odour concentration and for hedonic value and intensity above odour detection threshold. Manure samples were analysed for volatile fatty acids, and indolic, phenolic and sulphurous compounds, ammonium and total nitrogen concentrations. Reducing dietary CP from 18% to 12% lowered odour emission ( P < 0.05) and ammonia emission ( P = 0.01) from pig manure by 80% and 53%, respectively. Reduced dietary CP decreased total nitrogen, methyl sulphide, carbon disulphide, ethanethiol, phenol, 4-ethyl phenol, indole and 3-methyl indole concentrations in the manure ( P < 0.05). Volatile fatty acids and cresols concentrations in the manure of pigs fed different dietary CP levels were similar. A reduction of dietary CP and at the same time providing essential AA is an option to reduce odour emission as well as ammonia emission from pig manure.

Effects of crystalline amino acid supplementation to the diet on odor from pig manure.

The objective of this study was to determine the effects of specific crystalline AA supplementation to a diet on odor emission, odor intensity, odor hedonic tone, and ammonia emission from pig manure, and on manure characteristics (pH; ammonia N; total nitrogen; sulfurous, indolic, and phenolic compounds; and VFA concentrations). An experiment was conducted with growing pigs (n = 18) in a randomized complete block design, with 3 treatments in 6 blocks. Treatment groups were (1) a 15%-CP basal diet with 3 times the requirement of sulfur-containing AA (14.2 g/kg of diet, as-fed basis); (2) the basal diet with 2 times the requirement of Trp and Phe+Tyr (2.9 and 20.4 g/kg of diet, respectively, as-fed basis); and (3) the basal diet with AA supplementation to levels sufficient for maximum protein gain. Pigs with an initial BW of 41.2 +/- 0.8 kg were individually penned in partly slatted floor pens and offered a daily feed allowance of 2.8 times the maintenance requirement for NE (293 kJ/kg of BW(0.75)). Feed was mixed with water at 1:2.5 (wt/wt). Feces and urine of each pig was allowed to accumulate in separate manure pits under the slatted floor. After an adaptation period of 2 wk, and after cleaning the manure pits, manure was subsequently collected. In wk 5 of the collection period, separate samples were collected directly from each manure pit for odor, ammonia, and manure composition analyses. Air samples were analyzed for odor concentration and for hedonic tone and odor intensity above the odor detection threshold. Results showed that supplementing crystalline S-containing AA in surplus of the requirement increased odor emission (P < 0.001) and odor intensity (P < 0.05) and reduced odor hedonic tone (P < 0.05) from the air above the manure pits. Supplementing crystalline Trp, Tyr, and Phe in surplus of the recommended requirements did not affect odor emission, odor intensity, or odor hedonic tone. Regardless of dietary treatment, all pigs had similar performance levels. No differences were observed in ammonia emission from manure of pigs fed different levels of AA supplementation (P = 0.20). To reduce odor from pig manure, dietary S-containing AA should be minimized to just meet the recommended requirements.