Effects of a Partially Perforated Flooring System on Ammonia Emissions in Broiler Housing-Conflict of Objectives between Animal Welfare and Environment?

Abstract

A partially (50%) perforated flooring system showed positive effects on health- and behavior-based welfare indicators without affecting production performance. Ammonia (NH₃) is the most common air pollutant in poultry production, with effects on animal welfare and the environment. The objectives of animal welfare and environmental protection are often incompatible. Therefore, this study addresses the question of how a partially perforated flooring system affects NH₃ emissions. According to German regulations, three fattening periods were carried out with 500 Ross 308 broilers per barn (final stocking density: 39 kg m^-2). The experimental barn was equipped with an elevated perforated area in the supply section, accessible by perforated ramps. The remaining area in the experimental barn and the control barn were equipped with wood shavings (600 g m^-2). Besides the different floor types, management was identical. Air temperature (Temp), relative air humidity (RH), NH₃ concentration, and ventilation rate (VR) were measured continuously. Furthermore, dry matter (DM) content, pH, and litter quality were assessed. Towards the end of the fattening periods, the NH₃ emission rate (ER) of the partially perforated flooring system was higher compared with that of the littered control barn (all p < 0.001). This effect is mainly caused by the higher NH₃ concentrations, which are promoted by the lack of compaction underneath the elevated perforated area and the increase in pH value under aerobic conditions. Nevertheless, the partially perforated flooring system offers different approaches for NH₃ reduction that were previously not feasible, potentially contributing equally to animal welfare and environmental protection.

Keywords: alternative flooring; ammonia emissions; animal welfare; broiler production; environmental impact.

Figure 1

Illustration of the partially perforated flooring system, with an elevated perforated area in the section of feed and water supply, and the littered flooring system.

Figure 2

Floor plan view of the partially perforated flooring system, with an elevated perforated area in the section of feed and water supply, and the littered flooring system, including measurement positions for litter quality, litter dry matter (DM), litter pH (pH), air temperature (Temp), and relative air humidity (RH).

Figure 3

Illustration of the scores used during the litter quality evaluation.

Figure 4

Average daily air temperature inside the broiler houses with two different floor types, and the outside environment air temperature measured over three different fattening periods (n = 144 values per day and barn). Significant differences between both floor types within the three different sections (start, middle, end of the fattening period) are marked by asterisks: ** p < 0.01.

Figure 5

Average daily relative air humidity inside the broiler houses with two different floor types, and the outside environment RH measured over three different fattening periods (n = 144 values per day and barn). Significant differences between both floor types within the three different sections (start, middle, end of the fattening period) are marked by asterisks: * p ≤ 0.05, *** p < 0.001.

Figure 6

Average daily ammonia (NH₃) concentrations from broiler houses with two different floor types measured over three different fattening periods (n = 480 values per day and barn). Significant differences between both floor types within the three different sections (start, middle, end of the fattening period) are marked by asterisks: ** p < 0.01, *** p < 0.001.

Figure 7

Average daily ventilation rate from broiler houses with two different floor types measured over three different fattening periods (n = 1.440 values per day and barn). Significant differences between both floor types within the three different sections (start, middle, end of the fattening period) are marked by asterisks: *** p < 0.001.

Figure 8

Average daily ammonia (NH₃) emission rate from broiler houses with two different floor types measured over three different fattening periods (n = 24 values per day and barn). Significant differences between both floor types within the three different sections (start, middle, end of the fattening period) are marked by asterisks: *** p < 0.001.

Figure 9

Average dry matter (DM) contents of litter samples from (A) the littered side areas and (B) the supply area from broiler houses with two different floor types at the end of each of the three different fattening periods (n = 6 values per fattening period and barn in area (A); n = 3 values per fattening period and barn in area (B)). Significant differences are marked by asterisks: * p ≤ 0.05, ** p < 0.01, *** p < 0.001.

Figure 10

Average dry matter (DM) contents of litter samples from (A) the littered side areas and (B) the supply area (n = 6 values per day and barn in area (A); n = 3 values per day and barn in area (B)) from broiler houses with two different floor types measured over the spring fattening period. Significant differences are marked by asterisks: ** p < 0.01, *** p < 0.001.

Figure 11

Average pH values of litter samples from (A) the littered side areas and (B) the supply area from broiler houses with two different floor types measured over the spring fattening period (n = 6 values per day and barn in area (A); n = 3 values per day and barn in area (B)). Significant differences are marked by asterisks: * p ≤ 0.05, *** p < 0.001.

Figure 12

Mean scores of litter quality from (A) the littered side areas (n = 12 values per day and barn) and (B) the supply area (n = 3 values per day and barn) from broiler houses with two different floor types. n.a. = not assessed (no litter quality assessment underneath the perforated area in the supply area of the experimental barn).