**1. Introduction**

Poultry production has a lower environmental impact when compared to other livestock production chains [1], mainly due to its high efficiency in converting feed into meat. The main reason for this high efficiency ratio is related to the strong genetic selection carried out to increase productive performance. Modern broilers reach their slaughter weight earlier than ever before, with a

high yield of breast and other meat [2]. Unfortunately, these fast-growing strains can show welfare and health problems, skeletal imbalance [3], metabolic disorders, myopathy and other muscle disorders [4], which affect the appearance of the meat, nutritional traits and consumers acceptance [5].

A side-effect of this process is the reduction of genetic variability [6] and the vulnerability of these chickens to environmental stress [7]. Nevertheless, poultry meat production of western countries is based on these chicken strains and it is now accompanied by a growing concern for the health and welfare of these animals [8]. As a result, there is an increasing demand for poultry meat produced in extensive rearing systems [9]. These production systems, commonly named pastured poultry production (PPP), are more expensive than intensive systems but can help sustain biodiversity, local economies and farm multi-functionality, in addition to providing meat to which consumers attribute a high ethical value, quality and taste [10]. Indeed, PPP generally uses large outdoor runs (at least 4 m2/chicken), small number of animals and requires chickens adapted to a variable environment, without the strict control of temperature, humidity and ventilation of in the intensive systems [11].

It is widely known that the access to free-range areas greatly improves the welfare of poultry and that the presence of shrubs and trees in the pastures further increases the use of runs [12]. For these reasons, the PPP is often found in an agro-forestry production system (such as fruit orchards or olive orchards). This combination improves the environmental sustainability of production because two or more different productions (meat, fruit and crops) can be simultaneously obtained from the same land, providing advantages both for the chickens and for the orchard.

Chickens and orchards mutually benefit each other; chickens improve soil quality by adding organic matter and control both insect pests and weeds, while trees protect the chickens from adverse weather conditions as well as raptors and provide additional revenue for the farm [13].

Even though the pasture offers only a modest supply of energy and proteins—the pasture in PPP represent only 10–15% of the total feed intake—it provides many bioactive compounds, such as xanthophylls, antioxidants and vitamins [14,15]. Accordingly, the meat from PPP may have some nutritional benefits compared to standard broiler meat [16]. Several authors [17,18] reported that bioactive compounds are transferred from the pasture to chicken meat, as shown by a higher meat content of antioxidants and n-3 polyunsaturated fatty acids. Additionally, access to pastures may contribute to meat flavour, with some forage and herbs resulting in distinctive flavours [19,20].

As previously reported, PPP requires chickens that are adapted to the natural environment (high kinetic activity and foraging behaviour), with a well-developed immune system and adequate body conformation and skeletal development [11,21–23]. Previous research has shown that slow-growing chickens are more adaptable to outdoor runs due to suitable thermo-tolerance, foraging aptitude, immune response and antioxidant capacity compared to fast-growing strains [24–26]. In contrast, fast-growing broilers selected for intensive production systems are fit for living in controlled conditions (controlled environment, veterinary care and diets high in protein and energy) and do not adapt to PPP. Dal Bosco et al. [10] compared behaviour in the chickens and showed that slow-growing chickens covered an average daily distance of 1130 m, while fast-growing ones walked only 220 m.

Contrary to the popular belief, there are several disadvantages with respect to PPP that preclude further development and reduce the production capacity of this system. The main disadvantages are reported below:

**Cost of production**—The production cost of this meat is much higher than with a conventional system, mainly due to the lower growth performance and the breast meat yield of slow-growing genotypes.

**Risk of predation**—PPP systems are attractive to predators (foxes, birds and other wild animals). Permanent fencing is expensive and is not always effective at excluding predators from the pasture.

**Rules formulated for large-scale poultry farms**—Sanitary rules and technical standards of poultry production are often based on large-scale farms. Small farmers cannot afford to invest in requirements and protocols unsuited to their system of production [27].

Consequently, up and down-stream infrastructures (e.g., hatchery with genetic strains adapted to PPP or slaughter houses), services (know-how or vaccines for small number of birds) are lacking. In particular, one of the major bottlenecks is the slaughterhouse. During the last 20 years in western countries, there has been a huge decrease in the number of poultry slaughterhouses coupled with an increase in size of the existing ones. Moreover, nowadays slaughterhouses generally belong to food companies and are not available to other farms.

The lack of slaughterhouses strongly discourages the use of PPP and many farmers limit their production to less than 500 or 1000 birds per year. This quantity, according to European (853/2004) and USA (62) regulations, is considered to be primary production which can be sold directly to consumers without controlled slaughter. However, the restrictions on sales and the lack of small-scale poultry slaughterhouses prevent the creation of specialised poultry farms. Small-scale farmers who wish to sell poultry products locally must have them slaughtered and processed in inspected facilities that are usually far from the farms.

A possible solution which increases the use of PPP systems could be a Mobile Poultry Processing Unit (MPPU) mounted on a small truck or van which goes directly to the poultry farms. A MPPU is excluded from continuous inspections by the Food Safety Authorities but it is still required to meet all sanitation and requirements. These MPPUs are designed to eliminate regulatory impasses and increases marketability and profitability for small-farmers. The MPPU reaches the farm directly on the day of slaughtering and then another advantage is the absence of transport of live animals to the slaughterhouse. This positively influences animal welfare and meat quality (see Sections 5 and 6).

The main characteristics of MPPU are described later in the Sections 2 and 6 and pros and cons are summarized in Table 1.


**Table 1.** Main characteristics of Mobile Poultry Processing Unit vs. conventional slaughterhouse.


**Table 1.** *Cont.*

Beside the economic aspects, there are also social aspects connected with the use of PPP and MPPUs. In a sound productive chain, the system of production should be followed by a coherent transfer of goods and services (from farm to consumer). Each productive system should develop a proper system. For example, intensive poultry production has developed not only a proper production system but also a typical structure for exchange. Accordingly, standards arising from industrialised agriculture may be at odds with the principles of small-scale poultry systems [28].

Rural sociology suggests a general framework in which exist a correspondence between production systems and the structure for exchange. PPP, as other local production system, requires the creation of specific short and decentralised circuits that link the production with the consumption of food. This pattern is completely different from highly centralised paths constituted by large food processing and trading companies which operate on a large scale [29].

Our opinion is that the exchange structures promoted by industrialised processing may not be able to handle all the benefits of PPP and they could negatively influence its internal equilibrium [29]. Conversely, PPP is not able to exploit the benefits of the large-scale supply systems. Accordingly, PPP requires specific approaches to solve marketing issues; these approaches cannot be derived from the experience of other productive systems.

According to this view, a MPPU could be considered not only a solution to the slaughtering problem but also a resource to enhance the emergence of food circuits (e.g., farmers' markets and niche markets), which cannot feature within the global food chains [30–32]. Indeed, a MPPU can contribute to managing this emerging circuit, allowing the creation of a production chain which exploits the ethical value adapted to its dimension value, prize.

Moreover, through use of a MPPU, the cost of each farm owning a slaughterhouse (€50–80,000) is avoided. European legislation recognises and authorises on-farm slaughter but the slaughterhouse must be used only for animals raised on the farm. This causes high initial investment for each farmer. In the light of what is reported, the aim of this paper is to review the current MPPU technologies by examining:


In the USA, several types of MPPU have been available for about 10 years [33,34], whereas in Europe, mobile slaughtering facilities are rare and only a few data are available. Accordingly, the present review will focus mainly on EU regulations and the EU situation.

#### **2. Essential Requirements: Planning and Layout**

During the last 10 years, National Authorities have pointed out rules to allow the activity of these MPPU. The basic principles of slaughtering in the EU include the need to fulfil several requisites, specified in the Regulation EC/853/2004 (Annex II, Chapter I, III and IV point 1) and by the Sanitary Authority which eventually authorises the use of the MPPUs on different farms. In this way, it is possible to share the MPPU among several farms, thus reducing the slaughtering cost of each chicken.

Furthermore, the structure needs to be properly designed to avoid cross-contamination and it should be placed in a specific area of the farm where drinking water and electric power are available (unless a drinking water tank and a generator are present to directly supply the MPPU), regular pest control is performed and waste (water and slaughter by-products) can be easily managed.

The MPPU must be built with materials and equipment that are easy to clean by Sanitation Standard Operating Procedures (SSOP) and there must be adequate site managemen<sup>t</sup> and appropriate personnel hygiene and clothing. Personnel operating in the MPPU must be trained in slaughter procedures and a proper HACCP (Hazard Analysis and Critical Control Points) plan needs to be implemented in the MPPU.

With regard to the slaughter procedure, stunning, bleeding and plucking must be performed separately from evisceration. Stunning must be performed according to Regulation EC/1099/2009. Chilling and storage of carcasses and meat must take place immediately in the MPPU or on the farm. If chillers, generally static chillers, are available on the farm, they must be placed near the MPPU and a suitable system for protecting the carcasses during transport from the slaughter site to the chiller needs to be adopted to avoid exogenous contamination.

Animal by-products must be managed according to Regulation EC 1069/2009. Cleaning and disinfection of the MPPU must be performed at the end of each slaughtering session, eitherat the farm or in a specific staging area. Meat must be labelled with the date of slaughter, farm code and farm address. A proper traceability system has to be set up.

Not all poultry farms have these facilities and an evaluation of the best site on the farm for slaughter, supply of water and managemen<sup>t</sup> of wastewater, is needed.

In the United States, the hygiene requirements and SSOP are almost the same as in the EU (Mobile Poultry Processing Unit Farm & Food Safety Management Guide, 2012). Although the local area is considered as the State and the maximum number of birds slaughtered is higher than 10,000.

The other restrictions imposed by law in the EU are:


According to this set of rules, production from a MPPU is small, local and subjected to severe numerical and geographical restrictions, confirming this system as a close and small one.

At the short term, the geographical and numerical limitations imposed by EU regulations do not permit future development of MPPUs for medium- or large-scale production. Moreover, even if some technical (different stunning system, carcass decontamination and water bath chilling) or regulatory improvements (geographical limitation) of MPPUs were advisable, European legislation strictly limits further improvements. Indeed, the change of regulatory system, at least in EU, is very long and complex and needs multiple level of decision (European, National and National/Regional).

Nonetheless, other countries could take advantage of the European experience and improve MPPUs according to national legislation.

#### **3. A Case Study of MPPU in Italy**

According to these requirements, a MPPU has been planned and built in central Italy (Figures 1 and 2). This type of MPPU is the first in Europe and for this reason the study was carried out considering only whit this equipment.

The small dimension of this MPPU has made it possible to put the equipment in a small truck, which can be handled with a standard driving license. It is also possible to add a refrigerated trailer for the farmer to deliver the carcasses directly to the market after slaughtering.

**Figure 1.** Schematic layout of the Mobile Poultry Processing Unit (50 chickens/hour): external (**a**) and internal (**b**) configuration and refrigerated trailer (**c**).

The innovative point of this process consist in the absence of animals transport, in fact the MPPU reaches the farm the day of the slaughter improving the pre-slaughtering operations. The slaughter process begins by a withdrawing feed of 8–10 h and a sanitary control of animals. One hour before slaughter, all of the chickens are captured, caged and placed on the MPPU's external platform (Figure 1a).

The truck is internally divided into two areas as required by the regulations:



The employee in the dirty area carries out all the operations from stunning to plucking; in particular he takes the animals one at a time from the cage, electrically stuns them and places them in the bleeding cone.

The subsequent phases involve the processing of four animals at a time that are placed in the scalder at a temperature of 58–60 ◦C for 30–60 s to loosen the feathers and in a drum plucker for 40–50 s.

At the end the carcasses are hung in hooks and transferred to the clean area where the second operator provides to the eviscerating. The final two steps are represented by the refrigeration and packaging. The working capacity of this MPPU is about of 50 chickens/hour.

**Figure 2.** Photo image of a MPPU.

#### **4. Operational and Economic Efficiency**

Since a MPPU requires substantial investment by the farmers, an evaluation of the economic feasibility of a MPPU compared to the current processing methods would allow farmers to plan their production method [34].

Different MPPUs—from basic to more automated and expensive ones—have been developed worldwide, mainly in the USA. Naturally, the cost of the equipment can vary substantially (from about €10,000 to 180,000).

Starting from the case-study shown above, we calculated the cost of chicken processing (Figure 3). In our case-study, the MPPU was designed for a small truck (IVECO DAILY; l 5000 × w 2200 × h 2400 cm), whereas the dimensions of the refrigerated van were l 3240 × w 1550 × h 2105 cm.

The equipment for the slaughter of poultry was separated into two areas: "dirty area" and "clean area" (Figure 1). The "dirty area" comprises a platform for live animals, an electro-narcosis stunner, kill tank and cones, scalder, steriliser for knives, plucker and carcass guideway. The "clean area" comprises an evisceration table, a semi-automatic eviscerator, a steriliser for knives, a fridge, a table with a weighing scale and a generator.

As required by official controls on food safety, at least two people have to work in the MPPU, one in the clean area and the other in the dirty area. The number of birds/hour which can be processed is around 50.

The total cost of the equipment (truck + van) is roughly €150,000, which can be shared among different farms. In a case scenario of 10 farms, the cost would be reduced to about €14–15,000 per farm, compared with a cost of about €50–80,000 for a farm slaughterhouse.

In addition, the MPPU cuts out the costs related to the transport of live animals from the farm to the slaughterhouse and the subsequent transport of the refrigerated carcasses back to the farm or stores. Typically, the transport of live animals and carcasses must be carried out by different vehicles, the first one complying with the regulations concerning animal welfare, the second one complying with the hygienic-sanitary requirements for meat which mainly involves refrigeration.

It should also be taken into consideration that EU and National funds, which support the improvement of competition and the modernization of farm facilities, could partially cover (30–50% of the eligible cost) the purchase of a MPPU.

It should be underlined that the avoidance of transportation permits to improvement in the welfare of chicken, see the next section.

Naturally, the care of animals during catching and caging is also particularly important in a MPPU. To avoid excessive chicken shackling, the chickens should be caged just before slaughter. Caged animals are placed in the rear platform of the truck equipped with a cover, which serves as a rest area where the veterinarian can perform the pre-slaughter inspection of animals.

**Figure 3.** Slaughtering cost (€/kg) and number of working days according to the number of chickens slaughtered (our elaboration).

These costs are based on an actual Italian case study. According to Figure 3, when the number of chickens slaughtered is very low (<2000 per year) the cost is high (>€1/kg live weight processed), whereas the trend is for the cost to become consistently lower for numbers > 25,000. Accordingly, small farmers should efficiently plan the number of chickens to be slaughtered, with the possibility of collective use of the same MPPU. Other managemen<sup>t</sup> options are also available (e.g., leasing and rent) and can make the use of MPPUs less expensive.

Angioloni et al. [34] showed a similar trend (decreasing costs with increasing number of slaughtered chickens) and showed that ten farmers sharing the ownership of the MPPU can achieve a higher profit than using alternative off-farm inspected slaughter facilities. In the USA, current estimates show that the cost is variable but within a close range.

The cost of conventional slaughter includes:


In summary, the cost of slaughter for each animal ranges from €3.50 to €4.50.

In conclusion, the economic analysis indicates the cost of slaughter using a MPPU is, on average, on the same scale as the cost of an on farm stationary processing system when the number of animals is higher than 10,000 year (the maximum admitted for this stationary plan) and lower than costs involved with a commercial slaughterhouse.
