**2. Contaminants in organic animal products**

Organic farming refers to breeding systems that do not use chemical inputs in which the priority is given to animal welfare and quality of healthy products [4]. In organic livestock production system, vaccination is subjected to conditional permission [5]. Organic farming has increased intensely for the last 10 years in Europe. However, difficulties in the treatment of animal diseases due to failure in achieving the standards of organic farming has led to insufficient development of organic farming and to have a small share in the overall agriculture [4]. Although milk is the most commonly produced products among the organic animal products, its production amount is still considerably lower than that produced by the conventional method. The organic meat production has been recently introduced; therefore, it is difficult to find certified breeders [6]. According to 2001 data, concerning the organic animal breeding, Europe takes the first place with 57.9%, which is followed by the North (15.5%) and South America (13.9%). Organic animal product quality varies depending on various factors such as animal species and diet types. Although, concerning some parameters, organic animal products are superior to conventional animal products, generally, they are considered not to be superior to conventional ones in terms of quality [7]. Despite all this, the organic products are generally regarded as excellent products. For this reason, researches on the contamination in organic products, especially, organic animal products are limited [8]. However, unlike the conventional farming, lack of the use of protective products in organic products can lead to early deterioration of a product, to the risk for mold formation and to the emergence of harmful pathogens. On the other hand, despite all the strict rules of organic farming, inevitable factors such as atmospheric conditions, soil properties, climatic conditions, continuation of permanent pollutants for years may cause the residues in organic vegetables and cereals thus indirectly (with food intake) results in negative factors/residues in animal products [9].

#### **2.1. Bacterial contaminants in organic animal products**

In organic farming, various factors such as use of animal manure, the prohibition of the usage of certain food additives and antibacterials, keeping animals on pasture for longer duration, preferring slow-growing breeds and small slaughterhouses makes organic products vulnerable to bacterial contamination [2, 10, 11]. Studies on bacterial contamination of organically grown animals and animal products are very limited. In fact, concerning the risk of bacterial contamination among organic products, plant products have priority. In terms of organic animal products, poultry meat seems to be more risky. Salmonella and Campylobacter are the most important foodborne bacterial contaminants [10]. Salmonella can lead to disease in humans through consumption of contaminated beef, pork, poultry meat and eggs or vegetables contaminated with animal faces [12]. Differences are seen between the results obtained from the conventional and organic products in terms of contamination with bacteria. In a study, Salmonella was seen in none of the organic chicken farms (layers and broilers), whereas it is evident in approximately 10% of conventional farms, but Campylobacter was observed in all organic broiler farms [13]. Cui et al. [10] analyzed organic and conventional eggs collected from Maryland (USA) retail stores for Campylobacter and Salmonella, and detected Campylobacter in most of the organic (76%) and conventional (74%) chickens and Salmonella was seen in 61 and 44% of organic and conventional chicken, respectively. In the United Kingdom, Campylobacter was found in 80% of organically grown chicken. In a study conducted in Germany, it had been reported that organic chicken meat was contaminated with extended-spectrum beta-lactamase (ESBL) as much as conventional poultry meat [14, 15]. In organic or free-range hen breeding contamination of eggs with the faces and thus the risk of bacterial contamination of eggs is higher than the conventional cage breeding [16]. Antibiotic resistance of the bacteria isolated from organic and conventional chicken and also eggs derived from them differ. In a study, no difference was determined between organic and conventionally grown chickens regarding sensitivity of Campylobacter isolates to antibiotics [15]. In another study investigating antibiotic resistance against Gram-negative bacterial isolates, the resistance in isolates obtained from organically reared chicken is lower because of the limited use of antibiotics in organic farming [17]. Isolates obtained from Campylobacter and Salmonella positive organic chicken eggs were found sensitive to antimicrobial agents, whereas isolates derived from conventional chicken eggs were resistant to five or more antibacterial agents [10]. Similarly, in the Netherlands, antibiotic resistance was lower in microorganisms (except Campylobacter) isolated from faeces samples of organic broilers [13].

Organic farming, emerged in this context, is accepted as the farming not allowing the use of any of the substances/applications such as growth promoters, antibiotics, genetically modified organisms and irradiation, which are considered to be harmful to human health, and providing safer foods concerning nitrates, pesticides and harmful elements (heavy metals, particu-

Organic farming refers to breeding systems that do not use chemical inputs in which the priority is given to animal welfare and quality of healthy products [4]. In organic livestock production system, vaccination is subjected to conditional permission [5]. Organic farming has increased intensely for the last 10 years in Europe. However, difficulties in the treatment of animal diseases due to failure in achieving the standards of organic farming has led to insufficient development of organic farming and to have a small share in the overall agriculture [4]. Although milk is the most commonly produced products among the organic animal products, its production amount is still considerably lower than that produced by the conventional method. The organic meat production has been recently introduced; therefore, it is difficult to find certified breeders [6]. According to 2001 data, concerning the organic animal breeding, Europe takes the first place with 57.9%, which is followed by the North (15.5%) and South America (13.9%). Organic animal product quality varies depending on various factors such as animal species and diet types. Although, concerning some parameters, organic animal products are superior to conventional animal products, generally, they are considered not to be superior to conventional ones in terms of quality [7]. Despite all this, the organic products are generally regarded as excellent products. For this reason, researches on the contamination in organic products, especially, organic animal products are limited [8]. However, unlike the conventional farming, lack of the use of protective products in organic products can lead to early deterioration of a product, to the risk for mold formation and to the emergence of harmful pathogens. On the other hand, despite all the strict rules of organic farming, inevitable factors such as atmospheric conditions, soil properties, climatic conditions, continuation of permanent pollutants for years may cause the residues in organic vegetables and cereals thus indirectly (with food intake) results in negative factors/residues

In organic farming, various factors such as use of animal manure, the prohibition of the usage of certain food additives and antibacterials, keeping animals on pasture for longer duration, preferring slow-growing breeds and small slaughterhouses makes organic products vulnerable to bacterial contamination [2, 10, 11]. Studies on bacterial contamination of organically grown animals and animal products are very limited. In fact, concerning the risk of bacterial contamination among organic products, plant products have priority. In terms of organic animal products, poultry meat seems to be more risky. Salmonella and Campylobacter are the most important foodborne bacterial contaminants [10]. Salmonella can lead to disease

larly cadmium) and rich in phenolic compounds and vitamins [2, 3].

**2. Contaminants in organic animal products**

**2.1. Bacterial contaminants in organic animal products**

in animal products [9].

130 Livestock Science

It was observed that Salmonella contamination status varies in organic fattening pig farms depending on the breeding experience of the farms [12].

Organically grown animals have a lower risk of bovine spongiform encephalopathy (BSE, mad cow disease) just because they are fed with organic feed [7]. In cattle breeding, there is no basis (evidence) associated with organic production systems in terms of *Escherichia coli* (0157: H7) epidemics. In fact, a meat product such as undercooked minced meat is considered as responsible for the outbreaks due to this microorganism [18]. In a study monitoring the tetracycline residues (tetA and tetB) and tetracycline resistant bacteria in organic meat and vegetable-based baby foods, tet genes have been found in all organic products, particularly higher tetA have been detected in those from poultry origin, which indicates that organic foods are not better than conventional ones [19].

The bacterial count in raw milk is considered as an indicator of hygienic management of the farm. According to the European Union (EU) Council Directive (EC 92/46/EEC) for the production of heat-treated drinking milk, plate count (30°C) for per ml of milk should be ≤100,000, somatic cell count-SSC for per ml of milk should be ≤400,000 in cows' milk and plate count (30°C) for per ml of milk should be ≤1,500,000 in goat's and sheep's milk [20]. In a comparative study, total mesophilic bacteria count-TMBC (×10<sup>3</sup> CFU/mL) and coliform bacteria count-CBC (×10<sup>1</sup> CFU/ml) content of organic milk samples (for mesophilic n = 218; for coliform n = 101) were higher than conventional milk (for mesophilic n = 1168; for coliform n = 473) [21]. In one of the two different studies conducted in USA, no difference was present between organic and conventional (sum of grazing and not grazing) milk regarding SSC [22], and in the other study, very little difference was determined in terms of SSC and standard plate count [23]. Although no difference was found between organic and conventional milk samples concerning the diversity of spore forming aerobic bacteria, bacteria isolated from milk obtained from conventional farms were found to be more resistant to heat, and *B. cereus* organisms were abundant in organic milk, whereas *Ureibacillus thermosphaericus* were abundant in conventional milk. It has been suggested that this situation may be related to dietary strategy in the farm [24], and restricted silage use in organic ruminant breeding may reduce the bacterial contamination (*Listeria monocytogenes, E. coli* O157s) [24, 25].

## **2.2. Fungal contaminants and mycotoxins in organic animal products**

Mycotoxins are toxic molecules, which are synthesized by molds growing on plants. These highly toxic and heat-resistant toxins are transferred to animals with plants, and to humans with animal products through the food chain. Among the mycotoxins, particularly aflatoxin (AFL), ochratoxin (OTA), fumonisins, deoxynivalenol (DON), patulin and zearalenone are the most important mycotoxins for public health. Mycotoxin contamination in animal products is lower than in those from plant origin. Studies comparing the organic and conventional animal products concerning mycotoxin contamination is limited [25].

In Latvia, mold strains belonging to 15 genera were identified in the raw milk samples collected from organic farms between December 2011 and November 2012. Among these strains, the most common ones were *Absidia, Aspergillus, Apophysomyces, Mucor, Penicillium* and *Rhizopus* spp. [26]. In a study of Ghidini et al. [6], Aflatoxin M1 levels in organic (Mean 35 ng/L; Range <5–93 ng/L) was found to be higher than conventional (Mean 21 ng/L; Range <5–66 ng/L) milk samples. The Aflatoxin M1 levels in 49% of the organic and in 10% of conventional milk samples were higher than the legal limit of 50 ng/L, which was set by EU Regulation 466/2001. However, in general, the samples were accepted as safe. In a study analyzing the organic and conventional milk samples for mycotoxins, OTA was detected in 6 out of 40 (11–58 ng/L) conventional milk samples and 5 out of 47 (15–28 ng/L) organic milk samples. OTA was not found in any of 20 baby food. The levels found in milk were higher than 5 ng/kg/day, which is the value for tolerable daily intake-TDI. It has been reported that consumption of such milk would be harmful for children [27]. In Greece, aflatoxin M1 (AFM1) (range 5–10 ng/L) was detected by ELISA in 196 different types (conventional, organic and children's milk) of milk samples collected from the market between November 2009 and June 2010. However, the AFM1 level determined in only two of the samples were higher than the maximal limit set by EU [28]. In a study conducted in Italy, feed and serum of conventional and organic layers and broilers were analyzed, and ochratoxin A (OTA) was found in all of the feed samples (100%). But not above limits set by the EU. OTA rates were high especially in the sera of laying hens on both organic (73%) and conventional (52%) systems, but there was no statistical difference between the laying hens vs broiler group [29].

An OTA contamination (mean 0.05 μg/kg) in organic pork (4/7) was determined by a study conducted in Denmark between 1993 and 1994 [30].
