1. Introduction
Corn and wheat represent the primary energy source in the food animal’s daily diet, while wheat has been considered the third most-produced feedstuff globally [
1]. In the last ten years, studies and researchers have been struggling with the fungi of the genus
Alternaria, which has grown to be the leading cause of wheat grains contamination [
2]. The essential characteristics of
Alternaria genera is the production of melanin and the host-specific plant–fungi/toxin interaction [
3,
4,
5]. In addition, direct melanin emerges an indirect role in virulence, as well [
6]. Melanin poses the ability to function as the shield in plant fungi protections versus ecological stress or unfavorable conditions, which gives fungus permanency and endurance. Furthermore, melanin promptly responds with free oxygen radicals, versus the pathogen’s infiltration in the plant-host cells [
7,
8]. The blackening of the wheat grain lobes prior to cropping is typical indicator of contamination with
Alternaria spp. [
9]. At hand there is several forms of discoloration that can alter ordinary wheat (
Triticum aestivum L.). In nearly all areas where wheat is cultivated, the black point is usually correlated by
Alternaria alternata as a common discoloration of seed [
10]. The staining usually appears in the external pericarp and internal grain tissue and could broaden beside its adaxial side. Such kinds of grain color changes differ drastically in frequency and seriousness depending on grain during the maturation. Biotic and abiotic stresses can cause wheat grain color changes, often caused by high humidity and high temperatures [
11]. Those kinds of conditions are very favorable for fungi and mycotoxins occurrence in general [
12,
13]. Recently it has been confirmed that high humidity levels might stimulate the sporadic expansion of black point on wheat grain under controlled conditions [
14].
A. alternata was the primary cause related to black point occurrence on wheat grain [
15]. Likewise, pathogenicity and decrease of quality of wheat grains are influenced by a number of
Alternaria spp. the producers of toxic secondary metabolites known as
Alternaria mycotoxins [
16,
17].
Alternaria mycotoxins as alternariol (AOH) [
18], tenuazonic acid (TzA) [
19], alternariol monomethyl ether (AME) [
20], altenuene (ALT) [
2], altertoxin I (ATX-I) [
21], alterotoxin II (ATX-II) [
18], and stemphyltoxin III (STTX-III) [
22] could be toxic for animal health [
23].
Some of the previous mentioned toxins could cause a serious health damages in animals when ingested, between them, for instance, fetotoxicity and somatic or functional deficiencies in the fetus when the mother is exposed to toxins [
23].
A. alternata, as a separate mycotoxin, is mutagenic and clastogenic in various in vitro systems [
24]. Moreover, it has been recommended that
Alternaria toxins in grains be accountable for gullet pipe cancer [
25]. Consequently, because of toxic effects,
Alternaria toxins are of concern for public and animal health [
26]. The European Commission (EC), and European Food Safety Authority (EFSA) were therefore engaged to give a technical view on the hazards for community and animal wellbeing associated with the occurrence of
Alternaria mycotoxins in the commodities for human and animal daily nutrition. Subsequently,
A. alternata have been chemically characterized, and incidence in feed was recorded [
27]. Nevertheless, more than a few other
Alternaria toxins have been classified as well, respectively [
28].
Assessment of
Alternaria toxins consumption by food animals through daily feeding have been restricted to broilers since poultry have been single one animal race where certain information about mycotoxin toxicity is appropriate for hazard evaluation [
29,
30,
31]. Given that the incidence of feed data was lacking for the majority of the
Alternaria toxins, the exposure assessments have been restricted to AOH toxin. Estimated lower bound and upper bound introductions to alternariol (AOH) were around 0.003 mg/day and 0.006 mg/day, for chickens and layers, respectively.
Broilers in production conditions are subjected to a variety of stressors [
32]. The additional reactive oxygen species (ROS) and reactive nitrogen species (RNS) production and oxidative stress are the essential harmful outcomes [
33]. In the evolutionary process, antioxidant defense mechanism were built in birds to be able to stay alive in an oxygenated atmosphere [
34]. They consist of a dense system of inside integrated antioxidant enzymes, for instance, glutathione (GSH), coenzyme Q (CoQ), and outwardly provided by vitamins, carotenoids, and antioxidants [
34]. Furthermore, all antioxidants in the body work together to sustain the best oxidoreduction equilibrium [
35]. This equilibrium is a crucial component in supplying the required preconditions for cells indicating, stress adjustment, and homeostasis upkeep [
36]. While ROS and RNS are critical signaling molecules, their presence have been rigorously controlled by the antioxidant defense system linked with various transcript components and vitagenes [
37]. Physiology shows that change from optimum inner and outer circumstances causes stress [
38].
Additionally, a complicated flow of controlling systems is implicated in the stress reaction, causing the metabolic alterations triggering weakened live performance in broilers [
39]. When the ROS and RNS construction outstrips the antioxidant defense mechanism ability to neutralize them, oxidative stress arises [
38]. That includes polyunsaturated fatty acids (PAFAs), proteins, and DNA [
40], take the lead to damaging outcomes in wellbeing, progress, development, and overall animal welfare [
41].
Contemplating lucking research results and significant information’s on Alternaria mycotoxins and that the biochemical composition of more than a few is identified, this research’s precise aim was to visually characterize and investigate the effects of Alternaria spp. contaminated wheat grains in broiler chicken nutrition in the starter stage on productive parameters, oxidative stress, and overall welfare of this species of food animals. Obtained results from this research can serve in the future as the reference material for creating the new up-to-date guidelines on Alternaria toxins in foodstuffs and feedstuffs.
3. Results and Discussion
Results of proximate analysis of compound feed used in daily nutrition of broiler chickens during the experiment are presented in
Table 1.
Gained results are conferred in the range of the color properties of grain color properties of
Alternaria. Gained results are conferred in the range of the color properties of
Alternaria spp. contaminated wheat grains [
49]. Wheat grain samples were significantly different (
p < 0.05) in terms of all measured color parameters (
L*,
a*,
b*). Control wheat grain (A1) samples were significantly different in terms of lightness and dominant wavelength, compared to wheat grain samples (A2) and (A3), which have shown significant difference (
p < 0.05) compared to A1, but without any statistically significant difference (
p > 0.05) between themselves, nevertheless numerical differences (
Figure 1), respectively.
The results presented in
Figure 1 show that all wheat grain samples belong to the different groups by dominant wavelength values. Contemplating all stated, it can be concluded that infection entered the grain in a higher amount in some wheat samples (A2 and A3). Simultaneously, there were samples without visible infection and color changes on the grain (A1). Wheat grain samples without visible dark spots were commonly described by higher lightness and more prominent yellow tones [
50].
All wheat grain samples collected from the field and previously instrumentally analyzed were disinfected with 0.4% NaOCl and placed for incubation (
Section 2.4) for seven days. Results of fungi genera confirmation were carried out by microscopic examination, and the results have been shown in
Table 2.
Classification of field fungi in analyzed wheat grain samples showed that the significant field fungi were
Rhizopus spp., followed by
Alternaria spp., and
Fusarium spp. The ratio of contamination of wheat grain samples by
Alternaria spp. was the highest in A3 samples without significant difference (
p > 0.05) compared to A2, as previously stated. Differences in percentages between A2 and A3 could be explained by the fact that
Alternaria spp. produce melanin pigments of dark color, which can cause the differentiation in determination with instrumental measurement, respectively. Due to fungi growth in the field even at low temperatures, they are also responsible for spoilage of commodities during refrigerated transport and storage. Several
Alternaria species are known producers of toxic secondary metabolites known as
Alternaria mycotoxins [
23].
A. alternata produces several mycotoxins. TeA is harmful to several animal species, e.g., mice, chickens, and dogs [
23]. Many
Alternaria metabolites have been reported to occur naturally in cereals [
5,
12]. Alternariol, alternariol monomethyl ether, and tenuazonic acid were frequently detected in sorghum, wheat, and edible oils [
23]. Xu et al. [
51] have reported the importance and danger of exposure to
Alternaria toxins from grain and grain-based products because of its relation to human esophageal cancer in China. In their study, a total of 370 freshly harvested wheat grain samples were analyzed for the four
Alternaria toxins TeA, TEN, AOH, and AME. Field contaminated samples (95%) of the wheat grains were positive for more than one type of
Alternaria toxins [
51]. Li and Yoshizawa [
52] reported the first report of the natural occurrence of
Alternaria mycotoxins in Chinese wheat. Their wheat grains were significantly infested by
Alternaria species, mainly
A. alternata, with a median infection rate of 87.3%. The grains with low quality which is acceptable in some cases was researched in post-harvest period to investigate if the
Alternaria or
Fusarium influenced in adverse quality of the grains [
53]. The distribution of
Alternaria and
Fusarium spp. they were varied significantly in samples of reduced rate compared with acceptable samples. The results of Kosiak et al. [
53] revealed a negative interaction between
F. graminearum and
Alternaria spp. as well as between
F. graminearum and another
Fusarium spp.
Fusarium and
Alternaria fungi naturally occurring on the ears and the formation of their mycotoxins in the ripe grains. Müller et al. [
9] investigated the fluorescent pseudomonads colonizing wheat ears, which have a high antagonistic potential against phytopathogenic fungi. Unfortunately, the results of their findings indicate that extensive biological management of mycotoxin development by naturally arising pseudomonads with incompatible activity is very doubtful [
9].
Based on the gained results in the second phase of the experiment with the live broiler chickens, after the first experimental week, it could be noticed that the addition of wheat infected with Alternaria spp. in the amount of 25% in treatment A2 and A3 expressed adverse effects. The highest body weight of chickens of 140.40 g was recorded in broilers on control treatment A1 with statistically significant differences (p < 0.05) compared to treatments A2 (137.32 g) and A3 (135.35 g).
At the end of the second week of test period, a statistically significant (
p < 0.05) difference in body weight of broiler chickens could be noticed. The highest body weight of 352.68 g was recorded in control treatment A1, with statistically significant differences compared to other
Alternaria spp. treatments. The lowest body weight of chickens was recorded in treatment A3 (335.93 g), while significant differences (
p > 0.05) between chickens in
Alternaria spp. treatments were not recorded (
Table 3). The low broiler chicken body weight observed in
Alternaria spp. contaminated diet than control could be due to
Alternaria spp. toxin tenuazonic acid which was firstly described in 1987 [
54].
Numerous researches have registered a broad array of serious wellbeing impacts and medical indications after food animals was subjected to the elevated amount of toxins. Nevertheless, not a lot is seen concerning the wellbeing impacts of toxins at small amounts [
55]. Kolawole et al. [
55] conducted a long-term feeding trial in order to investigate the impact of small amounts of toxin combinations on the production of poultry fed with naturally contaminated complete feed. Total of eighteen tests with poultry production was performed, with closely of 2200 one-day-old Ross-308 birds per each test. As food animals are frequently subjected to low doses of mycotoxin, a cumulative risk evaluation in quantifying and alleviating counter to the economic, welfare, and health influences is necessary for mycotoxins. Hessel-Pras et al. [
56] stated that once
Alternaria mycotoxins passes the intestinal barrier, they can reach the liver to exert yet uncharacterized molecular effects. Hence, the same group of authors used hepatic in vitro systems to examine selected
Alternaria mycotoxins for their induction of metabolism-dependent cytotoxicity, phosphorylation of the histone H
2AX surrogate marker for DNA double-strand breaks, and relevant marker genes for hepatotoxicity. They have found evidence that 50 μmol/L of AOH, AME, TeA, and TEN might be associated with hepatotoxic effects, necrosis, and the development of diseases like cholestasis and phospholipidosis [
56]. Kemboi et al. [
57] discovered that other developing toxins and metabolites, counting
Alternaria,
Aspergillus,
Fusarium,
Penicillium toxins, were discovered at differing concentrations during their research. Such co-occurrences of mycotoxins could trigger synergistic and additive health effects, impeding the food animal production sectors worldwide.
Results of feed consumption and feed conversion ratio are shown in
Table 4 and
Table 5.
Alternaria spp. contaminated wheat grain showed some numerical differences between treatments but without any statistically significant differences in broiler chickens’ life stage of life.
In addition to wheat, corn is the main feed ingredient used in poultry nutrition. As a wheat grain, the corn can also be naturally infected with mycotoxins, especially with
Alternaria spp. Topi et al. [
58] have investigated the presence of
Alternaria mycotoxins in grains from Albania: alternariol, alternariol monomethyl ether, tenuazonic acid, and tentoxin. They have concluded that the contribution of AOH and AME originating from wheat was 0–31.7 ng/kg body weight per day. In contrast, the contribution of
Alternaria toxins through maize consumption was significantly lower.
Changes from optimal internal and external conditions lead to stress from a physiological point of view. Between the main stressors in broiler production, nutritional stressors have a significant role, and within them, the leading role is mycotoxins feed contamination [
34].
The highly probable clarification for the remarked results presented in
Table 6 is that the pathological modifications strengthen free radical processes by promoting catalytic activities of enzymes engaged in the antioxidative protection, POD, and GR. Still, through the disease phase, lipolysis from the lipid depots could be increased due to reduced feed consumption, which is not the case in our research. Moreover, tiredness of the organism could lead to escalation of free radical processes and higher amounts of lipid peroxides in blood. To defend himself, the body initiates its antioxidative safety mechanisms. Decrease of SOD activity was anticipated and is in accordance with other research [
59,
60].
The glutathione has a vital position in reducing the acute toxicity of xenobiotics and products of lipid peroxidation. A statistically significant decrease of POD activity compared to the A1 control treatment was expected since POD catalyzes various proton donors’ oxidation with hydrogen peroxide. Having in mind that mycotoxins are classified as hepatotoxins, nephrotoxins, neurotoxins, immunotoxins, and that there are to date, 400 mycotoxins identified and the most critical species producing mycotoxins belong to
Aspergillus,
Penicillium,
Alternaria, and
Fusarium genera, Ülger et al. [
61] have described their genotoxic effects on the organism. Uric acid increased accumulation, and reduced excretion is closely related to the pathogenesis of gout and hyperuricemia. Higher plants produce different metabolites, which might impede XOD, so disallow the oxidation of hypoxanthine to xanthine then to uric acid in the purine metabolism. Nevertheless, microorganisms generate a group of degrading enzymes, which catalyze uric acid degradation to ammonia. Xanthine oxidoreductase (XOR) has two forms; xanthine oxidase (XOD) and xanthine dehydrogenase (XDH), both of them catalyze the oxidation of hypoxanthine to xanthines, then to uric acid in the purine metabolism [
62]. Hafez et al. [
63] presented an analysis with the incidence of uric acid in plants and other organisms, especially microorganisms, in addition to the mechanisms by which plant extracts, metabolites, and enzymes could reduce uric acid in the blood. Overactivity of both enzymes (XOD and XDH) cause the accumulation of uric acid in the animal body and form a pathogenesis condition called gout [
64]. Additionally, XOD serves as a valuable biological source of oxygen free radicals that participate in various damages of animal tissues leading to many pathological states [
65], which could be caused by multiple stress triggers, e.g., mycotoxins [
66,
67,
68].
Serum biochemical parameters were significantly affected by
Alternaria spp. wheat in both treatments compared to control treatment during the starter dietary phase (
Table 7). Even though the
Alternaria spp. contaminated wheat had no significant effect on growth performance in broiler chicks, it induced the typical clinical signs of hepatic injury, including increased activities of AST and ALT, during the starter dietary period what is in accordance with results of other researchers [
48,
69,
70].
Oxidative stress plays an important role in the development of many animal diseases and it has been shown that have significant implications for the well-being and overall welfare of nonruminants [
71]. Various studies have shown that oxidative stress has a fundamental role in the etiopathogenesis of several acute and chronic diseases which are causally related to animal welfare [
72]. Over the years oxidative stress has been deeply investigated in human, while in poultry production the data are yet less uneven [
73]. Poultry welfare is fundamental in maintaining correct health and a good level of mental and physical well-being of the animal [
74]. In our study increased content of total glutathione levels in chicken dietary treatments (5.8 and 6.2 µmol/g Hb min) with addition of blackpoint wheat, indicates that chickens had increased antioxidant defense. These results are directly related with the impaired welfare of chickens. Likewise, certain indicators of impaired welfare of chickens in our expert are increased activity of GR (21.1 and 19.8 µmol/g Hb min), and decreased activity of SOD (25.5 and 29.1 µmol/g Hb min), respectively. The similar results were obtained by Brambilla et al. [
75] in their research related to influence of oxidative stress markers reactive oxygen metabolites (ROM) and anti-oxidant power (OXY) in swine welfare. Stresses in commercial poultry result from many various factors which negatively impact poultry health, production, and welfare [
76]. Oxidative stress is downstream of all these stresses. Oxidative stress in the cells results from an imbalance between free radical production and endogenous antioxidant defense [
77]. It is well documented that poultry feed is often contaminated with a wide range of environmental toxicants, bacterial and fungal toxins, and known to affect the health and welfare of poultry [
78]. Mycotoxins usually generates reactive oxygen species which induces lipid peroxidation, alters the cellular redox signaling, antioxidant status, and membrane integrity of the cells [
79]. Mycotoxins increase cellular apoptosis and affect poultry health, production, and welfare.