1. Introduction
Coccidiosis, caused by a number of
Eimeria species, is a significant parasitic disease known for pathological lesions in the intestines [
1]. This disease holds economic importance as one of the most prevalent and costly parasitic afflictions affecting the broiler industry. Typically,
Eimeria proliferates, causing severe alterations in the epithelial tissue of various intestinal segments through multiplication [
2]. The global prevalence of coccidiosis in countries with substantial poultry production leads to substantial economic losses, encompassing reduced weight, diminished feed efficiency, expenses related to anti-coccidial therapy, and increased mortality and morbidity [
2,
3]. Additionally,
Eimeria infections are associated with the disruption of digestion and absorption of vital nutrients, leading to reduced growth performance and immunocompromised states [
4].
In the current scenario, the primary strategy to combat coccidiosis on poultry farms includes employing antibiotics, vaccination, natural compounds [
2,
5,
6], or a combination of these approaches. Although these strategies have demonstrated high effectiveness in managing economically important parasitic infections, apprehensions have been raised regarding the emergence of antibiotic resistance in meat and eggs [
7,
8]. Consequently, researchers have focused on finding health-conscious solutions as an alternative to antibiotics [
9]. As a matter of fact, in the developed parts of the world, the application of antibiotics for the prevention of infectious diseases has been significantly reduced for more than a decade and a total removal is expected in the coming years [
10].
Numerous research reports have delved into the beneficial impact of herbal-based compounds on broiler performance, intestinal physiology, and the reduction in mortality. In recent times, with the goal of controlling coccidiosis, phytogenic compounds have emerged as a promising alternative to antibiotics, not only demonstrating efficacy in reversing
Eimeria infection but also showing little negative effects on bird health [
11]. Recent research findings have concluded the anti-
Eimeria characteristics of phytogenic compounds, such as powders and extracts [
1,
5,
6]. While the application of phytogenics represents an important option for reversing the
Eimeria challenge without the use of antibiotics in broiler production [
12], their adoption by poultry farmers could be enhanced if these products are derived from agricultural wastes, providing an even more potent alternative to antibiotics [
5].
Pomegranate (
Punica granatum) peel is rich in phenolic compounds, endowing it with higher antioxidant properties compared to other parts of the fruit. Additionally, it is known for its attributed anti-fungal, anti-parasitic, and anti-cancer properties [
13]. The fruit of pomegranate itself contains an array of valuable components including amino acids, minerals, various acidic compounds, antioxidants (punicalagin, anthocyanins, and ellagic acid), and anti-cancer agents [
14]. Studies in the past have also demonstrated the anti-parasitic potential of pomegranate peel, showing that it acts on the different stages of growth and development in parasites. Notable examples include its impact on the adult parasites of
Trichomonas tenax [
15],
Schistosoma mansoni [
16],
Giardia [
17], and
Cryptosporidium parvum [
18], as well as certain nematodes and
strongyles [
19].
Based on prior research, there is evidence to suggest that pomegranate peel exhibits notable anti-parasitic properties against Eimeria, a phenomenon explored in this particular study. Therefore, our research focused on assessing the impact of pomegranate peel powder on Eimeria by using various parameters including decreased oocyst excretion, diminished intestinal lesions, microscopic alterations in villi, and the influence of treatment on the growth metrics of broiler chickens.
3. Results
Table 2 illustrates that feed intake was not significantly (
p > 0.05) affected in weeks 1–3, or during the starter phase. However, in week 4, the feed intake in the NC group was significantly (
p < 0.05) higher than in the AT group, followed by the PPP3 and PPP6 groups, which were, in turn, significantly higher (
p < 0.05) than the PC group. Similarly, in week 5, the feed intake of the NC group was significantly (
p < 0.05) higher than in the AT group, followed by the PPP6, PPP3, and PC groups. At the end of the finisher phase, the feed intake remained higher (
p < 0.05) in the NC group compared to the AT group, followed by the PPP6, PPP3, and PC groups. Overall, the feed intake of the NC group was significantly (
p < 0.05) higher than the AT group, followed by the PPP6 and PPP3 groups, which were again significantly (
p < 0.05) higher than the PC group.
Table 3 shows the impact of pomegranate peel powder on the weight gain of broilers challenged with
E. tenella. At week 1 the weight gain recorded was not affected (
p > 0.05) by the inclusion of PPP in the diets. At week 2, the weight gain was higher (
p < 0.05) in the broilers of the PPP6 and PPP3 groups, followed by the AT, PC, and NC groups. In week 3, it was observed that the WG of the PPP6 group was significantly (
p < 0.05) higher than the PPP3 and NC groups, followed by the PC and AT groups. Furthermore, the PPP3 group exhibited a significantly (
p < 0.005) higher weight gain than both the PC and AT groups. During the starter phase, the weight gain was significantly (
p < 0.05) higher in the PPP6 group compared to the PPP3 group, followed by the NC, AT, and PC groups. In week 4, the weight gain in the NC group was significantly (
p < 0.05) higher than in the AT and PPP3 groups, followed by the PPP3 and PC groups. The week 5 weight gain showed that the NC group was significantly higher than the AT group, followed by the PPP6, PPP3, and PC groups. In the finishing phase, the weight gain results indicated that the NC group exhibited significantly (
p < 0.05) higher weight gain compared to the AT group, followed by the PPP6, PPP3, and PC groups. Overall, the weight gain in the NC group was significantly (
p < 0.05) greater than the AT group, followed by the PPP6, PPP3, and PC groups.
Table 4 shows that the FCR in the 1st and 2nd weeks was significantly similar (
p > 0.05). In the third week, the FCR in the PPP6 group was significantly (
p < 0.05) improved compared to the PPP3 group, followed by the NC, PC, and AT groups. During the starter phase, the feed conversion ratio (FCR) was significantly (
p < 0.05) lower in the PPP6 group compared to the PPP3 group, followed by the NC, AT, and PC groups. In the fourth week, the FCR in the PPP6 group was significantly (
p < 0.05) lower than in the NC group, which was further reduced than in the PPP3 and AT groups, followed by the PC group. By the fifth week, the FCR was significantly (
p < 0.05) lower in the NC group than the AT group, with no difference in the PPP3 and PPP6 groups, which were significantly (
p < 0.05) less improved than the PC group. In the finisher phase, the FCR was significantly (
p < 0.05) lower in the NC and PPP6 groups compared to the AT and PPP3 groups, followed by the PC groups. Over the entire period, the FCR was significantly (
p < 0.05) lower in the PPP6 and NC groups compared to the AT and PPP3 groups, followed by the PC group.
Table 5 illustrates the impact of PPP supplementation on lesion scores and mortality in broilers subjected to an
E. tenella challenge. The NC group, which remained uninfected, exhibited a normal cecal epithelium. In contrast, the PC group showed significantly (
p < 0.05) higher cecal lesions compared to the PPP3 group, followed by the PPP6 group and the AT group. Lesions were absent in the NC group, and the AT-treated group displayed the lowest lesions. Mortality rates were highest in the PC group, followed by the PPP3 and PPP6 groups. No mortality occurred in the NC and AT groups.
Table 6 presents the effects of pomegranate peel powder (PPP) supplementation on the oocyst count per gram (OPG) of feces in broilers subjected to an
E. tenella challenge. The OPG, in comparison to the NC and AT groups, was significantly (
p < 0.01) higher in the PC group on days 5, 7, and 9 post-infection (DPI). The OPG on day 7 DPI remained unchanged (
p > 0.05) between the PC group and PPP supplemental groups. However, in the second and third intervals (10 and 14 days) of the challenge, the OPG count significantly (
p < 0.05) decreased in the PPP supplemental groups compared to the PC group.
Table 7 illustrates the effect of supplementing broilers challenged with coccidiosis with PPP on the villus dimensions of the caecum. Significantly decreased villus height, width, and VH:CD were observed in the PC group compared to the NC and AT groups (
p < 0.05). Interestingly, the PPP3 and PPP6 groups exhibited significantly higher villus height, width, and VH:CD ratios compared to the PC group (
p < 0.05). Similarly, the crypt depth significantly decreased in the PPP3 and PPP6 groups compared to the PC group (
p < 0.05). Examination of the cecal epithelium (
Figure 1) in the PC group revealed prevalent signs of scattered
Eimeria oocysts, desquamation of the epithelium, aggregation of inflammatory cells, and hemorrhages. In contrast, both pomegranate peel powder-supplemented groups (at 3 g/kg and 6 g/kg) showed minimal pathological lesions and mild sloughing in the epithelium of the cecum of infected broilers. The broilers that were AT-treated after infection showed only minor damage to the cecum epithelium.
4. Discussion
In the current study, the effects of pomegranate peel powder (PPP) on the growth indices, oocysts excretion, and cecal histomorphology of broiler chickens subjected to induced
Eimeria challenge were evaluated. The results showed that PPP supplementation reduced lesion scores following
Eimeria infection, led to a decrease in
Eimeria oocyst numbers, and restored the cecal histological morphology of infected broilers. Notably, the impact of PPP6 was superior to PPP3 in terms of growth performance, with broilers challenged with
Eimeria exhibiting improved growth performance when their diet was enriched with PPP6. Khorrami et al. [
2] also reported improved growth performance and alleviation of coccidiosis symptoms in broiler chickens challenged with mixed
Eimeria species in response to 200 and 400 ppm pomegranate peel extract (PPE). Several studies have also explored the impact influence of PPP on growth indices in chickens, with Akuru et al. [
20] finding improved weight gain and feed efficiency in birds supplemented with 2 g/kg and 4 g/kg of PPP. Hamady et al. [
21] conducted a study involving the addition of 0.1% pomegranate peel extract powder in broilers’ diet for a period of six weeks. The results demonstrated that continuous supplementation led to an increase in weight gain. Another study by Rezvani and Rahimi [
22] investigated the effects of PPEx on various parameters including the weight gain, nutrient digestibility, immune response, and microbial population of broiler chickens. Their findings indicated that PPEx enhanced the daily weight gain and feed intake throughout the growing period. However, it did not have a significant impact on the FCR. Additionally, the extract of pomegranate peels was found to improve the digestibility of nutrients, promote the growth of beneficial microbial flora like Lactobacillus, and elevate the immune response [
22]. This enhancement is likely attributed to the growth-promoting properties of pomegranate peel, which are linked to its antimicrobial and antioxidant attributes. The presence of proanthocyanidins in pomegranate peel facilitates improvements in pancreatic and small intestinal digestive enzyme functions. Additionally, it helps counteract the detrimental effects of reactive oxygen species on intestinal enterocytes, ultimately resulting in improved nutrient digestion [
23,
24].
In this investigation, both supplements exhibited comparable efficacy in relation to OPG, lesion scores, and villus histology. Furthermore, the evaluation of PPP3 and PPP6 doses indicated that, although they demonstrated some anti-Eimeria effects, these effects were not parallel to the AT treatment concerning the mitigation of typical coccidiosis symptoms and the enhancement of growth performance.
Researchers posit that integrating phenolic compounds into the food chain can serve as an effective strategy for controlling parasitic diseases. It represents an affordable and straightforward means to enhance the health of poultry in their defense against parasitic infections. Specifically, pomegranate peel stands out as a valuable reservoir of bioactive compounds [
25]. In a study conducted by Elfalleh et al. [
26], various components of the pomegranate plant were compared for their levels of flavonoids, total phenolics, anthocyanins, and hydrolysable tannins. The study revealed that the pomegranate peel exhibited the highest concentration of these compounds. Various studies have also demonstrated the in vivo and in vitro antimicrobial and anti-parasitic properties of pomegranate peel [
26]. In addition, its anti-fungal effect against
Aspergillus niger and its anti-bacterial effect against
Staphylococcus aureus have been reported [
27]. Furthermore, its anti-parasitic effect on the adult worms of
S. mansoni and
Trichomonas tonax has been confirmed [
15,
16]. Al-Megrin [
28] also documented the anti-cestodal activity of pomegranate peel extract against
Hymenolepis nana, which is an infection caused by a dwarf tapeworm [
28]. Yet another study provided evidence for the efficacy of pomegranate peel extract in both the prevention and treatment of
Giardia lamblia infection [
17].
Pomegranate exhibits anti-coccidial activity similar to Amprolium, as evidenced by a significant reduction in the excretion of
E. tenella oocysts in the feces of infected birds. This reduction indicates that pomegranate hampers the development of parasites within the host before the formation and eventual release of the relatively inert oocysts [
9]. The antioxidative properties of pomegranate are primarily attributed to its phenolic compounds, including gallotannins, anthocyanins, gallagyl esters, ellagitannins, hydroxycinnamic acids, hydroxybenzoic acids, and dihydroflavonols [
29,
30]. These compounds in pomegranate have been reported to exhibit anti-cestodal, anti-nematodal [
31], anti-protozoan [
32,
33], and anti-bacterial effects [
34,
35]. In our study, the administration of a PPP-fortified diet resulted in an enhanced histological picture of the challenged broilers, which can be linked to the anti-protozoal effects of PPP, coupled with its potential anti-inflammatory and antioxidant activities. These attributes likely played a significant role in protecting the host tissue from damage caused by
Eimeria oocysts [
35]. The effectiveness of pomegranate extracts has primarily been attributed to their major chemical component, anthocyanins. This compound has been reported to exhibit both anti-coccidial and anti-protozoal activities [
18]. As natural products, pomegranates show considerable promise as potential sources for novel anti-coccidial agents to mitigate
Eimeria infection.