## 2 Materials and Methods
#### 3.2.3 Plasma Oxidative Status
The dietary supplementation with GP (5%, 7.5%, and 10% of the diet) for 42 days affected broilers' mucosa status and microscopic structure [34]. The GP supplemented compared with the unsupplemented broilers showed a significant reduction (by 35.2%) of villus height (VH) in jejunum, while those consuming the highest levels of GP had also shorter villus height (by 35.4%) compared with the VitE fed ones. Moreover, broilers supplemented with GP (7.5% and 10% of the diet) in comparison with the unsupplemented ones had significantly lower VH/crypt ratios above all in jejunum (with a mean reduction of 35.2%), whereas only those consuming the highest GP level compared with those receiving VitE showed a lower value (by 35.4%) [34]. This study confirmed the potential effect of polyphenols on intestinal digestive and absorption functions. In laying hens, when clove bud powder (CBP) was included at two different levels (2% and 4% of the diet) in two diets with different n-6:n-3 in comparison with VitE (200 mg/kg), it did not affect liver relative weight [50]. Nevertheless, when CBP (0.4% of the diet) was included in a HRD diet, it increased the hepatic tissue integrity score (HTI; by an average value of 47.8%) in laying hens. Moreover, fat vacuole numbers score (FVN) was reduced by consuming the CBP compared to the basal diet (on average 36.5%), but the VitE diet resulted in lower FVN value than the CBP treatments. The CBP inclusion (0.2% of the diet) in LRD diet increased the HTI score (by 46.37% on average), whereas the FVN score was lower (25.9-51.8%) in all the CBP fed animals in comparison with those consuming VitE (by 35.0%) [50]. These results suggest that reducing n-6:n-3 led to a detrimental effect on HTI; all the experimental groups exhibited higher values of HTI when fed LRD diets. However, both CBP and VitE exerted hypocholesterolemomic and hypolipidemic effects, which were confirmed by lower FVN and greater HTI scores. Conversely, grape polyphenols addition (0.0025%, 0.0050%, and 0.0075% of the diet) in broilers' diet did not cause any significant effects on histopathological features of kidneys and liver [59]. Among the potentially beneficial effects of PFA on avian health and performances, some studies investigated their effectiveness in controlling intestinal microflora and mucosa integrity [62]. Dietary supplementation with oregano aqueous extract (OAE; 0.02% of the diet) compared with VitE and unsupplemented diets positively affected gut secretion glyconjugates [42] by the goblet cells, which cover the gastrointestinal mucosal layer and have an important role in protecting the intestinal mucosa [63]. The PFA effectiveness in controlling pathogens is of great interest in livestock species, including poultry, especially in some critical phases of animals' lifespan [10]. Coliforms bacteria count was lower in OAE than in VitE and control groups (by an average proportion of 20.8%) [42]. Similar results were obtained in the following interval. OAE compared with VitE dietary inclusion reduced the _Escherichia coli_ count in broilers caecum at 21 (by 35.0%) and 42 (by 9.0%) days, respectively. Coliform species are of great interest, because some of them are pathogenic organisms, sometimes representing also a zoonotic threat [64; 65]. The dietary inclusion of OAE in comparison with VitE and unsupplemented diets for 3 weeks lowered (by 32.5%) ileal count of total anaerobic bacteria. At the following interval, this dietary treatment induced higher bacterial counts [42]. Additionally, in broilers' ileum, no differences were found among the treatments groups concerning _Staphylococcus_ spp., while lactic acid bacteria (LAB) increased in the OAE group throughout the time interval of 21 days. However, the count of these beneficial bacteria did not differ significantly among the three groups. Nevertheless, enterococci, lactobacilli, and staphylococci populations in caecum at both sampling times were not significantly affected by the different treatments [42].