of C. perfringens in the liver and caecum compared to non-in- fected treatment and other infected treatments. Compared with the infected control, infected broiler chickens receiving AGPs or different levels of EOA revealed a considerable decrease in the number of C. perfringens and E. coli in the liver and intestine. Intestinal health was further supported by increased levels of the beneficial bacteria Lactobacillus observed in both the AGP and EOA groups.


Immunity and gut barrier function Gut lesions and C. perfringens burden in the gut and liver are common parameters used to assess the preventive efficacy of adding various antibiotics alternatives to treat NE infection in chickens. In this study, necrotic enteritis infection caused gut injury, as indicated by severe gut lesions, increased C. per- fringens load in the caecum and liver, decreased villus height/ crypt depth, and goblet cell numbers. However, the villus height/crypt depth and the number of goblet cells increased while gut injury decreased by either adding EOAs (200 mg/ kg and 500 mg/kg) or the addition of AGP, which had effects similar to those of the non-infected groups. The researchers related a decrease in the level of gut injury to improved gut health and improved growth performance because of the antimicrobial and anti-inflammatory activities of essential oils or organic acids. The intestinal epithelium and tight junction proteins (TJPs) significantly contribute to maintaining the integrity of the intestinal mucosa barrier, immune hemostasis and intesti- nal health. In this study, enhanced goblet cell density and elevated claudin-1 mRNA were observed in the NE-infected chickens given different doses of EOA, indicating that EOA could alleviate intestinal barrier damage caused by NE. A low


proportion of proteobacteria in the EOA group compared to the AGP group indicated that the EOA blend could reduce intestinal inflammation and improve gut health more than by administering AGP. The researchers concluded that feeding a blend of essential oils and organic acids at an appropriate dose could allevi- ate necrotic enteritis-induced gut impairment and growth depression and modulate caecal microbiota composition, demonstrating its potential as an antimicrobial alternative. In this study, a blend at an inclusion level of either 200 or 500 mg/kg was beneficial compared to supplementation with an- tibiotics. The researchers emphasised the importance of con- sidering all the factors that could affect the efficacy of EOA products such as the structure of EOs or OAs, EOA formula composition, EOA coating and dosage, chicken health status, dietary form and composition, and rearing conditions.


Adding EOAs at 200 mg/kg or 500 mg/kg is beneficial in terms of weight gain and feed efficiency in broiler chickens with necrotic enteritis infection.


Table 2 – Effects of EOA on intestinal bacterial concentration and liver C. perfringens numbers of broiler chickens challenged with necrotic enteritis.


Item PC


Caecal: C. perfringens E. coli


Lactobacillus


Liver: C. perfringens


0.00c 6.54 9.55


0.32b NC


4.69a 8.00 8.92


1.93a AGP


0.00c 6.69 9.61


0.11c Diets EOA-200


2.26b 7.40 9.64


0.40bc EOA-500


2.23b 7.06


10.60 0.42bc a,b,c Means within the same row without a common superscript differ significantly (P < 0.05). ▶ ALL ABOUT FEED | Volume 30, No. 5, 2022 27 EOA-800


1.57b 7.87 9.61


1.09b


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