Moderate to serious congestion was within hepatic parenchyma in group B and hepatocytes enlarged, disoriented leading to sinusoidal spaces to seem less prominent. control. Experimental an infection withC. perfringens(1 108cfu/mL) was induced via dental route on times 17, 18 and 19 from the test in groupings B, D and C. Groupings C and D had been passively immunized by anti-clostridialIgYs@ 1 mL per parrot via dental and dental and intramuscular (I/M) routes respectively, on times 21 to Tetrahydrozoline Hydrochloride 24, and on times 22 and 24 from the test, respectively. Two necropsies had been performed (the initial on time 26th and the next on time 35th). Birds in group B showed behavioral indicators e.g., laziness, depression and diarrhea, gross post-mortem lesions e.g., increase in the relative weights (RW), due to acute swelling and congestion of liver and kidneys and ballooning and hemorrhages of jejunum and microscopic lesions e.g., congestion and necrosis in liver and kidneys parenchyma and disrupted epithelium with fewer goblet cells in jejunum, compared to the group A. Birds in groups C and D, showed significant improvements in clinical and behavioral indicators, RW of liver, kidneys and jejunum, swelling, congestion and mononuclear cells infiltration in liver and kidneys and damages in the jejunal-wall, compared to group B. The most significant Tetrahydrozoline Hydrochloride changes were found in birds of group C. Our study revealed ameliorative effects of EYAs on certain biological parameters however, further studies would be needed to justify a safer production and a reliable application of EYAs in NE outbreaks. Keywords:necrotic enteritis, egg yolk antibodies,Clostridium perfringens, microscopic, passive immunization, pathological == 1. Introduction == Over the years, the Pakistani poultry industry has emerged to be one of the most successful national industries, with an average annual growth rate of 7.5% since 2012 [1]. Infectious disease outbreaks of various bacterial, viral and fungal origin, e.g., necrotic enteritis (NE), avian influenza (AI) and aspergillosis have posed a significant economical and health threat to this industry. NE, caused byClostridium (C.) perfringens, is an important bacterial disease of the gastrointestinal (GI) tract in birds that may cost up to 56 billion USD per annum the global poultry industry [2]. This bacterium is usually a Gram-positive anaerobic bacillus, Tetrahydrozoline Hydrochloride which resides as normal gut microbiota [3].C. perfringensis grouped into five toxinotypes (AE) depending upon the type of toxins produced e.g., alpha, beta, epsilon, iota, and enterotoxin [4]. Recently, another type G was explained in birds generating both alpha and a pore-forming toxin known as NetB [5]. However,C. perfringenstype A negative fornetB, has been isolated from NE infected birds [6]. Tetrahydrozoline Hydrochloride NE shows indicators of dullness, diarrhea and poor body condition with gross post-mortem lesions, i.e., ballooned and hemorrhagic intestines and microscopic lesions, i.e., shortening of the villi with damaged epithelium in the intestines [7]. Antimicrobials targeting Gram positive bacteria are effective against acute NE in poultry. Recently, NE has significantly re-emerged due to a gradual shift in husbandry practices towards being more environmentally friendly, e.g., ban of the use of anti-microbial growth promoters (AGPs) by the European Commission rate (EC) of the European Union (EU) since 2006 and the human health-related antimicrobials in food animals by the United States Food and Drug Administration (FDA) since 2015 [8,9]. Hence, finding TSPAN32 a safe alternative remains indispensable. Egg yolk antibodies (EYAs) orIgYsare termed as protective antibodies produced in the egg yolk of immunized hens that can be used to neutralize specific pathogens of enteric origin and help to improve growth performance characteristics in infected birds [10,11]. Currently, EYAs have potential application in various immunodiagnostic and therapeutic methods used in animals and humans [12,13]. Keeping in view the protective role of EYAs, the current study aims to evaluate the influence of anti-clostridial EYAs around the gross and microscopic lesions found in infected broiler birds. == 2. Materials and Methods == == 2.1. Production of Anti-Clostridial EYAs == Ten (10) white leghorn hens (40 weeks of age) were immunized by injecting 1mL of inactivated whole cell antigen (WCA) ofC. perfringensin the breast muscle, as explained previously in detail [14]. Booster doses were administered on 42nd and 44th weeks [15]. EYAs were extracted as.