Relationship Between Broiler Body Weights, Eimeria maxima Gross Lesion Scores, and Microscores in Three Anticoccidial Sensitivity Tests

Abstract

Anticoccidial sensitivity tests (ASTs) serve to determine the efficacy of anticoccidial drugs against Eimeria field isolates in a controlled laboratory setting. The most commonly measured parameters are body weight gain, feed conversion ratio, gross intestinal lesion scores, and mortality. Due to the difficulty in reliably scoring gross lesion scores of Eimeria maxima , microscopic analysis of intestinal scrapings (microscores) can be used in the field to indicate the presence of this particular Eimeria. The goal of this study was to determine the relationship between E. maxima microscores and broiler body weights and gross E. maxima lesion scores in three ASTs. Day-old broiler chicks were raised for 12 days on a standard corn-soy diet. On Day 12, chicks were placed in Petersime batteries and treatment diets were provided. There were six birds per pen, four pens per treatment, and 12 treatments, for a total of 288 chicks per AST. The treatments were as follows: 1) nonmedicated, noninfected; 2) nonmedicated, infected; 3) lasalocid, infected; 4) salinomycin, infected; 5) diclazuril, infected; 6) monensin, infected; 7) decoquinate, infected; 8) narasin + nicarbazin, infected; 9) narasin, infected; 10) nicarbazin, infected; 11) robenidine, infected; and 12) zoalene, infected. On Day 14, chicks were challenged with an Eimeria field isolate by oral gavage. On Day 20, broilers were weighed, and gross lesion scores and microscores were classified from 0 to 4 depending on the severity of the gross lesion scores and E. maxima microscores. Data from three trials using different field isolates were statistically analyzed using a logarithmic regression model. There was no relationship (P = 0.1224) between microscores and body weight gain. There was a positive relationship between microscores and gross lesion scores (P = 0.004). However, there was also an interaction between isolate and treatment (P < 0.0001). Lastly, the interaction between isolate and gross lesion scores (P = 0.0041) demonstrates that the significance of the relationship between microscores and gross lesion scores may be dependent on pathogenicity of the challenge Eimeria or the amount of E. maxima in the inoculum.

Algae-based feed ingredient protects intestinal health during Eimeria challenge and alters systemic immune responses with differential outcomes observed during acute feed restriction

“…This response is in contrast to previous reports and may be the result of utilizing a less virulent vaccine strain of Eimeria rather than a wild strain. The low average lesion scores (<2) observed in this study are similar to those observed in other studies utilizing high-dose CocciVac-B52 ( Johnson et al., 2019 ; Savary et al., 2020 ) and suggest that vaccine-strain Eimeria cause low-grade tissue inflammation compared to other studies utilizing wild-type strains (lesion score >2; Barrios et al., 2017 ; Teng et al., 2020 ). Intestinal morphology roughly corresponds with intestinal health, with both VH and CrD being positively associated with increased surface area for nutrient absorption ( Amat et al., 1996 ; Bogucka et al., 2019 ).…”

Comparative Analysis of Evaluation Parameters in Broiler Chickens Infected With Major Parasitic Species of Eimeria&nbsp;

“…However, Chasser et al reported that weight gain in Ross broilers infected with E. maxima on day 14 after hatching, with a macroscopic lesion score of 0.9 (assessed on day 19), was similar to that of uninfected birds [15]. Additionally, for broilers inoculated with three isolates of E. maxima, each having different pathogenicity, there was no relationship between microscores and body weight gain on day 6 post infection [21].…”

“…Due to the emergence of drug-resistant parasites and increasing public concern regarding the presence of drug residue in chicken products, vaccines, probiotics and natural products have been considered as potential alternatives for coccidiosis control [9,11,[17][18]. Although the effectiveness of these alternatives has been evaluated in commonly assessed parameters, such as body weight gain, intestinal lesion score, or fecal oocyst shedding [16,[18][19][20], few studies have included these parameters when evaluating Eimeriainfected birds [15,[21][22]. Therefore, the present study aimed to compare the aforementioned parameters in broiler chickens infected with three major Eimeria species, including E. acervulina, E. maxima and E. tenella.…”

Evaluation of day of hatch exposure to various Enterobacteriaceae on inducing gastrointestinal inflammation in chicks through two weeks of age

“…With the added incidence of mild GI inflammation, birds would be even more susceptible to these pathogens. Several disease induction models for coccidiosis and necrotic enteritis capitalize on this increased susceptibility to infection, with acute exposure to Eimeria or Clostridium perfringens generally falling between 10 and 21 d ( Park et al., 2008 ; Lee et al., 2010 ; Singh et al., 2015 ; Barrios et al., 2017 ; Wilson et al., 2018 ). Further, early Salmonella Typhimurium exposure has resulted in increased susceptibility to NE infection ( Shivaramaiah et al., 2011 ), suggestive of a disruption to the GI tract that resulted in inflammation and pathogen susceptibility.…”