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Bacteriological Analysis of Cecal Samples from Broiler chickens reared on commercial gut health management programs

2021 CPRF
The use of antibiotics in livestock and poultry productions has been found to play an important role in the rise of antimicrobial resistance (AMR) which is a significant global threat to humans, poultry, socioeconomics, and the environment. In response to mandated restrictions on antimicrobial use, the poultry industry has adopted various gut health management programs to facilitate profitable, safe, and sustainable chicken production. However, comparative impact of these programs on AMR bacteria in the gut remained to be investigated. This study quantified antimicrobial resistant coliforms, and Escherichia coli numbers in the ceca of male and female broilers reared under commercial gut health programs in Ontario A total of 2,304 day-old broiler chicks (1,152 males and 1,152 females) were allocated to three different feeding programs: a basal diet with bacitracin and avilamycin (CON); a basal diet supplemented with avilamycin: raised without medically important antibiotics (RWMIA) and a non-mediated: raised without antibiotic (RWA) on the cecal coliforms and antimicrobial resistant Escherichia coli numbers. The birds were allotted to one of the feeding programs/gender combinations according to a 3 (diets) x 2 (gender) factorial design in 48 pens (48 birds/ pen). On day 28, two birds/pen were sacrificed to collect ceca samples for colony counting using MacConkey Agar (MAC), ChromoCult Coliform Agar (CCA) alone or supplemented with 4 μg/mL ceftiofur to quantify coliforms (COLIFORM), E. coli (ECOLI), cephalosporin resistant coliforms (CEFR-COL) and E. coli (CEFR-ECOLI), respectively after incubation at 37°C for 18h. Presumptive colonies were purified for future characterizations (susceptibility to 14 antibiotics, whole genome sequencing analysis for serotype, virulence and virulence genotype). DNA were extracted for 16S rRNA sequencing analysis. Statistical analyses on bacteria numbers were conducted using the General Linear Mixed Model procedure of the Statistical Analysis System. Treatments (diets) and gender (males or females) were used as sources of variations. Significant differences (P < 0.05) in colony forming unit per gram of cecal content (CFU/g) were detected between feeding programs while, significant interactions (P < 0.05) between bacteria types and gender were observed. The lowest Log10CFU/g of COLIFORM (5.4) was noted in RWA group compared to the two other groups (6.4). The number of CEFR-COL was lower in CON (Log10CFU/g = 2.3) and RWA (Log10CFU/g = 2.6) than in the RWAOHI (3.5). The Log10CFU/g of CEFR-ECOLI in the CON, RWAOHI, and RWA were 1.5, 1.4 and 1.3, respectively. The Log10CFU/g of COLIFORM and CEFR-COL were 5.8 and 6.3 and 1.6 and 1.2 in females and males birds, respectively. In ceca of birds from RWA, Log10CFU/g of CEFR-COL was significantly lower in females (1.80) than in males (3.4). This preliminary data showed that in a RWA program, gender (male of female) can influence AMR profile in 28-day old broiler ceca. Using machine learning, we will utilize the data from AST and sequencing to develop a predictive framework linking marker genes with genome function, that would allow to develop some AMR mitigation strategies.
Tags :
broilers,gut health
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PhD Student

Agriculture and Agri-Food Canada

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