Managing broilers gut health with antibiotic-free diets during subclinical necrotic enteritis

Abstract

Necrotic enteritis ( NE ) caused by Clostridium perfringens is among the most important enteric diseases in poultry production. This study examined the effects of 2 probiotics (Prob) and a synbiotic ( Synb ) during a naturally occurring NE challenge. On the day of hatch, 1200 Cobb male broilers were randomly allocated to 5 groups (8 pens/treatment, 30 birds/pen) including 1) negative control ( NC ): corn-soybean meal diet; 2) positive control ( PC ): NC + 453 g Stafac20/907 kg feed; 3) Prob 1: NC + 453 g Prob 1/907 kg feed; 4) Prob 2: NC + 453 g Prob 2/907 kg feed; and 5) Synb: NC + 453 g Synb/907 kg feed. One day after placement, birds were challenged by a coccidia vaccine to induce NE. Feed intake and body weights were measured on day 8 (NE onset) and end of starter (day 14) and grower (28) periods. On day 8, the small intestines of 3 birds/pen were examined for NE lesions. Ileal mucosal scrapings from one bird/pen were collected on day 8 and day 28 to profile the microbiota using 16S rRNA sequencing. Data were analyzed in JMP or QIIME 2 and significance between treatments identified by LSD or linear discriminant analysis effect size ( P < 0.05). The Synb group significantly lowered NE lesion scores on day 8 and reduced day 0-14 mortality by 50% compared with NC. FCR was significantly better in all the groups, whereas ADG was higher in PC, Synb, and Prob 2 groups compared with NC from day 0 to day 28. Lower lesion scores in the Synb group were accompanied by lower relative abundance of Alistipes , ASF356 , Faecalibaculum , Lachnospiraceae UCG-001 , Muribaculum , Oscillibacter , Parabacteroides , Rikenellaceae RC9 gut group, Ruminococcaceae UCG-014 , and Ruminiclostridium 9 compared with NC on day 8. On day 28, relative abundance of Lactobacillus was lower, whereas abundance of Bacteroides , Barnesiella , Butyricicoccus , CHKCI001 , Eisenbergiella , Eubacterium hallii group, Helicobacter , Ruminococcaceae UCG-005 , Ruminococcus torques group, and Sellimonas was significantly higher in the NC birds than in the Synb and Prob 2 groups. Collectively, these data indicate that during a subclinical naturally occurring NE, supplementation of specific additives could be effective in reducing intestinal lesions and mortality, and improving performance potentially through developing a signature microbial profile in the intestinal mucosal layer.

Recombinant Limosilactobacillus (Lactobacillus) delivering nanobodies against Clostridium perfringens NetB and alpha toxin confers potential protection from necrotic enteritis

“…In nature, NE occurs in two forms—acute clinical form and chronic subclinical form (Emami & Dalloul, 2021 ; Emami et al, 2021 ; Hofacre et al, 2018 ). Clinical NE is characterized by extensive necrosis of the small intestinal mucosa and high mortality (Emami & Dalloul, 2021 ; Emami et al, 2021 ; Hofacre et al, 2018 ).…”

“…In nature, NE occurs in two forms—acute clinical form and chronic subclinical form (Emami & Dalloul, 2021 ; Emami et al, 2021 ; Hofacre et al, 2018 ). Clinical NE is characterized by extensive necrosis of the small intestinal mucosa and high mortality (Emami & Dalloul, 2021 ; Emami et al, 2021 ; Hofacre et al, 2018 ). Subclinical NE is characterized by damage to the intestinal mucosa resulting in decreased digestion and absorption, reduced weight gain, and increased feed conversion ratio (Emami & Dalloul, 2021 ; Emami et al, 2021 ; Hofacre et al, 2018 ).…”

“…Clinical NE is characterized by extensive necrosis of the small intestinal mucosa and high mortality (Emami & Dalloul, 2021 ; Emami et al, 2021 ; Hofacre et al, 2018 ). Subclinical NE is characterized by damage to the intestinal mucosa resulting in decreased digestion and absorption, reduced weight gain, and increased feed conversion ratio (Emami & Dalloul, 2021 ; Emami et al, 2021 ; Hofacre et al, 2018 ). While clinical NE models use mortality as the primary study parameter, subclinical models use lesion score as the primary study parameter.…”

“…Subclinical NE is chronic and associated with damage to the intestinal mucosa, leading to reduced digestion and absorption of nutrients, decreased weight gain (3%–5%), and elevated feed conversion ratio (6–9 points) (Hofacre et al, 2018 ). Subclinical NE contributes to the majority of the economic losses associated with NE and is the most prevalent form of NE (Emami et al, 2021 ).…”

“…NE is caused primarily by Clostridium perfringens type A strains that infiltrate the mucosa of the small intestine and produce toxins such as NetB and α toxin (Al‐Sheikhly & Truscott, 1977a , 1977b ; Emami & Dalloul, 2021 ; Emami et al, 2021 ; Hofacre et al, 2018 ; Justin et al, 2002 ; Keyburn et al, 2008 ; Kiu et al, 2019 ; Lee et al, 2012 ; Sheedy et al, 2004 ). C. perfringens is a spore‐forming, anaerobic, Gram‐positive commensal that is ubiquitously found in the gastrointestinal tract of animals and the environment.…”