Essential Oils as an Alternative to Antibiotics to Reduce the Incidence and Severity of Necrotic Enteritis in Broiler Chickens: A Short Review

Due to the removal of antibiotic growth promoters (AGPs) and consumer pressure for antibiotic-free (ABF) or no antibiotics ever (NAE) poultry production, there is a need for sustainable alternatives to prevent disease in commercial poultry operations. Without AGPs, there has been a rise in diseases that were traditionally controlled by subtherapeutic levels of antibiotics in the diet. This has impacted the health of commercial poultry and has been a significant cost to poultry producers. To mitigate this, the industry has started to investigate alternatives to antibiotics to treat these forthcoming health issues, such as necrotic enteritis (NE). NE is an enteric disease caused by an over proliferation of toxigenic Clostridium perfringens (CP) in the gastrointestinal tract. Although CP is a commensal in the avian intestinal tract, dysbiosis caused by inflammation and impaired intestinal integrity facilitates uncontrolled replication of CP. Infectious agents, such as Eimeria maxima, appear to be a predominant predisposing factor that promotes NE. However, non-infectious stressors, including dietary changes, have also been associated with NE to some degree. As a result of increased pressure to restrict the use of antibiotics, there is a need for research evaluating the efficacy of alternatives, such as plant-derived essential oils, as potential tools to mitigate NE in commercial poultry flocks. The aim of this study is to review the effects of essential oils as an alternative to antibiotics to reduce the incidence and severity of necrotic enteritis in broiler chickens.

Potential of blended organic acids to improve performance and health of broilers infected with necrotic enteritis

Organic acids(OA)and their blends have been shown to positively affect performance and health of broilers.However,the data in the literature are not consistent.This study examined the potential of blended short-chain fatty acids(SCFA)with medium-chain fatty acids(MCFA)as alternatives to antibiotic growth promoters(AGP)on performance,health and welfare of broilers infected with necrotic enteritis(NE).The additives used were:A)a blend of SCFA,MCFA,and a phenolic compound(SMP);B)a blend of free and buffered SCFA with MCFA(SMF);C)a blend of free and buffered SCFA with a high concentration of MCFA(SHM).A total of 1,404 Ross 308 one-day-old male parental chicks were randomly distributed into 78-floor pens with 13 replicates of 18 birds each.Six treatments were the following:T1,unchal-lenged control(UCC);T2,challenged control(CHC);T3,challenged group plus zinc bacitracin(BAC);T4,challenged group plus additive SMP;T5,challenged group plus additive SMF;T6,challenged group plus additive SHM.Challenged birds were gavaged with Eimeria spp.on d 9 and Clostridium perfringens EHE-NE18 on d 14.Post NE challenge and cumulatively,BWG,FCR,and nutrient digestibility of birds were compromised(P<0.05)by NE challenge indicating a successful induction of sub-clinical NE.Additive SHM had higher BWG compared to CHC and BAC groups(P=0.001;d 10 to 24)but not different from SMP and SMF groups(P>0.05).All the 3 additive groups had lower FCR compared to CHC(P=0.001;d 0 to 35),and exhibited similar jejunal lesions(d 16)compared to BAC and apparent ileal protein di-gestibility(d 21)compared to UCC and BAC groups(P>0.05).Birds in additive SHM group had a higher concentration of serum IgA compared to all groups(P=0.001)except additive SMF(P>0.05;d 21).All the additive groups had lower footpad dermatitis and hock burns compared to CHC(P<0.05).The findings suggest the potential of blended OA as alternatives to BAC to protect broilers from NE indicated by improved FCR,immunity,digestibility,and bird welfare.

Organic acid blends improve intestinal integrity,modulate short-chain fatty acids profiles and alter microbiota of broilers under necrotic enteritis challenge

Controlling enteric diseases of broilers is crucial.Among many additives,organic acids(OA)and their blends are gaining attention to combat diseases in the post-antibiotic era.The current study evaluated the potentials of short-chain fatty acids(SCFA)and medium-chain fatty acids(MCFA)blends and/or phenolic compounds on intestinal integrity,intestinal pH,caecal microbiota,and caecal SCFA profiles of broilers under necrotic enteritis(NE)challenge.The additives used were:(A)a blend of SCFA,MCFA,and a phenolic compound(SMP),(B)a blend of free and buffered SCFA with MCFA(SMF),and(C)a blend of free and buffered SCFA with a high concentration of MCFA(SHM).A total of 1,404 male parental chicks of Ross 308 broilers were randomly allocated to 78 floor pens on hatching day with 6 treatments replicated 13 times with 18 birds per pen.The treatments were:UCC,unchallenged control;CHC,challenged control;BAC,challenged group plus zinc bacitracin;SMP,challenged group plus additive SMP;SMF,challenged group plus additive SMF;SHM,challenged group plus additive SHM.Birds were challenged with field-strain Eimeria spp.on d 9 and Clostridium perfringens on d 14.Birds challenged with NE increased fluorescein isothiocyanate dextran(FITC-d)concentration in serum,reduced acetate and butyrate concentrations,and increased Bacteroides and C.perfringens load in the caeca(P<0.05).Birds fed additives decreased FITC-d from gut to serum,reduced Bacteroides(d 16,P<0.05)and numerically reduced C.perfringens load compared to CHC group.Birds fed additive SHM had higher concentrations of acetate and butyrate(d 21,P<0.05)than CHC group but were not different from SMP and SMF groups.All the additives exhibited similar intestinal protection against NE compared to the BAC group indicated by FITC-d concentration in serum,acetate,propionate and butyrate concentrations in the caeca,and caecal bacterial loads except for the C.perfringens(P>0.05).The SMP group had a higher load compared to BAC(P<0.05).These findings suggest the promising effects of OA blends as alternatives to BAC to ameliorate the impact of NE challenge of broilers as indicated by improved intestinal health.