The withdrawal of antibiotic growth promoters from poultry feed has increased the risk of necrotic enteritis (NE) outbreaks. This study examined the effects of a probiotic (PROB) or probiotic/prebiotic/essential oil supplement (PPEO) during a subclinical NE challenge. On day (d) of hatch, 960 male broilers were randomized to four groups (8 pens/treatment, 30 birds/pen) including (1) negative control (NC): corn-soybean meal diet; (2) positive control (PC): NC + 20 g Virginiamycin/ton diet; (3) NC + 227 g PROB/ton diet; and (4) NC + 453 g PPEO/ton diet. One d after placement, birds were challenged by a coccidia vaccine to induce NE. Feed intake and body weights were measured on d 8 (NE onset) and end of each feeding period. On d 8, the small intestines of three birds/pen were examined for NE lesions. Jejunum samples and ileal mucosal scrapings from one bird/pen were respectively collected to measure mRNA abundance (d 8 and d 14) and profile the microbiota (d 8 and d 42). Data were analyzed in JMP or QIIME 2 and significance between treatments identified by LSD (P < 0.05). PROB and PPEO had significantly lower mortality (d 0–14) and NE lesion scores compared to NC. Feed conversion ratio was significantly lower in PC, PROB, and PPEO, while average daily gain was higher in PPEO and PC groups compared to NC from d 0–42. On d 8 and d 14, mRNA abundance of claudin-3 was higher in PPEO compared to NC. On d 14, compared to NC, mRNA abundance of sIgA and PGC-1α in PROB and PPEO were lower and higher, respectively. Compared to NC, PPEO increased mTOR abundance on d 14. On d 8, relative abundance of Clostridium sensu stricto 1, Ruminiclostridium9, Prevotellaceae, Prevotellaceae UCG-014, ASF356, and Muribaculaceae was higher in NC compared to PPEO and PROB, while Lactobacillus was lower in NC. Escherichia-Shigella had higher abundance in PC compared to PPEO and PROB. Collectively, these data indicate that during a subclinical naturally occurring NE, supplementation of PROB or PPEO supports performance and reduces intestinal lesions, potentially through modifying tight junction proteins, gut microbiota, immune responses, and cell metabolism.

Blackhead disease (histomoniasis) currently has no efficacious drug approved for use in poultry in the United States. Both chickens and turkeys can get the disease, but mortality is most often associated with turkeys. The lack of any approved therapies for blackhead is of concern, especially in the case of valuable turkey breeder candidate flocks. Due to the availability of efficacious drugs for many years, research focused on blackhead was minimal. However, without any drugs or reliable additives, blackhead will continue to be an issue in turkeys and broiler breeder chickens. The American Association of Avian Pathologists annual meeting in San Antonio, Texas, August 6-9, 2016, held a mini-symposium on blackhead. The mini-symposium included university researchers and industry veterinarians discussing blackhead in the United States and Europe including insights on the disease pathogenesis and epidemiology, as well as an update on the current state of blackhead in the United States since the removal of nitarsone from the market in January 2016. This review summarizes the information presented at the mini-symposium and discusses current control measures in an era without efficacious drugs.

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.

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.

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A series of 4 floor pen studies was conducted to evaluate the effects of environmental temperature modification on nicarbazin (NIC) responses in broiler chickens raised to 28 d of age. Birds were reared at either standard temperatures (recommended by the primary breeder for ages zero to 28 d) or at 3°C below this level. From placement to 28 d, birds were provided feeds containing zero, 100, or 125 ppm NIC, comprising a 2 × 3 factorial arrangement in each test. Two of the trials were conducted in the presence of an imposed coccidial challenge and 2 were conducted in healthy animals. At 18 and 28 d of age, performance was recorded; cloacal temperatures were measured at 7, 14, 21, and 26 days. Mortality data were collected daily and coccidial lesions were scored at 6 d post challenge. Results of these studies revealed that NIC improved coccidial lesion scores regardless of environmental temperature. In the absence of coccidial challenge, NIC depressed performance, but reductions in environmental temperature diminished the magnitude of these responses. Under conditions of coccidial challenge, NIC significantly improved body weight gains in both temperature environments. Compared to standard temperature conditions, lower environmental temperatures exerted a positive effect on feed conversion rates of NIC-fed broilers. Birds reared in the low temperature environment exhibited lower cloacal temperatures than standard environment groups throughout the test period. Irrespective of coccidial challenge, lower environmental temperatures significantly reduced nicarbazin mortality compared to standard temperature groups, resulting in a significant nicarbazin x temperature interaction. This finding indicates that temperature modification is a practical method for minimizing mortality over the course of 28-day nicarbazin usage.

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