Phytase, 25-hydroxyvitamin D3 and cocci vaccination to broilers fed a calcium and phosphorus-reduced diet under Eimeria spp. challenge: effects on growth performance and intestinal health

A study evaluated the effects of phytase, 25-hydroxyvitamin D3 (25OHD), and cocci vaccination on broilers fed a diet reduced in calcium (Ca) and available phosphorus (avP) under Eimeria challenge. A total of 840 one-day-old male broilers were assigned to a 2 × 5 factorial arrangement based on cocci vaccination and dietary treatments. Half of the birds were vaccinated against coccidia on d 1, and all birds were orally challenged with Eimeria spp. (sporulated oocysts: 12,500 of E. maxima, 12,500 of E. tenella, and 62,500 of E. acervulina) on d 14. Dietary treatments included: 1) a nutrient adequate diet (PC); 2) a diet reduced by 0.2% in Ca and avP (NC); 3) NC plus 1,500 FTU/kg of phytase (NC+PHY); 4) NC plus 3,000 IU/kg of 25OHD (NC+25OHD); 5) NC with both PHY and 25OHD (NC+PHY+25OHD). SAS was used for data analysis, with significance set at P ≤ 0.05. Pre-infection growth performance was comparable across the treatments. However, vaccinated birds exhibited higher body weight (BW) and body weight gain (BWG) from 0 to 6 d postinoculation (DPI; P < 0.05). The NC diet reduced BWG from 6 to 12 DPI and increased the feed conversion ratio (FCR) during 6 to 12 DPI and the overall period (0-26 d) compared to the PC birds. In contrast, the supplementation with phytase, 25OHD, or both, returned BWG and FCR to levels seen with the PC diet (P < 0.01). Vaccinated birds also had reduced gut permeability at 5 DPI, increased intestinal villus height, and lower expression levels of the tight junction proteins junctional adhesion molecule 2 (JAM2) and occludin (OCLN) at 6 DPI (P < 0.05). Interestingly, the cocci vaccine resulted in lower E. acervulina but higher E. tenella oocyst shedding at 6 DPI (P < 0.01). Interaction effects were observed for duodenal lesion scores and ileal crypt depth at 6 DPI (P < 0.05). In conclusion, coccidial vaccination improved growth performance, decreased intestinal permeability, enhanced intestinal morphology, and modulated tight junction protein gene expression under Eimeria infection. Reducing dietary Ca and avP levels adversely affected growth performance and FI during the recovery phase, but these negative effects could be mitigated by supplementing with phytase or 25OHD.

Immunoprotection against mixed Eimeria spp. infections in goat kids induced by X-irradiated oocysts

Strategies to control goat coccidiosis traditionally rely on the use of management practices combined with anticoccidial treatments, and limited effort has been made, so far, to address immunological control of caprine Eimeria infections. Previously, we showed that monospecific immunization with X-Rad-attenuated Eimeria ninakohlyakimovae oocysts induced considerable immunoprotection upon challenge. In the present study, we conducted a similar vaccination trial but using a mixture of caprine Eimeria species typically present in natural infected goats. For immunization, sporulated oocysts were attenuated by X irradiation (20 kilorad). All infections were performed orally applying 10⁵ sporulated oocysts of mixed Eimeria spp. per animal. In total, 18 goat kids were grouped as follows: (G1) immunized + challenge infected; (G2) primary + challenge infected; (G3) challenge infection control; and (G4) non-immunized/non-infected control. Overall, goat kids infected with attenuated oocysts (= immunized) shed less oocysts in the faeces and showed a lower degree of clinical coccidiosis than animals infected with non-attenuated oocysts. Animals of both challenge groups (G1 and G2) showed partial immunoprotection upon reinfection when compared to challenge infection control (G3). However, the degree of immunoprotection was less pronounced than recently reported for monospecific vaccination against Eimeria ninakohlyakimovae, most probably due to the complexity of the pathogenesis and related immune responses against mixed Eimeria spp. infections. Nevertheless, the data of the present study demonstrate that immunization with attenuated Eimeria spp. oocysts may be worth pursuing as a strategy to control goat coccidiosis.

Two Blackhead Disease Outbreaks in Commercial Turkey Flocks Were Potentially Exacerbated by Poor Poult Quality and Coccidiosis

Field visits at two different farms suggest a correlation between commercial turkey (Meleagridis gallopavo) flocks having increased mortality from blackhead disease (histomoniasis) if they suffer from poor poult quality at placement and coccidiosis (Eimeria spp.) before age 6 wk. In both cases, the flocks were all-in/all-out with curtain-sided houses and received a coccidiosis vaccine on day of hatch. At Farm I 2018, poults from different hatcheries were placed in two houses on the same farm (Houses 1 and 2). House 2 had poults considered poor quality and suffered from mortality associated with coccidiosis at 2 and 4 wk of age. At 8 wk, blackhead disease was diagnosed in both houses by postmortem examination. House 2 had mortality of >2000 poults, and the subpopulation of necropsied poults had gross lesions characteristic of histomoniasis. Gross lesions associated with blackhead disease were only found in eight poults in House 1, which was populated with good-quality poults and did not have a second spike in mortality due to coccidiosis. The Farm II 2020 poults were delivered from the same hatchery onto a three-house farm (Houses A, B, and C). House C had poults that were considered poor quality and had mortality associated with coccidiosis at 3 wk of age. At 8-9 wk, House C had mortality approaching 1000 birds, with all poults examined postmortem having clinical signs of blackhead disease. Houses A and B were populated with good-quality poults and had no diagnosed mortality from coccidiosis or blackhead disease. The similarity of these two cases suggest that poult quality at placement coupled with coccidiosis before 6 wk of age can influence the severity of blackhead disease in commercial turkey flocks.

Diagnosis and control of chicken coccidiosis: a recent update

Coccidiosis is a deadly disease that hampers chicken's productivity and welfare. Thus, the disease is a major menace to the global poultry industry. Coccidiosis which is caused by the apicomplexan parasite of the genus Eimeria has seven known species which affect the different parts of the intestinal tract of chickens. The disease which occurs by ingestion of sporulated oocyst has been associated with poor poultry management system. Mixed infection among the species of this parasite contributes to both pathogenicity and misdiagnosis of the disease. A progress in identification and diagnosis approach which cuts across pathological, morphological and molecular has been reported for this parasite. Control measures which include anticoccidial drugs, vaccines and natural products have dominated literature for this disease. However, the emergence of genetic and antigenic diversity with implication on resistance to anticoccidials among different strains of Eimeria parasite has generated concerns on the effectiveness of the current anticoccidial vaccines. A new look on the control strategy therefore becomes imperative. This study reviews the current trends on the identification and control of chicken coccidiosis with focus on (1) Avian coccidiosis (2) Epidemiology of chicken coccidiosis (3) Eimeria parasite and distribution in poultry (4) Diagnosis of Eimeria parasite (5) Control measures of coccidiosis (6) Threats posed by genetic and antigenic diversity of Eimeria parasite on coccidiosis control. Genomic study on diversity of Eimeria parasite becomes imperative for effective vaccine design against coccidiosis.