Bioefficacy of dietary inclusion of Nannochloropsis oculata on Eimeria spp. challenged chicks: clinical approaches, meat quality, and molecular docking

Although anticoccidial drugs have been used to treat avian coccidiosis for nearly a century, resistance, bird harm, and food residues have caused health concerns. Thus, Nannochloropsis oculata was investigated as a possible coccidiosis treatment for broilers. A total of 150 1-day-old male Cobb broiler chicks were treated as follows: G1-Ng: fed a basal diet; G2-Ps: challenged with Eimeria spp. oocysts and fed basal diet; G3-Clo: challenged and fed basal diet with clopidol; G4-NOa: challenged and fed 0.1% N. oculata in diet, and G5-NOb: challenged and fed 0.2% N. oculata. Compared to G2-Ps, N. oculata in the diet significantly (P < 0.05) decreased dropping scores, lesion scores, and oocyst shedding. Without affecting breast meat colour metrics, N. oculata improved meat quality characters. At 28 days of age, birds received 0.2% N. oculata had significantly (P < 0.05) higher serum levels of MDA, T-SOD, HDL, and LDL cholesterol compared to G2-Ps. Serum AST, ALT, and urea levels were all decreased when N. oculata (0.2%) was used as opposed to G2-Ps. Histopathological alterations and the number of developmental and degenerative stages of Eimeria spp. in the intestinal epithelium were dramatically reduced by 0.2% N. oculata compared to G2-Ps. Molecular docking revealed a higher binding affinity of N. oculata for E. tenella aldolase, EtAMA1, and EtMIC3, which hindered glucose metabolism, host cell adhesion, and invasion of Eimeria. Finally, N. oculata (0.2%) can be used in broiler diets to mitigate the deleterious effects of coccidiosis.

Field Study on the Prevalence of Ovine Footrot, Contagious Ovine Digital Dermatitis, and Their Associated Bacterial Species in Swedish Sheep Flocks

Ovine footrot and contagious ovine digital dermatitis (CODD) cause lameness in sheep, affecting welfare and economics. Previous Swedish studies focused on individual slaughter lambs, leaving flock-wide prevalence less explored. This study examined the prevalence of footrot and CODD in Swedish sheep flocks, focusing on adult sheep. From 99 flocks, 297 swabs were analysed using real-time PCR for Dichelobacter nodosus, Fusobacterium necrophorum, and Treponema spp. Sampled feet were photographed and assessed using scoring systems for footrot and CODD. Results indicated footrot prevalences (footrot score ≥ 2) of 0.7% and 2.0% at the individual and flock levels, respectively, whereas there were no signs of CODD. The individual footrot prevalence was lower than that from a 2009 study but aligned with a 2020 study, both conducted on slaughter lambs. Dichelobacter nodosus, F. necrophorum, and Treponema spp. were found in 5.7%, 1.3%, and 65.0% of sheep, and in 9.1%, 3.0%, and 82.8% of flocks, respectively. Compared to the 2020 study, there was a notable decrease in F. necrophorum and Treponema spp., while D. nodosus was consistent. In conclusion, the findings show a low prevalence of footrot, CODD, D. nodosus, and F. necrophorum in Swedish sheep flocks. Continuous surveillance and owner education are important to maintain this favourable status.

Resistance to Saprolegnia parasitica infection: A heritable trait in Atlantic salmon

A controlled Saprolegnia parasitica infection model was used to challenge 1158 fish representing 105 pedigreed Atlantic salmon families to evaluate the possibility of selecting for Saprolegnia resistance in a commercial breeding programme. Fish were infected in five study tanks and observed for 40 days post-infection for lesion score and survival. Survival analysis of the top 10 resistant and bottom 10 susceptible families indicated that the hazard of dying following Saprolegnia infection was 1509% higher in susceptible families. In all fish, a 10 g increase in weight correlated with a 7.8% increase in the hazard of dying while sex did not affect mortality. Resistance to Saprolegnia was estimated to have a heritability of 0.25, indicating that selection is possible. Genetic and phenotypic correlations indicated that the 11-point scoring system, developed in this study to quantify Saprolegnia infection severity, had a high negative correlation with survival as days to mortality at ≥-0.922(±0.005), suggesting that the scoring method could help assess lesion development in studies where mortality is not the primary biological endpoint.

Evaluation of Lesions and Viral Antigen Distribution in Domestic Pigs Inoculated Intranasally with African Swine Fever Virus Ken05/Tk1 (Genotype X)

The understanding of the pathogenic mechanisms and the clinicopathological forms caused by currently circulating African swine fever virus (ASFV) isolates is incomplete. So far, most of the studies have been focused on isolates classified within genotypes I and II, the only genotypes that have circulated outside of Africa. However, less is known about the clinical presentations and lesions induced by isolates belonging to the other twenty-two genotypes. Therefore, the early clinicopathological identification of disease outbreaks caused by isolates belonging to, as yet, not well-characterised ASFV genotypes may be compromised, which might cause a delay in the implementation of control measures to halt the virus spread. To improve the pathological characterisation of disease caused by diverse isolates, we have refined the macroscopic and histopathological evaluation protocols to standardise the scoring of lesions. Domestic pigs were inoculated intranasally with different doses (high, medium and low) of ASFV isolate Ken05/Tk1 (genotype X). To complement previous studies, the distribution and severity of macroscopic and histopathological lesions, along with the amount and distribution of viral antigen in tissues, were characterised by applying the new scoring protocols. The intranasal inoculation of domestic pigs with high doses of the Ken05/Tk1 isolate induced acute forms of ASF in most of the animals. Inoculation with medium doses mainly induced acute forms of disease. A less severe but longer clinical course, typical of subacute forms, characterised by the presence of more widespread and severe haemorrhages and oedema, was observed in one pig inoculated with the medium dose. The severity of vascular lesions (haemorrhages and oedema) induced by high and medium doses was not associated with the amount of virus antigen detected in tissues, therefore these might be attributed to indirect mechanisms not evaluated in the present study. The absence of clinical signs, lesions and detectable levels of virus genome or antigen in blood from the animals inoculated with the lowest dose ruled out the existence of possible asymptomatic carriers or persistently infected pigs, at least for the 21 days period of the study. The results corroborate the moderate virulence of the Ken05/Tk1 isolate, as well as its capacity to induce both the acute and, occasionally, subacute forms of ASF when high and medium doses were administered intranasally.

Scanning Electron Microscopic Findings on Respiratory Organs of Some Naturally Infected Dromedary Camels with the Lineage-B of the Middle East Respiratory Syndrome Coronavirus (MERS-CoV) in Saudi Arabia-2018

The currently known animal reservoir for MERS-CoV is the dromedary camel. The clinical pattern of the MERS-CoV field infection in dromedary camels is not yet fully studied well. Some pathological changes and the detection of the MERS-CoV antigens by immunohistochemistry have been recently reported. However, the nature of these changes by the scanning electron microscope (SEM) was not revealed. The objective of this study was to document some changes in the respiratory organs induced by the natural MERS-CoV infection using the SEM. We previously identified three positive animals naturally infected with MERS-CoV and two other negative animals. Previous pathological studies on the positive animals showed varying degrees of alterations. MERS-CoV-S and MERS-CoV-Nc proteins were detected in the organs of positive animals. In the current study, we used the same tissues and sections for the SEM examination. We established a histopathology lesion scoring system by the SEM for the nasal turbinate and trachea. Our results showed various degrees of involvement per animal. The main observed characteristic findings are massive ciliary loss, ciliary disorientation, and goblet cell hyperplasia, especially in the respiratory organs, particularly the nasal turbinate and trachea in some animals. The lungs of some affected animals showed signs of marked interstitial pneumonia with damage to the alveolar walls. The partial MERS-CoV-S gene sequencing from the nasal swabs of some dromedary camels admitted to this slaughterhouse confirms the circulating strains belong to clade-B of MERS-CoV. These results confirm the respiratory tropism of the virus and the detection of the virus in the nasal cavity. Further studies are needed to explore the pathological alterations induced by MERS-CoV infection in various body organs of the MERS-CoV naturally infected dromedary camels.

Validation of the M-stage scoring system for digital dermatitis on dairy cows in the milking parlor

A high prevalence of digital dermatitis (DD) and the benefits of early topical treatment highlight the need for simple tools for routine DD detection. The objective of this study was to determine the accuracy of scoring DD lesions using the 5 M-stage scoring system in the milking parlor compared with the trimming chute as the gold standard. Three observers inspected 3,585 cows and 6,991 hind feet from 9 farms in the milking parlor using a mirror (glued to a plastic kitchen spatula) and a headlamp, followed by inspection in a trimming chute within 5 d. Interobserver agreement for scoring DD in various settings was ≥82% (kappa >0.74; weighted kappa >0.76). At trimming chute inspections, 68% of cows had at least 1 DD lesion, 19% had 1 hind leg affected, and 49% had both hind legs affected. Within-herd DD prevalence ranged from 16 to 81% of cows affected. True within-herd prevalence was 2, 6, 0, 36, and 14% for M1, M2, M3, M4, and M4.1 lesions, respectively. At the foot level, DD prevalence was the same (58%) in the milking parlor and trimming chute inspection, but distribution of M-stages differed. Milking parlor inspection as a means of identifying the presence of DD lesions had a sensitivity of 92% and specificity of 88%, with positive and negative predictive values of 91 and 89%, respectively. Agreement between milking parlor and trimming chute inspections was 73% (kappa = 0.59, weighted kappa = 0.65) for the 5 M-stage scoring system and 90% (kappa = 0.80) if only the presence of a lesion was noted. Test characteristics varied greatly among M-stages, with the highest sensitivity for detecting M4 (82%) and M2 (62%) lesions, and the lowest for detecting M4.1 (20%), M1 (7%), and M3 (0%) lesions. In the milking parlor, 20% of M2 lesions were misclassified as M4.1, 8% of M4 lesions were misclassified as M0, and 68% of M4.1 lesions were misclassified as M4. The majority (87%) of DD lesions were located between the heel bulbs; 10 and 2% of DD lesions affected the interdigital space and the front of the foot, respectively. The sensitivity to detect the presence of a lesion when it occurred between the heel bulbs was 93%, but <67% if it occurred elsewhere on the foot. We concluded that inspection of the rear feet in the milking parlor was an inexpensive and simple method of detecting and scoring DD lesions. If the objective is to determine herd-level DD prevalence and routine monitoring, this method was adequately reliable. However, if the objective is to follow up DD in cows with history of interdigital hyperplasia or to detect M1 or M4.1 lesions, this method was not sufficiently reliable. Although DD scoring in the milking parlor as a routine practice should facilitate early detection, prompt treatment interventions, and herd monitoring, it was not sufficiently reliable to replace definitive identification of M-stages in the trimming chute.

Digital dermatitis: Natural lesion progression and regression in Holstein dairy cattle over 3 years

Bovine digital dermatitis (DD) is a leading cause of lameness in dairy cattle in the United States, with prevalence estimates as high as 30%. Whereas clinical lesions have been well described, little is known about the morphologic changes that are associated with the early stages of lesion development from normal skin to clinical lesions. This study used the Iowa DD scoring system to evaluate the epidemiology of natural lesion development by digitally photographing the rear legs of a cohort of dairy cows over a 3-yr period. Sixty-one adult Holstein dairy cows were monitored for 1,032 cow foot-months. The incidence rate of lesion development was 4 lesions per 100 cow foot-months, with the average time for a lesion to develop being 133 d. Whereas 20% of the 1,678 foot observations exhibited clinical DD lesions, an additional 55% of all observations exhibited preclinical stage 1 and 2 lesions that were indicative of DD lesion development. Utilizing the dichotomous categorization of preclinical lesions in the Iowa DD scoring system, it was found that first-lactation heifers had a higher rate of the thickened and crusted "B" type lesions, whereas the ulcerative "A" type lesions were more likely to be identified in multiparous animals. For clinical DD lesions that received topical treatment, scoring of the post-treatment lesions using the Iowa DD scoring system was found to be useful in prognosticating both the risk of recrudescence and the time until recrudescence. Systemic disease, systemic antibiotic therapy, and periparturient stress were not associated with an increase or decrease in DD lesion scores. Treatment with a single topical tetracycline wrap was associated with a significant decrease (-1.17) in DD lesion score. The results of this study demonstrate that the complex morphologic changes associated with digital dermatitis can be readily classified using the Iowa DD scoring system and the scores can be used to predict and monitor the effects of treatment and prevention measures.

Effect of coccidia challenge and natural betaine supplementation on performance, nutrient utilization, and intestinal lesion scores of broiler chickens fed suboptimal level of dietary methionine

The aim of the present experiment was to examine the effect of coccidia challenge and natural betaine supplementation on performance, nutrient utilization, and intestinal lesion scores of broiler chickens fed suboptimal level of dietary methionine. The experimental design was a 2 × 2 factorial arrangement of treatments evaluating two levels of betaine supplementation (0 and 960 g betaine/t of feed) without or with coccidia challenge. Each treatment was fed to 8 cages of 8 male broilers (Ross 308) for 1 to 21d. On d 14, birds in the 2 challenged groups received mixed inocula of Eimeria species from a recent field isolate, containing approximately 180,000 E. acervulina, 6,000 E. maxima, and 18,000 E. tenella oocysts. At 21d, digesta from the terminal ileum was collected for the determination of dry matter, energy, nitrogen, amino acids, starch, fat, and ash digestibilities. Lesion scores in the different segments of the small intestine were also measured on d 21. Performance and nutrient digestibility data were analyzed by two-way ANOVA. Lesion score data were analyzed using Pearson chi-square test to identify significant differences between treatments. Orthogonal polynomial contrasts were used to assess the significance of linear or quadratic models to describe the response in the dependent variable to total lesion scores. Coccidia challenge reduced (P < 0.0001) the weight gain and feed intake, and increased (P < 0.0001) the feed conversion ratio. Betaine supplementation had no effect (P > 0.05) on the weight gain or feed intake, but lowered (P < 0.05) the feed conversion ratio. No interaction (P > 0.05) between coccidia challenge and betaine supplementation was observed for performance parameters. Betaine supplementation increased (P < 0.05) the digestibility of dry matter, nitrogen, energy, fat, and amino acids only in birds challenged with coccidia as indicated by the significant interaction (P < 0.0001) between betaine supplementation and coccidia challenge. The main effect of coccidia challenge reduced (P < 0.05) starch digestibility. Betaine supplementation improved (P < 0.05) starch digestibility regardless of the coccidia challenge. For each unit increase in the total lesion score, there was a linear (P < 0.001) decrease in digestibility of mean amino acids, starch, and fat by 3.8, 3.4 and 16%, respectively. Increasing total lesion scores resulted in a quadratic (P < 0.05) decrease in dry matter digestibility and ileal digestible energy. No lesions were found in the intestine or ceca of the unchallenged treatments. In the challenged treatments, betaine supplementation reduced (P < 0.01) the lesion scores at the duodenum, lower jejunum, and total lesion scores compared to the treatment without supplements. In conclusion, coccidia challenge lowered the digestibility of energy and nutrients and increased the feed conversion ratio of broilers. However, betaine supplementation reduced the impact of coccidia challenge and positively affected nutrient digestibility and the feed conversion ratio.