Effect of Formaldehyde Treatment on Bacteria-Infected Hatching Eggs of Gallus gallus domesticus Linnaeus, 1758

The effectiveness of formaldehyde egg disinfection is well documented in literature despite its reported toxicity. This study focused on the need for an optimum formaldehyde concentration (FC) that significantly reduces microbial load with minimal damaging effect on egg viability and hatchability. Using a true experimental design, bacterial load on formaldehyde-treated (FT) and control groups of eggs and hatchability were compared. Gram-staining and biochemical tests identified five bacterial species: Escherichia coli, Enterobacter sp., Bacillus cereus, Staphylococcus aureus and Micrococcus sp. with the two coliform bacteria, E. coli and Enterobacter sp., dominating. Comparison of median differences of bacterial load on eggs before and after formaldehyde treatment by Wilcoxon Signed-Rank Test showed marginal significance in bacterial load reduction (Z = -2.016, P = 0.044). This difference was observed for bacterial load between the control group (CG) and the FT group with FC 30/20 ml/g (U = 3.0, P = 0.047). The hatchability of the CG differed significantly from four FT groups of eggs with FC 30/20 ml/g showing the highest level of significance [χ² (1) = 14.71; P = 0.0001]. A FC of 30/20 ml/g produced the best domestic fowl egg disinfection compared to other FCs and hatchability decreased with increasing formalin volume.

Immunological and pathological outcomes of SARS-CoV-2 challenge after formalin-inactivated vaccine immunisation of ferrets and rhesus macaques

There is an urgent requirement for safe and effective vaccines to prevent novel coronavirus disease (COVID-19) caused by SARS-CoV-2. A concern for the development of new viral vaccines is the potential to induce vaccine-enhanced disease (VED). This was reported in several preclinical studies with both SARS-CoV-1 and MERS vaccines but has not been reported with SARS-CoV-2 vaccines. We have used ferret and rhesus macaques challenged with SARS-CoV-2 to assess the potential for VED in animals vaccinated with formaldehyde-inactivated SARS-CoV-2 (FIV) formulated with Alhydrogel, compared to a negative control vaccine in ferrets or unvaccinated macaques. We showed no evidence of enhanced disease in ferrets or rhesus macaques given FIV except for mild transient enhanced disease seen at seven days post infection in ferrets. This increased lung pathology was observed early in the infection (day 7) but was resolved by day 15. We also demonstrate that formaldehyde treatment of SARS-CoV-2 reduces exposure of the spike receptor binding domain providing a mechanistic explanation for suboptimal immunity.

Low-Energy Electron Irradiation Efficiently Inactivates the Gram-Negative Pathogen Rodentibacter pneumotropicus—A New Method for the Generation of Bacterial Vaccines with Increased Efficacy

Bacterial pathogens cause severe infections worldwide in livestock and in humans, and antibiotic resistance further increases the importance of prophylactic vaccines. Inactivated bacterial vaccines (bacterins) are usually produced via incubation of the pathogen with chemicals such as formaldehyde, which is time consuming and may cause loss of immunogenicity due to the modification of structural components. We evaluated low-energy electron irradiation (LEEI) as an alternative method to generate a bacterin. Rodentibacter pneumotropicus, an invasive Gram-negative murine pathogen, was inactivated with LEEI and formaldehyde. LEEI resulted in high antigen conservation, and LPS activity was significantly better maintained when compared with formaldehyde treatment. Immunization of mice with LEEI-inactivated R. pneumotropicus elicited a strong immune response with no detectable bacterial burden upon sublethal challenge. The results of this study suggest the inactivation of bacteria with LEEI as an alternative, fast and efficient method to generate bacterial vaccines with increased efficacy.

Extrapolating the bypass potential of treated Madre de agua (Trichanthera gigantea Nees) leaf meal as protein source in Rumen-Fistulated Brahman Cattle

This study assessed the effectiveness of formaldehyde, heat, and tannic acid treatments of madre de agua leaf meal (MALM) in reducing the degradation of dry matter (DMD) and crude protein (CPD) in the rumen for increased supply of bypass protein at the intestinal level. The experiment utilized a rumen-fistulated Brahman bull fed with chopped Napier grass soilage (basal diet) and MALM (test diet) at 70:30 basal:test diet ratio. Nylon bags (porosity of ±53μm) containing the treated MALM were incubated in the rumen for 24, 48 and 72 hours following the “sequential addition” method forin situ degradation measurement. Results showed that DMD of MALM was significantly reduced by formaldehyde treatment after 24-h and 48-h period of incubation than the untreated. This was followed by tannic acid treatment, though the reduction was significant only after 48-h incubation than the untreated. At 72-h period of incubation, DMD remained to be significantly lowest with formaldehyde treatment than the untreated or heat and tannic acid treatments. A similar pattern of differences in DMD rate (%/h) was observed as that of DMD (%). The CPD of MALM was also significantly reduced with formaldehyde treatment after 24-h incubation than the untreated. At 48-h incubation, all treatment methods showed significant protection of protein in MALM over that of the untreated. At 72h, formaldehyde and heat treatments significantly reduced the CPD of MALM compared to the untreated. A similar pattern of differences in CPD rate (%/h) was observed as that of CPD (%). Among treatment methods, the use of formaldehyde is the best, followed by tannic acid treatment, in achieving rumen bypass and promoting greater amino acid supply at the intestinal level.

Impact of formaldehyde addition to spray-dried plasma on functional parameters and animal performance1

Experimental objectives of this study were to determine effects of formaldehyde treatment on the chemical composition of spray-dried plasma (SDP) and to test the hypothesis that growth performance of pigs fed formaldehyde-treated diets containing SDP or diets containing formaldehyde-treated SDP is not reduced compared with pigs fed untreated control diets. Sal CURB ASF liquid antimicrobial and CURB RM Extra liquid mold inhibitor (Kemin Industries, Des Moines, IA) were applied on SDP at 0.1% or 0.3% to determine effects of the products on chemical and functional properties of SDP. Regardless of product, there were no changes in SDP for analyzed protein, ash, pH, or moisture concentration, but IgG concentration in SDP was decreased 8% and 24%, respectively, for 0.1% and 0.3% inclusion of Sal CURB or CURB RM. Two feeding studies using weaned pigs were conducted to determine effects of formaldehyde applied at 0.3% to SDP (experiment 1) or 0.3% to a complete diet containing 5% SDP (experiment 2). Experiment 1 pigs (n = 265) were weaned at 20 ± 2 d of age and allotted to five treatment groups. Experiment 2 pigs (n = 135) were weaned in two groups at 20 ± 2 d of age and allotted to three treatments groups. In experiment 1, the untreated control diet contained soy protein concentrate (SPC) and test diets contained 2.5% or 5.0% SDP without or with formaldehyde treatment. In experiment 2, formaldehyde was applied to a diet containing 5% SDP and an untreated SPC control diet and an untreated diet containing 5% SDP were also included in the experiment. In experiment 1, linear increases (P < 0.05) in average daily gain (ADG), average daily feed intake (ADFI), and gain-to-feed ratio (G:F) were observed as SDP was included in the diets and the relative bioavailability of formaldehyde-treated SDP was 62% (P = 0.018) if calculations were based on ADG and 15% (P = 0.031) if calculations were based on ADFI. In experiment 2, pigs fed the SDP diet untreated or treated with formaldehyde had increased (P < 0.05) final body weight, ADG, ADFI, and G:F compared with pigs fed the control diet. However, formaldehyde treatment of the plasma-containing diet did not affect pig growth performance compared with pigs fed the untreated SDP diet. In conclusion, formaldehyde treatment applied directly on SDP affects analyzed concentrations of IgG and reduces growth rate of pigs. Treating a complete diet containing 5% SDP with formaldehyde did not affect pig growth performance, and pigs fed diets containing SDP had improved growth performance than those fed the control diet without SDP.