Vaccination for the Prevention of Neonatal Calf Diarrhea in Cow-Calf Operations: A Scoping Review

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Since 1950, 113 articles on vaccines for the prevention of neonatal calf diarrhea have been published in the English literature

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Results for field trials using commercial vaccines for E. coli, bovine rotavirus, and bovine coronavirus infections are variable

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No field trials for commercial Salmonella vaccines have shown efficacy

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Vaccines for protozoal pathogens causing calf scours as well as the importance of several emerging enteric viruses of cattle need further research

Neonatal calf diarrhea (NCD), also known as scours, is an important disease of preweaned calves that affects the production and welfare of beef herds. While hygiene and nutrition are important in reducing the incidence of NCD, vaccination of dams or calves is often employed for the prevention of NCD. The present scoping review summarizes the available peer-reviewed scientific English literature on vaccination of dams or calves for the prevention of NCD over the past decades. The online databases Medline, CAB Abstracts, and Biosis were searched for articles on the topic published between 1950 and 2020. Online software was used to systematically evaluate 2807 citations for inclusion through pre-determined criteria in a 2-step process. In the 113 articles included in the review, vaccines tested targeted the pathogens E. coli (n = 43), bovine rotavirus (BRV, n = 38), Salmonella (n = 29), bovine coronavirus (BCV, n = 14), bovine viral diarrhea virus (n= 7), and other pathogens (n = 8). Field trials for commercial vaccines have been published for the most important pathogens, and results on efficacy are variable for such vaccines targeting BRV, BCV, and E. coli. Meta-analyses exploring efficacy of these vaccines would be helpful to practitioners and producers. No field studies on commercial products have shown efficacy for Salmonella vaccines so that a meta-analysis would unlikely come to a different conclusion. Further research is needed on vaccines for protozoal pathogens like Cryptosporidium parvum as well as on the importance of several emerging enteric viruses in calves.

Reducing Foodborne Pathogen Persistence and Transmission in Animal Production Environments: Challenges and Opportunities

Preharvest strategies to reduce zoonotic pathogens in food animals are important components of the farm-to-table food safety continuum. The problem is complex; there are multiple pathogens of concern, multiple animal species under different production and management systems, and a variety of sources of pathogens, including other livestock and domestic animals, wild animals and birds, insects, water, and feed. Preharvest food safety research has identified a number of intervention strategies, including probiotics, direct-fed microbials, competitive exclusion cultures, vaccines, and bacteriophages, in addition to factors that can impact pathogens on-farm, such as seasonality, production systems, diet, and dietary additives. Moreover, this work has revealed both challenges and opportunities for reducing pathogens in food animals. Animals that shed high levels of pathogens and predominant pathogen strains that exhibit long-term persistence appear to play significant roles in maintaining the prevalence of pathogens in animals and their production environment. Continued investigation and advancements in sequencing and other technologies are expected to reveal the mechanisms that result in super-shedding and persistence, in addition to increasing the prospects for selection of pathogen-resistant food animals and understanding of the microbial ecology of the gastrointestinal tract with regard to zoonotic pathogen colonization. It is likely that this continued research will reveal other challenges, which may further indicate potential targets or critical control points for pathogen reduction in livestock. Additional benefits of the preharvest reduction of pathogens in food animals are the reduction of produce, water, and environmental contamination, and thereby lower risk for human illnesses linked to these sources.

β-Glucan plus ascorbic acid in neonatal calves modulates immune functions with and without Salmonella enterica serovar Dublin

To determine if β-glucan plus ascorbic acid affects adherence and pathogenicity of Salmonella Dublin and innate immune response in neonatal calves, 20 calves were fed control or supplemented diets (β-glucan, 0.9 g/d, plus ascorbic acid, 500 mg/d) until d 23. On d 21, 5 calves per treatment received 2.4 × 10(8)CFU of S. Dublin orally. S. Dublin spread through intestinal tissues into mesenteric lymph nodes (MLN), spleen, and lung tissues within 48 h. All supplemented calves had less mRNA expression of IL-1 receptor antagonist in liver. Leukocyte cell surface markers changed in lung cells, but not in blood, MLN, or spleen. CD14 in lungs was greatest for calves receiving supplement and challenge, but CD18 in lungs was greater for challenged than control calves. Lung DEC205 was greatest for challenged calves with and without supplement compared to controls, but more lung cells expressed CD14 for all treated groups compared to controls. These data show that S. Dublin briefly inhabited the intestinal tract, moving quickly to spleen, MLN, and lung tissues. Lung tissue was modulated by S. Dublin, but supplement alone increased CD14 expressing cells. The supplement appears not to attenuate invasiness but modified some lung cell populations by 48h.