New research indicates earlier Salmonella vaccination can optimise pullet protection
A recently published scientific paper indicates that vaccinating layer pullets against Salmonella as early as day one, can optimise disease protection and better vaccination take.
Dr Doris Mueller-Doblies, global food safety consultant at Elanco, says the recent scientific paper[1], supported by the Animal Plant Health Agency (APHA), investigated the success of early vaccination in layer pullets, to see if earlier protection could be secured.
“Chicks are most susceptible to Salmonella infection in the first 10-14 days of life, and this trial therefore aimed to see if earlier vaccination could offer better protection through the earliest possible colonisation of the gut with vaccine strains,” she said.
“Live vaccines can be administered in drinking water from the first day of life. However, there has been reluctance to do this, due to concerns around water intake versus length of the drinking line.”
Dr Mueller-Doblies said, to understand this further, a field trial was undertaken on three commercial layer pullet farms. The success of early vaccination using AviPro™ Salmonella Duo, which offers protection against both S. Enteritidis (SE) and S. Typhimurium (ST) strains, was investigated by analysing chick vaccine uptake.
“There were four vaccination time points – days one, two, three and five – and three houses on the same farm were vaccinated simultaneously in each trial. The vaccine was administered via the drinking water with the addition of the water stabiliser AviBlueTM and due to the length of the water line, the vaccine was administered over more than three hours,” she explained.
Water samples were taken at the end of the drinking lines to ensure correct administration of the vaccine. 48 hours post-vaccination, caecal and faecal samples were taken from 10 birds per flock, along with two pools of faeces per flock which were sent to AHPA for laboratory testing.
“Results showed excellent colonisation for birds vaccinated as early as day one for SE and ST, with levels of >106 cfu/g of each of the vaccine strains reached in caecal content from some birds,” Dr Mueller-Doblies explained.
“We saw slightly different colonisation levels of the caeca and the liver, depending on the age of the birds and when they received the vaccine. This is likely due to changes in the intestinal flora during the first days of life. Nevertheless, all pooled faecal samples were positive for both vaccine strains.
“There was an inverse correlation between age and caecal levels of vaccines, with the highest numbers seen in birds vaccinated at one day-of-age. Interestingly, S. Enteritidis vaccine strain levels in liver samples were highest when birds were vaccinated at five days-of-age.”
The overall conclusion is that all 120 birds analysed had the vaccine strains detected in at least one sample two days post-vaccination and therefore, every bird analysed was successfully vaccinated.
“Results demonstrate that layer pullets can be vaccinated successfully as early as day one of life, using a dual strain live vaccine containing both SE and ST strains,” she said.
She added that vaccination may need to take place over an extended period of more than three hours to be successful. This helps negate concerns regarding very young birds drinking insufficient quantities of administered vaccines – the results show that the AviPro Salmonella Duo vaccine strains are stable in water for several hours.
Further research is currently being carried out to determine the exact survival times of the vaccine strains in drinking water.
Learn more about Salmonella prevention
Cawthraw, S et al. 2024. Early vaccination of laying hens with the live bivalent Salmonella vaccine AviPro™ Salmonella Duo results in successful vaccine uptake and increased gut colonisation
