I want to do a challenge test in broiler at 2 weeks of age. so, I need to know how much I need to inoculate orally of Salmonella enteritidis and E. coli solution with which concentration?
You can see the literature and you will get the cfu to fed oraly to broiler. You need to standardize relation between the OD of your culture and cfu. Say How many cfu per ml of culture having OD of 0.1. For example if you have seen the at 0.1 OD of your culture is equivalent to 10^5 cfu per ml. And you are supposed to inoculate 10^4 cfu. That means you will have to allow the broiler drink 0.1 ml of your culture.
So, to find out the relation take the 5 hour grown culture. Find out its OD. Than using fresh media dilute the culture to the OD of 0.1. Then pour this culture onto nutrient agar plate after proper dilution. And then next day count the number of colonies. This will give you how much CFU per ml for 0.1 OD.
Hoping this would help.
Depends what you want to look at. Oral infection with E. coli is a waste of time unless you are looking at its role in microbiota. I would suggest an oral dose of 106 to 108 cfu of Salmonella as a reasonable starting dose. We use the latter in many studies
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