Author(s):

Umar Amin, Shayaib Ahmad Kamil, Masood Saleem Mir, Sabiya Qureshi, Manzoor Ur Rehman, Mohammad Tufail Banday and Rahil Razak Bhat

Abstract: Fowl typhoid is an acute septicemia disease of all ages of chickens. The disease is caused by Salmonella gallinarum. The term LD50 is defined as the least dosage that should be expected to cause 50% of mortality in animals that received it. Several methods have been proposed for estimations of the LD50. Present study for estimation of LD50 of Salmonella gallinarum in poultry is based on moving average method. Five animals were dosed per infective doses (n = 5) and the following mortalities resulted: 1 of 5 at 0.5 ×10⁹, 2 of 5 at 1 ×10⁹ ,2 of 5 at 2 ×10⁹, and 3 out of 5 at 4 ×10⁹. So from above it can be postulated that ID₅₀ of Salmonella gallinarum in day old poultry birds is 2.08×10⁹CFU. The determination of LD50 of each strain of Salmonella gallinarum is important for effective control and treatment of diseases caused by Salmonella.

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