Convenient method for diagnosing bacterial diseases in chicks at farms

I use 3 contact slides; Plate count agar with TTC, Macconkey agar, & XLD. Inoculate from an affected chick on one type of slide from yolk sac, liver & heart. After 18-24 hrs of incubation, a presumptive diagnosis can be achieved. Left-PCA with TTC. lower-from yolk sac; mid-from live; upper most - from heart blood middle slide- Macconkey- sequence of inoculation is as in the first from the same chick; Extreme right slide-XLD. The causative bacteria can be easily said.