for Energy digestibility or called Apparent metabolisable energy

You need to collect excreta, you can use oxygen bomb calorimeter, then use equation to know the GE for diet & excreta

AME = ((Feed Intake x diet GE) - (Excreta output x Excreta GE) ) / Feed Intake

where GE is gross energy

Ahmed,

There are two possible strategies:

a) you perform a quantitative excreta collection, i.e. for every single bird, or goup of birds, you measure any feed canumed and collect every excreta dropped. And then you apply the above mentioned equation. This requires to house birds on mesh wire.

b) you use a marker-based approach, which allows you to work with excreta spot samples.

Especially protein (rather: amino acid) digestibility should preferably be assessed by the determination of precaecal digestibility. This can only be conducted using a marker, for instance titanium dioxide.

Let me know if you need further information on that approach....

Christian Please give more details on the marker method, especially with regard to the principle behind use of such markers