This is the nearest I can get. I think that you are talking about some version of the following. I'll add a couple of links, in case you can get any closer:

ANTE PRANDIUM

in te sperant, Domine,+ et tu das illis escam in tempore opportuno.* Aperis tu manum tuam, et imples omne animal in benedictione. Gloria Patri, et Filio,* et Spiritui Sancto. Sicut erat in principio, et nunc, et semper, et in sæcula sæulorum. Amen.

http://www.traditio.com/tradlib/latpray.txt
http://www.europart.it/jubilaeum/preces2.html