Matthew Poole and continuators on Job 39:4

4. Their young ones are in good liking , they grow up with corn : they go forth, and return not unto them .

Or, grow strong or fat; notwithstanding their great weakness caused by their hard entrance into the World.

Which they find and feed upon in the Fields.

Or, as with Corn, i. e. as if they were fed with Corn; the Particle as being oft deficient and to be supplied. Or, in the Field, as this word in the Chaldee or Syriak Dialect signifies.

Finding sufficient Provisions abroad by the care and conduct of God's Providence.