Sentence:  The Merino sheep is likely to put his weight largely into tallow around the stomach, intestines and on his kidneys, instead of mixing fairly with the meat, instead of <WSD>marbling</WSD> the meat. 
Meaning of the word marked with <WSD> tags:  To cause meat, usually beef, pork, or lamb, to be interlaced with fat so that its appearance resembles that of marble.