Interesting question!
Most of the examples that I can remember of nobles investing in their estates are things like draining fenland to create more arable land, building mills to turn grain into flour (thus, climbing the value-added ladder), or building weirs and the like to shape trade. These improvements are more akin to investments to fixed plant or capital goods than investments in the productivity of the labor force.
That’s not to say that lords wouldn’t buy livestock or plows or the like, but they’d usually buy them for their own lands, as those kinds of moveable goods were considered individual property. Indeed, in many cases peasants were required to bring their own plows on those days when they had to perform labor on the lord’s land as part of their feudal service.