Unlike olive oil where people tend to go for the first pressing with hay grass the second cutting is usually superior. Hay analysis of my own hay in previous years shows that second cutting is slightly better than first cutting. However it is by no means clear as to why this should be. Is it the grass in a different stage of its growth cycle? Or is it simply the different weather with cooler evenings and cooler night times?
Maybe it really doesn't matter because it just is the accepted wisdom of hay making. The truth is the alpacas chow down on it no matter what I might think and do not show any preference for a certain age of hay... I guess like most animals including humans if they are hungry enough then they will eat it.