Regarding protein percentages in custom made diets versus forages; Last year I made some balage (wet hay that is wrapped to preserve) from some of my pasture in May. The pasture which consisted of ryegrass, orchardgrass and some dandelion was 12 inches when I cut it. The test results showed 24% protein. This year that stand has some clover in it which can hit 25%-31% protein. So 27% protein isn't too uncommon in a natural, heritage style environment. Add in a factor such as harvesting an an earlier stag and the protein could be higher. Sure some protein tests in hay can be below 10%, but that hay is usually older when cut, doesn't have clover and often consists of Timothy grass which isn't the highest for protein. BTW, last year I cut an old stand of alfalfa which had mostly chickweed. That tested 24% protein too! Add in the bugs, worms, etc and I'm sure protein could be very high.
In regards to soil biology. As a non-organic farmer who uses fertilizers, glyphosate, etc. Plant diversity goes a long way. Different plants can work off of each other such as grasses and nitrogen fixing legumes (clover, alfalfa, peas). Different root building plants such as yellow clover and tillage radish can dig deep while ryegrass can build many small fibrous roots that feed soil life. Then letting your grass grow taller can help increase soil organic matter, keep the soil from drying out quicker, aid in water absorption and help prolong the life of the grass. However, protein and digestible energy is lower when grass is harvested when older. For those reasons and more, I prefer not to graze or harvest older forage with my cows but prefer a younger more digestible forage.
In regards to soil biology. As a non-organic farmer who uses fertilizers, glyphosate, etc. Plant diversity goes a long way. Different plants can work off of each other such as grasses and nitrogen fixing legumes (clover, alfalfa, peas). Different root building plants such as yellow clover and tillage radish can dig deep while ryegrass can build many small fibrous roots that feed soil life. Then letting your grass grow taller can help increase soil organic matter, keep the soil from drying out quicker, aid in water absorption and help prolong the life of the grass. However, protein and digestible energy is lower when grass is harvested when older. For those reasons and more, I prefer not to graze or harvest older forage with my cows but prefer a younger more digestible forage.