English dairy farmers continue to use a pasture seed mix that includes a cocktail of grasses & clovers. Why? This certainly isnt the common practice in NZ or Australia nor, I discovered, on leading farms in Brittany France. Most so called "cocktail grass mixes" contain a few named varieties & are then bulked up using various other non descript "others". Within a few months most will have been grazed out by the cows unable to compete. The remainder will probably cross breed. So whats the point?
Select one or two late heading ryegrasses that have UK trial data on performance & add say two vigorous white clovers (one upright medium to large leaf variety & one smaller more compact variety) If you are in a drier region you might add say "Matrix" a new NZ crossbred grass or a summer active Fescue (both late heading). Keep it simple.
One of the management headaches that these "pasture cocktail mixes" create is a pasture that has a huge spread of heading dates...........very common in the UK at the moment. This is a nightmare to manage & it lowers the feed value of the grazed pasture. Admittedly the dry summer in some areas has brought out ryegrass seed heads on very short stems but the breeding & genetic makeup of the different grasses is the core problem.
Keep it simple one or two late heading ryegrasses ONLY in your pasture seed mix.