| A quick formula for success at turnout |
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 The ability to run a quick calculation of how much grass is in a particular field can be a useful asset at this time of year, when the herd are heading outside and in need of constant, high-quality feed. There’s not many faster ways to do this than the “Welly Test”. A horizontal mark painted on the outside of the boot lined up against the height of the grass gives an instant rule-of-thumb – or rule-of-leg! Exploring this concept a bit more, shows how useful it can be when the grass length is just above ankle height (8-9 inches) and lining up with a previously made mark on your Wellington boot, you will need just over 3 acres of grazing, per day, to feed 100 cows. That amounts to 8 tonnes of fresh grass every day. That means in good grazing conditions 100 cows would need 65 acres on a 21 day rotation. At the start of the grazing season grass growth rates increase rapidly as soil and air temperatures rise. To make the most of grazing adjust rotation lengths continuously throughout the grazing season, early season rotation lengths could be up to 28 days and in peak grass growth rotations could need to be as short as 18 days. Identify sward surpluses or shortfalls ahead of time through regular pasture monitoring. It’s important to have sensible and realistic expectations of the milk from grazing, especially in wet conditions or for freshly calved and higher yielding cows. To ensure milk production is maintained balanced buffer feeding is important. Kverneland mixer wagons, from Cornwall Farmers, give the ideal tool to buffer feed, providing cows at grass with a balanced ration, including sufficient Energy, Fibre, Protein (DUP) and Minerals. The flexibility that a mixer wagon offers can provide small amounts of quality feed when grazing conditions are good for higher yielding cows but increased levels of buffer feeding and supplementation when conditions are poor for the entire herd. In most years, a farm in the south west of England will probably experience a mix of weathers in early summer, so a certain level of supplementary feeding is advisable and being flexible is the key. Good quality and palatable forages are required; maize and whole crop silages are often used most successfully. Alongside the use of supplements, it is also worth remembering that one of the most effective ingredients in many spring diets is straw, giving structural fibre to the mix and scratch factor to any buffer feed. The main constraint cows experience at grass is what amounts to an effective shortage of energy due to relatively low intakes of forage from grazing, often as a consequence of low dry matter grass. This often reflects in poorer fertility at grass and analysis of the grazed grass is helpful in not overestimating the milk potential in grass, so adequate, flexible buffer feeding will ensure healthy and productive cows, giving cost effective milk production at grass.
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