SUPPLEMENTARY feeding mid or late lactation dairy cows at pasture is uneconomic when grass height is over 8cm (3in).
This is the view of Dr David Peers, ADAS senior consultant Ruthin. He claims buffer and concentrate feeding is only justified for high yielding early lactation cows and when grazing is in short supply.
"When cows go out in spring the grass should be capable of supporting cows yielding 25 litres," he says.
Higher yielders need a supplement low in starch and high in digestible fibre to complement the spring grass which will be high in sugar. It should also be high in energy and provide some undegradable protein.
"A compound with a range of ingredients, including products such as citrus pulp and sugar beet pulp, will give cows a healthier rumen function compared with a high cereal content product," he says.
However, Dr Peers urges close examination of the cost and quality of summer cakes given the high ingredient prices compounders face this spring.
For this reason the cheaper summer cakes may be poor quality and as such just replace rather than complement grass.
"But for higher quality compounds," he says, "you must look at the response in relation to milk price." Above 3-4kg a day the marginal milk yield response is less economic and is unlikely to be economic above 6kg. Up to 8kg could be justified for very high yielding summer calvers with high milk prices.