Metabolisable energy (ME) is still the best feed quality descriptor for New Zealand dairy farmers, says DairyNZ's principal scientist, Dr John Roche.
"When I hear people telling farmers that 'all energy is not equal' and they should 'focus on non-fibre carbohydrate instead of ME' when feeding their cows, I get quite frustrated," he says.
"It shows me that a little knowledge out of context can be a dangerous thing."
Dr Roche says the main reason the recommendation to focus on non-fibre carbohydrate is wrong for New Zealand farmers is that pasture-based cows are rarely short of protein.
"Management to produce more microbial protein, without providing additional energy when cows are not deficient in protein, will not increase milksolids production," he says.
"Fibre can produce the same amount of microbial protein as non-fibre carbohydrate, provided it is digestible in the rumen. For example, a cow eating the same amount of energy from pasture or pasture plus a high (60% DM) or low (30% DM) non-fibre carbohydrate supplement, produces the same amount of microbial protein. That cow also has the same amount of metabolisable protein reaching the small intestine and as a result of the similar metabolisable energy intake and metabolisable protein, produces the same amount of milksolids," says Dr Roche.
"With the current milk price and relative value of milk fat and milk protein, I would advise farmers to focus on the ME content of the feed and the price/MJ of ME."