29 November 1996

Pig producers told spuds low energy source

PIG producers must not overestimate the energy from potatoes fed in rations.

So warns Tony Andrews of the Royal Vet College. "Both pig and potato producers tend to be concentrated in the east of the country. So, with current low potato prices, many pig producers are feeding potatoes."

But he says some producers may overestimate the nutritional value of raw, whole potatoes. "Much of the carbohydrate in potatoes is not available unless the starch is broken down by heating or processing."

He acknowledges that heating potatoes is impractical, so warns that potatoes should be budgeted as a low energy source in the ration.

Signet pig specialist Mike Potter says a replacement rate of about four of potatoes to one of barley is about right; 1.8kg potatoes for every 0.45kg of barley fed.

"The energy value for barley is 12.7MJ/kg, with 10% crude protein. Raw potatoes have a digestible energy of 2.3MJ/kg, and 2.4% crude protein. Dry matter percentage for barley is 86%, but only 20% for raw potatoes.

"That means pigs have to eat a greater bulk of feed when potatoes are used. Because of that, they are best suited to pregnant sows, which can consume large amounts of food." &#42