Research undertaken in Northern Ireland has shown that reducing the crude protein of pig finishing diets by 1% offers an opportunity to cut piggeries’ ammonia emissions by 10%, but only when managed correctly.

Farmers have been warned to be cautious of efforts to reduce crude protein below 15% as any negative impact on pig performance could see lengthier finishing periods which actually increase ammonia emissions by having finishers remain on farms longer to hit target weights.

An overview of the research was discussed at Teagasc’s pig conference in Cavan last Wednesday by Elizabeth Ball of the Agri-Food and Biosciences Institute (AFBI).

Ball suggested that it is an opportunity to finish gilts on a 13% crude protein diet from weights of 60kg onwards when they have been separated from boars at weaning, but insisted that the higher growth potential of boars must be considered before their diets’ protein is cut.

AFBI’s feed study carried out in Northern Ireland found that switching boars on to 13% crude protein diets knocked off around 0.1kg liveweight gain compared with a standard 15% diet, with a hit taken on feed efficiency too.

“What we would conclude from this is to feed your gilts at 13% and they will perform just as well, but your boars will probably need that higher specification diet,” Ball said.

High-spec 13% diets

However, raising the amino acid specifications of diets fed to boars at this stage may pose an opportunity to move to 13% crude protein when feed intakes are high enough to ensure growth potentials are met.

“When we give them a little more lysine, a little more ammino acids, we can successfully implement that 13% crude protein,” Ball continued.

“But it is really important that we do not reduce the performance on farm, because you will get that hit in the days taken to finish which will have a big impact on nitrogen.”

No moves post-100kg

The researcher also stated that no changes to diets should be made late in the finishing stage, with the study finding that a switch in diets beyond 100kg liveweight saw pig performance taking a knock as the pigs adjusted to new diets.

“And that is really because every time you change a diet, you get a hit on intake, so changing that diet was actually detrimental to pigs’ performance.

“Even though they are getting a lower protein diet and getting a lower protein intake, because their performance is reduced, actually nitrogen excretion was not reduced because it took the pigs longer to get to target weight."