Nose-rings cut down damage
OUTDOOR pig producers could reduce risk of nitrogen pollution by nose ringing sows to help maintain grass cover throughout the year on sow paddocks.
So said SAC pig specialist, Sandra Edwards, who suggests inorganic nitrogen loading on soils is between 649kg and 668kg/ha/year for typical stocking rates of 27 in-pig sows a ha and 19 lactating sows a ha respectively, according to figures from the Cambac research centre, Chippenham, Wilts.
"These levels are equal to fertiliser applied to a commercial crop. But in many cases it is worse because theres no grass cover to use the nitrogen," warned Dr Edwards.
SAC trials have shown that five unringed sows can root up a 1700m sq paddock in a matter of days. Sows with nose rings do much less damage and a grass cover can be maintained throughout the year.
"Although ringing is the only practical solution to reduce pollution risk, a FAWC report covering outdoor units suggests it shouldnt be carried out on welfare grounds. Its a welfare question: Do we want green fields and no pollution or dirty paddocks with a greater risk of pollution but better welfare for sows?"
Dr Edwards suggested pollution risk is determined by many factors, such as neighbouring crops that could absorb excess nitrogen and the location of nearby watercourses. "Outdoor producers need to incorporate units into a whole farm management plan."
However, she warns producers to be aware of nitrogen hot spots that usually occur along fence lines and within 10m (33ft) of the pig ark. "It could be caused by a pigs natural instinct to mark its territory."
As a general guideline, Dr Edwards urges producers not to stock more than 15 lactating or pregnant sows a ha.
Nose-ringed sows do much less damage and grass cover can be maintained throughout the year reducing pollution risks..