Special Edition: Existing and Emerging Feed Risks

Are chickens at risk from erucic acid in rapeseed meal?

By Jane Byrne contact

- Last updated on GMT

© istock/rapeseed
© istock/rapeseed

Related tags: Rapeseed

EFSA has noted a potential health risk for poultry arising from exposure to erucic acid in rapeseed meal and oils. 

And the Authority, in an opinion published this week​,​ found a data gap in relation to available information on the carry-over of erucic acid in meat, milk and eggs resulting from feed use.

Following a request from the EU Commission, the EFSA Panel on Contaminants in the Food Chain (CONTAM) was asked to evaluate the toxicity of erucic acid for animals and humans, considering all relevant adverse health effects.

When the maximum levels of erucic acid were established by Regulation (EC) 1881/2006 ten years ago, the Commission deemed it necessary to review the maximum levels at a later date, based upon an updated risk assessment and weighing up the appropriateness of setting maximum levels for erucic acid in feed.

Rapeseed meal 

The panel said the main source of exposure to erucic acid is from the seeds of oilseed rape (Brassica napus​). Erucic acid is a component of the oil seed and after oil extraction, the remaining meal is widely used as a protein source in animal feeds.

However, the EFSA experts pointed out most of the erucic acid is extracted with the oil: “While some remains in the rapeseed expeller (after crushing) and even less in the rapeseed meal (after solvent extraction), levels are significantly lower than in the original seed.” 

Animal exposure to erucic acid was determined by its concentration in feed and the quantity of feeds consumed. In the absence of data on concentrations of erucic acid in compound feeds, EFSA said it used industry data on levels of inclusion of rapeseed meal and oil for livestock and fish.

It estimated exposures based on the maximum inclusion rates of rapeseed meal and oil in livestock diets. “Therefore, mean levels of exposure calculated in this opinion represent worst-case scenarios,”​ said the CONTAM panel.

Rapeseed meal use in livestock feed

EFSA said while some whole seeds are fed to livestock, generally restricted to pig and some poultry diets, most are subjected to oil extraction with the resulting cake or meal used as feed.

The Authority’s data shows, within the EU, some 6.8m tons of rapeseed meals were used in the manufacture of compound feeds in 2012/13, of which 5m tons originated in the EU.

Rapeseed meal is widely used in the diets of ruminants. EFSA said, in this opinion, the panel assumed an inclusion rate of 25% in the compound feed.

The use of rapeseed oil, regardless of the erucic acid level, is limited in ruminants due to potential adverse effects on rumen fermentation, although it may be present in blends of vegetable oils used in compound feeds. Estimates of exposure have assumed a maximum inclusion rate in the compound feed of 2%, said EFSA.

Levels of rapeseed meal in diets of pigs, poultry, salmonids and rabbits vary from 5% to 30%, depending on the species and/or age of the animal.

Levels of rapeseed oil also vary; in practice lower amounts are used in pig diets because of the effect on the level and composition of body fat. For poultry, it is common to add 1.0–1.5% rapeseed oil to the diet (Canola Council of Canada, 2015). Full-fat rape seed, after particle size reduction (rolling) is a key protein and energy ingredient in broiler diets in a number of EU countries, but in the absence of data on erucic acid content of full-fat rape seed this was been included in estimates of exposure in this evaluation, said EFSA.

Pigs and poultry

For monogastrics, the panel found the highest exposure was for fattening chickens.

In a risk assessment of erucic acid in feed for livestock, the panel said levels of erucic acid are unlikely to represent a health concern in pigs.

The panel identified a NOAEL of 700 mg/kg bw per day for myocardial lipidosis in pigs.

However, for poultry, the panel said the small margin between the lowest observed adverse effect level (LOAEL) and the estimated exposure may indicate a health risk where maximum inclusion rates are applied.

EFSA referenced a study that showed feeding poultry with diets containing high erucic acid rapeseed (HEAR) oil resulted in growth retardation and cardiac lipidosis. High doses of erucic acid also increased the incidence and severity of cardiac lesions, said the panel. 

While it said that studies in which poultry were fed diets supplemented with oils and meals derived from HEAR cultivars clearly demonstrated adverse effects on production-related factors, the possible effects of other dietary constituents or characteristics on feed intake, growth rate and egg production cannot be excluded.

The Panel identified a LOAEL of 0.02 g/kg bw per day for liver toxicity in poultry, which, it said, is about double the upper exposure range (12 mg/kg bw per day). 

Ruminants

EFSA said it was unable to conclude on the risk for ruminants, and fish due to the absence of adequate data.

Thought it did reference a study where a reduction in feed intake and milk yield by dairy cows was reported at an intake of  0.4 g erucic acid/kg bw per day from rapeseed meal. However, the panel said the possible role of glucosinolates or other antinutritional factors in the meal could not be ruled out.

“For ruminants, no NOAEL could be identified. The dietary exposure of dairy cattle is well below the dose at which no effect is observed on milk yield. However, the risk of other adverse effects or for other ruminants could not be assessed,”​ concluded the CONTAM panel.

The opinion can be read here​.

Related topics: Regulation

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