EFSA: trial does not allow safety evaluation of zinc compound

By Jane Byrne contact

- Last updated on GMT

© istock
© istock
EFSA was unable to conclude on the safety of zinc chelate of methionine sulfate as an additive for us in feed due to the limitations of the study the applicant submitted.

Spanish company, Norel, had sought authorization of a product based on zinc chelate of methionine hydrate when used as a feed additive for all animal species. The additive is zinc chelated with methionine in a molar ratio 1:1, with a minimum zinc content of 19.1%.

Based on literature studies and a specific study conducted with the additive under assessment, EFSA found zinc chelate of methionine sulfate is an available source of zinc for all animal species.

The Authority also noted the zinc compound, intended as a substitute for other authorized zinc additives, would not increase the environmental burden of zinc: “The FEEDAP Panel considers that the use of the additive in animal nutrition would not pose an additional risk for the environment.”

Juan José Mallo, technical and commercial director, Norel told us the company recognises the high safety standards in the EU and how the European Food Safety Authority (EFSA) works to ensure those standards are maintanied. He said the Spanish feed additive firm now awaits the opinion of the European Commission regarding the use the zinc compound in question in animal nutrition.

Zinc methionine complex is approved as a feed ingredient for use in the US (AAFCO, 2014) but has never been authorized in Europe – the Norel application represented the first attempt at EU registration for this trace element compound.

Norel’s product is for use in final feed for all animal species/categories up to a maximum total content in complete feeding stuffs of 180 mg Zn/kg for salmonids and milk replacers for calves, 150 mg Zn/kg for piglets, sows, rabbits and all fish species other than salmonids, and 120 mg Zn/kg for other species and categories.

The study

To investigate the safety for chickens for fattening, Norel conducted a feeding trial, conducted in two consecutive runs, with 300 one-day-old Cobb chickens of mixed gender.

The researchers placed the chickens in five experimental treatments with six pens of ten chickens per treatment (three pens per treatment and run). However, only a reduced number of replicates per treatment was reported, corresponding to a total of 260 day-old chickens. All chickens were fed ad libitum with mash feed (starter/grower) based on maize (31.9/33.4%), barley (20.0/23.3%), soybean meal (33.5/36%) and lard (6.6/7.3%) during the starting (days 0–21) and growing (21–35 days) period.

The control animals were given the unsupplemented diets that contained 31 and 30 and mg Zn/kg starter and grower feed, respectively. The experimental groups received diets with 150 and 450 mg supplemental Zn/kg feed from either zinc sulfate monohydrate or zinc chelate of methionine sulfate.  

Mortality, feed consumption and body weight were measured on days 21 and 35. At the end of the study, eight randomly selected birds per treatment (four males and four females, identified with leg rings and allocated to different pens) were subjected to blood sampling for analysis of blood chemistry and hematology parameters. At the same time, chickens were slaughtered and samples of skin, fat pad, bone, breast meat, liver, kidneys and pancreas were collected from one bird per pen for zinc analysis, according to the opinion.

EFSA concluded that the trial showed some weaknesses: “The study was conducted in two consecutive runs, the reason for the differences in the number of intended and assessed replicates was not given, the number of animals taken for blood sampling was not equally distributed among the two runs, the contribution of methionine (up to 935 mg/kg feed) from zinc chelate of methionine sulfate was not considered in the diet formulation (e.g. by lower supplementation of DL-methionine).”

The EFSA opinion can be read here​.

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