Copper: new legislation, practical consequences in post-weaning feed

The use of high copper levels (170 mg/kg) in piglet feed up to 12 weeks of age will be allowed until August 13th, 2019. From that moment, the new maximum permitted levels (MPL) of copper in piglet feed, according to the new Regulation (EU) 2018/1039, will come into force. The new European legislation presents a new challenge for nutritionists due to the use of two different MPLs depending on the age of the piglets (see Table 1).

Table 1. Maximum copper limits allowed (mg Cu/kg feed) in piglet diets according to Regulation (EU) 2018/1039

In July 2016, the EFSA's panel on additives and products or substances used in animal feed (FEEDAP) published a scientific opinion in which it recommended that the copper contents in pig feed (in all age groups) couldn't exceed 25 mg/kg. After more than a year of debate, the Standing committee on plants, animals, food and feed agreed on checking the MPLs for copper compounds in feed for piglets that the European Commission approved (150 or 100 mg/kg) in the aforementioned Regulation. This Regulation will came into force in August 13th, 2019, and it takes into account a period for ending the production of premixes (February 13th, 2019) and feed (August 13th, 2019) that contain the MPLs of copper allowed by the previous legislation.

The MPL recommended by the FEEDAP (25 mg/kg, total copper) was based on a bibliographic study on nutritional recommendations (5-15 mg/kg, according to several authors) and on the consequences of the use of high copper levels on the environment and the resistance to antibiotics. This shows that in the not-so-distant future it is probable that the European Commission reduces the MPLs again. In fact, in section 8 of Regulation 2018/1039 we can read that: “With the objective of a further reduction when the maximum contents are next reviewed to meet the maximum of 25 mg/kg for piglets directly after weaning, feed business operators and research institutes should be encouraged to collect new scientific data about the impacts of the levels recommended by the Authority on the health and welfare status of piglets and to promptly explore the use and effectiveness of alternatives to supplementation with copper as mentioned by the Authority.”

The beneficial effect of growing copper levels on the production performance during the nursery stage is related to a greater feed consumption and a decrease in soft faeces (Bikker et al., 2015). The same authors checked that the decrease in copper levels (from 160 to 15 mg/kg Cu supplemented) at 14 days post-weaning entailed a drop by 20% in average daily gain and an increase in the percentage of soft faeces in comparison with the treatment in which the reduction in copper levels was carried out at 28 days post-weaning. Due to this, it is important to consider what strategies can be implemented to stimulate feed consumption and favour gut health.

At a commercial level, in Northern European countries, such as The Netherlands, the efficacy of various nutritional strategies directed towards the promotion of a better gut health without resorting to antibiotics or minerals (zinc and copper) has been proved. These strategies include the use of low protein levels combined with the use of highly digestible ingredients and synthetic amino acids, and the use of inert fibre sources. These nutritional strategies are directed towards the promotion of the gastrointestinal tract maturation and the avoidance of an excessive growth of pathogens in piglets in the post-weaning period. Diluting the diets with inert fibre sources until reaching levels below 2,000 kcal have also been related to a greater feed consumption by the piglets (Gerritsen et al., 2012). In Table 2 we can see the production figures obtained by Gerritsen et al. (2012), that compared three post-weaning diets: positive control diet (PC) with highly digestible ingredients, standard commercial diet used as negative control (NC), and the same standard diet with 15% of inert fibre (I-CHO, oat husk and wheat straw).

Table 2. Effect of the dilution of the diet on the growth during the two first weeks in nursery piglets.

ADG = average daily gain; ADFI = average daily feed intake; FCR = feed conversion ratio

As mentioned before, one of the challenges that the new legislation entails is a different MPL depending on the age of the animals. From a practical viewpoint, and depending on the logistic possibilities of each company, the use of two different post-weaning diets seems recommendable (e.g. until 2-4 weeks, and from 5 to 8 weeks post-weaning) with the appropriate copper, protein, energy and fibre levels for the age and intestinal maturity of the piglets.