EFSA's Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) adopted an opinion revising maximum levels of copper in feed at its plenary in Brussels in July.
Copper (Cu) is an essential trace element for pigs, mainly as a component of a large number of metabolic enzymes.
There are environmental concerns in relation to the use of Cu in feed. Because of the low body retention of Cu of around 1.1 mg/kg body weight (BW) (Corpen, 2003) the majority is excreted into the manure. After manure spreading, this amount of Cu is said to substantially contribute to the accumulation of Cu in the soil and in ground and surface water.
Taking environmental aspects into consideration, it recommended lowering Cu for piglets, the species with the highest Cu supplementation allowance in the EU, to 25mg/kg of feed, as opposed to the current level of 170 mg/kg of feed.
“I am very surprised that this reduction in copper content is proposed,” Jan Fledderus, innovation manager piglets, Nutrition Innovation Center, ForFarmers Group, told us this week.
He said the conclusion of a 2015 study at Wageningen University by Bikker et al, partly financed by the feed industry and the Dutch government, was that the addition of 25 mg Cu/kg is sufficient to avoid Cu related deficiency problems in piglets, but that there is a very strong positive linear response on growth and feed efficiency when Cu contents are increased up to 170 mg/kg.
“Any reduction of the copper content will increase the environmental pollution, since more feed will be needed to realize the same piglet performance. In addition, it is also likely [that there would be] an increase in mortality when the Cu content will be reduced to maximum of 25 mg/kg.
And the positive effect of Cu on growth performance and feed efficiency are not restricted to the weaner phase,” argued Fledderus.
The Wageningen University researchers found the highest performance and lowest percentage of growing pigs with soft feces was realized when 160 mg Cu/kg was supplied in the entire trial period - they said this finding indicated any reduction in level or duration of Cu supplementation causes a small, but significant, decrease in both animal performance and fecal consistency.
They said the reduction in level or duration of the Cu supplementation did not significantly affect the mortality and required medical treatments. “Nonetheless, the number of medicated piglets was numerically higher at some of the lower levels and periods of Cu supplementation, thus a possible effect cannot be fully excluded and should be taken into consideration,” said the team.
They noted relatively good results were realized when growing pigs were fed 120 mg Cu/kg from Day 0-56 and in pigs fed 160 mg Cu/kg until Day 28 with subsequent adaptation to a low Cu diet in the nursery period. “Because of the large reduction in usage and excretion of Cu, this would reward further evaluation,” added the researchers.
But the researchers stressed no alternative health supporting products were included in the diet when the Cu content was reduced: “Hence, we cannot advice whether these might alleviate the effect of a reduction in level or duration of Cu supplementation.”