3 tips to help cut zinc oxide from weaner diets

Reducing protein levels and increasing feed intake are helping a growing number of Danish piggeries remove zinc oxide from weaner diets.   

A study of the practices on Danish farms weaning piglets without medical use of zinc oxide also found that good staff were critical to success.  

Zinc oxide is widely added to weaning diets to control post-weaning diarrhoea, but its use will banned in June 2022.

The work, co-ordinated by Seges, the Danish agricultural research and extension organisation, has been used to update national advice on post-weaning management.

See also: 5 zinc oxide alternatives for pigs compared

About the research

To find common management features on farms successfully weaning pigs without zinc, Dr Christian Fink Hansen, director, Seges, recruited a group of 26 farms known by vets to be weaning without the additive.

The trial farms produced a total of 600,000 weaners a year. All farms had cut zinc oxide use and three had been zinc-free for more than a year.

Farm facts: Seges group averages

  • Scale of operation 1,560-80,000 weaners
  • Average lactating days 29.4
  • Weaning weight 5.5-8.5kg
  • Average daily gain 462g (same as Danish average)
  • Average weaner mortality 2.1% (Danish average is 3.1)

The farms were interviewed about their management systems, herd health, feed, hygiene, staffing, weaner rations, productivity reports and vaccination schemes.

Antibiotics data for each farm was taken from Vetstat, Denmark’s national drug use reporting and monitoring programme.

The process found three common elements on farms that had successfully removed zinc oxide:

1. Increased feed intake

Of the 26 farms surveyed only two were not actively trying to increase feed intake to help drive growth in the weaners immediately after weaning.

There were several strategies employed to increase the volume of food offered, food eaten or the feed space given to piglets. These included:

  • 10 farms were offering extra feeding on the floor
  • Five farms were offering extra feeding spaces by using more troughs
  • Four farms had increased the number of drinking spaces to increase intakes
  • Three farms had started feeding milk products to improve intakes
  • Two had started gruel feeding.

2. Trained staff

Skilled and experienced workers were a critical part in the equation of removing zinc oxide.

A designated weaner manager was essential and low turnover of staff helped.

“In many cases this might be more important than what exact protein levels are in diets,” said Dr Fink Hansen.

  • 20 of 26 farms had a manager of weaned piglets in place for more than one year.
  • 18 had a manager with more than three years’ experience.

3. Low-protein feeding

All 26 zero-zinc farms were experimenting with low protein levels to differing degrees.

There was considerable variation in overall protein and lysine levels. Crude protein levels in piglet diets varied from 14.8% to 20.5% and the average was 18.8%.

Why reduce protein? 

Feeding lower levels of protein in post-weaning diets reduces the amount of undigested protein in the hindgut.

This helps cut protein fermentation, which in turn reduces microbial metabolites (NH3, amines). These can damage the lining of the digestive tract (colonic epithelium), interrupt mucosal function and increase villous atrophy (death of the cell walls). Reduction can also limit colonisation of E coli bacteria.

Recommended protein level

Low-protein feeding is working on the piggeries in the study group and has also been found to deliver good results in a recent Seges trials (see box below).

Seges has added low-protein feeding to its nutritional recommendations.

Danish farms are now advised to feed 17.5% protein in phase one (6-9kg) and phase two (9-15kg) of the post-weaning stage.

Protein feeding trial 

A recent Seges trial looked at altering protein levels across the three post-weaning feeding phases (see table).

The trial found the best approach was to feed low protein (17.5%) in the first two phases and a higher level of protein (19.5%) in the third phase.

Soybean meal content did not vary across the six diets and was increased across all six diets for each feeding phase. Overall protein levels were adjusted by altering soy protein concentrate, potato protein and fish meal.

There were three feeding phases for three different ages of pigs on six diets.

  • 6-9kg (7% soybean meal)
  • 9-15kg (14% soybean meal)
  • 15-30kg (21% soybean meal)

Low protein in the first two phases led to the lowest number of treatment days among the zinc-free diets.

Varying protein levels in weaner diets

Protein level (phase 1/phase 2/phase 3)

Average treatment days

Daily gain (g/day)

Feed conversion (kg feed/kg gain)

Normal protein with zinc

2.08

520

1.43

Normal protein

4.19

519

1.44

Low/normal/normal

3.75

516

1.44

Low/low/high

3.1

504

1.44

Very low/high/high

3.68

517

1.40

Very low/medium/high

3.24

504

1.42

Protein levels: High 19.5%; medium 17.4%; normal 18-19%; low 16-16.5%; very low 14%

Study facts
• Six treatment groups
• Five zinc-free diets compared with a zinc oxide diet
• 6,800 pigs in 75 pens
• Danbred pigs in experimental herd
• Pelleted feed.

Study findings
The pigs on the low/low/high protein programme saw the lowest diarrhoea treatment days among the zinc-free diets and had an equally good feed conversion ratio as the normal protein zinc diet.

However, pigs on the low/low/high diet grew 15g/day less than the pigs on normal protein and no zinc.

Danish progress

The Danish pig industry cut average medical zinc use from about 14.5g a piglet in 2015 to 13g last year.

This was done alongside a drop in antimicrobial use, which fell from about 340 doses a pig to below 260 doses from 2013 to 2019. 

Dr Hansen said: “We are seeing a drop in zinc usage but it’s a reduction in doses that is the main driver.”

He said many farms had successfully reduced zinc oxide from 2,500 parts per million (ppm) to 1,500ppm with no adverse side effects, but only 5-10% of Danish piggeries were weaning without zinc oxide.

Dr Fink Hansen said: “The goal is to find a cost-effective solution without increasing antibiotic usage.

“It is not an easy task for Danish farms. We still have a long way to go over the next couple of years.”

He stressed while there were three common factors in achieving zero zinc, each piggery must find what works for its own system and pigs.

“It’s on the agenda for everyone. We currently have a small number of producers who can do this successfully. Some of them have to use more antibiotics, unfortunately, so I am still a little concerned about what might happen to our antibiotic usage.

“We have a hard deadline of June 2022 and I don’t believe it’s going to change.”


This information is from a webinar, part of Biomin’s Antibiotics Reduction Expert Series, where Dr Christian Fink Hansen, director of the Seges pig research centre was speaking.

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