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Replacing Zinc Oxide and Antibiotics in Piglet Starter Diets Using an Acidifier and a Phytogenic Feed Additive

Zinc oxide (ZnO) is used to prevent post-weaning diarrhea in piglets. But from June 2022, therapeutic doses of ZnO will be banned in animal feeds. An alternative approach using a combination of additives ensures no loss of zootechnical performance or profitability when removing ZnO and antibiotics from the ration.

Ákos Várnagy

In Brief

● Therapeutic doses of zinc oxide in piglet feeds will be banned from June 2022.
● It is possible to maintain high levels of zootechnical performance using the combination of an acidifier and a phytogenic feed additive product in piglet diets.
● The cost of the additives is covered by the improvement in animal performance.
● An additional uplift in profitability comes from improvements in mortality rates.

Maintaining high levels of pig performance has previously been acheived using a combination of antibiotic growth promoters (AGPs) and zinc oxide (ZnO) in piglet diets. The routine use of antitbiotics in animal production has been linked with rising levels of antimicrobial resistance (AMR) which has serious implications for both animal and human health. The European Parliament banned the use of antibiotics as growth promoters in September 2003 (Regulation (EC) No 1831/2003). Following this ban, and with increasing consumer demand for antibiotic-free products, antibiotics are now being used more prudently. The swine industry has had to look for alternatives to maintain gut health and close the performance gap.

Zinc exit

A ban on therapeutic doses of ZnO in piglet feeds will come into force in Europe in June 2022. While there are many benefits of using ZnO in piglet diets linked to improving gut health, there are more negative effects (Table 1). Increases in antibiotic resistance, decreases in the absorption of micro- and macro elements, and a heavy metal effect on the environment are some of the reasons why the use of therapteutic levels of ZnO are being banned.

Table 1. Positive and negative effects of ZnO
Negative effects of ZnOPositive effects of ZnO
Increases the occurrence of antibiotic resistance (Vahjen et al., 2015)Morphology changes in the large intestine leading to better mucose production and thus immune response (Liu et al., 2014)
Encourages the selection of multi resistant E. coli strains (Bednorz et al., 2013)Boost in production performance due to improved mucose secretion and immune respones (Liu et al., 2014)
Decreases the absorption of macro- and micro elements (Sandström, 2001)ZnO compensates for any weaknesses of technology, management, animal health and feed
Decreases the effectiveness of phytase (Lizardo, 2004)Can be the most cost effective solution
Decreases the effectiveness of organic acids (Mavromichalis, 2014) 
Heavy metal effect on the environment (Dourmad and Jondreville, 2007) 

Post weaning diarrhea

Post weaning diarrhea (PWD) in piglets is caused by E. coli and remains a big problem for most swine farms around the globe. When using classic piglet feeding systems, there is a risk of diarrhea occuring after birth if ZnO is not used. In severe cases, mortality levels rise causing direct economic damages as well as a longer-term impact from the loss of genetic potential in the herd.

Post weaning diarrhea in piglets is caused by E. coli and remains a big problem for most swine farms around the globe.

To avoid problems with PWD, farms usually administer high doses of ZnO in combination with an antibiotic in the prestarter feed, and continue to use ZnO in the starter feed as well (Figure 1).

Figure 1. Four approaches for avoiding PWD | Source: BIOMIN
Figure 1. Four approaches for avoiding PWD
Source: BIOMIN

From June 2022, ZnO will no longer have marketing authorization as a veterinary product. It can still be used as a feed additive, but at a maximum permitted dose rate of 150ppm.

The ban on AGPs and ZnO is forcing pig farm managers to reconsider their diet formulations and look for alternative solutions for the prevention of PWD.

What alternatives to ZnO and antibiotics are there for piglet diets without compromising mortality, growth rate or feed conversion ratio (FCR)?

Consider these possible alternatives:

  1. Check the feed formulation
  2. Apply a combination of feed additives
  3. Reduce protein levels

Check the feed formulation

Changing the feed formulation can greatly help reduce the occurence of PWD. A reduction in the energy concentration is the first step. If the diet is too rich for the piglet, diarrhea will likely result. Highly digestible sources of protein should be used such as fish meal, potato protein and soy protein concentrates. Reducing the crude protein levels to 18.3% in the prestarter and 16.8% in the starter will also help.

The ratio of amino acids can affect the likelihood of PWD, especially for the following amino acids:

  • Lysine
  • Methionine
  • Threonine
  • Tryptophan
  • Valine
  • Isoleucine
  • Leucine

All sources of fiber should be functional, including fermentable and non-soluble sources.

As well as altering the key components of the ration, using additives such as prebiotics, probiotics, medium chain fatty acids (MCFA) and plant oils is advisable. To remove antinutritional phytate from the feed, a superdose of phytase should be included.

Replacing ZnO and antibiotics can be carried out successfully when Biotronic® Top3 and Digestarom® DC are included in the diet.

BIOMIN solutions

Following extensive long-term research and development in this area, we can confirm that replacing ZnO and antibiotics in piglet feeds is not only possible, but can be carried out successfully when the combination of our Biotronic® Top3 acidifier and Digestarom® DC Xcel phytogenic product is included in the diet.

Biotronic® Top3 controls the Gram-negative bacteria thanks to its permeabilizing complex. This complex is able to break the thick, lipopolysaccharide cell wall of the bacteria, clearing the path for the non-dissociated forms of formic, acetic and propionic acid to get into the bacteria cells to work as a bactericide. A further bacteriostatic effect will be delivered by the cinnamaldehyde content in the product which inhibits cell division of the bacteria. The special carrier (SRM) secures the effectiveness of the components not only in the middle part of the small intestine but also in the jejunum, ileum and caecum.

Digestarom® DC Xcel is a phytogenic feed additive containing essential oils, herbs, spices and plant extracts which all contribute to the healthy development of the gut system and the emergence of a stable intestinal flora. This product plays an important role in ensuring the maximum genetic potential of the piglet is achieved in terms of feed consumption, average daily weight gain (ADG) and feed conversion ratio (FCR).

Reduce dietary protein when taking out ZnO

A trial using 430 Danbred piglets split into four treatment groups evaluated two crude protein levels, with or without 2,500 mg/kg ZnO or insoluble fiber in the prestarter diet (Table 2).

Table 2. Treatment groups of a trial investigating the effect of reducing the protein level when removing ZnO from the prestarter diet
TreatmentTreatment ATreatment BTreatment CTreatment D
Protein level18.3%18.3%16.5%16.5%
ZnO inclusion level2,500 mg0 mg2,500 mg0 mg
Insoluble fiber-Yes-Yes
Total feed intake (g/d)583605564566
Total average weight gain (g/d)417422396392
Total mortality (%)

There was no change in daily feed intake or in average weight gain after the starter period, indicating that it is possible to achieve the same performance levels with or without ZnO. During the trial, it was noted that the color of the feces varied depending on whether ZnO was present or not. With no ZnO the feces were dark brown or black compared to a brown-green color when ZnO was included. Also, the feces were softer without ZnO, but the form was still acceptable and not liquid. These changes in fecal color and consistency remained to the end of the starter phase.

Focus on performance

In another trial, the combination of 2 kg/ton of Biotronic® Top3 and 150 g/ton of Digestarom® DC Xcel was tested in the prestarter and starter diets on a 200 sow Danbred swine farm in Hungary. In the trial, the piglets never had antibiotics or ZnO. The results showed:

  • an ADG improvement of 15 grams
  • a decrease in FCR from 1.39 kg/kg to 1.31 kg/kg (Figure 2)
  • a decrease in mortality from 7.14% in the control group vs 1.79% in the treatment group (Figure 3)
Figure 2. FCR in the control and treatment groups | Source: BIOMIN
Figure 2. FCR in the control and treatment groups
Source: BIOMIN
Figure 3. Mortality in the control and treatment groups | Source: BIOMIN
Figure 3. Mortality in the control and treatment groups
Source: BIOMIN

Product costs covered by performance improvements

In another trial on a larger (1,500 Danbred sow) swine farm, 10,000 piglets were split into two groups. Piglets in the treatment group were fed the control diet plus Biotronic® Top3 at 2 kg/ton and Digestarom® DC Xcel at 150 g/ton. Mortality in the treatment group of this larger trial was only 0.74%. The cost of the product inclusion was covered by the improvements in ADG and FCR. The improvement in mortality rate delivered an uplift in profitability in both the aforementioned trials.


These trial results confirm that feeding piglets without ZnO or AGPs can be achieved by including an acidifier and a phytogenic feed additive. Zootechnical performance can be maintained and mortality rates can be reduced to improve the profitability of the farm. Biotronic® Top3 and Digestarom® DC Xcel are a successful replacement for ZnO and antibiotics in piglet diets.



Bednorz, C., Oelgeschläger, K., Kinnemann, B., Hartmann, S., Neumann, K., Pieper, R., Bethe, A., Semmler, T., Tedin, K., Schierack, P., Wieler, L.H. and Guenther, S. (2013).

The broader context of antibiotic resistance: zinc feed supplementation of piglets increases the proportion of multi-resistant E. coli in vivo. International Journal of Medical Microbiology. 303(6-7). 693-403.

Dourmad, J-Y. and Jondreville, C. (2007).

Impact of nutrition on nitrogen, phosphorus, Cu and Zn in pig manure, and on emissions of ammonia and odours. Livestock Science. 112(3). DOI: 10.1016/j.livsci.2007.09.002.

Liu, P., Pieper, R., Rieger, J., Vahjen, W., Davin, R., Plendl, J., Meyer, W. and Zentek, J. (2014).

Effect of dietary zinc oxide on morphological characteristics, mucin composition and gene expression in the colon of weaned piglets. Plos One. 9(3). e91091. https://doi.org/10.1371/journal.pone.0091091.

Lizardo, R. (2004).

Expert talk: Zinc oxide in phytase-low phosphorus diets. Pig Progress. [Online]. Available at: https://www.pigprogress.net/Home/General/2012/3/Expert-talk-Zinc-oxide-in-phytase-low-phosphorus-diets-PP008475W/ [Accessed 14/08/20].

Mavromichalis, I. (2014).

Zinc oxide buffers organic acids in piglet feeds. Watt Ag Net. [Online]. Available at: https://www.wattagnet.com/articles/20467-zinc-oxide-buffers-organic-acids-in-piglet-feeds [Accessed 14/08/20].

Sandström, B. (2001).

Micronutrient interactions: effects on absorption and bioavailability. British Journal of Nutrition. 85(S2). S181-S185.

Vahjen, W., Pietruszyńska, D., Starke, I.C. and Zentek, J. (2015).

High dietary zinc supplementation increases the occurrence of tetracycline and sulfonamide resistance genes in the intestine of weaned pigs. Gut Pathology 7(23). doi: 10.1186/s13099-015-0071-3.


DVM Ákos Várnagy
Key Account Manager, BIOMIN Magyarország Kft.