Road to Zero Zinc Oxide

Yeast-derived mannan-rich fraction as Zinc Alternative.

Up to now Zinc Oxide has been an effective management tool in the pig industry. With environmental sustainability now being the important issue, heavy metal use in feed has been marked as massive area of concern. With an EU ban in June 2022, a sustainable replacement needs to be sourced.  I have looked at Chinese research published this September in the Journal ‘Animal Feed Science and Technology’, where Yeast-derived mannan- rich fraction (MRF) was tested at managing control of post weaning diarrhoea.

The study aim was to find the effect of partially or fully replacing zinc oxide with MRF derived from yeast, on pigs for 28 days post weaning. Treatments consisted of a basal diet (control), basal + zinc oxide, basal + MRF and a basal + zinc/MRF diet. Pigs daily gain, feed intake, incidence of diarrhoea, immune response, zinc excretion was measured along with diet digestibility (Zhang et al. 2021).

‘The current study demonstrated that partial or complete replacement of zinc oxide by a mannan-rich fraction in diets had comparable or better effects.’- Study Authors suggest.

It was found that MRF and partially supplemented MRF treatments had the highest daily gain. MRF treatments had the highest gain to feed ratio and a much lower diarrhoea incidence than control with 5.43% vs 11.98%, slightly lower than zinc oxide supplemented treatments. MRF had highest dry matter digestibility and lowest zinc excreted in faeces. A 97% reduction compared to zinc oxide and 94% reduction to zinc oxide/MRF treatments. MRF supplemented treatments had highest blood IGF-1 concentration, improved gut villus height/crypt depth and enrichment of microbiome (Zhang et al. 2021).

‘ZnO represents one of the major strategies for managing detrimental symptoms and bacterial infections, but severe threats arise from ZnO environmental pollution and its contribution to the spread of bacterial resistance’-

A research article looking at feeding strategies in managing post weaning diarrhoea stated. Zinc oxide has proven ability in improving digestion, antioxidant levels, intestinal morphology, and ghrelin/pancreatic enzyme secretions. It improves immune function and contains antimicrobial effects. However, there is low zinc utilisation, leading to high excretion levels in manure. Over supplementation can lead to toxicity, and it has been found to been present in meat. It’s use leads to creation of antibiotic resistant & heavy metal tolerance genes (Bonetti et al. 2021).

Zinc oxide ban means innovation is key to improve environmental sustainability. It was clear MRF whether partially or fully replacing zinc oxide competed just as well at maintaining pig health and performance. Even giving the additional benefit of improved gut microbiome diversity and a massive reduction in heavy metal emissions. Zinc oxide up to now has been very effective in its role as a growth promoter but the environmental impact has been too great. This is an extremely promising study. Findings are very positive and showed the potential us humans have at overcoming adversity and finding sustainable innovations.

By:         Neal Folliard M.Sc.

References

Bonetti, A., Tugnoli, B., Piva, A. and Grilli, E. (2021) ‘Towards Zero Zinc Oxide: Feeding Strategies to Manage Post-Weaning Diarrhea in Piglets’, Animals, 11(3), 642.

Zhang, G., Zhao, J.B., Dong, W.X., Song, X.M., Lin, G., Li, D.F. and Zhang, S. (2021) ‘Yeast-derived mannan-rich fraction as an alternative for zinc oxide to alleviate diarrhea incidence and improve growth performance in weaned pigs’, Animal Feed Science and Technology, 281, 115111, available: http://dx.doi.org/https://doi.org/10.1016/j.anifeedsci.2021.115111.