Short-term supplementation of zinc nanoparticles in weaned piglets affects zinc bioaccumulation and carcass classification

Abstract

High doses of zinc have been used as a prevention against weaned piglets' diarrhea for many years. Nevertheless, since 2022 high doses of zinc oxide have been banned in EU. Currently, there are several studies about the potential of zinc nanoparticles in lower doses which could maintain a preventive effect. Several concerns about nanoparticles' toxicity and bioaccumulation have been raised in many other fields of research. The aim of this short follow-up study is focused on the impact of zinc nanoparticles used as a prevention of diarrhea for weaned piglets, on the classification of slaughtered pigs’ carcasses and on zinc retention in muscle tissue. Seventy piglets (10 groups of 7 piglets) were fed a standard diet. The treated groups’ diets were supplemented with zinc oxide (ZnO), and phosphate-based nanoparticles: spherical- shaped type A (ZnA) and irregular-shaped: type C (ZnC), at the doses of 500, 1000 and 2000 mg Zn equivalent per kilogram of diet. The control group´s diet was not treated with zinc in any form. The feed experiment started when the piglets were 28 days old and lasted for 10 days. Experimental animals were grown to the final weight 120 ± 10 kg and slaughtered in a slaughterhouse. The pig carcasses were evaluated according to S/EUROP standards: the pigs’ weight, back fat thickness and lean meat content were monitored. Moreover, zinc concentrations in M. longissimus dorsi et thoracis were analyzed. The results have not proved significant changes in S/EUROP standard classification and zinc bioaccumulation in muscle tissue. This follow-up experiment was carried out as part of maintaining a precautionary approach to the use the nanoparticles in piglet fattening. In our study we did not confirm their effect on the assessment of carcass classification and their bioaccumulation in muscle tissue.