TRENDING FILE 52 FEED & ADDITIVE MAGAZINE May 2022 As shown on Figure 2 (see yellow highlighted area), a zinc supplementation below requirements (estimated to be at 100 mg/kg, NRC 2012) lead to low blood zinc levels. Although the majority of the observations indicated a low zinc in the blood in this range, some trials observed a high concentration of zinc in the blood of piglets. This could be due to a high Zinc status at weaning due to intake of zinc rich creep feed before weaning. An increase on blood Zinc levels (from 0 to 1.3 mg/L) linked with higher ZnO supplementation dosages, (from 200 to 500 mg/kg) is also observed in a dose-response manner. However, the supplementation of ZnO from 500 up to 1500-2000 mg/ kg zinc in the complete feed, seems to reach a plateau on blood levels (see figure 2, green highlighted area). This illustrates how piglets are maintaining their homeostatic regulation and buffering the excess of dietary zinc. When the zinc supplementation exceeds 2000 mg/ kg zinc (see figure 2, red highlighted part), the homeostatic regulation capacity of piglets is exceeded and blood zinc concentration rise again. At such high levels, higher variability of blood zinc concentrations is also observed. This might be related to weaning age and individual feed intakes of piglets involved in this set of literature review. The higher ZnO supplementation is, the higher will be the feed consumption, resulting in a higher risk of piglet toxicity due by-passed homeostatic regulation capacity. ANY CORRELATION BETWEEN BLOOD ZN CONCENTRATION & PIGLET PERFORMANCE? A second exhaustive literature review was performed from AniLib scientific database. Out of 151 publications on pharmacological use of ZnO in weaned piglets, 19 papers were selected for the purpose of this new review. Filtering criteria were: daily weight gain, blood zinc concentration (at the end of 2-6 weeks studies) and ZnO supplementation levels (2-3000 mg Zn/kg complete diet). References of selected papers: 2018 2015 2021 2020 2012, 2013 2014 1993, 1996, 1999, 2001, 2002, 2009 2014 2018 2010 2008 2015 2016 Animal Feed Science and Technology Animal Animals Asian Australian JAS Asian Journal of Animal and Veterinary Advances British Journal of Nutrition Journal of Animal Science Journal of Animal Science and Technology Journal of Trace Elements in Medicine and Biology Murdoch University report KSU Swine Day Veterinarni Medicina WUR report Figure 2: Review of blood Zn concentration in piglets fed different dietary Zn content for 2 weeks post weaning.
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