Versatility of Dietary Zinc Levels from Zinc Hydroxychloride is Beneficial in Broiler Chicken Production

Zinc is an essential trace mineral in broiler nutrition. However, in commercial practice it is often fed above requirements to prevent any deficiencies. To prevent deficiencies, Zinc hydroxychloride (HTM) (IntelliBond®, Trouw Nutrition, Netherlands) provides versatility to optimise the producer’s trace mineral program and allow them to feed levels lower than those commercially used today in the form of sulfate trace minerals (STM).

Raw data of nine studies was combined into one dataset to be used in the meta-analysis. All nine studies included a comparison between HTM and STM fed at 80 mg/kg and/or 20 mg/kg Zn. All studies were performed in Europe in experimental conditions mimicking commercial practice by using a wheat-based diet, high stocking density, and/or environmental challenges. The meta-analysis was conducted in SAS using PROC MIXED for growth performance and PROC GLIMMIX for carcass yields. Three comparisons were made between 80 mg/kg Zn from HTM (HTM80) and STM (STM80), between 20 mg/kg Zn from HTM (HTM20) and STM (STM20), and between HTM20 and STM80.

The results show that, at current commercial levels, HTM80 outperformed the STM80 group, resulting in a higher BW (2689.7 g for HTM80 vs 2664.8 g for STM80, P=0.0374), and ADG (70.4 g/bird/day for HTM80 vs 69.6 g/bird/day for STM80, P=0.0294). Similar results were obtained when Zn levels were reduced to 20 mg/kg. At lower levels, HTM outperformed STM resulting in a higher BW (2695.1 g for HTM20 vs 2654.5 g for STM20, P=0.0245), ADG (70.5 g/bird/day for HTM20 vs 69.4 g/bird/day for STM20, P=0.0249), ADF (97.9 g/bird/day for HTM20 vs 96.3 g/bird/day for STM20, P=0.0413) and breast meat yield (27.1% for HTM20 vs 26.6% for STM20, P=0.0202). Comparing 20 mg/kg Zn from HTM to the commercially used dosage of 80 mg/kg STM, resulting in a tendency towards a higher BW (2695.1 g for HTM20 vs 2664.8 g for STM80, P0.0694), ADG (70.5 g/bird/day for HTM20 vs 69.6 g/bird/day for STM80, P=0.0674) and ADFI (97.9g/bird/day for HTM20 vs 96.5 g/bird/day for STM80, P=0.0531), while breast meat yield was significantly improved compared to 80 mg/kg Zn fed as STM (27.1% for HTM20 vs 26.7% for STM80, P=0.0169).

Although no significant difference in mineral depositions could be found in the animals (Olukosi et al., 2018), the above obtained results indicate a difference in mode of action between HTM and STM. Another study looked at the effects of HTM and STM on the microbiota in the ileum and caecum (van Kuijk et al., 2021). These authors showed a modulation of the microbiota by HTM which was most visible in the caecum between HTM20 and HTM80. This corresponded with significantly higher levels of Zn in the caecum in the HTM80 group compared to the HTM20 group. Although faecal excretion was not measured, the latter results indicated that feeding lower levels in the form HTM not only can be beneficial for the growth performance, but also for the environment.

From these results, it can be concluded that feeding HTM resulted in a better growth performance, at commercial Zn levels but also at lower Zn levels.