Feed & Additive Magazine Issue 3 April 2021

ISSUE FOCUS FEED & ADDITIVE MAGAZINE April 2021 45 acid, in a fat matrix (from Novus In- ternational, Inc.) on growth perfor- mance and faecal microbial profile of piglets in field conditions as replace- ment of ZnO added at high dose. The field trial was run in collab- oration with the Universidad Com- plutense de Madrid. In the trial, a total of 3448 piglets reared in 4 commercial farms located in Spain were assigned to two treatments based on their initial body weight (BW) and sex: i) a commercial diet supplemented with 2.5 g/kg of zinc oxide (ZnO, 1720 piglets) or ii) the same basal diet but includ- ing 2.5 g/kg of a commercial prod- uct that is a combination of embed- ded aromatic compounds, including among other benzoic acid, in a fat matrix (PBA 1728 piglets,). All the farms selected were using routinely ZnO at pharmacological dose. The animals received the treat- ments for a total of 6 weeks (4 weeks during suckling and 2 weeks after weaning). Cumulative performance from weaning to 6 weeks post-weaning were calculated and fresh faeces for each one of the farms (8 replicates per group) were taken at the end of the experimental period. The bacterial DNA was isolated and extracted and the V3-V4 region of the 16S rRNA gene was amplified and sequenced by the University of Bologna. WHAT DID WE FIND? Piglets receiving PBA showed higher daily gain (ADG, P <0.01) and lower feed conversion ratio (FCR, P <0.05) in all the farms compared to ZnO. Also, it was observed a reduction of mortality and diarrhoea incidence in pigs from the PBA compared the ZnO (P <0.01): see Figure 1. In addition to these changes in performance, we also observed changes in gut microbiota. Faecal microbiota was characterized by a higher alpha diversity in the PBA treatment . The alpha diversity plot (Figure 2) showed a higher microbial diversity in the PBA group compared with the ZnO group. A higher diversity is considered a marker for a more balanced, healthier, and mature microbiota. Fact that could be be- hind the improvements we observed on performance. The microbial composition was also influenced by treatment (P <0.01). Piglets receiving PBA showed high- er abundance of Ruminococcus (P <0.01), Prevotellace- ae (P <0.01) and Fibrobacteraceae (P <0.05). 0,5 0,7 0,9 1,1 1,3 1,5 1,7 300 320 340 360 380 400 420 Zn0 1Z n0 2 Zn0 3Z n0 4 PBA 1P BA 2 PBA 3P BA 4 Performance parameters measured ADG FCR 0 1 2 3 4 5 6 7 8 9 Zn0 1 Zn0 2 Zn0 3 Zn0 4 PBA 1 PBA 2 PBA 3 PBA 4 Mortality, % Diarrhea, % Figure 1. Data related with performance and health status of pigs for each one of the farms included in the trial: ADG, FCR, Mortality and Diarrea Incidence.