Insights into the mode of action of tannin-based feed additives in broiler chickens: looking for connections with the plasma metabolome and caecal microbiota

Abstract

This study assessed the effects of three tannin-based feed additives on the productive performance, foot-pad conditions, plasma metabolome, and caecal microbiota of meat-type chickens. A total of 2,340 male broilers were divided into 4 treatments (9 replicates each) fed either a commercial basal diet (CON) or the basal diet supplemented with one of the three tested products (A, B, or C) up to 49 days. According to manufacturers’ instructions, product A was added to the basal diet at 0.3% from 0 to 49 d, while B and C at 0.13% from 0 to 21 d and 0.12% from 22 to 49 d. Compared to CON, tannin-supplemented birds consumed less feed (6.59 vs. 6.37, 6.49, and 6.35 kg, for CON vs. A, B, and C, respectively; p < .001) and reached a lower slaughter weight (3,599 vs. 3,494, 3,546, and 3,472 g, for CON vs. A, B, and C, respectively; p < .05). Feed conversion ratio (FCR) was not affected by the tannin supplementations, except for the starter phase when CON exhibited lower FCR than the other groups (p < .01). The observed differences in the plasma metabolome between CON and treated groups might indicate an impaired energy metabolism of tannin-supplemented chickens. The significant reduction in the caecal microbial diversity and short-chain fatty acid producer bacteria can also be related to the depressed performance of tannin-fed chickens. In contrast to earlier findings, pododermatitis was unaffected by our treatments. Further dose-response studies can help better exploit tannin-based additives in broiler diets.

Highlights

• Two tannin-based feed additives out of the three tested in this study significantly reduced feed intake and body weight gain of broiler chickens.

• The tannin-produced shifts in the plasma metabolome and caecal microbiota may have been two reasons for the productive performance depression.

• Further dose-response trials can help the poultry industry to better elucidate the role of tannins as feed supplements for broiler chickens.

Keywords:

• Broiler chicken
• tannin
• performance
• metabolome
• microbiota

Acknowledgements

The authors acknowledge Stefano Pignata and Roberto Donatini (Dipartimento di Scienze e Tecnologie Agro-Alimentari, Alma Mater Studiorum - University of Bologna) for their technical support.

Disclosure statement

The authors declare that there is no conflict of interest.

Ethical approval

This experiment was approved by the Ethical Committee of the University of Bologna (ID: 933/2018).

Data availability statement

All data produced and analysed in the study have been included in this paper and its supplemental materials. The microbiota data set is available on Sequence Read Archive (SRA) with BioProject ID PRJNA658526.

Additional information

Funding

This work was supported by the Emilia-Romagna Rural Development Programme 2014-2020 under Grant Operazione 16.2.01, Focus Area 3A - Progetti di filiera, Avviso D.G.R. N. 227 del 27/02/2017.