How feed restriction interferes with ileal microbiota in broilers

Stress models based on feed restriction have been used in broilers to understand specific metabolic process. If feed restriction can modulate animal metabolism, can also used to understand the microbial colonization in broilers intestine. The aim of this study was investigated the response of ileal microbiota of fast (Cobb500^TM) or slow-growing (Label Rouge) broilers submitted to two feed restriction programs (energetic or quantitative). Two experiments were conducted; experiment I with Cobb500^TM, and experiment II with Label Rouge broilers. Up to 21 days, the birds received the same diet. At 22 days of age, birds were divided into 3 experimental treatments (8 replicates of 20 birds): 1. Control (ad libitum - 3.176 Mcal/kg ME and 19% CP); 2. Energetic restriction (2.224 Mcal/kg ME and 19% CP) up to 42 days with consumption equivalent to control; 3. Quantitative restriction (70%, i. e., restricted broilers ingested 30% of the quantity consumed by the control group - 3.176 Mcal/kg ME and 19% CP) for 7 days, followed by re-feeding ad libitum until 42 days. Mucosa and content ileal samples of metagenomics DNA were collected at 28 and 42 days, processed and quantified by qPCR method. The energetic restriction leads to: decrease in Lactobacillus (P<0.05) and increase in Enterobacteriaceae (P<0.10) in ileum mucosa and content of fast-growing broilers; and decrease in copy numbers of Enterococcus (P<0.05), Clostridium cluster IV (P<0.05) and Clostridium cluster XIV (P<0.05) in ileum content of slow-growing broilers. Quantitatively restricted fast-growing broilers showed decrease in Lactobacillus (P<0.05) and Clostridium cluster IV (P<0.10) counts in ileum mucosa, and increase of Enterococcus (P<0.05) in ileum content. For slow-growing broilers, restriction leads to increase in Enterobacteriaceae (P<0.10) and Enterococcus (P<0.05) at ileum content. After the refeeding period, no difference were found in ileal microbiota (P>0.10) of fast-growing broilers. For slow-growing broilers, all groups decreased (P<0.10) in restricted group. In conclusion, host genetics, and changes in their physiological status facing of the environmental conditions are determinant for the response of intestinal microbiota to feed restriction programs.