Fig. 1

Research design, sample collection and relationship between lactating sow leftover and housefly-carried microbiota. (A) Proposed study design. 20 gestating sows from the BB were assigned to BB and NFB when they were 31 days before the FDD, whose feces were collected when they were 21 days before the farrowing due date. After sample collection in the NFB, a 30-day removal lactating sow leftover treatment was implemented in the NFB, which change the farrowing house from NFB to RFB. 10 gestating sows from the BB, which were assign to the RFB at 31 days before the FDD, had feces collected at 21 days before the FDD. In addition, housefly samples were collected in the BB, while housefly, gestating sow feed, lactating sow leftover, environmental microorganisms (gestating sow skin, crib and handrail) and dust were both collected in the NFB and RFB. (B) Changes in relative abundance of the top 10 dominant bacteria within the residual feed of lactating sows at the genus level and microbial contribution to housefly-carried microbiota at different time spots. (C) Removal of lactating sow leftover significantly reduced the contribution of residual microorganisms to housefly-carried microbiota. (D) Principal coordinate analysis of housefly-carried microbiota among BB, NFB and RFB. BB, breeding barn; NFB, non-removal of leftover feed farrowing barn; RFB, removal of leftover feed farrowing barn; FDD, farrowing due date