Abstract Preliminary data demonstrated that pigs supplemented with Bacillus subtilis and plant extracts maintained growth performance despite a reduction in feed intake and exhibited decreased diarrhea incidence during the post-weaning period. This improvement in feed efficiency was accompanied by a notable reduction in both the frequency and severity of post-weaning diarrhea. Building upon these findings, the present study aimed to further evaluate the effects of Bacillus subtilis combined with plant extracts on intestinal morphology in weaned pigs. A total of 240 pigs (6.12 ± 0.53 kg body weight) weaned at 19 ± 1 days of age were allotted to four dietary treatments in a randomized complete block design, with initial body weight as blocking factor (6 pigs/pen; 10 pens/treatment). The dietary treatments were: (1) Control (CON): basal nursery diet; (2) BPS: CON + 500 mg/kg Bacillus subtilis + plant extracts; (3) BPD: CON + 1000 mg/kg Bacillus subtilis + plant extracts; and (4) CBX: CON + 50 mg/kg carbadox (antibiotic). Pigs were fed for 28 days, divided into two phases (phase 1: day 0 to14; phase 2: day 15 to28). On days 14 and 28 post-weaning, one pig per pen was euthanized to collect duodenal, jejunal, and ileal tissue samples. All samples were fixed in 10% neutral-buffered formalin, sectioned, stained with hematoxylin and eosin, digitally scanned, and analyzed for villus height, crypt depth, villus width, villus area, and enterocyte count using QuPath (v0.6.0). On day 14 post-weaning, jejunal crypt depth was lower (P 0.05) in pigs fed BPS compared with CBX, with BPD being intermediate. On day 28 post-weaning, BDP reduced (P 0.05) crypt depth and increased (P 0.05) villi height-to-crypt depth ratio compared with CON. In the ileum, crypt depth was reduced (P 0.05) in BPS, BPD, and CBX relative to CON, accompanied by corresponding increases in villus height-to-crypt depth ratio. Overall, supplementation of Bacillus subtilis combined with plant extracts improved intestinal morphology and maturation in weaned pigs, producing effects comparable to antibiotic supplementation. These findings support the potential of Bacillus subtilis and plant extracts combination as a viable nutritional strategy to enhance intestinal integrity and post-weaning performance.
Trapp et al. (Wed,) studied this question.