By Juan Castillo Zuniga, Anlly M. Fresno Rueda, Ryan S. Samuel, Benoit St-Pierre and Crystal L. Levesque, South Dakota State University

Weaning is a critical stage in the swine production cycle as a significant transition for young pigs. During weaning, piglets experience dramatic changes in both their diet and environment, which severely affect multiple organ systems, especially the gastrointestinal tract.

Traditionally, the negative impacts associated with weaning, such as diarrhea and gut dysfunction, were managed through the preemptive use of antibiotics. However, due to the growing concerns over antibiotic resistance, the swine industry has continued to investigate potential tools to improve and support efficient production within the National Pork Board recommendations regarding responsible use of antibiotics by using them only for prevention, treatment and disease control.

Among the most promising alternatives to pre-emptive antibiotics are microbial-based products, such as direct-fed microbials (i.e. probiotics or containing live organisms) and postbiotics, which support gut health and overall animal performance. Direct-fed microbials or their postbiotic products aim to restore balance in the gut microbiota, a key factor in mitigating weaning stress. However, while these products offer potential, the efficiency of probiotics and postbiotics still needs improvement, which highlights the need for a deeper understanding of their mechanisms of action.

In a trial at the South Dakota State University commercial wean-to-finish research facility, 40 pens of mixed sex weaned pigs were fed one of four diets across a phase-feeding program from wean-to-finish (Castillo Zuniga et al., 2024). Two levels of a direct-fed microbial Lactobacillus-based probiotic (0.1% or 0.2%) and one level of a Bifidobacterium-based postbiotic (0.2%) were compared to a diet without direct-fed microbials or the postbiotic during the nursery phase. During the nursery phase of production, both products positively influenced piglet performance, particularly in the early stages following weaning (Day 0 to Day 10). Specifically, pigs supplemented with the direct-fed microbial or the postbiotic had a higher average daily feed intake. However, there were no subsequent differences between the groups in average daily gain, average daily feed intake, feed efficiency or hot carcass weight at slaughter.

Beyond animal performance, the study also explored the impact of the direct-fed microbial or postbiotic on gut microbial composition. The presence of Lactobacillaceae increased in pigs fed with either Lactobacillus-based probiotic or Bifidobacterium-based postbiotic, signifying that these supplements may encourage beneficial bacteria. Notably, certain bacterial strains affiliated to Congobacterium massiliense and Absicoccus porci were more abundant in pigs fed diets with the direct-fed microbial or postbiotic, which may play a role in enhancing gut health and function.

Conversely, a potentially harmful strain, Streptococcus alactolyticus, was found in lower abundance in Bifidobacterium-based postbiotic-fed pigs, which could indicate a protective effect of the postbiotic. Furthermore, the study provides histological evidence that direct-fed microbial supplementation leads to better gut health. The higher villus height/crypt depth ratio observed in the intestines of supplemented pigs suggests improved nutrient absorption capacity, a critical factor for growth and development during the nursery phase.

In conclusion, this study reinforces the potential of probiotics and postbiotics as effective alternatives to prophylactic antibiotics during the critical weaning stage. Specifically, during the first 10 days of the nursery, average daily feed intake was increased which could translate into an economic return on the investment. However, the exact mechanisms through which these direct-fed microbials or their postbiotic products exert their beneficial effects still require further investigation to optimize their use and maximize their efficiency in swine production.

References

Castillo Zuniga, J., A.M. Fresno Rueda, R.S. Samuel, B. St-Pierre, and C.L. Levesque. 2024. Impact of Lactobacillus- and Bifidobacterium-based direct-fed microbials on the performance, intestinal morphology, and fecal bacterial populations of nursery pigs. Microorganisms, 12, 1786.