Impact of bioactive substances on the gastrointestinal tract and performance of weaned piglets: a review

Abstract

The EU ban on in-feed antibiotics has stimulated research on weaning diets as a way of reducing post-weaning gut disorders and growth check in pigs. Many bioactive components have been investigated but only few have shown to be effective. Amongst these, organic acids (OA) have been shown to exert a bactericidal action mediated by non-dissociated OA, by lowering gastric pH, increasing gut and pancreas enzyme secretion and improving gut wall morphology. It has been postulated that they may also enhance non-specific immune responses and improve disease resistance. In contrast, relatively little attention has been paid to the impact of OA on the stomach but recent data show they can differently affect gastric histology, acid secretion and gastric emptying. Butyrate and precursors of butyric acid have received special attention and although promising results have been obtained, their effects are dependent upon the dose, treatment duration, initial age of piglets, gastrointestinal site and other factors. The amino acids (AA) like glutamine, tryptophan and arginine are supportive in improving digestion, absorption and retention of nutrients by affecting tissue anabolism, stress and (or) immunity. Glutamine, cysteine and threonine are important for maintaining mucin and permeability of intestinal barrier function. Spray-dried plasma (SDP) positively affects gut morphology, inflammation and reduces acquired specific immune responses via specific and a-specific influences of immunoglobulins and other bioactive components. Effects are more pronounced in early-weaned piglets and under poorer health conditions. Little interaction between plasma protein and antibiotics has been found, suggesting distinct modes of action and additive effects. Bovine colostrum may act more or less similarly to SDP. The composition of essential oils is highly variable, depending on environmental and climatic conditions and distillation methods. These oils differ widely in their antimicrobial activity in vitro and some components of weaning diets may decrease their activity. Results in young pigs are highly variable depending upon the product and doses used. These studies suggest that relatively high concentrations of essential oils are needed for beneficial effects to be observed and it has been assumed that these plant extracts mimic most of the effects of antibiotics active on gut physiology, microbiology and immunology. Often, bioactive substances protective to the gut also stimulate feed intake and growth performance. New insights on the effects of selected OA and AA, protein sources (especially SDP, bovine colostrum) and plant extracts with anti-bacterial activities on the gut are reported in this review.

Effect of free thymol on differential gene expression in gastric mucosa of the young pig

“…Thymol, the principal constituent of thyme-extract oil, is a phenolic compound with antimicrobial activity. Thymol has been proposed as an animal feed supplement to positively influence gut microbiota and consequently improve animal health and growth (Lallès et al, 2009;Khan et al, 2012). Research has suggested that thymol rapidly enters the bloodstream after it is ingested (Kohlert et al, 2002), and in pigs it is absorbed in the stomach (Michiels et al, 2008).…”

Antisecretory factor as a potential health-promoting molecule in man and animals

“…Indeed, weaning is the most stressful event in piglets' lives, reared in intensive piggeries. Weaning is frequently associated with a reduced nutrient intake, severe growth check, impairment of health status and a higher susceptibility towards infections and gut disorders (14,15) . For more than 50 years, the use of antimicrobial growth promoters (AGP) in animal diets improved growth performance and prevented the side effects of early weaning practice.…”

Stalboekje Konijnen 2017 : handboek voor natuurlijke konijngezondheidzorg met kruiden en andere natuurproducten : Kennis voor Beleid uitgave

“…Zuren door de voeding of het drinkwater kunnen een positieve bijdrage leveren aan de diergezondheid door hun bactericide werking, het verlagen van de pH van de maag, het stimuleren van de verteringsenzymen en het versterken van de darmintegriteit (Lallès et al, 2009;Partanen and Mroz, 1999).…”