September 02, 2018

Interpretive Summary: Supplementation with organic acids showing different effects on growth performance, gut morphology, and microbiota of weaned pigs fed with highly or less digestible diets.

Interpretive Summary: Supplementation with organic acids showing different effects on growth performance, gut morphology, and microbiota of weaned pigs fed with highly or less digestible diets.

By: Surely Wallace

In a July 2018 article published in the Journal of Animal Science, researchers conducted two studies to look at the potential benefit of organic acids (OA) on the growth performance and gut health of weaned pigs, when added to a highly digestible, versus a less digestible diet.

Post-weaning stress may impair growth performance in pigs due to diarrhea, malabsorption, and reduced gut health. Previously, antibiotics were added to pig feed as growth promoters to deal with these issues, but are longer allowed. Therefore, the authors chose to study OA to determine if it might act as a comparable growth enhancer.

In the first experiment, 240 weaned pigs were randomly fed one of five diets for 49 days. Six pigs were housed per pen (eight replicates/treatment). The diets were as follows: (1) negative control “NC” highly digestible carbohydrate basal diet, (2) positive control “PC” (antibiotics and NC), (3) “OA1” blend, (4) “OA2” blend, and (5) “OA1+OA2” blend (each a NC basal diet plus different OA blend). The second experiment was similar, with these differences: basal diet was comprised of less digestible carbohydrates, and OA2 was replaced with “OA3” blend. Eight pigs from each group were sacrificed on day 28 to collect gut tissue and digestive contents.

Results from the highly digestible diet experiment noted no significant changes to gut tissue or growth performance in pigs treated with OA compared to controls. However, reduced abundance of Escherichia–Shigella bacteria (associated with diarrhea) in the colons of pigs fed the OA2 diet suggested improved gut health. The digestive contents of pigs fed OA also had higher concentrations of the short-chain fatty acids acetic and propionic acid).

With the low digestible diet experiment, OA fed pigs had improved gut morphology (via increased villus height), reduced diarrhea post-weaning, higher average daily gain, and lower growth-to-feed ratio. Additionally, OA1+OA3 fed pigs had higher Prevotella bacteria in gut digestive contents (associated with healthy pigs). Like in the high digestible diet, a significant increase in acetic and propionic acid were noted in digestive contents of OA fed pigs. 

Overall, this study suggests OA added to post-weaning pig feed may have the potential to improve growth performance and gut health, possibly comparable to that of antimicrobials, in post-weaning pigs fed low digestible diets. The study also suggests a potential for OA to possibly improve gut health of post-weaning pigs fed high digestible diets. However, since different OA blends were used in this study, future studies looking at effects of individual types of OA, and determining the specific mechanism behind these potential observed benefits, e.g. effects of OA supplementation on the metabolic byproducts of gut microbes, is warranted.

To view the full article, “Supplementation with organic acids showing different effects on growth performance, gut morphology, and microbiota of weaned pigs fed with highly or less digestible diets,” visit Journal of Animal Science