Effects of Long-Term Dietary Protein Restriction on Intestinal Morphology, Digestive Enzymes, Gut Hormones, and Colonic Microbiota in Pigs

Abstract

Using protein-restriction diets becomes a potential strategy to save the dietary protein resources. However, the mechanism of low-protein diets influencing pigs’ growth performance is still controversial. This study aimed to investigate the effect of protein-restriction diets on gastrointestinal physiology and gut microbiota in pigs. Eighteen weaned piglets were randomly allocated to three groups with different dietary protein levels. After a 16-week trial, the results showed that feeding a low-protein diet to pigs impaired the epithelial morphology of duodenum and jejunum (p < 0.05) and reduced the concentration of many plasma hormones (p < 0.05), such as ghrelin, somatostatin, glucose-dependent insulin-tropic polypeptide, leptin, and gastrin. The relative abundance of Streptococcus and Lactobacillus in colon and microbiota metabolites was also decreased by extreme protein-restriction diets (p < 0.05). These findings suggested that long-term ingestion of a protein-restricted diet could impair intestinal morphology, suppress gut hormone secretion, and change the microbial community and fermentation metabolites in pigs, while the moderately low-protein diet had a minimal effect on gut function and did not impair growth performance.

Low Protein-High Carbohydrate Diets Alter Energy Balance, Gut Microbiota Composition and Blood Metabolomics Profile in Young Pigs

“…Therefore, the lower abundance Prevotella in the gastrointestinal tract of pigs received moderately low protein diet may partly explain their poor performance in the present study. Our data is not in parallel with previous research showing higher abundance of Prevotella in colonic contents of weaned pigs fed with low protein (14% and 17% CP) diets 71 or in cecal content of growing pigs fed with diets with reduced protein content (15% CP) 39 . The discrepancy in data may be attributed to the sources of carbohydrates used as well the dietary protein content in different studies.…”

Applicability of an Unmedicated Feeding Program Aimed to Reduce the Use of Antimicrobials in Nursery Piglets: Impact on Performance and Fecal Microbiota

“…This lower protein content of the UN diet was somehow proposed as a safeguard in front of intestinal disorders. Using low protein diets during the post-weaning period is largely recognized as a strategy to control post-weaning diarrhea [36], although this could mean reduced growth of piglets during this period [37]. In any case, the impairment of performance registered in our trial during the PI with the UN diet could have been minimized by the compensatory growth registered during the subsequent PII period, and live weight differences were not eventually observed during the entire nursery period, or at fattening.…”

Effects of Tributyrin Supplementation on Growth Performance, Insulin, Blood Metabolites and Gut Microbiota in Weaned Piglets

“…We selected these bacterial groups because pathogens are present among the Enterobacteriaceae and, in particular, strains of E. coli that are involved in diarrhea and other diseases [68]. However, lactobacilli and bifidobacteria are beneficial bacteria in both humans and animals since the final products of their sugar fermentation play a crucial role in establishing a positive network among bacterial groups of gut microbiota [69,70]. In the pig, this consideration is partially true since Bifidobacterium genus represents a small portion of the total bacteria of the gut microbiota, suggesting that other microbial groups play a crucial role in conferring benefits to the healthy animal [71,72].…”