Administration of encapsulated L-tryptophan improves duodenal starch digestion and increases gastrointestinal hormones secretions in beef cattle

Abstract

Objective: This study investigated the effects of oral administration of rumen-protected L-tryptophan (RPL-T) on duodenal starch digestion and gastrointestinal hormones (GIH) secretions using Hanwoo beef steers as the animal models. Methods: Four steers (423±24 kg) fitted with ruminal and duodenal cannulas were employed in a crossover design replicated twice. Treatments were control (basal diet) and RPL-T (basal diet+191.1 mg/kg body weight [BW]) group. Blood and duodenal samples were collected to measure serum GIH levels and pancreatic α-amylase activity at day 0, 1, 3, and 5 (-30, 30, 90, 150, and 210 min) of the study. Samples from each segment of the gastrointestinal tract were collected via ruminal and duodenal cannulas and were used to determine soluble protein and the starch digestion rate at days 6 (-30, 180, 360, and 540 min) and 8 (-30, 90, 270, and 450 min) of the experiment. Results: No significant difference in ruminal pH, NH 3-N, and total volatile fatty acid including the levels of acetate, propionate, butyrate, isobutyrate, valerate, isovalerate, and the acetateto-propionate ratio was observed between groups (p>0.05). Crude protein uptake was higher and feces starch content was lower in RPL-T group than the control group (p<0.05). The D-glucose contents of feces in RPL-T group decreased at day 5 compared to those in the control group (p<0.05), however, no change was found at day 0, 1, or 3 compared to the control group (p>0.05). Serum cholecystokinin (CCK), melatonin, duodenal pancreatic α-amylase activity, and starch digestion were significantly higher in RPL-T group than the control group (p<0.05). Conclusion: Taken together, oral administration of RPL-T at the rate of 191.1 mg/kg BW consistently increased CCK concentration, pancreatic α-amylase activity in duodenal fluids, and starch digestion rate in the small intestine and thus found to be beneficial.

Nutritional and Physiological Constraints Contributing to Limitations in Small Intestinal Starch Digestion and Glucose Absorption in Ruminants

“…Several amino acids including Arg, Leu, Ile, and Phe have been shown to influence pancreatic α-amylase activity in ruminants. Similarly, rumen-protected Trp supplementation to steers consuming a high-concentrate diet was associated with greater postruminal starch disappearance, increased luminal amylase activity in the duodenum, and increased serum CCK and melatonin [107]. We have found that melatonin supplementation to gestating ewes increased maternal pancreatic α-amylase activity [94] and small intestinal maltase, isomaltase, and glucoamylase activities [108].…”

Supplementing with L-Tryptophan Increases Medium Protein and Alters Expression of Genes and Proteins Involved in Milk Protein Synthesis and Energy Metabolism in Bovine Mammary Cells

“…Due to the pivotal importance of milk protein in human health, investigating supplementation with AAs (e.g., methionine, lysine) as the main nutrients that can positively stimulate milk protein synthesis in mammary epithelial cells (MEC) has been a priority as of late [ 2 ]. Tryptophan (Trp), known as a conditional EAA [ 3 ], can be supplemented in the diets of animals and humans when targeting maximal production, cell growth, and proliferation [ 4 , 5 , 6 ]. Furthermore, Trp has been widely introduced as a mostly harmless supplement for humans to cope with health issues such as stress and depression.…”

“…Furthermore, Trp has been widely introduced as a mostly harmless supplement for humans to cope with health issues such as stress and depression. In animals of different species, L-Trp is used for alleviating stress (e.g., heat and cold) [ 4 ] by simulating serotonin [ 7 ] and melatonin [ 4 , 5 , 8 ], improving muscle cell growth [ 6 ], antioxidation [ 9 ], and inducing milk protein, lactose, and unsaturated fatty acids, which can also enhance human health [ 10 , 11 ], as people are the primary consumers of the products. While L-Trp as a supplemental nutrient has been used to induce muscle growth and development in human athletes [ 12 , 13 ] and beef cattle [ 6 ], there is a lack of insight into defining the optimum doses for enriching milk quality components to avoid the risk of overdose effects and provide maximum positive effects.…”

“…In our laboratory, we took steps to examine the effects of L-Trp supplementation on muscle development and gene expression during heat and cold stress, and L-Trp proved to have anti-stress effects by simulating serotonin and melatonin in beef cattle [ 4 , 5 , 6 ]. Furthermore, in order to comprehend the mechanisms of L-Trp supplementation in influencing protein synthesis or affecting energy metabolism, metabolic pathways need to be investigated [ 10 , 12 , 13 ].…”

“Dietary supplementation of L-tryptophan” increases muscle development, adipose tissue catabolism and fatty acid transportation in the muscles of Hanwoo steers

“…L-Tryptophan (TRP) is an essential amino acid (AA) which requires to be supplemented in diets to meet the maximum production quality [ 1 – 3 ]. It is while most AAs are commonly assumed not to be deficient in cattle.…”