Intravenous administration of L-tryptophan stimulates gastrointestinal hormones and melatonin secretions: study on beef cattle

Abstract

This study aimed to determine the effective dose of intravenous administration of L-tryptophan (L-T) on gastrointestinal hormones (GIH) secretions and melatonin using Hanwoo cattle. Three steers (362 ± 23 kg) fitted with indwelling jugular vein catheters were assigned in a 3 × 3 Latin square design. Treatments were intravenous administration of saline (control), 28.9 mg L-T/kg body weight (BW; low) and 57.8 mg L-T/kg BW (high) L-T for 1 day with 7 days of adaptation. Samples were collected after adaptation period at −60, 0, 30, 60, 90, 120, 150, 180, 240, and 300 min of sampling day. The levels of serum cholecystokinin (CCK) and secretin were higher ( p < 0.05) in the high L-T group than those in the other groups. Serum Melatonin (MEL) levels were increased upon L-T administration ( p < 0.05) in the high L-T group. Taken together, the effective dose of L-T administration was defined at 57.8 mg L-T/kg BW in order to stimulate increase of GIH and MEL.

Effect of Dietary Rumen-Protected L-Tryptophan Supplementation on Growth Performance, Blood Hematological and Biochemical Profiles, and Gene Expression in Korean Native Steers under Cold Environment

“…L-tryptophan (TRP) is known to play a pivotal role in metabolic, physiological, and organ development and growth [11,12]. Lack of TRP may adversely affect feed intake and growth performance.…”

“…Lack of TRP may adversely affect feed intake and growth performance. However, in most ruminants, TRP is not deficient due to ruminal fermentation [11,13]. In particular, TRP in ruminants has been reported to increase the secretion and activity of pancreatic α-amylase, thereby increasing starch digestibility by promoting the secretion of the intestinal hormone cholecystokinin (CCK) [11,14,15].…”

“…However, in most ruminants, TRP is not deficient due to ruminal fermentation [11,13]. In particular, TRP in ruminants has been reported to increase the secretion and activity of pancreatic α-amylase, thereby increasing starch digestibility by promoting the secretion of the intestinal hormone cholecystokinin (CCK) [11,14,15]. TRP is also known as a constituent of niacin, a precursor of serotonin and melatonin, and to have antioxidative and stress-relieving properties [11,13].…”

“…In particular, TRP in ruminants has been reported to increase the secretion and activity of pancreatic α-amylase, thereby increasing starch digestibility by promoting the secretion of the intestinal hormone cholecystokinin (CCK) [11,14,15]. TRP is also known as a constituent of niacin, a precursor of serotonin and melatonin, and to have antioxidative and stress-relieving properties [11,13]. Thus, TRP is proposed as an essential amino acid (AA) that can help avert the decline in animal productivity due to a low temperature environment under climate change [11].…”

“…TRP is also known as a constituent of niacin, a precursor of serotonin and melatonin, and to have antioxidative and stress-relieving properties [11,13]. Thus, TRP is proposed as an essential amino acid (AA) that can help avert the decline in animal productivity due to a low temperature environment under climate change [11]. On the other hand, the amounts of essential AAs, such as TRP, supplied by microbes are sufficient only to support maintenance and normal milk and beef production and not maximal animal growth [10,12].…”