title: Effects of tryptophan supplementation on cashmere fiber characteristics, serum tryptophan, and related hormone concentrations in cashmere goats.
abstract: This study was designed to investigate the effects of tryptophan (Trp) supplementation on cashmere fiber characteristics and on serum Trp, melatonin (MEL), prolactin (PRL), insulin-like growth factor 1 (IGF-1), triiodothyronine (T3), and thyroxine (T4) concentrations in cashmere goats during the cashmere fast-growth period. Thirty-six Liaoning cashmere wether goats were stratified on the basis of body weight (28±0.8 kg) and assigned randomly to 1 of the following 4 rumen-protected Trp treatments: 0, 2.0, 4.0, and 6.0 g per goat per day. The experimental period lasted 137 d. Blood samples were collected monthly during the daytime (8:00 AM) and at night (8:00 PM). Tryptophan supplementation improved cashmere growth rates, cashmere weight, and body weight (P=0.001) and increased serum Trp levels, nighttime MEL concentrations, IGF-1, and T3 and T4 concentrations (P<0.05). Across the treatments and sampling months, a highly positive correlation between cashmere growth rate and nighttime serum MEL concentrations was observed (r=0.879, P=0.001). A moderately negative correlation between cashmere growth rates and serum PRL concentrations during the day and at night (rday=-0.645, P=0.007; rnight=-0.583, P=0.018) was observed. A moderately positive correlation between the cashmere growth rate and the daytime serum IGF-1 concentration (r=0.536, P=0.032) was observed, and no correlation was found between the cashmere growth rate and the other serum hormone concentrations. These data indicate that changes in serum concentrations of MEL, IGF-1, and PRL are related to cashmere growth in Liaoning cashmere goats during the cashmere fast-growth period. Under the experimental conditions of the current trial, we suggest that Trp may promote cashmere growth by increasing daytime IGF-1 and nighttime MEL secretion.
authors.affiliation: Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, People's Republic of China.
authors.forename: H
authors.initials: H
authors.lastname: Ma
authors.forename: W
authors.initials: W
authors.lastname: Zhang
authors.forename: W H
authors.initials: WH
authors.lastname: Song
authors.forename: P
authors.initials: P
authors.lastname: Sun
authors.forename: Z H
authors.initials: ZH
authors.lastname: Jia
mesh_terms: D000821:Animal Feed / Q000032:analysis; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D004032:Diet / Q000662:veterinary; D019587:Dietary Supplements; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D006041:Goats / Q000097:blood* / Q000502:physiology*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D008550:Melatonin / Q000097:blood; D011388:Prolactin / Q000097:blood; D013974:Thyroxine / Q000097:blood; D014284:Triiodothyronine / Q000097:blood; D014364:Tryptophan / Q000008:administration & dosage / Q000097:blood* / Q000494:pharmacology*
chemical_list: D014284:Triiodothyronine; D007334:Insulin-Like Growth Factor I; D014364:Tryptophan; D011388:Prolactin; D008550:Melatonin; D013974:Thyroxine