Journal
DOMESTIC ANIMAL ENDOCRINOLOGY
Volume 43, Issue 3, Pages 239-250Publisher
ELSEVIER SCIENCE INC
DOI: 10.1016/j.domaniend.2012.03.004
Keywords
Tryptophan; Melatonin; Prolactin; Insulin-like growth factor I; Thyroid hormone; Cashmere goat
Funding
- National Basic Research Program (973) of China [2011CB100805]
- Wool Cashmere Industry Technology System [nycytx-40-2]
- National Key Technologies R and D Program [2009BADA5B04]
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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 (T-3), and thyroxine (T-4) concentrations in cashmere goats during the cashmere fast-growth period. Thirty-six Liaoning cashmere wether goats were stratified on the basis of body weight (28.14 +/- 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 T-3 and T-4 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 (r(day) = -0.645, P = 0.007; r(night) = -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 or MEL, IGF-I. and PRL ate elated to cashmere growth in Liaoning cashmere goats during the cashmere fast-growth period. Under the experimental conditions of the current trial, we suggest that Tip may promote cashmere growth by increasing daytime IGF-1 and nighttime MEL secretion. (C) 2012 Elsevier Inc. All rights reserved.
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