Bello Alhassan Usman, Idrus Zulkifli, Meng Goh Yong, Narayan Edward J, Farjam Abdoreza Soleimani
Institute of Tropical Agriculture and Food Security, Universiti Putra Malaysia, 43400 Selangor, Malaysia.
Institute of Tropical Agriculture and Food Security, Universiti Putra Malaysia, 43400 Selangor, Malaysia; Department of Animal Science, Universiti Putra Malaysia, 43400 Selangor, Malaysia.
Gen Comp Endocrinol. 2018 May 1;260:146-150. doi: 10.1016/j.ygcen.2018.01.012. Epub 2018 Jan 12.
Tryptophan (Trp) has been associated with the regulation of several behavioral and physiological processes, through stimulation of serotonergic activity. Tryptophan utilization at the metabolic level is influenced by the competitive carrier system it shares with large neutral amino acids (LNAA). This study was carried out using meat-type chicken as a model, to investigate the dose response effects of Trp/LNAA on fear response (tonic immobility; TI) and hormonal responses, including corticosterone (CORT), serotonin (5-HT), triiodothyronine (T) and thyroxine (T). A total of 12 cages (48 birds) were assigned to each of the six experimental groups at 29-42 days of age. Experimental diets were formulated to have incremental levels of Trp/LNAA (0.025, 0.030, 0.035, 0.040, 0.045, and 0.050). The results revealed that, Trp/NAA had no significant effect on growth performance and TI of the birds. However, elevation of Trp/LNAA was concurred with a linear reduction in CORT (P < .0001, r = 0.819) and linear increases in 5-HT (P < .0001, r = 0.945), T (P = .0003, r = 0.403) and T (P < .0001, r = 0.937) levels. In conclusion, the results from the current study demonstrated that, although incremental levels of Trp/LNAA did not affect bird growth performance or fearfulness, it increased 5-HT, T and T and decreased CORT levels in a linear dose-dependent manner. Manipulation of Trp feeding levels could be applied to manage stressful conditions in birds.
色氨酸（Trp）通过刺激血清素能活性，与多种行为和生理过程的调节相关。色氨酸在代谢水平上的利用受到其与大中性氨基酸（LNAA）共享的竞争性载体系统的影响。本研究以肉用型鸡为模型，研究色氨酸/大中性氨基酸（Trp/LNAA）对恐惧反应（强直静止；TI）和激素反应的剂量反应效应，包括皮质酮（CORT）、血清素（5-HT）、三碘甲状腺原氨酸（T3）和甲状腺素（T4）。在29至42日龄时，将总共12个笼子（48只鸡）分配到六个实验组中的每一组。实验日粮的配方使色氨酸/大中性氨基酸（Trp/LNAA）水平逐步增加（0.025、0.030、0.035、0.040、0.045和0.050）。结果显示，色氨酸/大中性氨基酸（Trp/NAA）对鸡的生长性能和强直静止没有显著影响。然而，色氨酸/大中性氨基酸（Trp/LNAA）的升高与皮质酮（CORT）的线性降低（P < 0.0001，r = 0.819）以及血清素（5-HT）（P < 0.0001，r = 0.945）、三碘甲状腺原氨酸（T3）（P = 0.0003，r = 0.403）和甲状腺素（T4）（P < 0.0001，r = 0.937）水平的线性增加同时出现。总之，本研究结果表明，尽管色氨酸/大中性氨基酸（Trp/LNAA）水平的增加不影响鸡的生长性能或恐惧程度，但它以线性剂量依赖的方式增加了血清素（5-HT）、三碘甲状腺原氨酸（T3）和甲状腺素（T4）水平，并降低了皮质酮（CORT）水平。色氨酸饲喂水平的调控可用于管理鸡的应激状况。
