Shea-Moore M M, Thomas O P, Mench J A
University of Maryland, Department of Poultry Science, College Park 20742, USA.
Poult Sci. 1996 Mar;75(3):370-4. doi: 10.3382/ps.0750370.
In previous studies with feed-restricted broiler breeders, it was found that supplementation with dietary Trp decreases aggressive activity more in socially dominant males than in socially subordinate males. Although it is probable that this effect is mediated centrally by serotonin, an alternative possibility is that it is associated with other metabolic products of Trp such as niacin. The objectives of this study were to determine whether 1) supplemental dietary niacinamide decreases aggression in broiler breeder males, 2) elevated blood niacin levels are associated with a decrease in aggression, and 3) social status influences any of these effects on behavior. Using a randomized complete block design, a control (0.19% Trp, 22 mg niacin/kg), Trp (1.5% Trp, 22 mg niacin/kg), or niacinamide (0.19% Trp, supplemented with 140 mg niacinamide/kg) diet was assigned to each pen. There were 16 birds per pen and three pens per treatment. Birds were maintained on skip-a-day feed restriction throughout, and behavioral observations were conducted until the social hierarchy in each pen was determined. Treatment diets were then fed from 15 through 18 wk of age, and the number of aggressive pecks and threats per pen recorded in three 20-min observation periods/wk. Blood samples were collected from dominant and subordinate birds and assayed for niacin using Tetrahymena pyriformis. Supplementing the diet with Trp significantly (P < 0.05) decreased aggression. Niacinamide-treated birds did not differ from either Trp-treated or control-treated birds, and no decreases in aggression were seen in birds with elevated blood niacin levels. Blood levels of niacin were, however, higher in dominant niacin-treated birds than in dominant control birds (P < 0.05), although there were no differences among subordinate or Trp-treated birds. Thus, the modulatory effect of Trp on aggression does not appear to be mediated by increased niacin synthesis.
在以往针对限饲肉种鸡的研究中，发现日粮添加色氨酸对社会等级较高的雄性肉种鸡攻击行为的减少作用，比对社会等级较低的雄性肉种鸡更为明显。虽然这种效应很可能是由血清素在中枢介导的，但另一种可能性是它与色氨酸的其他代谢产物如烟酸有关。本研究的目的是确定：1）日粮添加烟酰胺是否会降低肉种鸡雄性的攻击性；2）血液中烟酸水平升高是否与攻击性降低有关；3）社会地位是否会影响这些对行为的效应。采用随机完全区组设计，为每个鸡栏分配对照（0.19%色氨酸，22毫克烟酸/千克）、色氨酸（1.5%色氨酸，22毫克烟酸/千克）或烟酰胺（0.19%色氨酸，添加140毫克烟酰胺/千克）日粮。每个鸡栏有16只鸡，每个处理有三个鸡栏。鸡只始终采用隔日限饲，进行行为观察直至确定每个鸡栏内的社会等级。然后从15至18周龄开始饲喂处理日粮，每周在三个20分钟的观察期内记录每个鸡栏的攻击啄击次数和威胁次数。从等级高和等级低的鸡只采集血样，使用梨形四膜虫测定烟酸含量。日粮添加色氨酸显著（P<0.05）降低了攻击性。烟酰胺处理的鸡只与色氨酸处理或对照处理的鸡只没有差异，血液烟酸水平升高的鸡只攻击性没有降低。然而，等级高的烟酰胺处理鸡只的血液烟酸水平高于等级高的对照鸡只（P<0.05），尽管等级低的鸡只或色氨酸处理的鸡只之间没有差异。因此，色氨酸对攻击性的调节作用似乎不是由烟酸合成增加介导的。
