Dietary tryptophan effects on growth and stress responses of male broiler chicks

Abstract

1. Three experiments were conducted to determine growth of broiler chicks fed on test diets formulated to be deficient or adequate in tryptophan (Trp) using gelatin by-product as a means of generating a Trp deficiency. Growth response estimates of broiler chicks to graduations of Trp were determined by dose-response criteria and regression analyses. Experiments were conducted using broiler chicks from 1 to 20 d of age. 2. Broiler chicks fed Trp-deficient diets had poor body weight gain, feed intake and feed conversion. Recommended total Trp needs were 2.0, 2.1 and 2.2 g/kg for feed intake, body weight gain and feed conversion, respectively. 3. Blood plasma Trp exhibited a sigmoidal trend while blood plasma glucose increased in a linear manner to supplemental Trp. Physiological stress variables measured were unaffected by dietary Trp.

Effect of heat and several additives related to stress levels on fluctuating asymmetry, heterophil:lymphocyte ratio, and tonic immobility duration in White Leghorn chicks

“…Addition of ascorbic acid, tryptophan, or brewer's yeast did not significantly change measurements for FA and tonic immobility duration because these values were similar in heat-stressed chicks with one of these additives and in heat-stressed chicks without any additives. The results agree with those reporting no significant effect of dietary tryptophan (supplemented at 2 to 6 g/kg) on tonic immobility duration of broiler chickens reared under normal temperatures (MacKenzie et al, 2004;Corzo et al, 2005). Although the heterophil:lymphocyte ratio was not measured in these 3 groups of chicks, Campo and Dávila (2002) did not find significant effects of ascorbic acid, tryptophan, or brewer's yeast supplementation on the heterophil:lymphocyte ratio of heat-stressed chickens.…”

Excess dietary tryptophan mitigates aflatoxicosis in growing quails

“…Elevated plasma levels of hepatic enzymes such as AST and ALT in the poultry species are a sign of hepatic cell damage caused by a variety of stressors or harmful agents (Bagherzadeh‐Kasmani & Mehri, ; Miazzo et al, ; Valdivia et al, ; Yarru et al, ). On the other hand, protective action of excess dietary TRP in stressful conditions has been reported in pig (Mao et al, ; Sève, Meunier‐Salaün, Monnier, Colléaux, & Henry, ), duck (Liu et al, ), broiler chicks (Corzo, Kidd, Thaxton, & Kerr, ) and laying hens (Dong, Azzam, Rao, Yu, & Zou, ). A part of beneficial effects of excess dietary TRP may originate from de novo synthesis of its metabolites such as, for example kynurenine, 5‐hydroxytryptophan and melatonin (Le Floc’h, Otten, & Merlot, ).…”

“…Miazzo et al, 2005;Valdivia et al, 2001;Yarru et al, 2009). On the other hand, protective action of excess dietary TRP in stressful conditions has been reported in pig (Mao et al, 2014;Sève, Meunier-Salaün, Monnier, Colléaux, & Henry, 1991), duck (Liu et al, 2015), broiler chicks (Corzo, Kidd, Thaxton, & Kerr, 2005) and laying hens (Dong, Azzam, Rao, Yu, & Zou, 2012). A part of beneficial effects of excess dietary TRP may originate from de novo synthesis of its metabolites such as, for example kynurenine, Floc'h, Otten, & Merlot, 2011).…”

Standardized ileal digestible tryptophan requirement for broilers

“…Furthermore, there was a significant (P=0.004) effect of the dietary SID-MET+CYS : SID-LYS ratio on estimated SID-TRP:LYS requirement ratios for BWG as shown in Figure 1. However, the relationship between dietary SID-M+C : SID-LYS ratio and estimated SID-TRP:LYS requirement ratios for minimum FCR was not significant (P=0.110) and was highly dependent on one very influential observation (observation from study of Corzo et al, 2005). Furthermore, even after removal of the observation of the study of Corzo et al (2005), the positive relationship between dietary SID-MET+CYS : SID-LYS ratio and estimated SID-TRP:LYS ratio for BWG remained positive and significant (P=0.041).…”