Comparative effects of low energy diets on blood parameters and liver HSP70 and iNOS gene expressions among Tanzanian local chicken ecotypes

Abstract

A study comparing effects of low energy diets on liver HSP70 and iNOS gene expressions and blood indices of three Tanzanian chicken ecotypes was conducted. Four weeks old hens belonging to Kuchi (KU), Ching’wekwe (CH) and Morogoro medium (MM) ecotypes were allocated to 9 pens in a 3 x 3 factorial design, with three replicates. They were fed 3 diets containing 40, 55 and 0% less energy than prescribed. Only KU 55% restriction groups had marked up-regulations (p<0.05) of HSP70 after 3 weeks. After 7 weeks, expression levels of HSP70 for KU and CH 55% restriction groups increased, while those for MM restriction groups remained unaltered. The iNOS levels were notably up-regulated for KU and CH 55% restriction groups after 3 and 7 weeks, respectively. Significant elevations (p<0.05) of serum corticosterone were only noted for KU restriction groups after 1 and 3 weeks. Serum uric acid was significantly increased (p<0.05) in all ecotypes and groups but triglycerides were markedly reduced as determined after 1, 3 and 7 weeks. There were no significant differences between controls and restricted groups in Hb and Hct levels except for CH ecotype, which showed lower (p<0.05) Hb and Hct levels after 5 and 7 weeks for both restricted groups. Results of this study show that low energy diets induced stress in chickens, and ecotype-specific tolerance was manifested through changes in liver HSP70, iNOS and blood parameters, with MM showing better tolerance at lowest energy levels and KU being least tolerant.

Keywords: Corticosterone, Dietary energy, Ecotypes, Haemoglobin, Restriction, Stress, Tolerance, Haematocrit