Association of heat shock protein 70 gene polymorphisms with acute thermal tolerance, growth, and egg production traits of native chickens in Taiwan

Hsiao-Mei Liang,Tsung-Ping Huang,Kuo-Hsiang Hung,Hsi-Hsun Wu,Hsiu-Luan Chang,Cheng-Yung Lin,Der-Yuh Lin,Yan-Der Hsuuw

doi:10.5194/aab-59-173-2016

Abstract

Abstract. Heat stress is among the most challenging environmental conditions affecting commercial poultry. It severely affects growth and egg production, particularly in tropical and subtropical regions. This study aimed to examine physiological responses – including triiodothyronine (T3) levels, enzymatic activity of creatine kinase (CK) and lactate dehydrogenase (LDH), respiratory rates, and cloacal temperature – to acute heat stress associated with different genotypes of the HSP70 gene and to evaluate the association of these polymorphisms with growth and egg production. Genotyping was performed by single-strand conformation polymorphism analysis. The polymorphisms identified were A258A, A258G, and G258G. Twenty 12-week old birds were randomly selected from each genotype and exposed to 40 °C ambient temperature for 1 h. Blood samples were collected at 0 and 1 h following heat stress. Respiratory rate and cloacal temperature were measured following 0, 30, and 60 min of exposure. After 1 h, the A258A genotype exhibited lower levels of CK activity and plasma T3. Neither respiratory rate nor cloacal temperature displayed a significant association with the genotypes. Body weight gain differed among the genotypes for males (F = 3.268, P = 0.041) and females (F = 14.029, P < 0.001), and the A258A genotype exhibited the greatest weight gain at 0–16 weeks of age for both genders. There were no significant differences among genotypes regarding egg weight at first egg or the number of eggs laid until 40 weeks of age. The A258A genotype displayed higher heat tolerance with no negative effects on growth performance and egg production.

Highlights

As the global climate changes, chicken production is occurring under increasing ambient temperatures
The results showed that the PCR products exhibited polymorphisms and indicated the presence of two alleles, which were denoted HSP70–A and HSP70–B
Two genotypes (AA and BB) were cloned and sequenced, and one single-base mutation was found at the 258th bp of the HSP70 gene from the start site; the mutation was an A → G non-synonymous nucleotide substitution

Summary

Introduction

As the global climate changes, chicken production is occurring under increasing ambient temperatures. High temperatures have a negative impact on productivity and produce stressful conditions for chickens, resulting in reduced performance, anorexia, heat stress, and mortality. Previous reports indicated that heat stress influenced muscle metabolism (Aksit et al, 2006; Lu et al, 2007; Gregory, 2010; Laudadio et al, 2012) and that acute heat stress caused skeletal muscle cell injury (Tang et al, 2013). Exposure to high ambient temperatures significantly increased the plasma CK level in broilers after different periods of heat stress (Tang et al, 2013). Increased plasma CK levels are indicative of skeletal muscle damage and are a consequence of the disruption of the function and permeability of the muscle cell membrane (Brancaccio et al, 2007)

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Discussion

Conclusion