Dietary Germinated Paddy Rice and Stocking Density Affect Egg Performance, Serum Biochemical Properties, and Proteomic and Transcriptomic Response of Laying Hens Exposed to Chronic Heat Stress.

Tossaporn Incharoen,Sittiruk Roytrakul,Wirot Likittrakulwong

doi:10.3390/proteomes9040048

Abstract

Germinated paddy rice (GPR) could be a good alternative feed source for poultry with stocking density and heat stress problems. A total of 72 Hy-line Brown laying hens raised under low (LSD, 0.12 m2/bird) and high stocking densities (HSD, 0.06 m2/bird) were investigated. Three dietary GPR levels (0, 74 and 148 g/kg) were used. It was found that average daily feed intake, hen-day egg production, and egg mass significantly decreased in the HSD group. The levels of serum glucose (GLU), phosphorous (P), corticosterone (CORT), total Ig, lysozyme (LZY), and superoxide dismutase activities (SOD) in the HSD group were higher than those in the LSD group. Dietary GPR significantly affected GLU, P, alternative complement haemolytic 50 (ACH50), total Ig, and LZY. Moreover, CORT level significantly decreased in 74 and 148 g/kg dietary GPR groups, whereas SOD significantly increased only in the 148 g/kg dietary GPR group. Serum samples were analyzed using liquid chromatography-tandem mass spectrometry, and 8607 proteins were identified. Proteome analysis revealed 19 proteins which were enriched in different stocking densities and dietary GPR levels. Quantitative real-time reverse transcription-PCR technique was successfully used to verify the differentiated abundant protein profile changes. The proteins identified in this study could serve as appropriate biomarkers.

Highlights

Heat stress (HS) is the most critical physical stressful factor for the poultry industry
No significant differences in hen-day egg production, egg mass, average daily feed intake or average egg weight were observed between both treatments
We identified the proteins and the mRNA expression levels in all treatments at different times

Summary

Introduction

Heat stress (HS) is the most critical physical stressful factor for the poultry industry. HS is caused by high ambient temperature, nutritional stress (nutritional imbalance), and high stocking density (HSD) [1]. HSD plays a major role in stimulating HS in poultry. Abudabos et al [2] showed that the body temperature of chickens is raised at HSD and was higher than that in low stocking density (LSD). Studies on the physiological responses of poultry to stocking density suggested that hens reared at HSD had lower egg performance, biochemical parameters, and immune activities [3,4,5,6]. Nutritional factors play an important role in alleviating the stress from HSD in laying hens

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