Investigation of the Effect of Heat Stress on Egg Quality in Laying Hens

Abstract

The thermoregulatory capacity of poultry kept in high-temperature environments is significantly impaired; heat stress can negatively affect their productive performance and health, leading to death. This study was aimed to determine the effect of high temperature on egg quality traits and the applicability of Brix refractometry in measuring total serum protein in eggs. A total of 24 Lohman Brown laying hens (12 control/12 heat stress) aged 30 weeks were used in the study. Laying hens were housed individually in an area of 1350 cm2. The experiment began one week after the laying hens were placed in the cages and lasted a total of four weeks. The room temperature in the control group was maintained at 24±2 °C (24 hours); the room temperature in the heat stress group was kept at 35±2 °C (09:00-17:00). The results showed that egg weight (g) decreased in the heat stress group (p=0.001). Additionally, it was determined that eggshell thickness (mm) significantly decreased in the stress-applied group (p=0.002). Similarly, egg yolk height (mm) was found to be significantly lower in the heat stress group (p=0.002); in contrast, the incidence of blood and meat spots in the eggs was found to be higher (p=0.01). These findings suggest that heat stress negatively affects various internal and external egg quality parameters. Moreover while the Brix refractometer appeared to offer a practical quick approach for estimating egg serum total protein it revealed no statistically significant differences. Therefore, while its use appears promising, further studies are needed to confirm its reliability under different physiological conditions.

Keywords

• Brix refractometer
• Egg quality parameters
• Heat stress
• Laying hen
• Total protein.

Yumurtacı Tavuklarda Sıcaklık Stresinin Yumurta Kalitesi Üzerine Etkisinin Araştırılması

Abstract

Yüksek sıcaklık ortamlarında tutulan kümes hayvanlarının ısı düzenleme kapasitesi önemli ölçüde bozulur; sıcaklık stresi, üretim performanslarını ve sağlıklarını olumsuz etkileyerek ölüme yol açabilir. Bu çalışmada, yüksek sıcaklığın yumurta kalite özellikleri üzerine etkisi ve Brix refraktometrisinin yumurtalarda toplam serum proteininin ölçümünde uygulanabilirliği araştırılmıştır. Çalışmada, 30 haftalık toplam 24 Lohman Brown yumurtacı tavuk (12 kontrol/12 sıcaklık stresi) kullanılmıştır. Tavuklar, 1350 cm2'lik bir alanda bireysel barındırılmıştır. Deney, yumurtacı tavukların kafeslere yerleştirilmesinden bir hafta sonra başlamış ve toplam dört hafta sürmüştür. Kontrol grubunda oda sıcaklığı 24±2 °C (24 saat) olarak tutulurken, sıcaklık stresi grubunda oda sıcaklığı 35±2 °C (09:00-17:00) olarak tutulmuştur. Sonuçlar, sıcaklık stresi grubunda yumurta ağırlığının (g) azaldığını göstermiştir (p=0.001). Ayrıca, stres uygulanan grupta yumurta kabuğu kalınlığının (mm) anlamlı düzeyde azaldığı belirlenmiştir (p=0.002). Benzer şekilde, yumurta sarısı yüksekliği (mm) sıcaklık stresi grubunda anlamlı olarak daha düşük bulunmuş (p=0.002), buna karşın yumurtalarda kan ve et lekesi görülme sıklığının ise daha yüksek olduğu tespit edilmiştir (p=0.01). Bu bulgular, sıcaklık stresinin çeşitli yumurta iç ve dış kalite parametrelerini olumsuz etkilediğini göstermektedir. Ek olarak, Brix refraktometresinin serum toplam protein düzeylerinin hızlı değerlendirilmesi için potansiyel bir araç olabileceği belirlenmiştir. Bu sonuçlar, hem sıcaklık stresinin yumurta kalite özellikleri üzerindeki etkisi hem de toplam protein ölçümü için alternatif yöntemlerin geliştirilmesi açısından literatüre katkıda bulunmaktadır.

Keywords

• Brix refraktometresi
• Sıcaklık stresi
• Total protein
• Yumurtacı tavuk
• Yumurta kalite parametreleri.

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