Heat Stress In Hens Research Articles

Molecular detected of heat shock protein70 gene in Layer hens (Lohmann breed)

The polymorphisms of the hsp70 gene have been associated with diverse resistance of heat stress in hens. The aim of the current study was to explore the genetic variation of the hsp70 gene in Layer hens that bred in Iraq. One hundred-fifty Lohmann breed hens aged 12 months were used in this study. Blood samples were collected during the period from 1st September to 31st December 2018 and examined for detection the polymorphism of hsp70 gene. We have detected four main polymorphisms groups in the coding region of hsp70 gene among these layer hens. A significant association between the silent and the missense mutations with the polymorphisms of hsp70 gene in Layer hens was found. There was a high homology of the hsp70 gene sequences that obtained from our local layer hens with the related sequences obtained from different hottest and coldest areas. In conclusion, this study demonstrates that the different mutations (silent and missense) in the coding region of the hsp70 gene of these local Layer hens predict improve birds’ability to the tolerance of stress conditions, and highlights the need of further investigations.

The Effect of Cooled Perches on Immunological Parameters of Caged White Leghorn Hens during the Hot Summer Months.

The objective of this study was to determine if thermally cooled perches improve hen immunity during hot summer. White Leghorn pullets at 16 week of age were randomly assigned to 18 cages of 3 banks at 9 hens per cage. Each bank was assigned to 1 of the 3 treatments up to 32 week of age: 1) thermally cooled perches, 2) perches with ambient air, and 3) cages without perches. Hens were exposed to natural ambient temperatures from June through September 2013 in Indiana with a 4 h acute heat episode at 27.6 week of age. The packed cell volume, heterophil to lymphocyte (H/L) ratio, plasma concentrations of total IgG, and cytokines of interleukin-1β and interleukin-6, plus lipopolysaccharide-induced tumor necrosis factor-α factor were measured at both 27.6 and 32 week of age. The mRNA expressions of these cytokines, toll-like receptor-4, and inducible nitric oxide synthase were also examined in the spleen of 32 week-old hens. Except for H/L ratio, thermally cooled perches did not significantly improve currently measured immunological indicators. These results indicated that the ambient temperature of 2013 summer in Indiana (24°C, 17.1 to 33.1°C) was not high enough and the 4 h heat episode at 33.3°C (32 to 34.6°C) was insufficient in length to evoke severe heat stress in hens. However, cooled perch hens had a lower H/L ratio than both air perch hens and control hens at 27.6 week of age and it was still lower compared to control hens (P < 0.05, respectively) at 32 week of age. The lowered H/L ratio of cooled perch hens may suggest that they were able to cope with acute heat stress more effectively than control hens. Further studies are needed to evaluate the effectiveness of thermally cooled perches on hen health under higher ambient temperatures.