Influence of Housing Density and Grazing on Heat Shock Protein 27 Expression in Skeletal Muscle of Beef Cattle
Heat shock proteins (HSPs) are used as a stress biomarker in several studies as well as other stress biomarker, but the influence of different rearing environment on HSPs expression with other stress biomarker in cattle is unclear. To clear this point, two experiments were conducted to investigate the influence of rearing environment on HSP 27 in steer muscle. In experiment 1, 10 Japanese black steers were divided into 2 groups for a housing density stress experiment: a high-density (HD) group and freedom (FR) group. IgG levels and the neutrophil-to-lymphocyte (N/L) ratio in blood was analyzed as a stress marker. IgG levels and N/L ratios in the HD group were higher than those in the FR group. HSP 27 expression in the semitendinosus (ST) muscle of the HD group was higher than that of the FR group. These results suggest that HSP 27 expression may reflect the influence of the stress response with IgG levels and N/L ratios. READ
Figure 1: Experiment 1: Design and schedule for the housing density stress study in Japanese Black steers. The experimental period of the present study comprised high-density housing (HDH) and general-density housing (GDH) periods. Steers were housed in a free barn with narrow space (9.6 m2; 3.7- m width × 2.6-m length) in the HDH period and wide space (22.4 m2; 5.9-m width × 3.8-m length) with a paddock (30.6 m2) in the GDH periods. Ten steers were divided into 2 groups for a housing density stress experiment: a highdensity (HD) group and freedom (FR) group. Six steers in the HD group were switched to HDH (0 day of the HDH period; 1.6 m2/head) after the first GDH period. Four steers in the FR group were housed in a wide space during the experimental period. Samples from both groups were collected at the start of the experimental period (-12 days), at 3 and 9 days of the HDH period, and at the end of the experimental period (30 days).