The objective of this work was to investigate the expression of heat shock protein 70 (HSP70) by Western blot (WB) in swine liver. Subsequently, the study aimed to apply this method to two experimental groups of heavy pigs raised in different confinement systems: intensive/indoor (Group A) and extensive/outdoor (Group B). Thirty-six crossbred commercial heavy pigs were divided as follows: Group A (eight castrated males and eight females) was equally distributed into two single-sex indoor pens (1.02 m 2 /pig); Group B (11 castrated males and nine females) was kept in one single (partially grassy and partially wooded) open area of about 6000 m 2 . Group A was slaughtered at 41 weeks of age (170 6 9 kg) and Group B at 48 weeks of age (172 6 13 kg). At the abattoir the livers of all the animals were collected and analyzed by WB assay in order to quantify the levels of HSP70. Moreover, a further liver sample was taken from the same animals in order to investigate the cellular localization of HSP70 by immunohistochemistry (IHC). The interaction between sex and group resulted statistically significant ( P 5 0.001). When stratified by sex, Group A showed significantly higher HSP70 values compared with Group B for both male and female subjects ( P , 0.001). Stratifying by group, males showed significantly higher HSP70 values than females in Group A ( P , 0.001), whereas no statistical differences were observed between sexes for Group B ( P 5 0.653). The IHC results evidenced cytoplasmic immunoreactivity in a granular pattern in both groups. The different expression pattern observed by WB could prove to be a useful tool in the assessment of pig health and welfare.Keywords: HSP70, Western blot, liver, IHC, heavy pig
ImplicationsThe need to investigate more sensitive and reliable indicators of animal health and welfare is of primary importance, not only to research, but also with a view to possible applications in the field. Heat shock proteins (HSPs) have become increasingly important because of their correlation to some pathological and poor welfare conditions. HSP70 expression has never been investigated in pig liver, and this study proposes a quantification analysis by Western blot. Moreover, this method detected significant differences between pigs belonging to the same original group and reared in intensive/indoor v. extensive/outdoor conditions.
IntroductionSeveral factors in modern pig production, such as limited freedom of movement, the lack of stimuli, aggressive temperament, noise, low lighting levels, atmospheric ammonia, and the rapid growth rate, may be stressful for pigs (D'Eath et al., 2010;O'Connor et al., 2010;Parker et al., 2010). As part of the multidisciplinary approach of scientific research on Animal Welfare, major efforts have been made in the investigation of new, reliable and sensitive physiological parameters: acute phase proteins (Murata et al., 2004), serum antioxidants (Brambilla et al., 2002) and stress hormones (Kaneko, 2008) are well-known examples. These variables respond to stressful situa...