Gastric parakeratosis-ulcer complex of pre-slaughter fasting pigs: Correlation between histological pattern, proliferative activity and apoptosis

In pigs, the effects of different pre-slaughter feed deprivation periods on the prevalence and severity of lesions of the gastric pars oesophagea (PO), were evaluated. 1131 pigs (160 kilos I. w., same fattening ration) were held, in the lai-rage, without food prior to slaughter as follows: 4 hours (149), 18hrs (189) and 27-42 hours (793). Of 1131 stomachs, examined on slaughter line, 16 % had no lesions of the PO (N), 32% and 21% had slight (PI) or heavy (P2) parakeratosis respectively, 20% parakeratosis + erosions (P3), 6.5 % active ulcers and 3.3% chronic ulcers. The more severe PO lesions (P3, U) were more prevalent (P3= 27%; V = 7%) in pigs slaughtered after a prolonged feed deprivation time (27-42 hrs) and resulted less frequent (P3= 9%; U= 3%) after shorter deprivation time (18h.), while normal stomachs (N) were 79% and only parakeratosis (20%) was detected after 4 hours' feed deprivation. Ki67 immunohistochemical staining and AgNOR proteins silver staining, were used to assess cell proliferation in normal and parakeratotic (parakeratotic hyperkeratosis) epithelia of the PO. Apoptotic activity was also assessed with the TUNEL assay. Longer feed deprivation pre-slaughter time proved to be associated with higher incidence of PO lesions, (P1, P2, P3) and excess acidity injury is presumably one of the principal mechanisms inducing a rapid PO parakeratotic hyperplasia. Early lesions of the PO were characterized by a significant increase in epithelial proliferative activity while no modification was revealed in the apoptotic activity between normal and parakeratotic epithelia.