Effects of heat stress and high dietary antioxidant supplementation on the ileal digestibility of nutrients and certain minerals in pigs

Abstract

Heat stress (HS) can impair the pigs' intestinal integrity, jeopardizing nutrient and mineral digestibility. Our study aimed to investigate HSs' impact on the ileal digestibility of nutrients and minerals in pigs and whether high dietary antioxidants (vitamins C and E, and micro-minerals Se and Zn) supplementation can improve their digestibility. A total of 24 Danbred barrows weighing 65.1 ± 2.81kg were distributed into four different groups, which were placed in thermo-neutral (TN) (19.5 ± 0.9°C, RH- 85.9±7.3%) and HS (28.9 ± 0.9°C, RH- 60.4 ± 4.3%) condition and fed with their respective dietary treatment. Pigs in the TN room only received the basal feed (B) (TC), and in the HS room, B (HC), elevated 1 (elevated dietary antioxidants) (HT1), and elevated 2 (dietary antioxidants doubled) (HT2) diets were given in ad libitum. Pigs were euthanized at the end of the trial for the collection of digesta from the ileum. Nutrient (crude protein (CP), fat, fiber, ash, organic matter, and nitrogen free extract (NFE)) and mineral (Ca, P, Zn, Se, and Na) content were measured from diets and digesta. Aside from crude ash (P < 0.05), HS did not significantly affect the ileal digestibility of other nutrients and minerals in pigs (P > 0.05). However, pigs fed the elevated 1 diet (HT1) had significantly greater digestibility (P < 0.05) of CP, crude ash, Zn, Se, and Na than HC. Further increase in vitamin and micro-mineral supplementation (HT2) did not improve the pigs' ileal digestibility of the measured nutrients and minerals. In conclusion, pigs can be resilient to HS adverse effects on the parameters studied. Antioxidant-fortified diet at elevated 1 level could improve pigs' nutrient and mineral digestibility under the HS challenge.