The Effect of Heat Stress and Vitamin and Micro-Mineral Supplementation on Some Mineral Digestibility and Electrolyte Balance of Pigs

SIMPLE SUMMARY: The deleterious effects of heat stress and its induced stressors on health and intestinal integrity may compromise the performance of pigs. Their physiological and behavioral mechanisms to promote thermoregulation can potentially influence electrolyte losses and compromise digestive capacity. The varied response exhibited by pigs under different durations of exposure to high ambient temperature led to our study on pigs and (1) the effect of the duration of heat stress on the digestibility of some minerals, (2) the balance of major electrolytes, and (3) the alleviation capability of vitamins and micro-minerals supplemented in combinations and at higher levels than recommended for pigs. Our results revealed that heat stress alone did not affect the digestibility of the minerals studied. However, supplementation of high levels of vitamins and micro-minerals improved the digestibility of some minerals, including calcium, selenium, and zinc, despite the exposure of the pigs to heat stress. Heat stress caused a significant reduction in the plasma chloride concentrations of pigs, which indicated an imbalance. Vitamin and micro-mineral supplementation corrected this issue. ABSTRACT: Heat stress (HS) can have detrimental effects on intestinal integrity and can jeopardize the digestibility performance in pigs. With prolonged exposure to heat, some thermoregulatory processes in pigs are potential causes for electrolyte imbalance. The adverse effects of HS on mineral digestibility and electrolyte balance are not widely studied and information on its abatement through vitamin and micro-mineral supplementation in combinations above the recommended level in pigs is limited. The aim of this study is to research this area. Thirty-six Danbred hybrid barrows (65.1 ± 2.81kg) were distributed among the four treatments (n = 9 per treatment): (1) thermo-neutral (19.5 ± 0.9 °C, RH- 85.9 ± 7.3%)+ control diet (TC) (NRC, 2012), (2) HS (28.9 ± 0.9 °C, RH- 60.4 ± 4.3%) + control diet (HC), (3) HS +diet with elevated levels of vitamins (vitamin E and C) and micro-minerals (Zn and Se) (HT1), and (4) HS + diet with further elevation of vitamins and micro-minerals (HT2). Plasma samples were collected on days 7 and 21 of the experiment to investigate electrolyte concentration. During the experimental period, feces samples were collected from pigs placed in digestibility cages (six pigs from each treatment) to investigate the digestibility of Ca, P, Na, Se, and Zn. HS did not decrease the digestibility of minerals, but elevated supplementation of the selected vitamins and trace minerals improved it significantly. HS caused a significant decrease of Cl(−) (p < 0.01) in plasma, indicating an imbalance. In conclusion, pigs can have some resilience against heat stress in terms of mineral digestibility. Proper vitamin and trace mineral supplementation are key factors in the ability of pigs to overcome the negative effects of HS.