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Simple Summary: Oleanolic acid is an organic natural compound, abundant in olive leaves, with various beneficial health effects in humans and animals. However, its in vivo efficacy is questioned given its low solubility, which hinders its bioavailability, that is, the capacity of a molecule to reach circulation. We investigated the digestibility and plasma concentration of oleanolic acid as an estimate of bioavailability in growing pigs. Because it is important to know the effects of oleanolic acid in the animal, growth, organ weights, digestibility of nutrients and plasma biochemical profile have been reported as well. Although there is a concern in the scientific community regarding the low bioavailability of oleanolic acid, in vivo data are lacking. We have demonstrated that, while digestibility of oleanolic acid was unexpectedly elevated, the appearance of the molecule in systemic blood was weak, probably indicating hepatic metabolism. No negative effects of oleanolic acid on growth or internal organs were observed. Oleanolic acid (OLA) has beneficial health effects in animals, but in vivo efficacy in monogastric animals is questioned due to its low bioavailability. To gain further insight on the nutritional effects of OLA it was administered as part of a diet. We investigated digestibility and plasma OLA in pigs and the associated influence on growth, organs, digestibility of nutrients and plasma biochemical profile. Twenty-four crossbred barrows (23.7 ± 1.0 kg BW) were assigned one of three treatments: Control (basal diet without OLA), OLA-1 (basal diet with 260 mg/free OLA) and OLA-2 (basal diet with 260 mg/kg cyclodextrin-OLA). Diets included chromium oxide to estimate digestibility. Blood samples were collected on day 14 for OLA analysis and feces on days 22–24 for determining digestibility. Pigs were slaughtered on day 31 (39.9 ± 2.43 kg BW) and their blood collected for analysis. Growth and organ weights were not affected (p > 0.05). OLA-1 decreased apparent total tract digestibility (ATTD) of energy (p < 0.05). OLA-2 increased ATTD of dry and organic matter compared with Control pigs (p < 0.05). OLA-1 increased plasma calcium and alkaline phosphatase (p < 0.05). Ileal digestibility of OLA was not affected (0.88), although OLA ATTD increased in OLA-1 compared to Control pigs (0.75 vs. 0.82; p < 0.05). OLA-1 and OLA-2 increased plasma OLA compared to Control pigs (p < 0.05 and p = 0.083). In conclusion, although the OLA was digested and absorbed, plasma concentration was low (4.29 µg/L), and pig growth, organs and plasma parameters were not affected. [ABSTRACT FROM AUTHOR]

Simple Summary: As pigs are sensitive to heat, high temperature produces large economic losses in pig production. The Iberian pig (Sus mediterraneus) is a rustic breed that thrives in the Mediterranean forest in the southwest of the Iberian Peninsula, with hot summers, with a peak in July (32–36 °C) being more frequent due to the appearance of heatwaves in the Mediterranean area. It is well known that betaine and zinc are growth promoters in pigs under thermoneutral conditions. Betaine acts as an osmolyte, decreasing basal heat production, and zinc is very important as an enzymatic cofactor and structural element for proteins, and improves intestinal functionality. Whether betaine and zinc may mitigate heat stress in pigs remains unclear. Our aim was to study the effect of heat, and the dietary supplementation of betaine or zinc on the heat production of Iberian pigs. At 30 °C, betaine or zinc supplementation had no effect on heat production; in addition, these parameters were not affected by temperature, indicating that Iberian pigs are well adapted to hot environments. However, the ratio of CO2 production/O2 consumption indicated that supplementation with betaine may have a positive effect on lipogenesis and, thereafter, overall growth. The effect of heat, and dietary betaine or zinc on the heat production (HP) of Iberian pigs was studied. Thirty barrows (44 kg) were individually housed for 28 days and assigned to one of five treatments: (1) thermoneutrality (20 °C) and fed a control diet (TN-CON) ad libitum; (2) hot (30 °C) and fed a control diet (HT-CON) ad libitum; (3) thermoneutrality and pair fed a control diet (TN-CON-PF) to HT-CON; (4) hot and fed a betaine-supplemented (0.5%) diet (HT-BET) ad libitum; and (5) hot and fed a zinc-supplemented (0.012%) diet (HT-ZN) ad libitum. On the 18th day, pigs were moved to a respirometry chamber (two chambers) under their respective treatment. The metabolizable energy (ME) intake, HP and respiratory quotient (RQ) were measured over 24 h. No differences (p > 0.05) were found in HP and RE between treatments. For RQ, TN-CON was greater (p < 0.01) than HT treatments, except for HT-BET. All RQs indicated an overall lipogenesis where betaine supplementation showed an intermediate value, indicating that it may have a positive effect on lipogenesis and overall growth. At 30 °C, betaine or zinc had no effect on HP and RE; ME intake was not reduced, indicating a genetic adaptation of Iberian pigs to heat. [ABSTRACT FROM AUTHOR]