Effect of Simultaneous Dietary Supplementation of Betaine, Selenomethionine, and Vitamins E and C under Summer Conditions in Growing-Finishing Pigs

Simple Summary Due to climate change, heat waves occur more often, and the annual average temperature increases, which may contribute to the negative effects of heat stress in pigs. This study explored ways to help growing-finishing pigs cope with heat stress during hot weather. Two groups of pigs were given different diets-one standard and one enriched with specific feed additives. The pigs' respiration rates, rectal and skin temperatures, performances, and meat qualities were monitored. During a heat wave, the group with the enriched diet did not need as much drinking water compared to the standard diet group. Both groups, without distinguishing between dietary treatments, showed increased respiration rates and skin temperatures during higher heat loads. The findings suggest that the enriched diet may help reduce the need to increase daily water intake during hot periods. Furthermore, this study highlighted the sensitivity of the parameter of respiration rate in pigs suffering from (mild) heat stress.Abstract Heat stress in pigs negatively affects welfare, health, and performance. Osmoprotectants and antioxidants may alleviate oxidative damage during hot periods. We investigated whether an additive-enriched feed can reduce negative effects in pigs during summer conditions. Sixty growing-finishing pigs were allocated into two groups: the control (CF) and summer feed (SF) group. The CF group contained 0.4 mg/kg inorganic selenium and 100 ppm vitamin E, while the SF group contained 0.3 mg/kg inorganic selenium, 0.1 mg/kg selenomethionine, 200 ppm vitamins E and C, and 0.2% betaine. Feed was offered ad libitum. Respiration rate, rectal and skin temperature, behaviour, and weight gain were assessed weekly. Daily measurements of these parameters were performed during a 3-day heat wave (temperature humidity index (THI) >= 75) and during an artificial heating period. Individual average daily water intake (ADWI) and feed intake were measured using RFID systems. The ADWI of the SF group did not change during heat load while it increased for the CF group. Independent of dietary treatment, increases in increment THI or the THI were accompanied by significant increases in both respiration rate and skin temperature. In conclusion, the SF may induce a reduced need to increase ADWI during hot periods. In addition, mainly skin temperatures and especially respiration rates revealed the sensitivity of pigs to heat stress.