Gestational heat stress and phytogenic supplementation influence sow growth, bioenergetics, thermoregulation, and subsequent offspring resilience

Abstract

Abstract The study objectives were to determine whether a phytogenic supplement reduced physiological stress in heat-stressed (HS) gestating sows and to evaluate how HS alters maternal growth responses and postweaning growth and stress responses in their piglets. Twenty-six pregnant Large White × Landrace sows (parity = 2.0 ± 1.2) were exposed to thermoneutral (TN; 20.72 ± 0.97 °C) or cyclical HS (26 to 36 °C) from gestation d 5 to 58, then maintained at TN until farrowing. Sows received ad libitum water (C) or ad libitum water with a phytogenic supplement (P; 0.2 mL/L) from gestation d 5 to 58 yielding treatments: TNC (n = 5), TNP (n = 6), HSC (n = 9), HSP (n = 6). During gestation, respiration rates (RR) and ear (Tear), shoulder (Tshoulder) rump (Trump), and tail (Ttail) temperatures were measured daily (0800, 1200, 1600, 2000 h). Vaginal temperatures were measured in 10-min intervals. Sow body weight (BW) was measured weekly to calculate average daily gain (ADG). All sows consumed the full daily feed allotment (2.72 kg/d) and feed efficiency (G:F) was calculated using ADG: 2.72 kg/d. Sow backfat was assessed on gestation d 4 and 58. Piglets were weaned and transported on d 19.6 ± 1.2 of age then allotted into nursery pens (n = 4 pigs/pen; n = 9 TNC, 7 TNP, 10 HSC, and 10 HSP pens). Blood samples were obtained (n = 2 pigs/pen) pre- and post-transport, and on d 1, 3, 7, 14, 21, and 28 post-weaning for cortisol analyses. Piglet BW and feed intake were assessed weekly. Sow, litter, pen, or piglet were the experimental units. Sow RR was reduced (P < 0.01; 16.1%) in HSP versus HSC sows, and sow Tear, Tshoulder, Trump, and Ttail were reduced (P < 0.01; -0.53, -0.42, -0.56, and -0.30 °C, respectively) in HSP versus HSC sows. Sow BW, ADG, G:F, and backfat were greater (P < 0.01; 3.41, 26.8, 28.6, and 292.9%, respectively) in HS versus TN sows. More piglets were weaned (P < 0.01; 27.0%) in HSP versus HSC, TNC, and TNP litters. Cortisol was reduced (P = 0.03; 6.65%) in HSP versus HSC litters but similar in TNC and TNP litters. Nursery ADG was greater (P = 0.05) for in utero (IU) TNC versus IUHSC (+60 g/d), IUHSP (+100 g/d), and IUTNP (+90 g/d) piglets, and IUHSC piglet ADG was greater than IUTNP (+30 g/d) and IUHSP (+40 g/d) piglets. In conclusion, HS increased sow growth rate, while P reduced sow RR and skin temperature but had limited effects on stress biomarkers in sows or IUHS offspring, with only marginal improvement in piglet cortisol and no growth benefit.

The authors' abstract, as published at the source. Journal of Animal Science, 2026 · DOI ↗