0
The purpose of this investigation was to establish the role biological sex plays in circulating factors following heat stress.
Methods: Barrows and gilts (36.8 ± 3.7 kg body weight) were kept in either thermoneutral (20.8 ± 1.6 °C; 62.0% ± 4.7% relative humidity; n = 8/sex) conditions or exposed to heat stress (39.4 ± 0.6 °C; 33.7% ± 6.3% relative humidity) for either 1 (HS1; n = 8/sex) or 7 (HS7; n = 8/sex) d.
Results: Circulating glucose decreased as a main effect of the environment. Circulating non-esterified fatty acid had an environment × sex interaction as HS1 barrows had increased non-esterified fatty acid compared to HS1 gilts and non-esterified fatty acid from HS7 gilts increased compared to HS1 gilts and HS7 barrows. Cortisol, insulin, glucagon, T3, and T4 were reduced as a main effect of environment. Creatinine was increased in HS1 and HS7 animals compared to thermoneutral, indicative of decreased glomerular filtration rate. White blood cell populations exhibited differential patterns based on sex and time. Neutrophils and lymphocytes had an environment × sex interaction as circulating neutrophils were increased in HS1 barrows compared to thermoneutral and HS7 barrows, and HS1 gilts and HS7 barrows had less neutrophils compared to thermoneutral barrows, whereas they remained similar in gilts. In contrast, barrow lymphocyte numbers were similar between groups, but in HS7 gilts they were decreased compared to thermoneutral and HS1 gilts.
Conclusion: In total, these data demonstrate that heat stress alters a host of circulating factors and that biological sex mediates, at least in part, the physiological response to heat stress.
Rudolph TE, Roths M, Freestone AD, White-Springer SH, Rhoads RP, Baumgard LH, Selsby JT. Heat stress alters hematological parameters in barrows and gilts. Journal of Animal Science. 2024; 102: skae123. https://doi.org/10.1093/jas/skae123