Phenotypic, endocrinological, and metabolic effects of zearalenone exposure and additive effect of heat stress in prepubertal female pigs

Independently, both heat stress (HS) and zearalenone (ZEN) compromise female reproduction, thus the hy-pothesis that ZEN would affect phenotypic, endocrine, and metabolic parameters in pigs with a synergistic and/ or additive impact of HS was investigated. Prepubertal gilts (n = 6-7) were assigned to: thermoneutral (TN) vehicle control (TC; n = 6); TN ZEN (40 mu g/kg; TZ; n = 6); pair-fed (PF; n = 6) vehicle control (PC; n = 6); PF ZEN (40 mu g/kg; PZ; n = 6); HS vehicle control (HC; n = 7); and HS ZEN (40 mu g/kg; HZ; n = 7) and experienced either constant 21.0 +/- 0.10 degrees C (TN and PF) or 35.0 +/- 0.2 degrees C (12 h) and 32.2 +/- 0.1 degrees C (12 h) to induce HS for 7 d. Elevated rectal temperature (P < 0.01) and respiration rate (P < 0.01) confirmed induction of HS. Rectal tem-perature was decreased (P = 0.03) by ZEN. Heat stress decreased (P < 0.01) feed intake, body weight, and average daily gain, with absence of a ZEN effect (P > 0.22). White blood cells, hematocrit, and lymphocytes decreased (P < 0.04) with HS. Prolactin increased (P < 0.01) in PC and PZ and increased in HZ females (P < 0.01). 17 beta-estradiol reduced (P < 0.01) in HC and increased in TZ females (P = 0.03). Serum metabolites were altered by both HS and ZEN. Neither HS nor ZEN impacted ovary weight, uterus weight, teat size or vulva area in TN and PF treatments, although ZEN increased vulva area (P = 0.02) in HS females. Thus, ZEN and HS, inde-pendently and additively, altered blood composition, impacted the serum endocrine and metabolic profile and increased vulva size in prepubertal females, potentially contributing to infertility.