Colostral transfer of tumor necrosis factor-α to neonates is not associated with their health status

Abstract

Timely and adequate colostrum intake is vital for the equine neonate. In addition to immunoglobulins, colostrum contains bioactive substances. Tumor necrosis factor-α (TNF) has been suggested to help prevent neonatal infections (Secor et al., Vet Rec 2012;170:51). Transfer of TNF to neonates via colostrum was assessed in healthy mares (n=101) foaling in a veterinary clinic. Concentration of TNF (ELISA Equine TNF-α duo-set; R & D Systems) and IgG was determined in colostrum and neonatal blood immediately after delivery and 18h thereafter. Neonatal health was assessed via a modified sepsis score. Foals were assigned to two groups: failure of passive transfer (FPT; n=32) or control (C; n=66) based on serum IgG concentration below or above 0.8 g/l at 18 h of age. Three foals were excluded. Statistical analysis between groups was done by chi2 test or t-test (IBM SPSS statistics 27.0). Values are given as mean±SD. A p-value <0.05 was considered significant. Groups did not differ with regard to parity of dams (ns), gestation length (FPT 343±10, C 340±8 days, ns) and foal sex (ns). Premature lactation (milk running from >12h before parturition) which may reflect bacterial placentitis was noted in 9/32 and 5/66 dams of groups FPT and C, respectively (p<0.01), but no mare received treatment.All foals were born mature. Concentration of serum IgG in neonates differed between groups (FPT 4.9±1.8, C 13.4±4.5 g/l; p<0.001). No foals had detectable TNF in serum at birth (lower detection limit of assay: 2.1 pg/ml). In colostrum, TNF was detectable in 81% and 83% of dams in groups FPT and C, respectively (ns). In 34% and 54% of their foals, TNF was present at 18h (ns). Concentrations of TNF in colostrum at birth and in foals at 18h varied considerably but did not differ between groups (colostrum FPT 5968±9022, C 9980±31493 pg/ml, ns; foal FPT 2214±5851, C 2412±5327 pg/ml, ns). The sepsis score categorized 27 and 64 foals of groups FPT and C at 18h as normal, while 5 and 2 were slightly compromised respectively. From the 32 FPT and 66 C foals, 18 and 4 were treated with equine plasma (1l intravenously). None of the foals developed clinical signs of sepsis within the following days. The results demonstrate that TNF is transferred from the mare to the neonate via colostrum. The TNF blood concentration of a foal was not associated with its health status. An involvement of macrophage-secreted TNF in the morphogenesis of the mammary gland (Gouon-Evans et al., Breast Cancer Res 2002, 4:155-164) has to be considered in horses.