Postnatal colostrum management and its impact on IgG blood levels of neonatal foals

There is ongoing need to investigate the quality, quantity, and timing of colostrum intake in neonatal foals as their ability to ward off infectious diseases largely relies on colostral maternal antibodies. The aim of the study was to evaluate whether postnatal colostrum management has an impact on plasma gamma globulin levels, on the incidence of failure of passive transfer of immunity (FPTI) and on the risk of disease. For this purpose, first of all the usefulness of plasma total globulin (TG) for the detection of FPTI was determined. The study was designed as a prospective cohort study with three groups and included 182 foals, which were randomly assigned to one of the three groups. The foals were assisted in standing and finding the udder if necessary. All foals were free to ingest colostrum by nursing from the udder. Foals in group 1 (n = 58) were not given any colostrum by bottle. Foals in group 2 (n = 66) received two times 150 ml of the mare's colostrum one and two hours postnatal by bottle-feeding. Foals in group 3 (n = 58) were two times bottle-fed 150 ml of pooled colostrum one and two hours postnatal. Pooled colostrum had been obtained from mares of the same stud and foaling season ahead of the study. Foal blood samples were taken 12 and 24 hours postnatal. Gamma globulin levels were determined using capillary zone electrophoresis and plasma total globulin was calculated by using an in-house dry chemistry analyzer. The different postnatal care practices did not result in significantly different average gamma globulin concentrations neither 12 hours postnatal (group 1: 1219 +/- 472 mg/dl; group 2: 1191 +/- 437 mg/dl; group 3: 1360 +/- 446 mg/dl) nor 24 hours postnatal (group 1: 1109 +/- 423 mg/dl; group 2: 1059 +/- 406 mg/dl; group 3: 1230 +/- 389 mg/ dl). Feeding colostrum via bottle to group 2 and group 3 foals resulted in a delayed suckling from the udder (time between birth and first unassisted colostrum intake: group 1: 1.6 +/- 0.8 hours; group 2: 2.6 +/- 0.7 hours; group 3: 2.6 +/- 0.7 hours). Neither the incidence of FPTI (IgG concentration < 800 mg/dl; group 1: 25.9 %, group 2: 21.2 %, group 3: 13.8 %) nor the morbidity (group 1: 19.0 %; group 2: 24.2 %; group 3: 19.0 %) did differ significantly between the three groups. 38 of 182 foals developed an infectious disease, but foals with FPTI were not more likely to become sick than foals with adequate IgG levels (p < 0.57). Results of the current study suggest that there is no general need in feeding additional colostrum to healthy neonatal foals to ensure a sufficient IgG level in plasma. No correlation was observed between FPTI and the development of infectious diseases. IgG concentrations determined by electrophoresis were highly correlated with plasma globulin levels.