102 Probiotic administration post-foaling may reduce parasite shedding in foals

Abstract

The use of probiotics in horses to affect changes in gut physiology is expanding rapidly. Typically, probiotic administration is aimed at improving gastrointestinal health through alteration of the host microbiome. However, administration of these novel bacterial strains may have wider-reaching effects. Internal parasites pose a risk to the health of horses. The principle method of parasite management is targeted anthelmintic administration, although increased parasite resistance is of concern. Data from studies in humans and production animals has indicated that certain probiotics may interfere with the physiology of parasites, reducing overall parasite load. To test the hypothesis that probiotic administration would reduce parasite load in horses, a blend of specific bacteria was administered to young horses over the course of 3 consecutive foaling seasons (2017–2020). Twenty-nine Quarter horse foals were randomly assigned to either a control (n = 14) or treatment (n = 15) group. Foals in the treatment group were administered 35 g of a paste containing 2.5 × 10 9 cfu each of B. subtilis, B. infantis , and L. acidophilus twice daily for 8 d. Paste administration began 2 d post foaling to allow for gut closure. Foals in the control group received no paste. All foals were housed in individual stalls alongside their dams. Mares were offered an average of 8 lb/d of Purina Ⓡ Ultium Ⓡ Growth and 12 lb/d Timothy hay split into 2 feedings at 0700 and 1500. Mare and foal pairs in similar treatment groups were allowed turnout into drylots following the AM feeding and brought back to stalls before PM feeding. Foals were offered 0.5 lb/d of Purina Ⓡ Ultium Ⓡ Growth starting at 28 d of age, which was increased to 1 lb/mo of age through the end of the study along with 1.5% BW as Timothy hay. At 150 d of age, a fecal grab sample was obtained from foals and analyzed for parasite load utilizing a modified Wisconsin Fecal Egg Flotation Method. Foals received no anthelmintics before this time point. Samples were analyzed for the presence and number of strongyle and roundworm eggs. Data were analyzed using the MIXED procedure in SAS 9.4 (Cary, NC). No differences existed between foaling seasons ( P = 0.54 ). Foals in the treatment group had fewer strongyle (1.07 vs 4.57/gm of feces; P = 0.02 ) and roundworm eggs (101.33 vs 216.00/gm of feces; P = 0.01 ) than those from the control group. These data indicate that the administration of the probiotic paste to otherwise identically managed groups of foals may reduce their overall parasite load. Further research is needed to understand the mechanisms by which this is occurring and to determine if these effects persist.