Age-related changes in select fecal bacteria in foals

Abstract Text:

Adult horses depend on the microbial community in the hindgut to digest fiber and produce VFAs that are utilized for energy. Microbial colonization in the gastrointestinal tract of foals is essential to develop a healthy symbiotic relationship and prevent proliferation of pathogenic bacteria. However, colonization is not well understood. The objectives were to evaluate the age-related changes and effects of maternal diet on select fecal bacterial groups in foals from 1 d to 28 d of age. Thoroughbred foals (n=19) were from dams fed one of two concentrates: an oat-based (OB) or corn and wheat middlings-based (CWB) pelleted concentrate. The mares began the experimental diet at 310 d of gestation and remained on the assigned diets until 28 d postpartum. The foals had access to assigned concentrates and a mixed grass and alfalfa hay and cool season grass pasture were available ad libitum. Fecal samples were collected from foals at 1 d (14-36 h), 4 d, 14 d, and 28 d. Foals were continuously monitored on sample days to collect fecal samples immediately after defecation by catch into sterile specimen cups or from the center of the pile using sterile gloves. Fecal samples were transported to the laboratory in an insulated cooler (37°C) under CO₂. Samples were serially diluted 10-fold before inoculation of selective media. Enumerations were performed for Lactobacillus spp., total starch utilizing bacteria (TSU), and cellulolytic bacteria (CB). Enumeration data were log transformed then analyzed with PROC MIXED (SAS 9.3) to test the main effects of maternal diet (OB or CWB), time of sample, and interaction between maternal diet and time. Results were considered significant when P < 0.05. There was no effect of maternal diet on bacterial enumerations (P > 0.05). There was an interaction between maternal diet and time in Lactobacillus spp. with CWB foals having more lactobacilli than OB at 1 d and 4 d (P < 0.05), however there were no differences observed at 14 d (P > 0.05). These results indicate that maternal diet may influence some bacteria in foals. Fecal lactobacilli, TSU, and CB increased with age in foals (P < 0.05) with CB first appearing between 4 d and 14 d. It is evident that colonization of the hindgut is a sequential process beginning early in the foal’s life.

Keywords: bacteria, maternal diet, foal