Grass Meal Acts as a Probiotic in Chicken

Probiotics can act as an alternative to antibiotics in animal feeding, but their use is minimal due to their expensive production. Dry grass is rich with bacteria beneficial for animal feeding and can be used as a probiotic. However, data about the quantitative dependence of the grass microbiome on environmental factors and seasons remain insufficient for preparing “grass-meal-based probiotics”. Four grass samples were collected in two geographically remote regions of Russia; their microbiome was characterized by metagenomic sequencing of 16S rDNA libraries and microbiological seeding, and biological testing of the grass meal was carried out on 6 groups of birds containing 20 Ross 308 cross broilers each for a period of 42 days. The positive control group (PC) obtained 16–25 mg/mL toltrazuril (coccidiostatic agent) and 0.5 mL/L liquid antibiotic enrostin (100 mg/mL ciprofloxacin and 106 MU/mL colistin sulfate in the commercial preparation) within the drinking water, while the negative control group (NC) obtained no medicines. Four experimental groups were fed the diet supplemented with 1% grass meal over the period of 7–42 days of life; no commercial medicines were used here. A spontaneous infection with Eimeria was registered in the NC control groups, which caused the loss of 7 chickens. No losses were registered in the PC group or the two experimental groups. In two other experimental groups, losses of coccidiosis amounted to 10% and 15%, respectively. All specimens of the grass meal demonstrated a significant effect on the average body weight gain compared to NC. Taken together, these observations support the hypothesis that the grass meal may substitute toltrazuril for protecting the chickens from parasitic invasion and increase average daily weight gain (ADG) as effectively as the antibiotic enrostin.