Star-Labs, the laboratory and manufacturer of PrimaLac, has been at the forefront of research in animal agriculture for decades. Star-Labs also leads the field with additional cooperative research addressing EPA concerns. Browse and download our industry recommended research below, or for more details on PrimaLac’s effect on specific species, browse, select and request our proprietary trial data.


“Effects of direct-fed microbial supplementation on digestibility and fermentation end-products in horses fed low-and high-starch concentrates”
Fifteen mature Thoroughbred geldings were assigned to trial diets to assess how Direct-Fed Microbials might increase digestibility and reduce acidosis from a higher starch equine diet. The paper relates a higher starch diet to enhanced nutrient digestibility but suggests DFM supplements should be studied in a different diet to assess impact.


“Direct fed microbial supplementation repartitions host energy to the immune system”
Chicks are assigned to two dietary groups to investigate the effects of a Direct-Fed Microbial diet on energy metabolism in different broiler tissues. The data show an increased antibody production and energy re-partitioning to the immune system in DFM fed animals, independent of whole body metabolism and without any loss in growth performance.
“Effects of Different Levels of Direct Fed Microbial (Primalac) on Growth Performance and Humoral Immune Response in Broiler Chickens”
Body weight gains and feed conversion ratio in broiler chickens dosed with probiotic dietary treatments is shown to be significantly higher than control treatments without it. Direct-Fed Microbial supplementation is also shown to enhance humoral immune response.
“Mucin Dynamics and Microbial Populations in Chicken Small Intestine Are Changed by Dietary Probiotic and Antibiotic Growth Promoter Supplementation”
This study looked closely at the effect of changing intestinal microbial populations on mucin dynamics—the dynamics of the intestinal mucous layer that acts as a barrier from pathogenic bacteria. Chicks fed a dietary probiotic showed changes in microbial populations which in turn altered mucin dynamics and gut health.
“Metabolic and Physiological Impact of Probiotics or Direct-Fed-Microbials on Poultry: A Brief Review of Current Knowledge”
This paper presents a review of current research suggesting the likelihood of beneficial changes in disease prevention and growth enhancement from animal exposure to probiotics. There is a discussion of intestinal micriobiota, Direct-Fed Microbial effects on gut health and performance, and immune system response by competitive exclusion processes.
“The effect of a direct-fed microbial (Primalac) on turkey live performance”
Two trials comparing turkey performance—a pen trial and field trial—showed body weight significantly increased for turkeys fed a Direct-Fed Microbial diet. Field trials showed improved live performance associated with the DFM diet, in body weight, cost of production, and livability.
“Effect of a direct-fed microbial (Primalac) on structure and ultrastructure of small intestine in turkey poults”
Researchers studied the effect of a Direct-Fed Microbial PrimaLac diet on the small intestinal structures of turkey poults. They observed changes in the structures supporting the conclusion that gut health and animal performance, even when challenged by Salmonella, are improved by DFM supplementation diets.
“Effects of a Direct-Fed Microbial (Primalac) on Turkey Poult Performance and Susceptibility to Oral Salmonella Challenge”
Poultry scientists organized a study to determine the effect of dietary Direct-Fed Microbial on turkey poults. Results showed DFM diets improving body weight and feed to gain ratios, reduced Salmonella susceptibility, and no effect from feed processing the DFM.
“Enhanced Mucosal Immunity Against Eimeria acervulina in Broilers Fed a Lactobacillus-Based Probiotic”
Investigators fed one group of broiler chicks a standard diet and another a diet with Lactobacillus-based PrimaLac and studied their immune response when challenged by infection with Eimeria acervulina. Intestinal cells were studied and describe increased resistance to E. acervulina in the probiotic-fed group.
“The Effects of Direct-fed Microbial, Primalac®, or Salinomycin Supplementation on Intestinal Lactate Isomers and Cecal Volatile Fatty Acid Concentrations in Broilers”
This study examines the role that DFM plays in controlling enteric pathogens by looking at the concentrations of lactic acid and volatile fatty acids in the cecum and intestines of poultry. The effects of a Direct-Fed Microbial PrimaLac diet are compared with a control and salinomycin antibiotic diet, to show acid concentrations generally reduced with DFM feeding.
“Microarchitecture and Spatial Relationship Between Bacteria and Ileal, Cecal, and Colonic Epithelium in Chicks Fed a Direct-Fed Microbial, PrimaLac, and Salinomycin”
In two trials, researchers studied the intestinal effects of providing PrimaLac Direct-Fed Microbial in a standard diet for broiler chicks, compared with the standard diet control and the diet with added salinomycin antibiotic. Gastrointestinal characteristics—pertaining to microvilli, intervilli spaces, and muscle thickness—in the DFM treated chicks, demonstrate an altered physiology that works to prevent the attachment of pathogens to the track lining.
”Direct-Fed Microbial PrimaLac and Salinomycin Modulate Whole-Body and Intestinal Oxygen Consumption and Intestinal Mucosal Cytokine Production in the Broiler Chick”
Poultry scientists studied 3 groups of broiler chicks assigned to different diets—a control, a diet with added salinomycin antibiotic, and a diet with added PrimaLac—in order to measure energy expenditures and inflammation. Results demonstrate highly reduced energy expenditure in the PrimaLac group compared to others, correlating with changes to intestinal physiology and metabolism.
“Performance of Broiler Chickens Fed Diets Supplemented with a Direct-Fed Microbial”
Two experiments study the effects of adding Direct-Fed Microbial (DFM) to the diets of broiler chicks over several growth phases. The DFM addition has positive effects on apparent nutrient retention even when nutrient density is reduced.