نوع مقاله : مقاله پژوهشی
عنوان مقاله English
نویسندگان English
Introduction: The pre-weaning period represents one of the most critical phases in the life of dairy calves because the gastrointestinal tract and immune system are not fully developed. For many years, antibiotic growth promoters have been incorporated into calf-feeding programs to improve health and productivity. However, increasing concerns regarding antimicrobial resistance and the global restrictions on the use of antibiotics in animal production have encouraged the development of natural alternatives. Among these, probiotics and phytogenic feed additives have received considerable attention because of their potential to improve gut health, nutrient utilization, antioxidant status, and immune function. Echinacea purpurea (E. purpurea) is a medicinal plant rich in bioactive compounds, including alkamides, caffeic acid derivatives, polysaccharides, and phenolic compounds, which exhibit immunomodulatory, antioxidant, and anti-inflammatory activities. Likewise, probiotics such as Protexin® may enhance intestinal microbial balance and nutrient digestibility, thereby promoting animal health. Nevertheless, comparative information regarding the efficacy of E. purpurea extract and probiotics relative to antibiotic supplementation in dairy calves remains limited. Therefore, this study was conducted to compare the effects of colistin sulfate (positive control), E. purpurea extract, and Protexin® on growth performance, feed intake, blood metabolites, hematological indices, and immune parameters of Holstein dairy calves.
Materials and Methods: Twenty-four one-day-old Holstein female calves (36 ± 4 kg body weight) were randomly assigned to one of three experimental treatments in a completely randomized design with eight calves per treatment. The dietary treatments consisted of colistin (2 g/calf/day), E. purpurea extract (1,050 mg/calf/day), and Protexin® probiotic (1 g/calf/day). The additives were administered individually to each calf through milk until weaning and thereafter in drinking water at the predetermined daily dose and a specified volume. Calves were managed under identical housing and feeding conditions throughout the experiment. Body weight was recorded on days 60 and 90, while starter feed intake was measured during the pre-weaning, post-weaning, and overall experimental periods. At the end of the trial, blood samples were collected for determination of biochemical metabolites (glucose, cholesterol, blood urea nitrogen, triglycerides, albumin, alanine aminotransferase, and aspartate aminotransferase), hematological indices (hematocrit, red and white blood cell counts, mean corpuscular volume, platelet count, lymphocyte, neutrophil, and monocyte percentages), and immune parameters, including interleukin-10 (IL-10), immunoglobulin G (IgG), and tumor necrosis factor-α (TNF-α). Data were analyzed using the General Linear Model procedure, and treatment means were compared using Duncan's multiple comparison test at P < 0.05.
Results and Discussion: Growth performance and starter feed intake were not significantly affected by dietary treatments throughout the experimental period, indicating that replacement of colistin with either E. purpurea extract or Protexin did not compromise calf growth or feed consumption. Among blood biochemical variables, only glucose concentration was significantly influenced by treatments (P = 0.02). Calves receiving Protexin exhibited higher blood glucose concentrations than those receiving colistin, whereas the E. purpurea group showed intermediate values. The increased glucose concentration in the probiotic group may reflect improved nutrient utilization and energy metabolism resulting from beneficial modulation of gastrointestinal microbiota. In contrast, serum cholesterol, blood urea nitrogen, triglycerides, albumin, alanine aminotransferase, and aspartate aminotransferase remained unchanged, indicating that neither probiotic nor E. purpurea supplementation adversely affected liver function or general metabolic status. Similarly, hematological parameters, including hematocrit, erythrocyte and leukocyte counts, platelet count, and leukocyte differential, were not influenced by dietary treatments, suggesting that both feed additives were physiologically safe under the experimental conditions.
In contrast, significant improvements were observed in immune responses following E. purpurea supplementation. Calves receiving E. purpurea extract exhibited significantly higher concentrations of IL-10, IgG, and TNF-α than calves receiving either Protexin or colistin (P < 0.05). Elevated IgG concentration indicates enhancement of humoral immunity, whereas increased IL-10 suggests improved regulation of inflammatory responses. Although TNF-α is generally recognized as a pro-inflammatory cytokine, its concurrent increase with IL-10 may reflect activation of innate immune responses accompanied by appropriate anti-inflammatory regulation rather than excessive inflammation. These findings support the immunomodulatory properties of E. purpurea, which have been attributed to the biological activities of alkamides, caffeic acid derivatives, and polysaccharides that stimulate macrophages, antigen-presenting cells, and lymphocyte function. In contrast, Protexin did not significantly alter immune variables compared with the positive control, indicating that under the present experimental conditions its primary effect was associated with energy metabolism rather than immune modulation. Overall, the results demonstrate that E. purpurea primarily enhanced immune function, whereas Protexin improved blood glucose concentration without affecting growth performance or health-related hematological variables.
Conclusion: The present study demonstrated that supplementation with Protexin and E. purpurea extract, compared with colistin, did not adversely affect growth performance, feed intake, blood metabolites, or hematological indices in Holstein dairy calves. Protexin supplementation increased blood glucose concentration compared with the colistin treatment, which may indicate alterations in energy metabolism or nutrient utilization; however, the other measured blood metabolites and hematological indices were not significantly affected by the experimental treatments. In contrast, supplementation with E. purpurea extract increased the concentrations of IL-10, IgG, and TNF-α compared with Protexin and colistin, suggesting a potential modulatory effect of the extract on selected immune responses in dairy calves. Given the limitations of the present study, further research is warranted to investigate the effects of these feed additives on gut health, gastrointestinal microbiota composition, vaccination responses, and long-term animal performance
کلیدواژهها English
