Effects of Selenium-Enriched High-Protein Concentrate Supplementation on Blood Metabolites and Pregnancy Rate in Beef Cows Fed a Rice Straw-Based Diet

This study evaluated the effects of supplementing a selenium-enriched high-protein concentrate, designed to improve both protein-energy nutrition and selenium supply, on feed intake, blood profiles, and reproductive performance of Brahman crossbred cows maintained on a rice straw-based diet. A total of 60 multiparous cows (389 ± 60.02 kg body weight, aged 3-4 years) were randomly allocated into two groups: control (CON), fed ad libitum rice straw plus 3 kg/head/day basal concentrate, and supplemented (SUP), fed ad libitum rice straw plus 2 kg/head/day basal concentrate and 1 kg/head/day selenium-enriched high-protein concentrate (0.30 ppm). Estrous synchronization was performed using prostaglandin F2α, followed by artificial insemination with Belgian Blue semen. Nutrient intake, blood metabolites, hematological, and reproductive hormones were measured, while pregnancy was confirmed via transrectal palpation at 90 days post-insemination. Results showed that SUP cows had significantly higher crude protein and total digestible nutrient intakes (P<0.001), accompanied by lower crude fiber intake (P<0.001). Hematological parameters improved in the SUP group, with significant increases in lymphocyte count, red blood cell concentration, haemoglobin, and hematocrit (P<0.05). Biochemically, SUP cows exhibited elevated serum selenium (P<0.05) and blood urea nitrogen levels (P<0.05). Hormonal analysis revealed markedly higher progesterone concentrations in SUP cows (P<0.01), while pregnancy rates improved substantially (46.67 vs. 10.00). In conclusion, supplementation with selenium-enriched high-protein concentrate enhanced metabolic status, hematological health, and reproductive performance in Brahman crossbred cows through the synergistic effects of improved protein-energy balance and selenium fortification. This nutritional strategy effectively addresses the limitations of rice-straw-based diets, offering a practical approach to improving fertility and productivity in tropical beef cattle systems. Copyright: 2025 by the authors. Licensee ResearchersLinks Ltd, England, UK.