Lactation Performance and Rumen Fermentation in Dairy Cows Fed a Diet Supplemented with Monensin or Gum Arabic-Nano Montmorillonite Compost

Abstract

The exploration of natural alternatives to antibiotics for enhancing productivity and performance in dairy cows is a crucial objective in farm animal management. This is the first study aimed at developing and evaluating the physicochemical properties and effects of Arabic gum–nano montmorillonite (AGNM) compost compared to ionophore monensin as feed additives on rumen fermentation, blood metabolites, and milk production of Holstein dairy cows. In a replicated 4 × 4 Latin square design, four multiparous mid-lactation Holstein dairy cows with an average body weight of 520 ± 15 kg were enrolled. The dietary treatments included a control diet (basal diet without feed additives), monensin diet [a basal diet supplemented with 35 mg/kg dry matter (DM) monensin], and AGNM diets comprising basal diet supplemented with two levels: low (L-AGNM) at 1.5 g/kg DM, and high (H-AGNM) at 3 g/kg DM. AGNM as a feed additive demonstrated promising physiochemical parameters, including containing highly bioactive components (α-amyrin and lupeol), functional groups (OH and Si-O), and essential mineral contents (Mg2+). Supplementations with H-AGNM significantly improved ruminal (p = 0.031) concentrations of total volatile fatty acids (VFAs), acetic (p = 0.05) and butyric (p = 0.05), enhanced (p < 0.05) digestibility of fiber and organic matter, while decreased (p = 0.013) estimated methane production. However, an increase (p = 0.04) in blood high-density lipoprotein levels and decrease (p < 0.05) in concentrations of creatinine (CREA), bilirubin (BILT), cholesterol (CHOL), and sodium (Na) were observed with H-AGNM supplementation. Both monensin and H-AGNM improved (p = 0.008) feed efficiency compared to L-AGNM; however, neither AGNM nor monensin affected the milk composition or energy status indicators of the dairy cows. The findings of this study highlight the potential of AGNM as a natural candidate to replace monensin in enhancing ruminal VFA production, nutrient digestibility, feed efficiency, blood metabolites, and milk yield in dairy cows.