Dietary betaine for fattening Californian rabbits: in vivo and in silico insights into growth, blood physiology, and nutrient utilization

Noura H Gouda, Hassan M El-Kelawy, Mustafa Abd-El-Rahim, et al.. Trop Anim Health Prod. 2025 Jul 21;57(7):312.

To find safe alternatives to antibiotics in rabbit feeds, this study examined the effects of dietary supplementation betaine (trimethylglycine) on fattening Californian rabbits. Seventy-two male Californian rabbits, weaned at 5 weeks of age, were randomly allocated to three dietary treatment groups (n = 24 per group) using a completely randomized design. The experimental diets included a basal diet supplemented with betaine (BET) at 0, 1, or 1.5 g/kg (BET0, BET1, and BET1.5, respectively). The effects of these BET levels were assessed on growth performance, blood hematology, metabolic profile, carcass traits, nutrient digestibility, and feeding values as well as molecular docking analysis. The results showed that dietary BET significantly improved live body weight (LBW) and weight gain at 13 weeks (P < 0.01), while feed intake was reduced (P < 0.05). A significant improvement in the feed conversion ratio (FCR) was also observed, as indicated by lower FCR values (P < 0.05). BET supplementation did not alter carcass traits significantly (P > 0.05). Dietary BET supplementation significantly improved red blood cells (RBCs) count (P < 0.01), hemoglobin (Hg) concentration (P < 0.01), platelet count (P < 0.05), and hematocrit (Ht) levels (P < 0.01) in a dose-dependent manner. Conversely, the white blood cells (WBCs) count was significantly reduced (P < 0.01) in response to BET addition. Rabbits fed a diet supplemented with BET exhibited higher albumin levels and lower aspartate aminotransferase (AST) values (P < 0.01) compared to those fed a BET-free diet. Dietary BET supplementation significantly improved the digestibility coefficients of organic matter (OM), crude protein (CP), crude fiber (CF), and nitrogen-free extract (NFE) (P < 0.05), as well as the feeding values of digestible crude protein (DCP), total digestible nutrients (TDN), and metabolizable energy (ME) (P < 0.05). Molecular docking analysis shed light on BET’s mechanism, revealing its strong binding affinity to proteins involved in antioxidant and apoptosis/inflammatory signaling pathways in growing rabbits. The calculated binding energies confirmed this interaction, showing affinities of -3.58 kcal/mol for cyclooxygenase-2, -3.33 kcal/mol for SOD, -3.23 kcal/mol for BAX, and − 2.89 kcal/mol for caspase-3. In summary, supplementing fattening rabbit diets with BET positively impacted growth attributes, feeding values, nutrient digestibility, and blood metabolic pathways. These benefits are attributed to BET’s antioxidant and anti-apoptotic/anti-inflammatory activities. Our findings suggest that BET has significant potential as a safe and effective alternative to antibiotic growth promoters in rabbit farming, fostering a more sustainable and environmentally conscious industry.

https://doi.org/10.1007/s11250-025-04554-w