Nutrition has a direct influence on the fertility of ruminants due to the supply of specific nutrients essential for gametogenesis, ovulation, and fertilization, among other events. Providing nutrients according to the animal’s needs may seem straightforward; however, nutrition may affect the proteomic composition of the seminal plasma (SP). Therefore, this study aimed to analyze the protein composition of seminal plasma from 12 Santa Inês rams fed with detoxified Ricinus communis meal. Rams were divided into three groups, according to feeding stategy: FS (soybean meal), FMDP (sieved detoxified castor bean meal), and FMD (non-sieved detoxified castor bean meal). Semen samples were collected using electroejaculation at three-day intervals, after 77 days of feeding. SP proteins were precipitated with cold acetone, quantified, and after reduction, alkylation, and trypsin digestion, the resulting peptides were desalted and analyzed by mass spectrometry (Orbitrap Q Exactive™ Plus). Protein identification was performed using PatternLab (Comet/UniProt), and bioinformatic analyses included gene ontology, KEGG pathways, and protein–protein interaction networks. LC-MS/MS analysis identified, on average, 409, 240 and 200 proteins in the seminal plasma of FS, FMDP and FMD groups, respectively. Binder of Sperm Proteins (BSPs) were the most abundant protein in all sampless, based on enrichment score and spectral count. In the groups fed with desolventized castor bean meal, the main proteins identified in seminal plasma were BSP1, Clusterin, Mucin-2, EGF, Fetuin-B, Inactive Ribonuclease, Spermadesin Z13 and Member 1D of the secretoglobin family. In the group fed with unsieved bran (FMD), BSP5 ​​and angiotensin-converting enzyme (ACE) were also detected, which were absent in the group that received sieved bran (FMDP). The set of all proteins identified across the three groups was analyzed using miRNet software, which revealed five key genes: ECM1, PYY, LPO, MSMB, and EDIL3. These genes were associated with 79 microRNAs (miRNAs) identified by the platform. Moreover, using the network explorer module of miRNet, the recovered miRNAs were found to regulate genes involved in toxicity (12 miRNAs), apoptosis (16 miRNAs), cell division (7 miRNAs), neurotoxicity (6 miRNAs), cardiotoxicity (5 miRNAs), among others. The biological processes commonly shared across all three groups (FS, FMDP, and FMD) included cellular mechanisms, metabolic processes, biological regulation, localization, and response to stimuli. Notably, all biological processes were identified in the three groups except for those related to cell growth and signaling, which were absent in the FMDP group. The main cellular components shared by the three groups were cell anatomical structures and protein complexes, with the FS group showing the highest number of associated genes. The molecular functions were related to ATP-dependent activity, catalytic activity, and binding capacity. Based on the proteomic analysis, a similar protein profile was observed among the groups, with BSPs being predominant. However, the presence of proteins associated with toxicity in the FMDP group highlights the need to evaluate potential impacts on fertility.