Simple SummaryDespite scientific evidence and a ban by the European Union, antibiotic growth promoters (AGPs) are still commonly used in intensive pig production systems in many countries to decrease gastrointestinal problems and improve feed efficiency and growth. Concerns over the adverse effects of antibiotics on human health have led to a search for natural alternatives. Previous studies evaluated the effects ofLactobacillus plantarum(L. plantarum) CAM6, isolated from the Colombian Creole pig Zungo and registered in Genbank, on weaned piglets and sows during gestation–lactation. However, the effect of this probiotic strain on growing pigs is unknown. The results showed that oral administration ofL. plantarumCAM 6 modified the weight of the digestive organs, the histomorphometry of the concentric layers, and the depth and width of the cecal crypts; decreased cecal lesions; and stimulated the growth of lactic acid bacteria (specifically autochthonous strains) without affecting the blood count compared to the control. These findings suggest thatLactobacillus plantarumCAM6 could be considered as an effective alternative to subtherapeutic antibiotics in growing pigs.AbstractThis study aimed to investigate the effects of oral administration withL. plantarumCAM6 on the hematological profile, relative weight of digestive organs, and cecal traits in growing pigs. A total of 36 castrated male pigs [(Landrace × Pietrain) × Duroc] aged 49 to 139 days old were randomly assigned to 3 experimental groups with 12 animals per treatment. The treatments included a control diet without additives (CTRL), a positive control with subtherapeutic antibiotics (TRT1), and CTRL supplemented with 5 mLLactobacillus plantarumCAM6 preparation providing 109CFU/pig/day (TRT2). The TRT2 group showed a higher (p≤ 0.05) small intestine length and the cecum relative weight compared to the CTRL group. Moreover,L. plantarumCAM6 supplementation promoted (p≤ 0.05) increased thickness of the muscular and mucosal layers, as well as enhanced depth and width of the cecal crypts. The TRT2 group also showed well-defined crypts without lesions, while the CTRL and TRT1 groups exhibited congestion, lymphocytic infiltration in the crypt, and intestinal-associated lymphoid tissue atrophy, respectively. Additionally, TRT2 stimulated (p≤ 0.05) the growth of the autochthonous cecal microbiota compared to other experimental groups. Overall, the results indicate that oral administration ofL. plantarumCAM6 improved intestinal health and enhanced the growth of autochthonous cecal lactic acid bacteria and had no impact on the complete blood count in growing pigs.