Effects of Plantago lanceolata on rumen microbiota, blood parameters, and mineral status in lambs

This study evaluated the effects of Plantago lanceolata (PLA) herbage on rumen microbial composition (16S rRNA amplicon sequencing), blood biochemical parameters, and mineral status in lambs, in comparison with ryegrass ( Lolium multiflorum ; IRY) and sainfoin ( Onobrychis viciifolia; SAI). Twenty-four male Akkaraman lambs were randomly assigned to three dietary treatments ( n = 8) and fed total mixed rations (TMR's) containing about 70% forage and 30% concentrate, with forage sources consisting of PLA, IRY, or SAI. Dietary treatments significantly affected rumen microbial composition. Lambs fed PLA showed higher relative abundance of Methanobacteriota , Lachnospirales , Lachnospiraceae , and Lachnospiraceae_NK3A20_group compared to other groups ( P < 0.05). Similarly, Saccharimonadia and Saccharimonadales were more abundant in the PLA group than in IRY, with SAI showing intermediate values ( P < 0.05). These changes indicate a shift toward fibrolytic microbial populations in the PLA diet, whereas IRY and SAI supported greater abundance of Bacteroidota -related taxa, associated with non-fiber carbohydrate fermentation. Blood biochemical parameters were also influenced by forage source. GGT activity was higher in lambs fed PLA ( P < 0.05), while total protein concentrations were higher in the Italian ryegrass group ( P < 0.05). In a lamb diet containing a high proportion of forage, PLA increased serum Fe concentrations, whereas IRY increased P levels and reduced LDL concentrations compared to the other treatments. As a result, P. lanceolata altered rumen microbial structure toward fibrolytic populations and modified mineral metabolism in lambs, indicating its potential as an alternative forage source with distinct physiological and microbial effects.