The potential of novel Festulolium (2n=4x=28) hybrids as productive, nutrient-use-efficient fodder for ruminants

The field performance and potential future use of F1 Lolium multiflorum and Lolium perenne × Festuca arundinacea var. glaucescens and Festuca mairei hybrids (2n = 4x = 28) are described. Foliar trait expression in the hybrids was largely determined by the Lolium rather than their Festuca parent ensuring maintenance of high-forage quality. All four Festulolium populations comprised high-yielding genotypes, but the L. multiflorum populations were particularly erect and tall, while the L. perenne populations had significantly higher numbers of tillers and were prostrate. Forage yields of the Festulolium populations assessed in field plot trials were either not significantly different from, or were superior to leading L. multiflorum and L. perenne cultivars used as controls. Endogenous plant proteases contribute to excessive proteolysis in the rumen which causes environmental N pollution. Protein degradation due to plant-mediated proteolysis was assessed by in vitro exposure of leaves to the environmental conditions of the rumen (39°C, anaerobic) and calculated based on the time taken for protein levels to be reduced to half their original levels (t½). Leaf proteins were significantly more stable in L. multiflorum × F. arundinacea var. glaucescens and L. perenne × F. arundinacea var. glaucescens F1 hybrids (t½ 18–21 h) than in their respective Lolium parental genotypes (t½ 4–5 h), and there was a highly significant genome interaction. The t½ in the majority of the L. multiflorum × F. arundinacea var. glaucescens F1 hybrids studied often exceeded 24 h, whereas t½ of their Lolium and Festuca parents was consistently <14 h. Although inferior to the F1, F. arundinacea var. glaucescens genotypes tested had significantly greater t½ than L. perenne under rumen-simulated conditions. Significant variation in protein stability was apparent within the F1 and their respective parent species' groups. The initial protein content of the F1 hybrids was lower than their respective parents, but following 24-h exposure to anoxia at 39°C, the protein content of both parent and hybrid genotypes was similar. The differences in protein stability between parental and hybrid genotypes was due to the greater rate of protein decline observed in the Lolium genotypes. Hence, uptake of these Festulolium hybrids as forage crops has potential to directly mitigate environmental impact of livestock farming without affecting production capacity.