Forage Grass Mineral CompositionInvestigation of variation in Lolium perenne, multiflorum and boucheanum as a means of managing hypomagnesaemic tetany in UK livestock

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Student thesis: Master's ThesisMaster of Philosophy

Original languageEnglish
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Award date2021
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Mineral composition of forage underpins livestock health. Grass genotypes which accumulate certain minerals have been demonstrated to alleviate symptoms of nutrient deficiency in livestock (Kumssa et al., 2019a; Moseley and Baker, 1991). In this project, mineral composition was evaluated (experiment 19MG) on putatively high and low magnesium (Mg) accumulating varieties of Lolium perenne, multiflorum and boucheamum created during the MAG-NET project which preceded this. Positive relationships were found between Mg and Calcium (Ca), and Phosphorus (P) and Potassium (K), although variation in mineral concentrations were not significantly different between varieties. More data will need to be collected from this trial to draw conclusions on variety potential. The mineral status of L. perenne was surveyed from generations of the IBERS diploid late and intermediate heading populations (2 and 3 generations, respectively). Mg ranged from 0.06-0.14% DM (dry matter) across breeding lines with higher concentrations in the intermediate heading population than the late. Ca ranged from 0.34-0.61% DM, K 1.06-2.61% DM and P 0.26-0.37% DM. Ca and K concentrations had a greater effect on Forage Tetany Index (FTI) than Mg in these data, though a positive correlation between Ca and Mg was found. Increasing Ca concentration could also be key in reducing FTI. Overall, this project established the baseline for minerals in a range of IBERS grass breeding germplasm and suggests there is suitable variation existing in the core populations for genetic improvement. Results showed that all minerals should be considered in selections to decrease FTI, not just Mg, and suggest that trial management will be critical to the efficacy of selections (soil pH for example). After following investigations in 19MG, hybrid ryegrass varieties (such as bAB1157) present a viable option for exploitation of Mg accumulating L. multiflorum genetics to decrease the likelihood of causing hypomagnesaemic tetany