11Forage nutritive value impacts animal nutrition, which underpins livestock productivity, reproduction 12 and health. Genetic improvement for nutritive traits has been limited, as they are typically expensive 13 and time-consuming to measure through conventional methods. Genomic selection is appropriate for 14 such complex and expensive traits, enabling cost-effective prediction of breeding values using genome-15 wide markers. The aims of the present study were to assess the potential of genomic selection for a 16 range of nutritive traits in a multi-population training set, and to quantify contributions of genotypic, Genomic selection for nutritive traits 2 39 Genomic selection for nutritive traits 4 program. From each population, 102 to 117 plants that tested positive for endophyte infection (Epichloё 126 festucae var lolli) by immunoblotting (HAHN et al. 2003), were polycrossed in isolation during spring 127 2012 in Palmerston North, New Zealand (FAVILLE et al. 2018). Polycrosses were performed separately 128 for each population, without admixing, and seeds from the maternal parents were harvested and 129 cleaned. In total 543 half-sib families were harvested for seed, however only 517 families had sufficient 130 seed (≥ 3.6g) for sowing field trials. 131 A total of six trials were sown (FAVILLE et al. 2018), of which two were used for the current study. 132 These were trials established at Lincoln (Canterbury region, southern New Zealand, 43.38°S 172.62°E; 133 Wakanui silt loam) and Aorangi (Manawatu region, central New Zealand, 40.34°S 175.46°E; Kairanga 134 sandy loam), during the autumn of 2013. The experimental design at each site was row-column with 135 three replicates. Within each replicate, populations were blocked, and families randomized within 136 blocks. Multiple repeated checks (clonal replicates) were also randomly allocated within and across 137 the replicated blocks. Half-sib families were evaluated as a 1m row of plants (referred to from now as 138 plots), by sowing 0.2 g of seed (which is equivalent to 14 kg ha -1 , if a sward was sown at 7 rows m -1 ). 139 Nitrogen and phosphate fertilizer was applied at the rate of 15-30 kg N ha -1 and 8.8 kg P ha -1 , in late 140 autumn each year (FAVILLE et al. 2018). 141 2.2 Phenotypic measurements 142