I have to import this txt file into R but I don't know what to add to my mice

Mouse Day12 Day6 Day18 0.388 1.132 0.393 0.852 0.823 2 0.729 3 0.700 Day9 Day21 0.621 1.191 0.568 1.004 0.549 0.925 0.645 1.069 0.520 0.751 0.502 0.751 0.498 0.910 4 0.850 5 0.530 Day3 Day 15 0.109 1.078 0.218 0.839 0.394 0.783 0.209 1.001 0.193 0.641 0.201 0.641 0.202 0.795 0.190 0.819 0.219 0.709 0.255 0.796 0.224 0.869 0.187 6 0.530 7 0.650 8 0.666 9 0.699 10 0.690 11 0.756 12 0.525 0.870 0.419 1.026 0.362 0.640 0.361 0.640 0.370 0.858 0.350 0.879 0.399 0.822 0.400 0.825 0.381 0.929 0.329 0.621 0.471 1.001 0.929 0.578 0.953 0.545 0.836 0.577 0.999 0.441 0.796 0.606 1.105 0.10/ 13 OLIO 0.770 0.278 0.888 Mouse Day12 Day6 Day18 0.388 1.132 0.393 0.852 0.823 2 0.729 3 0.700 Day9 Day21 0.621 1.191 0.568 1.004 0.549 0.925 0.645 1.069 0.520 0.751 0.502 0.751 0.498 0.910 4 0.850 5 0.530 Day3 Day 15 0.109 1.078 0.218 0.839 0.394 0.783 0.209 1.001 0.193 0.641 0.201 0.641 0.202 0.795 0.190 0.819 0.219 0.709 0.255 0.796 0.224 0.869 0.187 6 0.530 7 0.650 8 0.666 9 0.699 10 0.690 11 0.756 12 0.525 0.870 0.419 1.026 0.362 0.640 0.361 0.640 0.370 0.858 0.350 0.879 0.399 0.822 0.400 0.825 0.381 0.929 0.329 0.621 0.471 1.001 0.929 0.578 0.953 0.545 0.836 0.577 0.999 0.441 0.796 0.606 1.105 0.10/ 13 OLIO 0.770 0.278 0.888