PERIOD OF GESTATION IN EWES

New Zealand Mail, Issue 1636, 8 July 1903, Page 61

PERIOD OF GESTATION IN EWES

SOME- INTERESTING AMERICAN EXPERIMENTS. This interesting' matter in connection with sheepbreeding has formed the subject for a long series of exeperiments at riio Wisconsin Experiment Station, TT.S.A., where the college flock 524- head of several pure breeds and their crosses. The conclusions given are based upon a long series of years—some twelve to fourteen and are consequently of considerable value, for the period of time during which observations have been taken is of sufficient length to* give plenty of opportunities for any abnormal event of any year to be counterbalanced by those of another, and thus the results may be fairly considered to be what under ordinary circumstances will prevail. At this station all rams are kept separate from the ewes, which are brought to them for service, so that a correct record for each individual ewe was readily kept. A table is given in the report, from which it is seen that the 52-1 ewes dropped their lambs during a period which ranged from. 140 to 156 days after coupling. The largest number of e-wesr—ll3, or 21.6 per cent.— dropped their lambs on the 146th day. The next largest fall occurred on the 147th day. when 81, or 15.5 per cent, lambed. Seventy-three ewes, or 13.9 per cent., lambed on the 145th day, fifty ewes, or 9.5 per cent., on the 142nd, 143rd, and 144th day; seventy-six, or 14.5 peT cent., lambed on the 148th day; sixty-one, o-r 11.7 per cent., lambed on the 149th dav; thirty-one, or 5.9 per cent., lambed on the 150th day; and thirty-six ewes, or 6.8 per cent., lambed between the 15tr:t and 154th day, leaving three to be accounted for. One of these lambed on the 140th day, and one on the 155th (lay. and the other on the 156t1i day the lambs in each of these cases being tifiad. From these results it may, therefore, be safely assumed that 83.1 per cent, of the ewes may be expected, on the a\ erage of years, to drop their lambs durin 0 lbo period covered by the 145th to the 150th day from the date of coupling. If therefore, the flockiu aster took means to ascertain the actual state of the coupling, what a very large amount ot trouble and bother could be prevented. In many flocks the period of lambing runs well over the month, and all through that period, or nearly so, the ewes are marched to the lambing fold at night and back again next day. With this reliable i" formation at command —for the conclusions are based oil actual experience it is now quite possible for the

birth of the lambs to be ganged within a reasonable certainty, and . Provision made accordingly. Another interesting point brought to light m this experiment is that, taking a series of the proportion of males and females is practicaly identical. During the twelve S in Which accurate records have been kept the percentage of males was 49 94 and females 50.0 b. . ~ „ Dividing the lambs born into three groups, small weighing less than 81b. at birth, medium weighing from 81bs to lOlbs inclusive, and large weighing above 101 b, it was found that 60 per cent, of the small lambs were carried 146 days or less, and the balance over that period. Of the medium lambs, 34 per cent, were carried 146 days or i eS9 ’ , ail !rP er cent, were dropped after the 146th day. Of the large lambs, only 31.6 were born within 146 days, 68.4 per cent, being carried in excess of this period. Phis information would then, appear to indicate that the earlier born lambs are smaller, and the heavier lambs are carried a longer period.