CONTROLLING THE SEX.

Otago Witness, Issue 2803, 4 December 1907, Page 6

CONTROLLING THE SEX.

One of those physiological problems which suggest themselves when purebred stock are much in evidence, as they are at show time, ifi the possibility of controlling the. sex of the progeny. Numerous experiments have been conducted with a view to discovering what controls the sex of the offspring, and much attention has from time to time been given to the point by scientists and practical breeders. An American, rancher claims to have discovered that the sex of the possible progeny changes regularly every time the female is in season. And in order to, put this theory to the test an English writer ("Spero ) is reported in the Live Stock Journal to have selected 19 pedigree shorthorn cows for trial. In describing the result, he says:— "The cows were served at the usual time after calving, the intervening period being carefully noted. As cows vary very much in the time elapsing between calving and their first heat, it follows that some were served at their first heat, and others at their third or fourth. Again, some of them 'turned' two or three times, but that, of course, made no difference to the value of the experiment, except perhaps to add emphasis to the working of the lay, by increasing the enormous odds against^ coincidence. In only one case out of 19 did the theory fail to justify itself. Thoee cows which had produced a bull calf and were in calf again at the finst, third, or fifth period had cow calves, and those which produced females and bred again at the odd numbers in the heats had bull calves. Those which bred at the second, fourth, and sixth* periods produced calves of the same sex as before. Some years after the above trial I changed the breed of the herd, and bred Jerseys, and then, of course, heifer calves became preferable. As far as possible in a large herd this rule by which keifcrs should be produced was adhered to, but absolute certainty in selecting the odd or even, number of the heats is not always possible, and it is only fair to say that occasional disappointments were met with. Tliis happened rarely, however, and never when there was no room for doubt. ... It came to my knowledge that a gentleman who was struck with my account of it applied the theory to his. poultry. Selecting a prolific hen, he placed her eggs in two baskets as they were laid. They -were then hatched out, with the result that one lot were all cockerels, and the other all pullets." "Shepherd Boy," in his valuable work on "Modern Sheep," quotes an experiment which was tried in France some time ago with a .view of gaining light on this subject. At a meeting of the Agricultural Society of Severac a breeder suggested that young rams should be put to the ewes from which the greater number of ewe lambs were desired, and the flock put on the richest and mosfe abundant pasture, while to obtain a majority of ram lambs strong old rams should be used, and the ewes put on rather inferior pasture. Two members tried the experiment, with the following result : — From the flock for ewe lambs served by two rams 15 months and two years oldSex of lambs. Age of ewea. Male. Female. Two years .. .. t? -.. 14 26 Three years tt 16 29 Four years 5 21 Five years and over .... 18 8 53 84 \From the flock for ram lambs, served by two rams four and) five years old — Sex of lambs. Age of ewes. Male. Female. Two years ..• tsi ..- ..7 3 Three years .v 15 1* Four years 33 14 Five years and over .. .. 23