BREEDING PROBLEMS.

New Zealand Herald, Volume LXVI, Issue 20255, 15 May 1929, Page 20

BREEDING PROBLEMS.

o—•' DANGERS OF CROSSING. PITFALLS FOR INEXPERIENCED. SUGGESTIONS TO BEGINNERS. UY 11.8. T. New Zealand farm slock, particularly sheep, may be said to bo emerging from an era of crossing. With flocks originally founded on the Merino, it was inevitable that rams of the long wool and mutton breeds should b.e introduced to these when the export of frozen meat began to assume importance. Crossing, however, was not confined to ihe production of fho half-bred Merino longwool. It was, unfortunately, employed between almost all breeds, nor was any particular method of crossing employed in the majority of cases. ' Ignoring the lessons regarding crossing that breeders had learned even 100 years ago in Great Ilritain, farmers tried putting a " dash " of this or that breed into their flocks, with resultant chaos. Why cross-breeding became the vogue to such an extent in this Dominion was largely becauso the progeny of a first cross is almost always superior to either of the parents. Uniformity, or type, however, is at once lost, and subsequent rnatings back and forth with sires of the two original breeds merely serve to increase the confusion of types, while ultimately the superiority noticeable in the first cross is also lost. One of the worst forms of crossing was encouraged by the " fashion " for big sheep. Pastoralists brought the biggest rams of the biggest breeds procurable to put with their small-framed ewes with the object of increasing the size and wool of the progeny. This was done, very often without the least consideration whatever being given to the class of land on which the crossbreds were to graze. Efforts Foredoomed to Failure. The attempt to produce more profitable sheep by this method were foredoomed to failure, and as many farmers on light country are still busy learning this bitter lesson, it may be well to discuss some of the reasons why success cannot be achieved by this. seemingly quick and easy route. In the first place, it may be generally accepted that stock which has been reared for a number of years in any particular locality has becomo acclimatised and fitted in size of frame and constitution to survive, if not to thrive, under prevailing conditions. Disaster usually follows an attempt to increase the size and production of such a flock without first increasing the quantity or quality of their food, by which the size and production of any animal is largely regulated. Nor is this so only because the progeny has a bigger frame which demands more nourishment. To mate a very big male with a small female, even within one breed, is a bad practice, for the small female has neither the available nourishment nor the capacity to properly nourish and develop in good proportion the large foetus. The result of the mating of an abnormally big malp and a small female is almost always an ungainly animal, big in the bone and frame, but lacking even development, and is generally a •" bad doer." : The reason for this is that even before birth and until growth is completed, the skeleton or bony structure makes first claim on all nourishment, the proportional development of flesh and sinew_ being far loss, while a reserve of fat is entirely absent. • Feed Improvement and Selection. When a ram of a different and bigger breed is introduced to a flock of small ewes on hard country, the result is even more disastrous, for the offspring inherits the features of the sire which fitted him for survival on rich, abundant pastures, and these become marked weaknesses in the new environment. The only satisfactory method of increasing the size of the animals is to first improve the pasture on which they graze. Then it is safe to select larger sires of the same breed, reared in similar conditions, and to improve the size and quality of the flock with these. Where increased size is the object of crossing, the cross breed must be _ fed considerably better—especially while it is growing—than the acclimatised parent. Hence, if good stock can be secured by improvement through selection within the native breed, this is always the most satisfactory method. It is more difficult than is generally imagined to get rid of the imperfections in a crossbred. They recur with remarkable persistency for many generations after the original cross has been discarded. The only method of getting back to a satisfactory fixed type is to breed consistently to rams having the desired characteristics and of an established breed. Crossing a Specialist's Job. It. may bo contended that most of the recognised pure breeds of stock are the result of a crossing of various breeds, followed by fixing the desirable characteristics in the, crossbred by selection. This is true only to a very limited extent. Certainly, most, present-day breeds of sheep and cattle bear traces of having had an introduction of alien blood. This probably occurred during that time—about 100 to 150 years ago—when crossing was popular in England. It has been asserted by many _ authorities that the undesirable characteristics introduced into various breeds at that time have far out-balanced any gains received from crossing. Cross-breeding is chiefly of value when rams of a small-framed, early-maturing breed arc mated with bigger-framed and coarser ewes with the object of producing rally-maturing lambs, all of which will go to the butcher. Again, cross-breeding is of value to the stud breeder who thoroughly under? stands his business, and by close breeding can fix the desirable features of both breeds in an entirely new breed. This needs much knowledge and patience, and is quite beyond the average farmer who is handling a large flock of breeding ewes.