10 



BULLETIN 996, U. S. DEPARTMENT OF AGRICULTURE. 



There does not appear to be any connection between lamb produc- 

 tion and the fact of sires and dams having been singles or twins. 



Table 5. — Effect of breeding on twin production of Southdown ewes in Government flock. 



Ewes' breeding. 



Number 

 of ewes. 



Number 



of 

 lambings. 



Lambs 

 dropped 



Born twins: 



Sires twins, dams twins 



Sires singles, dams twins . . 

 Sires twins, dams singles. . 

 Sires singles , dams singles . 



Average for twin ewes . . . 



Born singles: 



Sires twins , dams twins . . 

 Sires singles, dams twins. . 

 Sires twins, dams singles . 

 Sires singles, dams singles . 



Average for single ewes . 



12 

 84 

 12 

 131 



Per cent 

 133 

 142.9 

 116.6 

 142. .5 



140.9 



14 

 70 

 21 

 111 



157.1 

 145.7 

 109.5 

 132.7 



136.2 



A safer way of appraising the possibility of increasing twin pro- 

 duction by selection is to take into account the full records of female 

 ancestors rather than a single birth in which the particular sire or 

 particular dam was produced. 



VALUE OF TWIN LAMBS IN COMPARISON WITH SINGLES. 



Sheep raisers differ in their ideas of the desirable size of the lamb 

 crop. At one extreme are ranchmen chiefly interested in wool pro- 

 duction who consider twins as undesirable because feed conditions 

 are unfavorable to a ewe's furnishing more than sufficient milk for 

 one lamb. Even in such cases, however, it is always likely that a 

 number of ewes will lose their lambs and a corresponding number of 

 pairs of twins would allow transferring one from each pair of twins 

 to a ewe in milk and without a lamb. This would render possible 

 the rearing of 100 per cent of lambs. 



There are, also, a few breeders of registered sheep who believe that 

 there is no gain in obtaining twin lambs. Their position is based 

 upon the fact that some twin lambs do not develop so fully as singles. 

 Since a good individual animal sold for breeding purposes may bring 

 as much as or more than two inferior ones, single lambs might be an 

 advantage, provided they always proved more valuable at selling age. 

 * At the other extreme are raisers of market lambs in whose hands a 

 pair of twins, even though comparatively underdeveloped and sold 

 perhaps at a lower price per pound, still will bring a much larger 

 amount than the single lamb. 



With ewes lambing for the first time, it is less desirable to have 

 twin lambs than with older ewes. Young ewes do not ordinarily 

 milk so well nor look after their lambs so faithfully, and thus they 



