A STUDY OF CROSSBREEDING SHEEP K. P. MILLER AND D. L. DAILEY

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A STUDY OF CROSSBREEDING SHEEP K. P. MILLER AND D. L. DAILEY University ] Minnesta 1 OST crssbreeding experiments reprted have used rams f M varius breeds in matings t Rambuillet ewes.

1 A STUDY OF CROSSBREEDING SHEEP K. P. MILLER AND D. L. DAILEY University ] Minnesta 1 OST crssbreeding experiments reprted have used rams f M varius breeds in matings t Rambuillet ewes. One f the earliest f these reprts was by Miller (1935) wh fund that crssbred lambs frm Rambuillet ewes and Sufflk, Hampshire and Shrpshire rams grew faster and had a higher appraised value at 3~ t 4 mnths f age than Iambs sired by Rambuillet rams. Suthdwn- and Rmneysired lambs were lighter, but the Suthdwn Iambs had a higher appraised value than the Rambuillet sired lambs. Shrpshire and Suthdwn rams sired lambs f highly desirable carcass quality, but the Sufflk and Hampshire rams sired the fastest grwing lambs that had the highest appraised value. Hultz et al. (1935) used rams f six different breeds n range ewes. The lambs sired by Sufflk rams grew fastest, fllwed by Hampshire, Lincln, Rambuillet, Crriedale and Suthdwn sired lambs, in that rder. Lambs frm Rambuillet ewes and Clumbia rams were heavier than thse sired by Crriedale, Lincln, r Rmney rams at 14 clays f age, accrding t Grman et al. (1942). The ewes bred t Lincln rams had the highest prductivity fllwed by thse bred t Crriedale, Rmney and Clumbia rams, in that rder. This difference in prductivity was due largely t a difference in survival f the lambs. Hrlacker (1933) bserved that Ryeland X Chevit lambs weighed 1 punds mre than purebred Chevit lambs at 84 days f age. This difference was attributed t differences in breed size, hetersis, and the fact that mre f the purebred lambs were twins. Since there is little in the literature reprting crsses using ewes f the muttn breeds, and since the flcks at the several University f Minnesta branch statins were already n a recrd f perfrmance breeding prgram as utlined by Winters et al. (1946), it seemed desirable t test these breeds in crssing. The grade Rambuillet ewe has Nrth Central Experimental Statin, Grand Rapids, Minnesta.

2 CROSSBREEDING SHEEP 463 becme ppular amng Nrthern Minnesta sheepmen. It was desirable t cmpare the perfrmance f these ewes with the muttn breeds and t determine what breed rams crssed mst successfully with these Rmbuillet ewes, under nrthern Minnesta cnditins. Experimental This study reprts 1295 matings made at the fur University branch statins during the years Seven hundred frty f these were purebred matings f the Shrpshire, Hampshire, and Clumbia breeds. Five hundred fifty-five crssbred matings were made, invlving 17 different cmbinatins. Shrpshire ewes were mated t Clumbia, Oxfrd, Targhee, Hampshire, and Brder Leicester rams. Sme f the Hampshire ewes were mated t Oxfrd rams and a few Oxfrd ewes were mated t Shrpshire rams. The Clumbia ewes were mated t Hampshire, Sufflk, Shrpshire and Targhee rams and the Grade Rambuillet ewes were bred t Oxfrd, Shrpshire, Hampshire, Chevit, Clumbia and Brder Leicester rams. The Rambuillet ewes were grade Mntana ewes f the type cmmnly called western White-faced ewes, that clip fine and half-bld fleeces. The purebred Shrpshire flck at each statin was used as a basis fr cmparisn since all statins had Shrpshire flcks. These flcks had all been bred fr perfrmance a number f years befre crssing began. Cmparisns were made with ther purebreds when available, and with the varius crsses. It was nt pssible t make cmparisns between all breeds used in crssing and purebreds f that breed. Cnditins varied between the fur statins. Envirnment, feeding, lambing dates, and scring varied t the extent that cmparisns between statins cannt be made, hence direct cmparisns are made nly between matings at each statin fr each year. Prductivity was calculated accrding t Winters et al. (1946) as fllws: 1Xlb.Lamb+ (Lb.greasewlX3.4) Prductivity per 1 lb. ewe~ Weight f ewe The lambs were weighed at birth and at 14 days f age. Wl was crrected by the factr 3.4, because it was fund that ver an 18-year perid, a pund f wl sld fr 3.4 times as much n the Bstn wl market as a pund f lamb at Suth St. Paul. The ewe weight is an average f tw weights taken n Nvember 1st and June 1st each

3 464 K.P. MILLER AND D. L. DAILEu prductin year. Average prductivity is prductin f all ewes bred, whether they lambed r nt. All lambs were given a numerical scre when they were weighed at 14 days f age. This scre ranged frm 1 t 5, with 1 being tp market grade and 5 being a cull. Results Table 1 is a cmparisn f all purebred matings with crssbred matings fr the Clumbia, Shrpshire, and Hampshire. When used fr crssing, the ewes prduced 12% t 22~ mre lamb per 1 punds f ewe than when lambing purebred lambs. This increase averaged 19% and was due t faster grwth rate in the case f the Shrpshire crsses and the greater number f crssbred lambs raised per ewe fr all crsses. The Clumbia and Hampshire ewes had a slightly higher lambing percentage when bred t a ram f anther breed. The death lss amng the purebreds was greater in all cases; 27.4~ f the purebred lambs brn alive did nt live t 14 days f age, cmpared t 19.1% fr the crssbred lambs. When ttal prductivity is figured, the ewes had 16% greater prductivity when used in crssing, cmpared t ewes lambing purebred lambs. The Crssbred Shrpshires and Clumbia lambs scred higher than the purebreds. Fr this particular character, the Clumbias gained mst frm crssing. Winters et al. (1946) pinted ut that ewes' prductivity is increased mst when mated t rams f the larger breeds. This pint is further brn ut by the much greater grwth rate fr the Shrpshire crsses cmpared t n increase in rate f grwth fr the Clumbia and Hampshire crsses. The Clumbia and Hampshire crsses were by smaller breeds, yet the lamb weights were as high as the purebreds. A pssible hetersis effect is suggested by the greater number f crssbred lambs brn alive per ewe fr the Hampshire and Clumbia crsses. N figures are available n lambs brn dead, but fetal mrtality may have been higher fr the purebreds. The slightly lwer lambing percentage fr the Shrpshire ewes used in crssing may partially be explained when we nte that the average age f the ewes lambing crssbred lambs was nly slightly ver tw years, whereas thse lambing purebred lambs averaged almst three years. The Rambuillet ewe perfrmed very satisfactrily when cmpared t the Shrpshire; especially when mated t Brder Leicester rams. This

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466 K.P. MILLER AND D. L. DAILEY cmparisn is shwn in table 2. Rambuillet ewes were mstly tw-year lds at lambing, whereas the Shrpshires were mstly three and furyear lds.

5 466 K.P. MILLER AND D. L. DAILEY cmparisn is shwn in table 2. Rambuillet ewes were mstly tw-year lds at lambing, whereas the Shrpshires were mstly three and furyear lds. This may explain the difference in lambs brn per ewe. In every ther respect, the Rambuillet excelled the Shrpshire. The Rambuillet ewes sheared 3%, r abut 2 punds, mre wl than the Shrpshires, althugh the latter ewes were several punds heavier. The death rate f the purebred Shrpshire lambs was 21%, and fr the Rambuillet crsses, 12%. The lambs frm the Rambuillet ewes weighed 13 punds mre than the purebred Shrpshire lambs at 14 days f age. The Rambuillet lambs scred almst ne grade higher n the average than the purebreds. These lambs were larger at birth, mre vigrus and better able t take care f themselves than the purebred lambs. The Rambuillet ewes prduced, per 1 punds, 5% mre wl than the Shrpshire and 2% mre lamb than the Shrpshires lambing purebred lambs. The ttal prductivity was 27% mre than the Shrpshire ewes, even thugh the fertility was nly 78% f the Shrpshire. These ewes had less truble lambing, were nt subject t wl blindness and were less likely t be caught by bears than the Shrpshire ewes. A cmparisn between the different breed rams is shwn in table 2. Perfrmance was highest when the Rambuillet ewes were mated t Brder Leicester rams. The Clumbia, Oxfrd, and Hampshire were als ver 2% heavier than the purebred Shrpshire lambs. The Chevit lambs lacked weight at 14 days, but were all well finished, had excellent livability, and were easy t raise. Of the six different breed rams tried n Rambuillet ewes, the Shrpshire ranked sixth. Summary I. Shrpshires, Clumbias, and Hampshires prduced 19% mre lamb per I Ibs. f ewe when mated t anther breed. The average ttal prductivity was 16% mre fr the ewes used in crssing. The crssbred lambs were heavier and had higher livability than the purebreds. 2. This increase in prductivity was likely due t heter~is and difference in breed size. 3. The Rambuillet ewe was 27% mre prductive, when used in crssing, than the Shrpshire ewe mated t a Shrpshire ram. This greater prductivity was due t mre wl and faster grwing lambs.

6 CROSSBREEDING SHEEP 467 I ~r ~,~1 ~ ~ " W4W W~WdW WWW ddw Wdd 2~ ~14 WdW ddddd ddd idw W64 N~ ~ r...) z r~ Z M S-" ~ Z ~.~,~-,--1 < ~ ~ E~ ~,..m ~

7 468 K.P. MILLER AND D. L. DAILEY 4. Brder Leicester, Hampshire, and Clumbia rams sired the fastest grwing lambs when mated t Rambuillet ewes. Hwever, the Brder Leicester crsses resulted in the largest ttal prductivity and resulted in the greatest advantage ver the Purebred and Shrpshire matings. Literature Cited Grman, J. A., F. S. Hultz, O. G. Hankins, and D. A. Spencer Crssbreeding fr lamb and wl prductin. Wy. Agr. Exp. Sta. Bul Hrlacker. L. J A cmparisn f the grwth f purebred Chevit and crssbred Byeland X Chevit lambs. (Abstract) Prc. Amer. Sc. An. Prd. p Hultz, F. S., J. A. Grman, S. S. Wheeler Crssbreeding with Western ewes. Wy. Agr. Exp. Sta. Bul. 21. Miller, Rbert F Crssbreeding investigatin in the prductin f Califrnia spring lambs. Calif. Exp. Sta. Bul Winters, L. M., D. L. Dailey, O. M. Kiser, P. S. Jrdan, R. E. Hdgsn, and W. W. Green Factrs affecting prductivity in breeding sheep. Minn. Agr. Exp. Sta. Tech. Bul. 174.

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