BORDER LEICESTER AND FINNSHEEP CROSSES. II. PRODUCTIVITY OF F1 EWES 1

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1 BORDER LEICESTER AND FINNSHEEP CROSSES. II. PRODUCTIVITY OF F1 EWES 1 A. F. Magid 2, V. B. Swansn 2, J. S. Brinks 2, G. E. Dickersn a and G. M. Smith 4 Clrad State University, Frt Cllins 80523, and US Department f Agriculture, Clay Center, NE Summary Prductin data n 285 lambings f crssbred ewes were cllected at the Rman L. Hruska US Meat Animal Research Center, Clay Center, Nebraska, and used t cmpare Finnsheep (Finn)- and Brder Leicester (BL)-sired ewes in matings with Sufflk sires. Matings were carried ut in 1973, 1974 and 1975, and lambs were brn in 1974, 1975 and Lambs frm BL-sired ewes were (.6 kg) heavier at birth than lambs frm Finn-sired ewes, and had superir vigr scres and less lambing difficulty, but were nt significantly better in survival, preweaning gain r weaning weight. When adjusted fr their lwer rate f twinning, BL-sired lambs were nly.3 kg heavier than Finn-sired lambs in birth weight, but 14% prer in survival t weaning and n better in lambing difficulty, lamb vigr r weaning weight. BL-sired ewes were significantly belw Finn-sired ewes in number f lambs brn (-.39), number alive at birth (-.41), number alive at 28 days (-.28) and number alive at weaning (-.29), as well as in ttal weight f lambs brn (-.4 kg) and weaned (-3.6 kg) per ewe lambing. Fertility was similar fr BL- and Finn-sired ewes (68%). BL-sired ewes were nly 1.3 kg heavier than Finn-sired ewes but prduced.3 kg heavier clean fleeces and 1.7 cm lnger stapled wl and 2.6 gtm carser fibers. z Published as Paper N. 2521, Jurnal Ser., Clrad Exp. Sta., Frt Cllins. Partial publicatin f senir authr's thesis research. Present address: Univ. f A1 Fateh, Tripli, Libya. 2Graduate student, assciate prfessr and prfessr, respectively, Dept. f Anim. Sci., Clrad State Univ., Frt Cllins Rman L. Hruska US Meat Animal Research Center, SEA, USDA, Clay Center, NE Dept. f Anim. Sci., Texas A&M Univ., Cllege Statin (Key Wrds: Finnsheep, Brder Leicester, Crssbreeding, Ewe Prductivity.) Intrductin Crssbred ewes can have prductin efficiency superir t that f parental purebred ewes. Since existing breeds differ in ecnmically imprtant traits, crssbreeding als can be used t prduce desired cmbinatins f traits that are nt present in existing breeds. Reprts frm Nebraska (Dickersn 1974, 1975), Minnesta (Bylan, 1975), Oklahma (Thmas et el., 1975; Thmas and Whiteman, 1979) and Idah (Price, 1975) indicate that 89 and 88 crssbred ewes have much higher lambing rates than parental straightbred dmestic breed ewes at 1, 2, 3 and 4 years f age and prduce nly slightly smaller lambs than straightbred dmestic (US) breeds. Als, the survival rate f their lambs is nearly as gd as that f Iambs frm the dmestic ewes. In Nrth Dakta experiments (Light et el., 1970; Failer, 1975), Brder Leicester-sired ewes weaned mre than 1.8 lambs and sheared heavier fleeces than straightbred and crssbred Clumbia and Rambuillet ewes. This reprt presents results frm an experimental cmparisn f the prductivity f Brder Leicester (BL)- and Finnsheep (Finn)- sired ewes, when mated with Sufflk sires. Fertility, lambing rate, lamb survival, preweaning grwth ewe bdy size and wl prductin were evaluated. Materials and Methds Data were btained n 420 matings and 285 lambing f BL-sired and Finn-sired crssbred ewes prduced in 1973 and 1974 as a part f the Germ Plasm Evaluatin Prgram at the Rman L. Hruska US Meat Animal Research Center. Phase I f the experiment invlved the 1262 JOURNAL OF ANIMAL SCIENCE, Vl. 52, N: 6, 1981

2 PRODUCTIVITY OF LEICESTER-AND FINN-CROSS EWES 1263 prductin f Finn- and BL-sired lambs (Magid et al., 1981a). In Phase II, all surviving Finnand BL-crssbred ewes that were prduced in Phase I were mated t Sufflk rams fr cmparisn f their maternal perfrmance. The fact that Finn-sired ewes frm 89 dams were backcrsses t Finn biases the cmparisn f Finn- versus BL-sired and 89 versus ther dam breeds. After weaning, the crssbred ewe lambs were cnfined in drylt and fed ad libitum diets cnsisting f apprximately 50% crn silage and 50% dehydrated alfalfa hay (IFN ) plus enugh supplemental prtein (IFN ) and minerals t meet their requirements (Magid et al., 1981a). Ewes were mated (1) frm December 11, 1973, t January 21, 1974 (41 days), t lamb in May 1974; (2) frm December 4, 1974, t January 8, 1975 (35 days), t lamb in May 1975, and (3) frm September 29, 1975, t Nvember 6, 1976 (38 days), t lamb in February/March Ewes frm each f the eight breeding grups and 2 birth years were distributed randmly each year t multi-sire drylt pens; six Sufflk rams were used in 1973, 13 were used in 1974 (ne repeated) and 11 were used in 1975, a ttal f 29 different rams frm the bradly based Sufflk ppulatin maintained at the Center. Ewes were fed alfalfa hay ad libitum in the breeding pens and were shifted during gestatin and lactatin t a mixed diet f crn silage (60%) and a crn r crn-mil, sybean meal, mineral and vitamin cncentrate (40%) cntaining abut 70% dry matter and 13% crude prtein (CP); this diet was als fed ad libitum. Lambs brn in 1974 and 1975 were weaned n July 9 and 17, respectively, at ages ranging frm 29 t 80 days. The lambs brn in 1976 were weaned n May 4 at ages ranging frm 46 t 72 days. Mean weaning age ver the 3 years was 67 days. Lambs were fed a crn-sybeanalfalfa creep diet (abut 17% CP in 1974 and 1975 and abut 19% CP in 1976) befre weaning and fr several weeks afterwards. Lambs in excess f tw per ewe were reared in a nursery frm 2 days f age. The number f lambs brn, the number alive at birth and surviving t 28 days f age and t weaning age, as well as lamb weights at birth and weaning (including nursery-reared lambs), were recrded fr each ewe lambing. Birth weights r survivr weaning weights f twins r triplets were summed t prvide ttal weight f Iambs brn r weaned fr each ewe lambing and fr nly thse ewes that weaned ne r mre lambs. Fertility was calculated as the prprtin f ewes expsed that lambed. Bdy weight, cnditin scres and fleece weights f the crssbred ewes were recrded in May 1976, 1 week after the lambs were weaned, when the ewes were 2 r 3 years f age. Clean fleece weights were estimated by the mechanical methd f Neale et al. (1958). Lck samples frm the hip, shulder and side areas were used t determine staple length and estimated wl grade. The sample wl grade was cnverted t an average fiber diameter in micrmeters fr analysis f fleece data (USDA, 1966). All traits were analyzed by least-squares prcedures fr data with unequal subclass numbers, as described by Harvey (1975). The statistical mdel f fixed effects used fr the analysis f birth and weaning traits (lamb perfrmance) included discrete classes fr age and birth year f ewe, sex and type f birth r rearing f lambs, sire breed f ewe, dam breed f ewe and the sire breed dam breed f ewe interactin. Weaning age f lambs was included as a cntinuus variable. Residual errr included degrees f freedm fr sires f ewes, individual ewes and lambs within ewes, as well as fr the nnsignificant interactins. Thus, statistical significance may have been slightly verestimated, particularly fr sire breed f ewe, fr which unbiased errr wuld have been f the amng-sire grups f ewes within breed f ewe term. BecauSe age f the ewe was cnfunded with year,~ these tw effects were cmbined as fllws: I-1 = i year in 1974, 1-2 = 1 year in 1975, 2-2 = 2 years in 1975, 2-3 = 2 years in 1976 and 3-3 = 3 years in Because f lamb mrtality r incmplete grwth data fr many f the lambs weaned, type f rearing was classified simply as single brn and reared r multiple brn r reared fr weaning traits. Fr the estimatin f actual expected breed f sire and breed f dam effects (i.e., including the effects f lambing rate), birth and weaning traits als were analyzed when type f birth r rearing was mitted frm the mdel. The mdel fr ewe prductivity traits was the same as that fr birth and weaning traits, except that sex and type f birth r rearing were mitted entirely and weaning age was mitted fr litter size and lambing difficulty. Preliminary analyses were perfrmed t test fr all pssible tw-way interactins between the main effects fr all traits. The analysis indicated that nly the interactin f sire

3 1264 MAGID ET AL. breed dam breed f the ewe was imprtant, and that this ccurred nly fr sme traits. The statistical mdel used fr analysis f ewe bdy weight, cnditin scres and wl traits included the effects f birth year f the ewe, sire breed, dam breed and the tw-way interactin f sire breed dam breed. Age f ewe's dam had n effect n these traits and was mitted frm the mdel. Results and Discussin Birth and Weaning Traits. The effect f age and lambing year f ewe was significant fr all birth and weaning traits (table 1). Differences in birth traits and livability amng year-age classes were due partly t yearly variatin, while differences in preweaning grwth were strngly influenced by age f ewe. Type f birth significantly influenced all birth traits. Single-brn iambs were heavier than twins and triplets at birth (+.9 and 1.5 kg) and had higher survival t weaning (+11 and 47%). Single-reared lambs exceeded multiple-reared Iambs by 3.5 kg in weaning weight, 47 g in preweaning daily gain and 3.9 kg in adjusted 70-day weight. The regressin f weaning weight n lamb age was slightly greater than mean daily gain (209 vs 181 g/day) because f the slightly higher daily gain f the earlier brn lambs (b =.8 g/day f age) and cnsequent effect n 70-day weight (b = 56 g/day f age). When data were adjusted fr type f birth r rearing, sire breed f ewe significantly influenced nly birth weight and survival t weaning; lambs frm BL-sired ewes weighed.3 kg mre at birth but had a 14% lwer survival t weaning than lambs frm Finn-sired ewes (table 2); crrespnding differences in lamb vigr, lambing difficulty, weaning weight, average daily gain and 70-day weight were nt significant. Dam breed f ewe influenced lamb vigr and survival t weaning; lamb survival was best fr ewes fr 89 Finn dams, prest fr thse frm Rambuillet dams and largely unrelated t ranking fr birth weight and lamb vigr scres. Actual sire and dam breed f ewe effects, ineluding effects f different lambing rates, were estimated with type f birth r rearing mitted frm the mdel (parentheses in tables 1 and 2). Lambs brn t BL-sired ewes were actually.6 kg heavier at birth, but had a 5% lwer survival rate than lambs frm Finn-sired ewes, in spite f significantly better vigr scres and fewer triplets and excess nursery-reared lambs with less than 30% survival (table 1). The advantages fr BL-sired ewes in weaning weight (+.9 kg) and 70-day weight (+.7 kg) were nt statistically significant. Fr all traits, breed f dam f ewe.effects ranked in apprximatley the same rder as they did when adjusted fr type f birth r rearing. Dickersn (1975, 1977) reprted that market lambs frm Finn-crss ewes were smaller at birth (-.9 kg) and at 10 (-2.3 kg) and 22 weeks (-2.3 kg) f age, but gained just as rapidly frm 10 t 22 weeks as lambs frm Rambuillet-crss ewes. M. R. Light (persnal cmmunicatin) als has reprted that BLsired crssbred ewes were larger than Finnsired ewes and prduced lambs that were heavier at birth (+ 1.0 kg), 28 days (+ 1.3 kg) and 90 days (+3.6 kg). Fertility, Litter Size and Lambing Difficulty. Effects f age-lambing year f ewe n number f lambs brn (NB), number brn alive (NBA), number alive at 28 days (NA28) days and number alive at weaning (NAW) per ewe lambing all were significant, (table 3) and were due mainly t age f ewe effects within years. NB, NBA, NA28 and NAW were lwer (P.01 r.001) fr BL-sired ewes than fr Finn-sired ewes by.4,.4,. 3 and. 3, respectively, and fewer BL crsses than Finn crsses were expected t lamb at 1 year f age (Dickersn, 1977). Hwever, average number f lambings per ewe expsed (fertility) did nt differ between BL- and Finn-sired ewes and BL-sired ewes had less apparent lambing difficulty (P.05). Althugh ewes frm 89 Finn dams were highest in NA28 and in NAW (1.3), nne f these breed f dam effects was statistically significant. Dickersn (1974, 1975, 1977)and Dickersn and Laster (1975) reprted that Finn-crss ewes surpassed bth 89 crssbred and purebred ewes in NB and NBW and in fertility f ewe lambs bred t lamb at 1 year f age. Bylan (1975) btained similar results and cncluded that the %- and 1A-Finn ewes were superir t straightbreds. M. R. Light (persnal cmmunicatin) reprted that BL-sired ewes were belw Finn-sired ewes by.46 lambs in NB and by.38 in NAW at 2+ years f age, in agreement with the results presented here, but fertility f ewe lambs was nt reprted. Ttal Weight f Lambs Brn and Weaned. Effects f age and lambing year f ewe and weaning age were significant fr ttal weight f Iambs brn (TBW) and weaned (TWW) per ewe weaning ne r mre lambs, (table 4). Differ-

4 PRODUCTIVITY OF LEICESTER-AND FINN-CROSS EWES 1265 XO'~ v "4,,,',',.n- t-..~ g"ca,, ~"4 a',6,6 ~ ",,4 "G. It~ 0t~ v ua.1 t= z,,g :,,g.4,,6..-;t-: 9.. '~-G', G',~" r ",O.... t-g-g ~,g : ",4.1 [-,, t~ :E,,1 re~ E z >. m g 0a ~= = t z v~ z,.~ e.leq ~- ~= :a.1 :,,g,,g ~ v c~.1 r ~a ~a ta '=~ '~.= =.=..q, :*

5 1266 MAGID ET AL, "9 I=1 9 ii "~ ~.~ ~ v v v ~ v ~ z~ [.-, X v v v v v ~ v v ~ v v m e~ I',, ',r..,i-i ~ ~.... ~. ~ U,4 0 0.a.. ~ ~ ~ ~ ~ d d d d d d d N d d M M E ~ "~,~,,, x~=~=~:~.. ~ 9 0.!!.,-4

6 PRODUCTIVITY OF LEICESTER-AND FINN-CROSS EWES 1267 ences in TBW and TWW between years within age classes (1-1 vs 1-2 and 2~2 vs 2-3) were large, but thse between ages within a year (1-2 vs 2-2 and 2-3 vs 3-3) were even larger. TBW was lwer, and TWW was higher fr lder lambs at weaning. Sire breed f ewe influenced (P.05) TWW but nt TBW. Effects f dam breed f ewe were nt significant, and the interactin f sire breed x dam breed was barely significant fr TBW and TWW. The majr cause f the interactin was the shift f ta Finn dams frm last in TBW amng Finncrsses t first amng BL crsses, and frm last in TWW amng Finn crsses t secnd amng BL crsses; these shifts are explainable by lwer expected hetersis in the Finn backcrss ewes. The ttal weight f lambs weaned each year frm a flck generally depends mre upn the number f lambs weaned than upn the weights f individual lambs. Sidwell and Miller (1971) and Sidwell et al. (1962) fund this t be true fr Hampshire, Merin, Shrpshire and Suthdwn crssbred lambs. Number f Iambs weaned is a functin f bth the number f lambs brn alive and livability f lambs brn. BL-sired ewes that gave birth t and weaned TABLE 3. LEAST-SQUARES MEANS FOR EWE PRODUCTIVITY TRAITS, BY YEAR-AGE, SIRE BREED AND DAM BREED OF EWE N. Lambing Factr f ewes a Fertility, % NB b NBA b NA28 b NAW b difficultyc U 285 (420) Age-year (95) (92) (90) (85) (58) Sire breed f ewe Finn 156 (228) BL 129 (192) Dam breed f ewe Hampshire 67 Rambuillet 51 Targhee Sire X dam breed f ewe Finn Hampshire 44 Rambuillet 27 Targh ee BL Hampshire 23 Rambuillet 24 Targbee Errr standard deviatin 273 df anumbers in parentheses are numbers f ewes expsed t breeding. These were used t calculate percentage fertility. bnb, NBA, NA28, NAW are, respectively, number f lambs brn, number brn alive, number alive at 28 days and number at weaning per ewe lambing. CFrm analysis f means fr each ewe lambing; lwer scres better. See ftntes t table 1. *P.05. **P.01. ***P.001.

7 1268 MAGID ET AL. lambs had lwer TBW (--.5 kg) and TWW (-2.1 kg) than Finn-sired ewes, but the verall BL-crss disadvantage in TWW was abut 3.6 kg because fewer f the lambing BL-crss ewes weaned lambs (78 vs 86%). M. R. Light (persnal cmmunicatin) reprted that TBW f lambs per ewe lambing first at 2 years f age was n less fr BL-sired than fr Finn-sired ewes, but that the ttal weight f lambs fr BL-sired ewes was mre than 3 kg less at 28 and 90 days f age. The difference in TBW and TWW per ewe expsed t breeding was less (-.3 and -2.6 kg) because mean fertility was nly 68% fr bth types f ewe. Ewe Bdy Weight, Cnditin Scres and Wl Traits. The lder ewes (3 vs 2 years ld) were 11 kg heavier and had.7 higher cnditin scres, with.42 kg heavier grease fleeces and.62 kg heavier clean fleeces f 1.3 cm lnger staple and 1.4/am greater fiber diameter (P.O1; table 5). Sire breed f the ewe had significant effects n all traits except bdy weight and grease fleece weight. Dam breed f the ewe significantly affected bdy weight, cnditin scre, estimated clean fleece weight, staple length spinning cunt and fiber diameter. BL-sired ewes differed little frm Finn-sired ewes in bdy weight but had a.3 higher cnditin scre and prduced.33 kg mre clean fleece with 1.7 cm lnger staple and 2.6 /am carser fiber. Bdy weights and cnditin scres were significantly highest fr ewes frm Hampshire and Targhee dams and lwest fr the 89 Finn dams. Clean wl yield was abut.4 kg greater fr ewes frm Targhee and Rambuillet dams than fr ewes frm 89 Finn dams. Staple length was abut 1 cm shrter fr ewes frm Hampshire and Targhee dams than fr thse frm Rambuillet and 89 Finn dams. Fiber diameter was smaller and spinning cunt higher fr ewes frm Targhee dams than fr thse frm the ther three breeds f dam. Light et al. (1970) and Faller (1975) have reprted that BL-crssbred ewes were smewhat heavier than straightbred Rambuillet and Clumbia r reciprcal crsses f these breeds, and that they prduced lnger staple fleeces. M. R. Light (persnal cmmunicatin) als reprted that BL crss ewes prduced.8 kg mre grease wl and were larger than Finn crss ewes. Price (1975) reprted that wl grades were lwer fr Finn crsses than fr pure Rambuillet r Targhee and that grease fleece weights were lwer, variatin in fiber diameter was greater and wl g~ ~O z~ m~ m~ ~m L~ O e~ e~ m [- m [- t~ b, Im m I:m l:m.=. e~

8 PRODUCTIVITY OF LEICESTER-AND FINN-CROSS EWES 1269 xo00 O',~.S "O e~, ~.0q. ee~ ee~ e, t~ r~,~- ~.,q. IJ z X "O,! O A L- v-~ eq eq O t 9 O t~ t~

9 1270 MAGID ET AL. :L r- 4~ Nrf~ e N~f~fl~..= F- J ~,rq ~(~lr~(~ "4" (~,4~ ~ ~, ~ " == E L~ II ~ II [... M ~4 M ('4 c~ II r~.g II H ~q [-.:~. M ~ v'~.

PRODUCTIVITY OF LEICESTER- AND FINN-CROSS EWES 1271 fibers were carser in the Finn crsses. Bylan (1975) als reprted that 89 ewes prduced carser but lighter fleeces than did Targhee ewes.

10 PRODUCTIVITY OF LEICESTER- AND FINN-CROSS EWES 1271 fibers were carser in the Finn crsses. Bylan (1975) als reprted that 89 ewes prduced carser but lighter fleeces than did Targhee ewes. Discussin BL crss ewes were nly 1 t 2 kg larger in bdy size than Finn-crss ewes. BL crsses were as fertile as Finn crss ewes but prduced.4 fewer lambs at birth per ewe lambing that were.6 kg heavier than lambs frm Finn-crss ewes. Lambs frm BL-crss ewes gained n faster and were slightly prer in survival t weaning, even thugh fewer f them were triplets and nurseryreared lambs. Thus, BL-crss ewes weaned.3 fewer lambs and 3.6 kg less ttal weight per ewe lambing. Hwever, BL-crss ewes had higher cnditin scres and prduced.3 kg mre estimated clean wl f slightly lnger staple but carser grades. The Finn-sired ewes and ewes frm 89 dams were biased relative t BL-sired ewes and ther dam breeds by the fact that ne f the fur breeds f dam was 89 This means that bth the Finn-sire and the 89 dam breeds included backcrsses t Finn nt balanced by cmparable backcrsses t BL. Thus, the advantage f Finn- ver BL-sired ewes was underestimated by 1/8 f Finn-crss hetersis fr maternal traits but included n average an additinal 1/8 Finn fr additive maternal traits. Similarly, prductivity f 89 dams was underestimated by 88 fr maternal hetersis, but the Finn dam additive maternal effect was verestimated by 88 Cmparisns f BL- and Finn-crss ewes fr pstweaning grwth and carcass perfrmance f their Sufflk-sired lambs and fr verall efficiency in market lamb prductin are presented in a cmpanin paper (Magid et al., 1981b). Literature Cited Bylan, W. J Place f Finnsheep. Prc. Sheep Breeding and Feeding fr Prfit Symp., Siux Falls, SD, July 31-August 2, 1975, p Sheep Industry Develpment Prgram, Denver, CO. Dickersn, G. E Crssbreeding perfrmance f Finn and dmestic (U.S.) breeds f sheep. Prc. Symp. n Breed Evaluatin and Crssing Experimentts, eist, Netherlands, p Dickersn, G. E Chsing yur breeds-u.s. and wrld. Prc. Sheep Breeding and Feeding fr Prfit Syrup., Siux Falls, SD, July 31--August 2, 1975, p Sheep Industry Develpment Prgram, Denver, CO. Dickersn, G. E Crssbreeding evaluatin f Finnsheep and sme U.S. breeds fr market lamb prductin. Nrth Central Regin Pub. N. 246, USDA and Univ. f Nebraska, Lincln. Dickersn, G. E. and D. B. Laster Breed, hetersis and envirnmental influences n grwth and puberty f ewe lambs. J. Anim. Sci. 39:940. Failer, Timthy C Selected breeds and crsses f sheep. M.S. Thesis. Nrth Dakta State Univ., Farg. Harvey, W. R Least-squares analysis f data with unequal subclass numbers. USDA, ARS--H 4. Light, M. R., B. L. Jhnsn and T. Failer Prductivity f selected breeds and crsses f sheep. I. Experimental ewes. Farm Research. Nrth Dakta Agr. Exp. Sta. 28, 701:26. Magid, A. F., V. B. Swansn, J. S. Brinks, G. E. Dickersn and G. M. Smith. 1981a. Brder Leicester and Finnsheep crsses. I. Livability, grwth and carcass traits f F 1 lambs. J. Anita. Sci. 52:1253. Magid, A. F., V. B. Swansn, J. S. Brinks, G. E. Dickersn and G. M. Smith. 1981b. Brder Leicester and Finnsheep crsses, lli. Market lamb prductin frm crssbred ewes. J. Anim. Sci. 52:1272. Neale, P. E., G. M. Sidwell and J. L. Ruttle A mechanical methd fr estimating clean fleece weight. New Mexic Agr. Exp. Sta. Bull. 417, p. 3. Price, D. A Crssbreeding fr imprved efficiency. Prc. Sheep Breeding and Feeding fr Prfit Symp., Siux Falls, SD, July 31--August 2, 1975, p. 99. Sheep Industry Develpment Prgram, Denver, CO. Sidwell, G. M., C. O. Eversn and C. E. Terrill Fertility, prlificacy and lamb livahility f sme purebreeds and their crsses, J. Anim. Sci. 21:875. Sidwell, G. M. and L. R. Miller Prductin in sme purebreeds f sheep and their crsses. I. Reprductive efficiency in ewes. J. Anim. Sci. 32:1084. Thmas, D. L. and J. V. Whiteman Effects f substituting Finnsheep and Drset breeding fr Rambuillet breeding. I. Prductivity f yung spring-lambing ewes. J. Anita. Sci. 48:256. Thmas, D. L., J. V. Whiteman and J. E. Fields Prductivity f crssbred ewes f Finnsheep, Drset and Rambuillet breeding. Oklahma Agr. Exp. Sta. Res. Rep. MP--94. USDA Official standards f the United States fr grades f wl. Title 7, Part 31, April. US Cnsumer and Marketing Service.

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

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