.AMB PRODUCTON FROM WS OF FOUR BRDS AND THR TWO.BRD AND THR.BRD CROSSS J. A. VSLY and H. F, PTRS' Research Station, Agriculture Canada, Lethbridge, Alberla, Canada T 481, Received 9 July 1974, accepted 23 Sept. 1974. Vrsrlv, J. A..lxo Pruns, H. F. 1974. Lamb production from ewes breeds and their two-breed and three-breed crosses. Can. J. Anim. 543-549. Fertility, prolificacy, numbers of lambs weaned and marketed, and total weight of lamb weaned and marketed per ewe bred (exposed to rams) were studied with the Romnelet, Columbia, Suffolk, and North Country Cheviot breeds of sheep and their two-breed and three-breed crosses. During a period of 4 yr, there were 1,675 matings, which resulted in 1,138 lambings with 1,818 larnbs at birth. Fertility was improved (P < 0.05) by cross,breeding but prolificacy was not. Surrdval ability of lambs was improved by crossbreeding. Nurnber of lambs weaned (at 3-4 mo of age) per 100 ewes bred and percentage of larnbs surviving to end of a 75-day postweaning feeding period were 83 and 75 for purebred lambs, 94 and 83 for tworbreed, and 104 and 86 for three-breed crosses. n total weight of lamb marketed per ewe bred, the two-breed and three-breed crosses surpassed purebreds by 16.6 and 32.5Vo, res,pectively. Total weight of 'lamb weaned per ewe in the foundation purebred flocks during their lifetime averaged 149.5 kg for the Sufiolk, 146.6 for Romnelet, 119.3 for Columbia, and 92.1 for N.C. Cheviot. Longevity of ewes was highest for he Romnelet and Colurnbia breeds and lowest for the N.C. Cheviot. At the end of 8/z yr of production, the percentages of ewes rema'ining in the Romne,let, Columbia, Suffolk, and N.C. Chev,iot flocks were 22, 25, 5, and 0. On a 6tudi6 sur les moutons Romnelet, Columbia, Suffolk et North Country Cheviot, ainsi que sur leurs croisements i deux et trois races, les caractres suivants: fertilit6, pro1ificit6, nombre d'agneaux sevr6s et vendus, ainsi que le poids total des agneaux sevr6s et vendus par brebis saillie. Sur une p6riode de 4 ans, il y a eu 1,675 accouplements, qui ont donn6, 1,138 mises bas de 1,818 agneaux. Le croisement a am61ior6 (P < 0.05) la fertilit6 des brebis et le taux de survie des agneaux, mais il n'a pas eu d'effet sur la prolifrcit6. Le nombre d'agneaux sevr6s (i 'dge de 3 ou 4 mois) par 100 brebis mises i la lutte, et les pourcentages d'agneaux en vie 75 jours aprd.s le sevrage ont 6t6 de 83 et 75 pour les agneaux de race pure de 94 et 83 pour les crois6s ir deux races, et de 104 et 86 pour les crois6s i trois races. Pour ce qui est du poids total des agneaux vendus par brebis, les croisements i deux et trois races ont d6pass6 de 16.6 el 32.5%, respectivement, les agneaux de race pure. Le poids total des agneaux sevr6s par brebis dans les troupeaux de base de race pure durant leur vie productive a 6t6 en moyenne de 149.5 kg pour les Suffolk, de 146.6 pour les Romnelet, de 119.3 pour les Columbia et de 92'1 pour les Cheviot. La long6vit6 des brebis Romnelet et Columibia a 6t6, la plus 61ev6e et celle des Cheviot, la plus faible. Au terme des 8Vz ann6es de production, le pourcentage de brebis encore en vie des troupeaux de Romnelet, Columbia, Suffolk et Cheviot 6tait, dans 'ordre, de 22,25, 5 et 0%, The Romnelet, Columbia, Suffolk, and North Country (N.C.) Cheviot breeds have been used in a crossbreeding experiment conducted at the Manyberries Substation of the 'Present address (H.F.P.): Animal Research nstitute, Agriculture Canada, Ottawa, Ontario. Can. J. Anim. Sci, 54: 543-549 (Dec. 1974) 543 of four Sci. 54: Lethbridge Research Station, Canada Department of Agriculture, The main purpose of this work is to determine the difference in performance of the most important production traits among the pure breeds and their two-breed and three-breed crosses. n addition, information will be sought as to what type of additive and non-additive gene ac-
544 CANADAN JOURNAL OF ANMAL SCNC tion is involved. The experiment was carried out in three stages: (1) production of purebreds only; (2) production of purebreds and all possible two-breed crosses; (3) production of purebreds, two-breed crosses, and three-breed crosses. arlier, we reported on growth performance to weaning and to market of purebred, two-breed cross, and threebreed cross lambs (Vesely and Peters 1972). Two-breed and three-breed cross lambs surpassed purebreds by 5.0 and l4.6vo inweaning weight and by 7.3 and 11.47o in final market weight. However, the merit of crossbreeding should be evident not only in the growth performance of the lambs but also in their survival, and in conception and twinning rates of the ewes. Traits studied include fertility (ewes lambing as percentage of ewes bred), prolificacy (lambs born as percentage of ewes lambing), total weight of lamb weaned and marketed from purebred and crossbred ewes, and survival ability (lambs surviving to market as percentage of lambs born) of purebred and crossbred lambs. Results on these traits are based on records of stage (3), which was carried out over a period of 4 yr. Longevity of ewes of the four pure breeds that lived from the beginning of the experiment also is evaluated. MATRALS AND MTHODS A total of 1,675 matings were made from which there were 1,138 lambings and 1,818 lambs born. The mating procedures and management were described in detail earlier (Vesely and Peters 1972). Fertility, prolificacy, total weight of lamb weaned and marketed and survival ability of lambs were analyzed by a least-squares model in which were included factors of year (1967, 1968, 1969, 1970), age of ewe (1 to 6 yr), and mating type, classified as (1) purebred ewes mated to rams of the same breed, (2) purebred ewes mated to rams of another breed, and (3) two-breed cross ewes mated to rams of a third breed. Survival ability of lambs was analyzed by a model using the same factors as the above, plus those of birth type (single or twin) and sex. The significance of differences among mating types was tested by Duncan's multiple range test as modified by Kramer (1956, 1957). Mortality in the foundation Romnelet, Columbia, Suffolk. and N.C. Cheviot flocks was measured each year as a percentage of the original flock size, comprising 60, 61,63, and 40 ewes, respectively. The flocks were established in 1966, each with about equal numbers of lambs and yearlings. The differences in mortality rates were tested each year over a period of 8/z yr by x" test using the breed distribution of the first year as the expected value. An overall merit in lamb production of the four pure breeds also was viewed as an average total weight of lamb weaned per ewe of each established flock. This trait was analyzed by the analysis of variance and the sum of squares of breed effect was partitioned by orthogonal contrasts. RSULTS AND DSCUSSON Productivity of the ewe can be influenced by her fertility. The most important factor influencing the ewe's fertility was her age (Table 1). Only 5O% of the ewe lambs exposed to rams conceived. Neither type of crossbred mating differed significantly in fertility from the purebred mating. However, the F-test for mating type was significant at P < 0.05, since the conception rate in crossbred ewes was higher than that in purebred ewes mated to rams of another breed (Table 1). Sidwell e:l al. (1962) reported also that fertility was not affected by crossbreeding with the Hampshire, Shropshire, Merino, and Southdown breeds. This lower fertility of the purebred ewe when bred to a ram of a different breed, noted both here and by Sidwell et al. (1962), could be the result of a lack of compatibility between the egg and sperm of the parental breeds. Prolificacy was not improved significantly by crossbreeding and only age of ewe had a significant effect on this trait. Prolificacy was lowest for the yearling ewes and highest for the ewes of 3-5 yr of age. n contrast, Sidwell et al. (1962) found prolificacy significantly higher in production of three-breed and fourbreed cross lambs than in production of purebreds, but when two-breed cross lambs were produced the pro;lificacy was significantly lower than in breeding purebreds. Again, the reason for this difference could be a lack of compatibility between the egg and sperm of the parental breeds. Survival ability of lambs was not significantly influenced by age of dam although a trend was evident that fewer lambs were raised to market by yearling ewes (Table 1).
VSLY AND PTRS-LAMB PRODUCTON FROM PUR AND CROSSBRD WS 545 Table l. Least-squares means and standard errors of fertility, prolificacy, lamb survival ability, and overall reproduction with tests of significance of differences from purebred and crossbred matings Fertility Prolificacy Survival ability Overall reproduction Factor Year 1967 968 1969 1970 Age of ewe (yr) 2 3 4 5 6 Mating type Pure breed Xd x pure breed XQ Pure breed Yd x pure breed X? Pure breed Zd x crossbred XY? Birth type Single Twin Sex Male Female wes lambing as 70 of ewes bred '74.8+2.7 87.l +2.4 81.2+2.1 '78.7 + 1.9 50.1+2-3 85-4+2.1 82.6+2.1 85.9+2.6 84.2+3.4 94.8+5.4 80.8 + 2.7 '77.'7ml+1.6 83.0 m+2.1 Lambs bom as 7o of ewes lambing NS 134.5 +3.9 141.2+3.3 144.6+3.O 143.7 +2.6 106.8+3.8 134.3+2.9 152.0+2.9 159.6 + 3.5 156.4+4.7 36.8 +7.1 NS 137.5+3.6 142.7 +2.3 142.8+3.1 o/o of lambs surviving to market 76.6!2.7 83.5+2. 81.0+ 1.9 85.3 + 1.7 NS 74.8+2.8 81.6+ 1.9 82.6+ l 8 85.6+2.2 83.2 +3.0 81.8+4.5 /).5 AD!2.3 83.4 a+ 1.4 86.1 b+2.0 84.9+ 1.6 78.3 + l 5 NS 80.1+ 1.5 83.1+1.5 *P < 0.05; **P < 0.01; NS, nor siqnificanr. tmeans followed by the sme leneiwithin column differ significantly: d,, signifyp < 0.01, andz signifiesp < 0.05. Lambs weaned as a of ewes bred 78.0+4.7 100.5+4.2 94.5+3.7 100.713.3 38.0+4.0 92.0+3.7 1O4.4+3.7 115.7 +4.6 107.3 +6.0 106.1+9.4 83.4 am+4.6 94.1 mb+2.8 1O4.4 ab+3.8 Survival ability of crossbred lambs was superior (P < 0.01) as 75 purebred, 83 twobreed cross, and 86 three-breed cross lambs were raised till market per 100 lambs born. Sidwell et al. (1962, 1964) also obtained significant effects of cross'breeding on lamb survival. Overall reproduction was improved (-P < 0.01) by crossbreeding; 83 purebred lambs, 94 two-breed cross lambs, and 104 threebreed cross lambs were raised till weaning per 100 ewes bred. Although fertility and prolificacy did not appear to be significantly affected by crossbreeding, their cumulative effect is apparent in the wider differences between the means of mating types (Table 1). Our results are very similar to those from three separate experiments (Sidwell et al. 1962, 1964; Sidwell and Miller 1971) in which the Hampshire, Shropshire, Southdown, Merino, Targhee, Suffolk, and Dorset breeds were used. The advantages of crossbreeding are more pronounced when the total weight of lamb weaned per ewe bred is considered since the component traits have a cumulative influence, For example, when growth rate to market was considered, the superiority of two-breed and three-breed cross lambs over purebreds was 7.3 and 1l.4Va (Vesely and Peters 1972). f, however, the total weight of lamb at market per ewe bred was analyzed (Table 2), the superiority in production of two-breed and three-breed cross lambs over the production of purebred lambs was increased to 16.6 and 32.57o. This experiment has not continued long enough to measure the effect of crossbreeding on longevity of ewes. However, we have been able to measure longevity of the founda-
546 CANADAN JOURNAL OF ANMAL SCNC il n d p! P o 6 @! g = 3 d l:) 4 {. { 6 F N! F! g U a 4 ;< u il v q '! s N NAS hh @r d; rn n :od s N N n o o on --------_lt.--------------] # r: d k9...l 6 N --o o! >o>= i..o o * 9 g g! -otr 9!9.o! 9: q + u!? 2p F c.d 3o 3s 2v t o d=.. c2?z
VSLY AND PTRS-LAMB PRODUCTON FROM PUR AND CROSSBRD WS 547 tion purebred flocks. The ewes of the two range breeds, Romnelet and Columbia, had lower (P < 0.01) mortality rates than Suffolk ewes and Suffolk ewes had lower (P < 0.01) mortality rates than N. C. Cheviot. The mortality rates were similar in all four flocks during the first 4 yr of their lives (Fig. 1 and Table 3). After 4 yr, however, the mortality rate increased in the N.C. Cheviot flock. The same phenomenon was observed in the Suffolk flock after 6 yr (Fig. 1 and Table 3). At the end of 8Vz yr of production, the percent-.9 roo -40 30 ---- -- suffolk - COLUMBA ORTH COUNTRY CHVOT RO MN L T...tr'...-.----'),/.r, ages of ewes remaining in the Romnelet, Columbia. Suffolk. and N.C. Cheviot flocks were 22,25, 5, and 0. Total annual and lifetime weight of lamb weaned per ewe of foundation flock is another way of expressing the overall economic advantage in production from various breeds or crosses because it takes longevity into consideration. This trait was analyzed for the four pure breeds (Table 4). Analysis of variance showed (Table 5) that the trait may be significantly influenced by breed and by year,..,i,t...' tl..,/ ; li i' /i 7 Ltmb3.l 1.2 2.3 Fig. 1. Cunrulative annual percent flock reduction of four breeds of sheep established in 1966 with approximately equal numbers of lambs and yearlings.
548 CANADAN JOURNAL OF ANMAL SCNC Table 3. 12 test of mortality of ewes of four breeds (cumulative annual percent flock reduction) over a period of 8 l/u yr. Any two breeds not underscored by the same line are significantly different (P < 0.05) in mortality rate Year N.C. Cheviot (40)t Suffolk (63) Columbia (61) Romnelet (60) 1961 r 968 1969 1910 191 1912 t9'73 1974 10.0 9.5 2s.0 r 9.0 19.7 21.7 3s0 23.8 34.4 26.7 4t.) 3t.1 36.0 -tb. / 61.5 85.0 92.5 r00.0 tnumber of eues in foundation flocks. 9.8 49.2 45.9 38.3 68.3 63.9 s0.0 84. l 95.2 8.3 12.1 63.3 75.0 78.0 Table 4. Average total weight (kg) of lamb weaned per ewe of four foundation breed-flocks over Sfz yr of product ion Year 1966 1961 968 1969 t910 197 1912 1973 Breed total for all years inumber of ewcs in foundation flock Romnelet (60)1 lt.5 22.9 lo.-1 24.4 20.7 t6.2 t2.7 5.9 146.6 Columbia Breed Suffolk (61) (63) tt.2 15.6 25.5 1A A 18.9 10.8 8.5 t19.3 27.9 25.2 30.1 28.3 16.7 ll.l 1.5 2.7 t49.5 N.C. Cheviot (40) 17.0 14.8 2t.9 20.0 12.0 4.5 1.9 0.0 92.1 Year total for all breeds t3.o 78.5 103.8 9'7.1 68.3 42.6 30.6 13.0 Table 5. Analysis of variance of average total weight (kg) of lamb weaned per ewe of four foundation breed-flocks over 81/z yr of production and partitioned breed sum of squares by orthogonal contrasts Source of variance Total Breed Orthogonal contrasts Romnelet - Columbia S uffolk - (Romnelet f Columbia) NCCt - (Romnelet * Columbia * Suffolk) Year rror df J-t 3 7 SS 2,282.30 2'.71.33 46.95 23.25 201.13 1,798.06 2t2.91 MS 90.44 46.95 23.25 201.13 256.8'7 9.26 s07.5 9.77** 5.O'74 2.5r ) 1 '1)** 2'.7.74** *Significant ar P < 0.05, **significantatp <0.01 lnorth Country Cheviot.
VSLY AND PTRS-LAMB PRODUCTON FROM PUR AND CROSSBRD WS 549 although the year-effect may be confounded by the age of the ewes. The Suffolk matures early and produces well above the average during the first 4 yr of life (Table 4). Orthogonal contrasts (Table 5) showed the Romnelet above (P < 0.05) the Columbia. However, the mean of the range breeds (Romnelet, Columbia) did not differ significantly from that of the Suffolk. Performance of the N.C. Cheviot was lower (P < 0.01) than the mean of the other three breeds. Total average lamb production per ewe of foundation flocks was 149.5 kg in Suffolk, 146.6 kg in Romnelet, 119.3 kg in Columbia, and 92.1 kg in N.C. Cheviot. Since such wide differences existed among the pure breeds, it is reasonable to expect that the range of the performance in this trait would be broadened with the addition of two-breed or three-breed cross ewes, We hope to verify this assumption in future work. KRAMR, C. Y. 1956. xtension of multiple range test to group means with unequal numbers of replications. Biometrics 12: 307-3,11, KRAMR, C. Y. 1957. xtension of multiple range tests to group correlated adjusted means. Biometrics 13: 13-18. SDWLL, G. M., VRSON, D. O. and TR- RLL, C.. 1962. Fertility, prolificacy and lamb livability of some pure breeds and their crosses. J. Anim. Sci. 2l: 875-879. SDWLL, G. M., VRSON, D. O. and TR- RLL, C.. 1964. Lamb weights in some pure breeds and cros'ses. J. Anim. Sci. 23: 105-110. S,DWLL, G. M. and MLLR, L. R. 1971. Production in some breeds of sheep and their crosses.. Reproductive efficiency in ewes. J. Anim. Sci. 32: 1084-1089 VSLY, J. A. and PTRS, H. F. 1972. Lamb growth performance of Romnelet, Columbia, Suffolk, and N. C. Cheviot breeds and all single and three-breed crosses among them, Can. J. Anim. Sci. 52: 283-293.
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