Maataloustieteellinen A ikakauskirja Vol. 60: 558—565, 1988 Performance, development and use of Romanov in France G. RICORDEAU, L. TCHAMITCHIAN and J. P. POIVEY I.N.R.A. Station d’Amelioration Genetique des Animaux, P.B. 27 31326 Castanet Tolosan Cedex, France Abstract. The Romanov (R) breed was imported to France in 1963. In 1987, there were 15 000 purebred and 80 000 FI ewes. The ewes have a high precocity and good adaptability to breeding season changes. Litter size (LS) is about 2.2 at 18 months and over 3 in adults, resulting from a high ovulation rate (OR) and a reduced embryonic mortality (EM). OR is less variable, but LS as variable as in other breeds. There are 0.8—1.9 % freemartins. In ewe lambs, the heritabilities of OR, EM and LS are 0.39, 0.09 and 0.02, resp. R has a favourable direct effect on lamb viability. Heterosis is high on fertility in ewe lambs, but less on OR and LS, favourable on lamb viability. The lack of performance regression from FI to F 4 in crosses with Berrichon du Cher has allowed the creation of a composite line (INRA 401), used on farms. Ewes suckle a maximum of twins. Lambs grow fast but have a low car- cass and meat quality. A good viability of crossbred lambs and a good productivity of FI ewes have been ob- served both in intensive and extensive conditions. In extensive system, R ewes are relatively susceptible to gastro-intestinal parasitism but are resistant to hepatic or pulmonary parasit- ism. R lambs seem to be susceptible to caseous lymphadenitis. Favourable results have been obtained with regard to prolificacy of FI or 1/4 R ewes and viability of lambs in six other European countries, but an unfavourable effect of heavy sum- mer heat on male activity and female fertility. Composite lines have been created in Spain and Hungary. Index words: Romanov, precocity, litter size, ovulation rate, embryonic mortality, lamb viability, Berrichon du Cher, heterosis, composite line I Situation in France Romanov (R) breed was introduced to France in 1963 (43). In 1987, there were 15 000 purebred ewes among which 4 000 registered to UPRA (Unite de Promotion de Race) in 54 flocks, raised in different breeding systems. These different systems are: 1) permanent- ly outdoors, principally mated in autumn (Sept, to Dec.); 2) outdoors and indoors, prin- cipally mated in autumn with about 20 % of matings out of this period; 3) principal mat- ing early in the season (Aug. to Oct.) and sec- ond mating in autumn (Nov. to Jan.); 4) ac- 558 JOURNAL OF AGRICULTURAL SCIENCE IN FINLAND https://www.c-info.fi/en/info/?token=7N_QM-06by4A3CbO.axefy50_OpbhfQR6S8V7FA.L5cwAJbY9_dXlk3xv5eCX593v4_MFyKBGAdMV5CSzQgMOZZEeCCwIlgQULYurGpKjD8NhoUY8gOqm8XYpcun2AsDrc78T8hhkTwG1Um14WRSnOJoMvNXTwKiODzvVQPM0t5NuDBKtLAbrg5prG2jWehlxxJT5ukHYglaK8i5lpkhKB2ZSNyuShmW2_1EVgLejg8z1O74EHlTVt1X 8 celerated lambing rhythm with 3 or 4 lamb- ing periods per year. II Reproduction I) Fertility R is characterized by early sexual maturi- ty, long sexual season (16, 31,61), good post- partum ovarian and sexual activity in April- May, with minimum silent ovulations (48), post partum interval of 36 days in season (58). Good performances are achieved in a system of 3 lambings in 2 years with synchronization of oestrus, with or without PMSG in season (14, 30). 2) Litter size and its component Examples concerning flocks from different breeding systems (1981 to 1986) are given in table 1. The average litter size (LS) is maxi- mum in system 1 (3.11) and at minimum in system 4 (2,55). In all these systems, LS varies from 1 to 5 (less than 2 % have LS of 6). LS is the result of a high ovulation rate (OR) and a reduced embryonic mortality (EM), (45, 46; table 2 and 3). OR is less vari- able in R ewes than in Finn ewes (CV = 20 to 24 % vs 33 to 37 %) but LS is as variable as in the other breeds (CV = 30 to 34 %) (2). The high OR of R ewes results from a more numerous population of recruitable follicles, together with a normal selection through atre- sia during the late follicular phase. On the contrary the high OR of the Finn ewes results from a markedly reduced incidence of selec- tion through atresia (18, 19). The mechanisms controlling OR are already present at 3—5 months of age (17). 3) Genetic parameters ofLS and its components (550 R ewes) (45): OR % EM LS Repeatability (inter-year) 0.30 0.07 0.12 Heritability (h ! ) 0.39 0.09 0.02 4) Frequency offreemartinism: (34, 35) 2 to 3 % of infertile ewe-lambs 0,8 to 1,9 % of freemartin (some are fer- tile) in 125 females of mixed litters. 5) Number of ovarian follicles at birth and at 4 weeks old The difference between R and Ile de France (IdF) was significant at birth but not at 4 weeks. At birth, the number of growing folli- cles is 58 in R (7 % of antral follicles) com- pared to 337 (26 % of antral follicles) in IdF lambs. At 4 weeks of age, atresia of antral fol- licles has appeared only in IdF and not in R lambs. Retardation of follicular development together withretardation in the establishment of ovarian sensitivity to gonadotrophins are typical features of R lambs ovaries during the post-natal period (54). 6) Gonadotrophin plasma levels In young males the mean levels of LH and FSH are at maximum between 6 and 8 weeks. In ewe-lambs, pituitary FSH concentration at birth is higher in R than in Berrichon du Cher (BC) or crossbreds (36). The level of FSH was maximum at 3 weeks, and at a much higher level than in Lacaune, and significant- ly higher than in males (44, 28, 29). The prepuberal plasma level of FSH is highly heritable, but not correlated with OR at the two first matings (2). 7) Testis growth and male fertility Testis diameter of R lambs are not higher than in crossbred lambs, when compared at the same age (50 to 100 days), although the latter have much heavier body weight (42). Daily production of semen in rams of 18 months of age was lower in R than in IdF. This difference between the two breeds cor- responds to a lower total number of Sertoli cells in the R at 3 months of age (26, 27). However, the daily production of semen of the 559 560 Table 1. Litter size of Romanov ewes in 4 systems of reproduction: Distribution of LS and influence ofage at lambing Mating periods LS Sept. to Dec. (100 %) Sept. to Dec. (80 %) Aug. to Oct. (50 %) June-July; Aug.-Sept.; only outdoors in and outdoors Nov. to Jan. (50 %) Jan-Feb.; Mar.-May in and outdoors indoors 1 5.5 % 9.0 % 5.8 % 9.7 % 2 20.4 30.5 29.0 40.3 3 38.4 41.9 46.7 37.1 4 28.9 16.0 17.4 11.5 5 6.3 2.6 1.0 1.5 6 0.4 n 3813 1815 1970 4280 CS 3.11 2.73 2.79 2.55 CV % 32.0 33.9 29.9 34.2 1 year (n) 2.24 (254) 2.13 (346) 2.16 (236) 2.28 (609) Ewe • 2 years (n) 2.83 (1641) 2.65 (461) 2.66 (352) 2.36 (1029) age adult (n) 3.24 (9662) 2.97 (1006) 2.93 (1382) 2.68 (2642) C 10—30 days 173 176 177 173 ADG< 130—70 days 185 225 189 200 n = No. of lambings. ADG = Average daily gain of lambs in g. Table 2. Distribution of ovulation rate in Romanov and Finn ewes (41). OR Romanov Finn 1 0.7 0.6 0.8 1.0 1.9 2 34.7 7.1 12.6 1.4 32.5 13.3 3 55.0 60.5 56.5 16.9 39.3 36.1 4 8.8 28.2 27.6 45.1 19.0 26.9 5 0.5 3.6 2.0 28.2 6.4 13.6 6 0.2 0.4 8.4 1.4 4.1 7 0.3 1.6 8 1.6 9 0.9 x 2.74 3.27 3.19 4.25 3.03 3.69 o 0.66 0.67 0.72 0.88 1.00 1.38 (V »o 24.1 20.5 22.4 20.8 32.9 37.4 n 556 496 246 71 295 316 age 10 mth 18 mth 10 and 2 to 7 1.5 to 3.5 >4 18 mth years years years Table 3. Litter size obtained at different levels of OR (embryonic mortality %) (From 41). OR 2 3 4 5 Romanov 1.90(5%) 2.61(13%) 3.17(21%) 3.58(28%) Finn 1.72(14%) 2.24(25%) 2.63(34%) 2.90(42%) Other 1.65(17%) 2.27(24%) 2.48(38%) breeds 1.1 to 2.0 1.9 to 2.7 1.3 to 3.2 R rams is less variable with the season. (15). Concerning the production of ejaculated sper- matozoa, a favourable effect on the accelera- tion of the intensity of collection has been ob- served (13). 111 Viability of lambs Mortality ofR lambs increases with increas- ing LS, but relatively less than in the other breeds. Also, in crossbreeding, R has favoura- ble direct effect on the viability of the lambs. So for the same birth-type or birth weight, mortality of the lambs is at minimum in R and intermediate in the crosses (Fig. 1) (3, 44, 46, 49, 22, 39, 63, 12). In the same flock, R lambs have a better viability in comparison with Finn lambs (10). Maternal behaviour during the first hours after parturition In primiparous ewes, disturbances in lick- ing lambs or acceptance at suckling was less frequent in R (10 %), than in Prealpes du Sud (35 °7o), or IdF (50 %). Aggressive behaviour was also less frequent in R ewes (38). IV Milk production R ewes have a lower milk production than BC or Lacaune ewes, but they suckle a maxi- mum of twin or triplets, without reducing via- bility until weaning nor growth after weaning (10, 21, 23). V Carcass quality Compared to meat breeds, the carcasses of R lambs have a bad conformation, a lower proportion of bone, a higher proportion of in- ternal fat, less a fibres and a higher propor- tion of (3 fibres in the muscle (1, 6, 52, 59, 64). Since 1978, a multibreed testing Station (Berrytest) was created to evaluate the within breed variability and to qualify breeding animals on growth rate and carcass quality (4). The breeding stock of the Berrytest Station consists of 200 R ewes and 750 crossbred R x IdF or R x BC ewes, managed according to a rhythm of 3 lambings in 2 years. In 1986, 496 sires from 9French meat breeds have been progeny tested through 13825 progeny lambs (5, 6). VI Resistance to parasitism, caseous lymphadenitis, cold exposure 1. Resistance of R ewes to gastro intesti- nal strongylosis: the results don’t show detectable relationship between hemo- globin type and resistance to haemon- chus contortus (32). Susceptibility to gastro intestinal nema- todes: on the Causse of Larzac, the R breed shows a higher natural suscepti- bility to gastrointestinal nematodes vs Lacaune breed (25). Fig. I. Mortality of Berrichon du Cher (BC), Romanov (RO) and crossbred (F 3 to F„) lambs, according to their birth weight: singleton and twins in BC; singletons, twins and triplets in crossbreds: twins and triplets in RO o—O BC; A—A RO; x X F 4 to F, (From 39). 561 Comparison between R, Merinos d’Arles (MA) and crossbreds ewes. The expression of parasitic level, based on faecal egg and larval counts, signifi- cantly increases from MA to crossbreed and R for gastrointestinal nematodes, moniezia spp., dictyocaulus filaria, and in contrast, decreases for fasciola hepatica and protostrongylus (mainly neostrongylus linearis). The mecanism of resistance involved seems different between the breeds for the two groups of helminth parasites. (11, 24). On irrigated grasslands (Camargue), the R and MA ewes suckling 1 or 2 lambs, have a similar grazing be- haviour. However, the R ewes which are heavier, have less dry matter intake per Kg of live weight (60). 2. Susceptibility to an experimental Corynebacterium Ps. inoculation. R lambs seem to have a greater suscep- tibility compared to Prealpes du Sud and IdF. They develop most and more severe typical abscesses (37). 3. Concerning the resistance to cold ex- posure, in condition of transhumance, cf. Vermorel et al. (62). VII Utilization of Romanov In pure bred: According with flock size or economic situation, about 20 to 40 % of the ewes are mated with R pure rams to produce replacement. The remainder ones are devot- ed to industrial crossing. Crossbreeding with R allows rapid upgrad- ing of LS to the optimal level of 2.0, either by producing FI ewes (80 000 in 1987), or es- tablishing synthetic line, the INRA 401 (57). 1) Production of FI ewes Several experiments of crossbreeding be- tween R and different local breeds have been realized in the INRA flocks and on farms. In all cases, we observe a good via- bility of crossbred lambs (FI or born from FI dams) compared with purebred lambs of local breeds, a favourable heterosis ef- feet on ewe lambs fertility (78 % for the FI R x Lacaune) (8) and a good adaptation of FI ewes to extensive conditions. In accelerated rhythm of reproduction (3 lambings in 2 years). FI RxLim. : 2,66 weaned lambs/ewe/year 6200 ewes, 4 years. Limousine : 1,93 FI Rx : 1,92 Merinos d’Arles 2 flocks. Marzin et al. (33) Merinos d’Arles : 1,24 Litter size according to reproductive rhythm (3 lambings in 2 years vs 1 lambing/year)lambing/year) FIR : 2,27 vs 2,46 1 Brelurut (9) Limousine : 1,66 vs 1,87 > IdF : 1,61 vs 1,98 J One lambing per year in very extensive con- ditions (Gausses du Larzac and Mediterrane- an area: 5400 ewes in 12 years): the FI ewes (R x Lacaune and R X MA) have a superiori- ty of 0.45 weaned lamb per year vs local breeds (8). 2) The INRA 401 (43, 47, 51). This line is selected (in INRA experimental farm, near Bourges) in a specific reproductive system which consists of a first mating at 15 months out of season (April-May) and a second post-partum mating in October of the same year. The results are: fertility 0.86 and 0.82 respectively; LS 1.7 and 1.9; h 2 of fertility 0,06 and 0,03; of LS 0,13 and 0,08 (39, 56). Since 1980, 450 males INRA 401 have been used on farms, to serve a population of about 21 000 ewes in 143 flocks (55). Insertion of the Booroola (F) gene in the R breed Since 1986, an experiment was undertaken, for the understanding of mechanisms under- lying the regulation of OR. Observations on the FI lambs concern FSH levels and OR (20, 17, 53), use of hCG between 3 to 5 months to distinguish lambs carrying or not Booroo- la gene. 562 Conclusion With 15 000 R ewes, 80 000 FI ewes and 21 000 ewes issued from INRA 401 program, the total population of R and crossbreds represents about 115 000 ewes. R breed has been also introduced in Spain, Portugal, Italy, Hungary, Czechoslovakia, West Germany, and more recently in the Southern Mediterranean countries (Algeria, Tunisia, Egypt, Israel), South Africa and Canada Acknowledgments. We are grateful to Eric Moreau, UPRA Finnois-Romanov, for his collaboration. References 1. Boccard, R., & Dumont, 8.L., 1986. Evolution possible de la technologic de la viande ovine et con- sequences sur la composition (rapport muscle/os) des agneaux. I It Journ. Rech. 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