Maataloustieteellinen A ikakauskirja Vol. 60: 530—533, 1988 Prediction of the performance of synthetic sheep strains utilizing Finnsheep and native sheep breeds in Egypt H. MANSOUR 1 and A. M. ABOUL-NAGA2 1 Department ofAnimal Production, Faculty of Agriculture, Ains Shams University, Shubra A l-Khaima, Cairo, Egypt 2 Animal Research Institute, Ministry of Agriculture, Dokki, Cairo, Egypt Abstract. This investigation was carried out to estimate individual and maternal heterotic components for ewe productivity traits to enable predicting the performance of synthetics in- cluding local (Rahmani (R) and Ossimi (O)) and Finn (F) inheritance. Reproduction performance traits studied were number of ewes conceived (ECJ), number of lambs born (LBJ), number of lambs at four months of age (L4J), kilograms born (KBJ) and kilograms at four months of age (K4J), all being per ewe joined, and number of lambs born (LBL), number of lambs at four months of age (L4L), kilograms born (KBL) and kilo- grams at four months of age (K4L), all being per ewe lambed. Results indicate an expected increase of 0.32, 0.19, 0.50 and 0.27 in LBJ, L4J, LBL and L4L for F.R and 0.32, 0.23, 0.59 and 0.40 in the same traits for F.O after two generations of inter se mating, respectively. For FR.R and FO.O the improvements were (0.18, 0.18), (0.13, 0.15), (0.22, 0.28) and (0.15, 0.22) in LBJ, L4J, LBL and L4L, resp. It can be concluded that introducing the F to the local subtropical sheep in Egypt would substantially improve their reproductive performance whether for implementation at the small farmer level (quarter F) or at higher intensification level (half F). Index words: Finnsheep, Rahmani, Ossimi, crossbreeding, heterosis, synthetics, fertility, prolificacy, ewe productivity 1. Introduction In 1974, the Egyptian Ministry of Agricul- ture (MOA) started a crossbreeding program to improve the productivity of two native sheep breeds through crossing with the pro- lific Finnsheep (F). The program aimed at the development of improved synthetic lines of sheep with higher reproduction rate than the local sheep and suited to the prevailing sub- tropical conditions. This investigation was carried out to esti- mate individual and maternal heterotic com- ponents for ewe productivity traits to enable the estimation of performance of synthetics 530 JOURNAL OF AGRICULTURAL SCIENCE IN FINLAND including different portions of local and F in- heritance. 2. Materials and methods Data were collected from two MOA ex- perimental farms and consisted of 5 520 records from 1 316 ewes during 1974—1986. Flocks were raised under an accelerated lamb- ing system of three crops every two years (each two years were considered a block). Mating seasons lasted for 35 days and were in Sep- tember, May and January, and lambs were weaned at eight weeks of age. The plan was to mate F rams to both Rah- inani (R) and Ossimi (O) ewes to produce half- breds (FR & FO), respectively which were used to produce both reciprocal back crosses ({F.FR & FR.R) and (O.FO & RO.O), respec- tively, that were inter se mated. Nine different measurements of reproduc- tion performance were evaluated. Those relat- ed to fertility were: number of ewes conceived (ECJ), number of lambs born (LBJ), number of lambs at four months of age (L4J), kilo- grams born (KBJ) and kilograms at four months of age (K4J), all being per ewe joined. Those related to prolificacy were: number of lambs born (LBL), number of lambs at four months of age (L4L), kilograms born (KBL) and kilograms at four months of age (K4L), all being per ewe lambed. Data were analyzed by a least-squares fixed model, including effect of flock, block, sea- son of mating, parity and interactions between flock and block, season and parity and block and season along with four covariate terms. The covariate terms accounted for: (1) differ- ence between each of R or O minus F for direct effect of individual genes (gi), (2) differ- ence between each of R or O minus F for maternal environment of genes of the in- dividual’s dam, (gm) (3) individual heterosis between R & F and O & F, (hi) and (4) mater- nal heterosis between R & F and O & F (hm). Coefficients of these covariate terms for different types of matings were, according to Dickerson (4), as follows (L = local): gi gm hi hm FF —1 —1 0 0 LL 110 0 FL 0 110 L.FL 1/2 0 1/2 1 FL.L 1/2 1 1/2 0 (FL.L)2 1/2 1/2 3/8 1/2 Both breed paternal effect and paternal heterosis were assumed negligible. 3. Results and discussion Dickerson (4,5) discussed methods for utilizing the genetic diversity among breeds and factors determining it such as (1) individu- al (IG), maternal (IM) and paternal (IP) per- formance of purebreds and recombinations (R) effects in gametes produced by crossbred parents and (2) heterosis for individual (hi), maternal (hm) and paternal performance (hp). IG, IM and IP performances of a specific breed are non-estimable. In contrast differ- ences between breeds in individual (gi), mater- nal (gm) and paternal (gp) are estimable. Flete- rosis for individual, maternal and paternal be- tween breeds are estimable if the models and breed combinations used for the estimation are appropriate. This study aims at estimating the differences between local (L) -F purebreds individual breed and maternal effects and both individu- al and maternal heterosis. Estimates of gi, gm, hi and hm and their standard errors, from R-F and O-F analyses, are presented in table 1. These estimates were utilized in predicting potential difference be- tween native sheep and pure F and different L X F crossbreds (table 2), calculations were made according to the genetic expectations of both pure- and cross-breds, as in A-N and G (1). The relatively large standard errors, as- sociated with the estimates in table 1, are mainly a result of the large estimates of the error mean square of the traits studied. The total coefficient of determination (R2) from fitting the proposed model in this study for ewe reproduction traits were too low, (0.09 — 531 532 Table 1. Least squares estimates of gi, gm, hi and hm (multiplied by 100) from Finn-Rahmani and Finn-Ossimi crossbreds (and standard errors). Finn-Rahmani Finn-Ossimi gi gm hi hm gi gm hi hm Fertility ECJ 34 —27 40 —27 —BO 91 —76 83 (17) (17) (17) (16) (54) (53) (54) (53) LBJ 27 —49 66 —49 —199 175 —159 175 (28) (28) (28) (27) (86) (85) (86) (85) L4J 36 —4l 69 —4l —145 136 —lO7 137 (27) (28) (27) (26) (81) (80) (81) (81) KBJ 184 —192 258 —l9O —559 543 —4BB 545 (87) (82) (86) (84) (277) (275) (277) (275) K4J 396 —345 825 347 —834 845 —3Bl 791 (397) (304) (391) (389) (1190) (1192) (1192) (1181) Prolificacy LBL —9 —5O 32 —5l —l9 55 —77 66 (22) (22) (22) (22) (64) (63) (64) (63) L4L 5 —29 38 —3l —77 45 —37 55 (25) (25) (24) (24) (72) (72) (72) (72) KBL 70 —137 124 —139 —303 214 —252 255 (61) (61) (62) (62) (193) (192) (194) (192) K4L —2O —97 357 —132 683 —921 1108 —B5B (378) (378) (372) (371) (1096) (1088) (1098) (1088) Table 2. The predicted values for the difference between performance of different genotypes minus the local Räh- mäni and Ossimi. Difference Fertility Prolificacy ECJ LBJ L4J KBJ K4J LBL L4L KBL K4L Rahmani * • • * « F.F 14 —46 —lO —0.17 1.02 —llB —4B —1.34 —2.32 F.R —6 —4O —33 —0.74 —4.29 —42 —33 —0.54 —3.76 R.F —33 —BB —74 —2.67 —7.74 —9l —26 —1.91 —4.72 (R.F)2 14 —7 1 0.52 —0.15 —24 —l2 0.10 -1.62 (F.R)3 0 —32 —l9 —0.43 —l.BB —5O —2B —0.60 —2.28 R.FR —3 —2O —l6 —0.40 —2.13 —l9 —l4 —0.25 —1.53 FR.R —3 —2O —l6 —0.37 —2.14 —2l —l7 —0.27 —l.BB (FR.R)2 2 —l2 —8 —0.06 —l.ll —l6 —ll —O.ll —1.26 (FR.R)3 —1 —lB —l3 —0.30 —1.54 —23 —l5 —0.28 —1.42 Ossimi F.F 23 —4B —l7 —0.30 0.24 —129 —63 —1.79 —4.76 F.O —4 —4l —3B —0.71 —4.52 —42 —4O —0.51 —4.26 O.F 97 35 99 4.72 3.93 12 58 1.63 —13.46 (0.F)2 —34 —2O —92 —3.17 —5.88 —92 —6B —2.18 0.66 (0.F)3 8 —32 —23 —0.44 —1.93 —59 —4O —0.91 —3.63 O.FO 6 —2O —l9 —0.37 —1.72 —32 —29 —0.66 —2.76 FO.O —2 —2O —l9 —0.36 —2.26 —2l —2O —0.26 —2.13 (F0.0)2 —7 —4O —32 —0.97 —2.47 —36 —29 —0.78 —1.06 (F0.0)3 3 —lB —l5 —0.29 —1.48 —2B —22 —0.46 —2.13 Estimates are multiplied by 100. 0.18) and (0.18—0.30) for fertility and ture (3). Also, the contribution of the genetic prolificacy traits, respectively. This is in agree- part to the intra-breed total variation for these ment with R 2 estimates reported in the litera- traits are low (6). This would lead to a rela- lively large contribution of the unexplained variation. Egyptian native breeds, though are well adapted to the environment and the ewe is fer- tile all year round (2), greatly lack on litter size, a useful trait in any intensification sys- tem. MO A plan was to produce a ewe with low F inheritance, hence the 1/4 F 3/4 L, where the small holder can afford the inputs required. However, with some intensive lamb production systems, now in operation in Egypt with more than 15 000 ewes, there seems a room for larger degree of intensifica- tion utilizing ewes of higher inheritance of prolific breeds i.e. 1/2 F 1/2 L. Results in table 2 indicate an expected im- provement of (0.32, 0.19), (0.32, 0.23), (0.18, 0.13) and ((0.18, 0.15) in LBJ and L4J for F.R, F.O, R.RF and O.OF after two genera- tion of inter se mating, respectively. The ex- pected increase in LBL and L4L are (0.50, 0.28), (0.59, 0.40), (0.23, 0.15) and (0.28, 0.22) for the same synthetics, respectively. It can be concluded that introducing the F to the local Egyptian breeds would substan- tially improve their lamb output at different levels of F inheritance. However, the costs of these schemes in relation to their potential eco- nomic benefits and the performance of these crosses under the breeders condition should be evaluated before any wide scale applica- tion. References 1. Aboul-Naga, A.M. & E.S.E. Galal (1973). A note on the effect of interbreeding among backcrosses of sheep breeds. Anim. Prod. 16 (1): 87—90. 2. Aboul-Naqa, A.M., M.B. Aboui.-Ela, H. Mansour & M. Gabr (1988). Reproductive Performance of crosses between Finn and non-seasonal Egyptian sheep breeds under accelerated lambing system. Small Ruminant Res. (Submitted). 3. Alm ahoy, H. (1987). Estimation of genetic parameters of some reproductive traits in native fat- tailed sheep. M. Sc. thesis. University of Assiut, As- siut Egypt. 4. Dickerson, G.E. 1969. Experimental approaches in utilizing breed resources. Anim. Breed. Abstr. 37: 191. 5. Dickerson, G.E. 1973. Inbreeding and heterosis in animals. In: Proc. of Animal Breeding and Genetics Symp. in Honor of Dr. Jay L. Lush. pp. 54—77. Amer. Soc. Anim. Sci., Champaign, IL. 6. Hankahan, J.P. & J.F. Quirke (1985). Contribution of variation in ovulation rate and embryo survival to within breed variation in litter size. In Genetics of Reproduction in Sheep. (Eds. Land, R. and Robin- son, D.): 193—201. 533