Maataloustieteellinen A ikakauskirja Vol. 60: 540—545, 1988 Performance of crossbreds of Polish Merino dams with F, rams: Finnsheep X Polish Merino. A. Semi-intensive fattening of ram-lambs up to 40—45 kg M. OSIKOWSKI, B. BORYS and M. A. OSIKOWSKI Institute of Zootechnics, Experiment Station Koluda Wielka 88-160 Janikowo, Poland Abstract. The investigations were carried out to evaluate fattening ability , carcass quality and wool production of semi-intensively fattened ram lambs the progeny of F, rams: Finn- sheep (F)x Polish Merino (PM) mated to PM ewes. Two experiments were performed, on a total of 73 crossbreds and 73 purebred PM lambs. The lambs were housed together in a shed and fed farm-produced roughages, supplemented by commercially available concentrates. The crossbred lambs under semi-intensive feeding were found to have similar fattening ability as the purebreds: daily gains FxPMxPM 196 g and PM 191 g, energy consumption per 1 kg of body weight gain 26.1 and 27.0MJ, respectively. Crossbreeding did not affect slaughter value, but the commercial evaluation of live lambs was poorer in the crossbred groups. The tested crossbreds had generally better wool performance: their clean fleece weight was 1.09 kg, while that of the purebreds was 0.98 kg, rendement respectively 59.3 and 53.0 %, fibre length 6.7 and 5.4 cm, while fibre diameter was similar in the both groups. Index words: Finnsheep, Polish Merino, crossbreeding, fattening, semi-intensive, carcass quality, prolificacy, slaughter value Introduction Studies on two-stage commercial cross- breeding of Polish Merino (PM) using Finn- sheep (F) rams showed (6), in the first stage, that F, ewes had a much higher prolificacy (by about 50 %), but their wool production was lower than that of purebred PM (by 5.5 % clean yield), and F, ram lambs had a lower fattening ability and poorer slaughter value than purebred ram lambs. The positive effect of crossbreeding with F on prolificacy and negative on F, ram lambs slaughter value was also found by other authors (1). Therefore, studies were undertaken on a crossing scheme in which instead of F rams, F, Fx PM were used in the first stage. It was assumed that the female progeny would have lower prolificacy, but better wool production, and the male progeny better fattening perfor- 540 JOURNAL OF AGRICULTURAL SCIENCE IN FINLAND https://www.c-info.fi/en/info/?token=RGzLoMwR_Y9HI5nV.xTZmQjSiM2WjM8HPSaiImQ.oMcUsjcGzQiunROygeO_loFHpRC0yMT7NIYxkzRb4NYFHFgE4YNSfngSKn3_vONX3jUg50UrgA8V9LdT4mtuOm8a-9CLm9bdoXPZytQ952HXhozESgn4gcum5Pp3etED6p9pB7ATMuEBnaeuPL7prOu4_Q4CUE5GyT-CKe_PWsao9yaHyXgEfqHWrpw8D1cPCo42CNNp2gw mance than the progeny of F rams. Thus us- ing F, rams can be more effective than using purebred F rams, especially in large flocks, where at high prolificacy there are problems with lamb rearing. The immediate objective of the present in- vestigations was to evaluate fattening ability, slaughter value and wool production of ram lambs fed semi-intensively to 45 kg body weight. Materials and methods Two experiments were performed, in two replications each. The experimental flock con- sisted of 73 ram-lambs: progeny of PM dams mated to F, rams FxPM. The control group consisted of 73 PM purebreds. The lambs were fed in groups according to the standards of the Institute of Zootechnics for semi-inten- sive fattening (3); the feed consisted of farm- produced roughage and commercially availa- ble concentrates. Feed consumption was recorded every day, and the amount of residues was measured twice a week. The lambs were sheared upon reaching at least 37 kg body weight. Wool samples taken from the side were laboratory analysed for rende- ment, fibre length and diameter. Slaughter value was evaluated on lambs randomly select- ed for slaughter (in experiment 1 ten lambs from each group and replication; in experi- ment 2 eight lambs). The remaining lambs were commercially evaluated live, at the time when they were sold for export. Experimen- tal slaughtering, carcass division and partial dissection of the right half-carcass leg and breast was performed according to the Insti- tute of Zootechnics procedure (2). Muscle and fat tissue content in the half-carcass was esti- mated using multiple regression equations of Osikowski (5). Analysis of results was based on means, and significance of differences was estimated by double-factor (breed and replication) vari- ance analysis according to Ruszczyc (7). Results and discussion In the first experiment, no significant differ- ences were found in daily gains (DG) and body weight (BW) of the compared genetic groups (table 1). Also nutrient consumption per 1 kg gain (FE) was similar in both groups. In the second experiment the crossbred lambs (F x PM x PM) had better fattening performance: their superiority over purebred PM was 5.5 % in DG and 4.7 % in final BW (both at FE was lower in the crossbreds; by 6.4 °/o of energy and 6.1 % of total protein. In the first experiment, better fattening results were obtained in the first replication; in the second experiment also, but the differ- ences were less pronounced. Considerable differences were only found in FE. Fattening performance of both crossbreds and purebreds was poorer in the first than in the second experiment; in the latter it was similar to that normally obtained in fattening PM (4). The difference between the experi- ments and between replications may have been caused by different environmentalconditions, which varied with the year of the experiment. In neither experiment was there any clear difference between the tested groups, as regards their slaughter value (table 2). The only significant difference was the superiority of purebreds in the percentage of valuable cuts by 1.1 %. In both experiments the crossbreds tended to have a slightly higher dressing percentage, thicker fat and at the same time greater proportion of muscle tissue in comparison to the purebreds. More evident differences were found in live evaluation of lambs sold abroad, especially in experiment 2. In experiment 1, although all crossbreds and 95.4 °/o purebreds were sold, more purebreds were sold as »class extra» (by 6.4 %). The total number of lambs sold in this class from experiment 1 was very small. From experiment 2 the number of purebred lambs sold for export, including those classified as »extra» was high and did not differ from that obtained normally in semi-intensive fattening of PM lambs. The results of the crossbred 541 542 Table 1. Results of semi intensive fattening Experiment First Second Replication I+ 11 I II Interac- I+ 11 I II Interac- Breed FxPMxPM PMxPM FxPMxPM + PMxPM FxPMxPM PMxPM FxPMxPM + PMxPM " 0 " : breed x breed x repli- repli- cation cation Number of lambs 37 37 32 42 36 36 36 36 Body weight (BW) (kg): 2 days after birth 4.9 4.7 5.0 4.7 4.3 4.4 4.4 4.2 at the end of fattening 44.0 42.8 44.8 42.4 46.7» 44.6" 46.4 44.9 Age at the end of fattening (days) 216 215 204» 224» x 205 205 204 205 Daily gain (DG) (g) 183 184 198 A 173 A x 109» 198» 206 201 Consumption per 1 kg body weight gain (FE): energy (M J) 28.9 29.2 26.5 31.6 23.3 24.8 23.0 25.1 crude protein (g) 847 859 748 957 634 673 623 684 aa—Pso.os AA—P^O.OI x—PsJO.OS 7 Table 2. Slaughter value Experiment First Second Replication I+ 11 I II Interac- I+ 11 I II Interac- Breed FxPMxPM PMxPM FxPMxPM + PMxPM , t10 "' FxPMxPM PMxPM FxPMxPM + PMxPM J""? breed x breed x repli- repli- cation cation Number of lambs 20 20 20 20 16 16 16 16 Body weight before slaughter (kg) 44.3 43.6 44.0 43.8 45.8 44.5 45.8 44.4 Dressing »cold» (%) 45.5 44.7 45.1 45.1 46.4 45.7 45.7 46.5 Valuable cuts (%) 44.1 44.7 45.0 43.7 43. 3a 44. 4a 44. 9 A 42. 8 A Area of the »eye»of loin (cm 2 ) 13.8 14.2 13.4» 14.5" 16.2 15.8 15.4 16.6 Fat thickness overthe ribs (mm) 8.1 7.3 8.9A 6.4A 9.5 8.3 10.7 A 7.2A Estimated tissue composition of the half carcass(%) muscular tissue 62.9 62.1 63. 8 a 61.2 a 59.7 57.3 58.1 58.9 fat tissue 19.1 19.6 19.3 19.4 22.2 22.2 22.8 21.6 Classification of lambs sold for slaughter: number of lambs 17 22 17 22 23 24 21 26 % of lambs sold for export 100.0 95.4 94.1 100.0 78.3 95.8 71.4 100.0 % of lambs sold in extra class 11.8 18.2 11.8 18.2 26.1 58.3 19.0 61.5 aa— AA—P^O.OI 543 group were considerably worse: in percentage of lambs sold by 17.5 %, and in percent- age of lambs classified as »extra» by 32.2 %. The reason why the crossbreds had worse results of commercial evaluation of live lambs although their carcass performance did not differ from that of the purebreds, was prob- ably that in the commercial evaluation body conformation is the main factor taken into ac- count, and in this respect some crossbred ram lambs were inferior to the PM they had flatter trunks and less muscled thigh. On the other hand, many studies have shown (2, 5) that in lambs the correlation between live evaluation and carcass quality parameters is rather low. Considerable differences were also observed in both slaughter value and live evaluation, be- tween the two experiments as well as between the replications within one experiment. In most cases they were caused by the above mentioned differences in fattening perfor- mance, and in the case of commercial clas- sification by subjective evaluation. The investigated crossbreeding scheme had a significant effect on wool production of the lambs (table 3). Although greasy woolproduc- tion was similar in the both genetic groups, the crossbreds had over 6 % higher rendement (P<0.01) and thus their clean fleece weight was, in the first experiment 15.4 ®/o (signif.) and in the second experiment, 4.3 % (not sig- nif.) higher than in the purebreds. In both ex- periments the crossbreds had a greater fibre length (by 27.3 and 18.5 %, respectively P<0.01), while fibre diameter was similar in both groups. The significant interaction in rendement and fibre length found in experiment 1 is due to the fact that in the first replication differ- ences between groups were much greater than in the second one (11.7 versus 0.2 respective- ly in rendement, and 35.7 and 18.5 % in fibre length). On the whole, the effect of the investigat- ed crossbreeding scheme on wool production Table 3. Wool production Experiment First Second Replication I+ 11 I II Interac- I + II I II Interac- Breed FxPMxPM PMxPM FxPMxPM + PMxPM 1,"°!!' FxPMxPM PMxPM FxPMxPM + PMxPM '""V breed x breed x repli- repli- cation cation Number of lambs 36 36 32 40 36 36 30 42 Greasy wool 1 (kg) 2.2 2.1 2.2 2.1 xx 1.6 1.7 1.5 A 1.7 A Rendement (%) 57.6 A 51.0* 54.5 55.4 xx 61.5 A 55. 1 A 58.9 57.9 Clean wool' (kg) 1.22» 1.04» 1.13 1.12 0.97 0.93 0.89» 0.99» Fibre length 1 (cm) 7.0* 5.5 A 6.6 A 5.9 A x 6.2 A 5.4 A 5.6» 6.1» Fibre diameter (urn) 23.3 23.3 23.7 22.9 23.9 23.2 23.7 23.5 x aa—P 550.05, AA— Pso.ol, x—Pso.os, xx—P^O.ol 1 Values adjusted for average growth period: in the first experiment l9B days, in the second lB2 days. 544 of semi-intensively fed ram-lambs was posi- tive. Conclusions Male progeny of F, rams F x PM mated to PM ewes under semi-intensive fattening up to 45 kg body weight, in comparison with purebred PM, had the following characteris- tics: 1. similar, and in good environmental conditions even better fattening ability 2. similar carcass quality (dressing per- centage, tissue composition, loin eye area, fat thickness), and a little poorer performance at live commercial evalu- ation lower classification results due to flatter trunk and poorer thigh mus- cle of some the crossbreds 3.— better wool production: higher clean fleece weight and longer fibre but of similar fineness. References I. Maijala, K., 1979. Experiences of Finnsheep and its crosses as dams for fat lambs. Symp. Intens. Sheep Prod., Helsinki, 2—9. 2. Nawara, W., Osikowski, M., Kluz, I. & Modelska, M,, 1963. Wycena trykow na podstawie badania war- tosci potomstwa w Stacjach Oceny Trykow Instytutu Zootechniki za rok 1962. Wyd.wl. IZ nr 166,PWRiL Warszawa. 3. Normy zywienia zwierzat gospodarskich 1982. PWRiL Warszawa. 4. Osikowski, M., 1976. Organizacja i technologia produkcji owczarskiej w specjalistycznych gospodarst- wach indywidualnych. WOPR Minikowo 1/11. 5. Osikowski, M., 1977. Badania nad wspolzaleznoscis( miedzy pomiarami przyzyciowymi i poubojowymi a rzezna merynosowych. Rozprawa habilitacyjna. Wyd.wl. IZ nr 390. 6. Osikowski, M., Borys, B. & Korman, K., 1981. Dwustopniowe krzyzowanie towarowe owiec merynosowych z trykami ras plennych i mie.snych. Sprawozdanie z realizacji tematu PR-4, 4712.3. IZ Krakdw ZZD Koluda Wielka. 7. Ruszczyc Z., 1978. Metodyka dosvviadczeri zootech- nicznych PWRiL Warszawa. 545