Arch. Tierz., Dummerstorf 49 (2006) Special Issue,

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1 Arch. Tierz., Dummerstorf 49 (2006) Special Issue, Rzeszów University of Technology, Faculty of Management and Marketing, Poland 2 Department of Food Science, Cracow University of Economics, Kraków, Poland MACIEJ POMPA-ROBORZYŃSKI 1 and WŁADYSŁAW KĘDZIOR 2 Effects of crossbreeding and different feeding systems on slaughter value and meat quality of lambs reared in natural pastures of the Beskid Sądecki Mountains Abstract Polish Mountain Sheep (PMS) lambs and their crossbreds with Bergschaf and Weisses Alpenschaf rams ( and ), fed extensively on pasture or semi-intensively on pasture and indoors, were investigated. The crossbreeding of PMS lambs with alpine rams had a positive effect on both live and slaughter traits. Superior live and slaughter traits were found in semi-intensively fed lambs, while their extensive grazing resulted in their lower fatness. Water holding capacity (centrifugal drip), the content of intramuscular fat and the fatty acid profile were considerably differentiated by the crossbreeding scheme used. Compared to semi-intensive feeding, extensive feeding had a significant effect on higher drip loss, lower level of unsaturated acids and higher level of saturated acids, and lower level of polyunsaturated fatty acids. The meat of the lambs was characterized by high sensory scores. Key Words: crossbreeding, lamb, feeding, slaughter value, meat quality Introduction Thanks to their unique natural diversity, the Beskid Sądecki Mountains have been included in the Natura 2000 European network of nature conservation sites on a transfrontier scale. A mountain lamb produced under these conditions should be associated with the origin and quality guaranteed trademark (DROŻDŻ and GÓRA- DROŻDŻ, 1999) and given an eco- or bio- label (VLACIL and MARGETIN, 1999). The Polish Mountain Sheep (PMS) is the only native breed of sheep for which mountains are the natural habitat. The breed has poorly developed meatiness traits, which makes this sheep hardly suitable for fattening (CIURUŚ and DROŻDŻ, 1995). This resulted in the need to import the Aalpine breeds Bergschaf (BF) and Weisses Alpenschaf (WAS) into Poland. These breeds are characterized by good meatiness, aseasonality, and resistance to harsh environmental conditions. The aim of the study was to determine the slaughter value and meat quality of The Polish Mountain Sheep and their and crosses with the Bergschaf and Weisses Alpenschaf rams, kept in different feeding systems (extensive on pasture or semiintensive on pasture and indoors). Material and Methods The experiment was carried out in the Sheep Research and Implementation Centre in Piorunka n. Krynica Zdrój, in the years , using 50 PMS lambs of equal age and their and crosses with the Bergschaf and Weisses Alpenschaf rams. Lambs were fed either in the extensive or semi-intensive system. The group of lambs reared extensively stayed on pasture throughout, in specially prepared rotational paddocks. Lambs from the second feeding group were grazed on pasture (regardless of weather conditions) and returned at night to the fold, where they received ground grain (0.25

2 269 kg/day/animal). Animals of both groups had access to water and salt licks with minerals. At 200 days of age, lambs were slaughtered and their carcasses cut using the method of NAWARA et al. (1963). Commercial classes of carcass muscling, developed as part of the EUROP grading system (Verordnung Deutsches Ministerium, 1993), were determined. Percentage of valuable cuts (best end of neck, saddle, leg and shoulder) was determined in right halfcarcass. Detailed dissection of the leg was performed. Musculus longissimus dorsi (Mld) area was determined using ECHOSCAN 2 software. Mld muscle was analysed for dry matter (PN-ISO 1442:2000), crude protein (PN 75/A-04018, 1975), fat (PN ISO 1444:2000), ph of meat after 24 h cooling (PN-A ), and water holding capacity (centrifugal drip) using the Grau and Hamm method (TYSZKIEWICZ, 1969). Sensory characteristics of meat (Musculus semimembranosus) were evaluated on a 5-point scale (BARYŁKO-PIKIELNA, 1975). Higher fatty acids were analysed using gas chromatography (VARIAN 3400) after previously extracting lipids according to FOLCH et al. (1957) and converting free fatty acids into methyl esters. The results were analysed statistically using multivariate analysis of variance, with genetic group and feeding system as differentiating factors (VOLK, 1973). Post-hoc analysis was performed using the Tukey s honestly significant difference (H) test. (OSTASIEWICZ, 2001). Results Throughout rearing, the lowest daily weight gains were obtained by PMS lambs (141 g), resulting in a preslaughter weight of kg. Compared to the other genetic groups, differences in the values of these traits were highly significant. Semiintensively fattened lambs had more rapid gains (by 44 g per day) and achieved body weights that were 16.5 kg higher than those obtained by extensively reared lambs (P 0.01) (Tab. 1). The lowest dressing percentage was obtained by PMS lambs (38.24%), which differed highly significantly from the other groups of crossbreds by 2.61 percentage units. The poor meatiness of PMS lambs is confirmed by the percentage of valuable cuts in half-carcass (54.42%), compared to 56.52% in the group of BF PMS and 60.15% in the group of WAS (WAS PMS) crossbreds (P 0.01). The difference between these groups of crossbreds was statistically significant. At the same level of significance, a difference of 2.12 percentage units was also found between feeding groups. Similar differences were also found among animal groups in loin eye area. All the crossbred groups had the highest content of muscle tissue ( %) compared to only 65.04% in the PMS group (P 0.01). In addition, legs of MPS lambs were characterized by the highest content of fatty tissue (9.63%) (P 0.01). The content of muscle tissue was significantly differentiated, and the content of fatty tissue highly significantly differentiated, by the type of feeding. These values were and 5.79% in the extensive group, and and 8.96% in the semi-intensive group. In the EUROP classification, best scores were given to the carcasses of crossbreds, especially WAS (WAS PMS) (60% in classes E to R) and poorest scores to the carcasses of PMS lambs (50% in classes O and P). The other 50% of carcasses were outside class P (Tab. 1).

3 270 Table 1 Daily gains, slaughter results and EUROP carcass classification Genetic group Trait Daily gain (g) Pre-slaughter body weight (kg) Dressing percentage Carcass grade (number/%) Valuable cuts (%) Loin eye area (cm 2 ) Leg tissue composition (%) ( ) WAS x Pog WAS x (WAS x ) Feeding group extensive semiintensive n A A A 165 B Bc Bc B Bc Bc B Bc Bc 173 B Bd Bd ** ** ** ** 5.2 E 1 / 10 1 / U 1 / 10 3 / 30 1 / 10 1 / 10 1 / 4 5 / 20 R 1 / 10 3 / 30 2 / 20 4 / 40 3 / 12 7 / 28 O 1 / 10 3 / 30 2 / 20 4 / 40 2 / 20 5 / 20 7 / 28 P 4 / 40 3 / 30 2 / 20 3 / 30 2 / / 44 3 / 12 Out of class 5 / 50 2 / 20 5 / 20 2 / 8 meat fat bones 54.2 A A A A 25.3 A 56.2 Bc B B B B Bc B B B B 1.6 Notes: PMS Polish Mountain Sheep, BF Bergschaf, WAS Weisses Alpenschaf A. B values with different letters differ highly significantly, P 0.01** a. b values with different letters differ significantly, P 0.05* 56.2 Bc B B B 2 B Bd B 72.6 B B B 56.4 * * ** * * ** 1.8 No significant differences were found between genotype groups in the basic chemical composition of meat and in the content of dry matter and crude protein, although significant differences were found in the content of fat (P 0.01). The highest level of crude fat was found in PMS lambs (3.40%), followed by % in the crossbreds. The highest centrifugal drip was found in the group of BF PMS crossbreds (27.30%) and the lowest in the WAS (WAS PMS) and BF (BF PMS) groups 23.46% and 24.50%, respectively (P 0.01). The drip loss of the meat was highly significantly differentiated by feeding. It was 28.08% in the extensive group and only 23.68% in the semi-intensive group (P 0.01). There were also differences in ph values between these groups (5.62 and 5.93, respectively; P 0.01). The feeding system did not significantly affect the chemical composition of meat, despite differences in crude fat content were found (2.54-3,04%). The meat of the genetic and feeding groups studied did not show significant differences in terms of sensory traits, while the high scores for these parameters point to the high eating quality of the meat (Tab. 2). 22.8

4 271 Table 2 Chemical composition, physical and sensory traits of lamb Genetic group Trait Dry matter (%) Crude protein (%) Crude fat (%) Water holding capacity (%) ph Aroma (pts) Tenderness (pts) Juiciness (pts) Palatability (pts) ( ) WAS x WAS x (WAS x ) Feeding group extensive semiintensive n For explanations see Table a AB , b A , b B , b AB , b B , ** , ** 2.69 Table 3 gives the composition (profile) of fatty acids. The fatty acid profile was considerably differentiated by the crossbreeding scheme used. Significant differences were found in the total level of particular groups of acids: saturated (P 0.01) and unsaturated (P 0.05), including polyunsaturated (P 0.01 and P 0.05), which resulted from differences in the level of the C10:0, C12:0, C14:0, C16:1, C18:0, C18:1, C18:2 and C20:4 acids. The meat fat of PMS lambs was significantly different from that of the crossbreds in the higher level of C18:2 (10.87%), C20:4 (1.86%) and PUFA acids (14.44%). Of the animal genetic groups studied, the meat of WAS (WAS PMS) was characterized by a significantly higher level of unsaturated (P 0.05), monounsaturated and polyunsaturated (also PUFA n-3) acids, and lower level of saturated acids (P 0.01). Significant differences in CLA content were not found in feeding and genetic group. Compared to semi-intensive feeding, extensive feeding significantly decreased (P 0.05) the level of C16:1 and C18:1 acids and the total level of unsaturated acids, and thus increased the level of saturated acids, as determined mostly by the higher proportion of the C18:0 acid. In the group fed in the semi-intensive system, there was a lower level of n-3 polyunsaturated fatty acids , Discussion The lowest weight gains obtained in the PMS group conform with the results of other authors (CIURUŚ and DROŻDŻ, 1995). Dressing percentage depends on many factors, in particular the breed and utility type of animals. The available literature provides inconsistent information on the dressing percentage of PMS lambs. In the

5 272 Table 3 Fatty acid profile of the musculus longissimus dorsi of lambs Trait C10:0 C14:0 C16:0 C16:1 C18:0 C18:1 C18:2 γ C18:3 C18:3 C20:4 SFA UFA MUFA PUFA PUFA-3 CLA PMS BF PMS Genetic group BF (BF PMS) WAS PMS WAS (WAS PMS) Feeding group extensive semiintensive N ab ab ab A AB Aa ab a A a AB A a a 3.25 a ab AB AB AB ab ab AB ab AB Ba ab ab b ab A A Ab ab ab AB ab AB B ab For explanations see Table 1, PUFA n-3: C18:3, C20:5 (EPA), C22:6 (DHA) 0.14 b 3.06 ab a A A B a b A a A Bb b ab ab b B B Ab b ab B b B B ab * * * ** * * * * * * * ** * * * * 0.89 studies of other authors (CIURUŚ and DROŻDŻ, 1988), dressing percentage was 37.8% and it was similar to our own findings. In a different study (CIURUŚ and DROŻDŻ, 1995), this parameter ranged from 41.7 to 42.0%.. Fat is that component of meat which shows the greatest dependence on genetic and environmental factors (KĘDZIOR, 2005). This has also been also confirmed by the present study, although studies investigating the effect of breed and crossbreeding on the chemical composition of meat also pointed to stable (KĘDZIOR, 1991) and differing content of protein (ROBORZYŃSKI et al., 2000). The results of studies indicate that the composition of fatty acids depends on genetic and nutritional factors. A review of literature (KĘDZIOR, 2004) shows that genetic factors, similar to the present study, result in significant differences in the level of

6 273 C12:0, C18:0, C18:1 and C18:2, as well as C16:0, C18:3, SFA, MUFA and PUFA acids. It is concluded from the present and other studies (ENDER et al., 2001; FISHER et al., 2000; GRUSZECKI et al., 2001; NÜRNBERG K. et al., 1966) that compared to the medium intensive and semi-intensive feeding systems, the pasture management of lambs results in a lower concentration of the C18:1 acid and a lower total level of unsaturated acids, and thus a higher level of saturated acids, while having an effect on the higher level of essential n-3 PUFA and their favourable ratio in relation to n-6 acids. Conclusions It was shown that the crossbreeding of the Polish Mountain Sheep with the Bergschaf and Weisses Alpenschaf alpine rams has a positive effect on both live (higher daily gains) and slaughter traits (higher dressing percentage, leg tissue composition, loin eye area). Lambs fed semi-intensively dominated in terms of live and slaughter traits, while their extensive grazing increased the muscle tissue content of leg and decreased leg fatness. The low scores of PMS ram carcasses on the EUROP scale in the higher weight standards prevent the use of this breed for the production of heavy lambs weighing between 35 and 45 kg. The carcasses of crossbreds were within the upper range of the classification and thus are suitable for marketing and exporting to EU countries. The crossbreeding scheme largely resulted in differences in water holding capacity of meat, the content of intramuscular fat and the profile of fatty acids. Compared to semiintensive feeding, extensive feeding had a significant effect on higher drip loss, lower level of unsaturated acids and higher level of n-3 polyunsaturated acids, and higher level of saturated acids. The meat of the genetic and feeding groups studied received high scores for sensory characteristics, being indicative of its high eating quality. References BARYŁKO-PIKIELNA, N.: An outline of sensory analysis of food (in Polish). WNT, Warszawa, (1975) CIURUŚ, J.; DROŻDŻ, A.: Comparison of the slaughter value of Polish Mountain Sheep and its three-breed crosses (in Polish). Rocz. Nauk. Zoot., T. 15, z. 1 (1988 ), CIURUŚ, J.; DROŻDŻ,A.: Studies on the slaughter value of meat lambs with different genotypes (in Polish). Rocz. Nauk. Zoot. 2 (1995), DROŻDŻ, A.; GÓRA-DROŻDŻ, E.: Sheep farming in shaping the landscape and development of mountain regions (in Polish), Aura 3 (1999), ENDER, K.; GRUMBACH, S.; ZUPP, W.; NÜRNBERG, K.: Influence of breed and production system on meat and fat composition in lambs, International Symposium Results of New Studies on Small Ruminants, AR, Poznań, (2001), s. 44 FISHER, A.V.; ENSER, M.; RICHARDSON, R.J; WOOD, J.D.; NUTE, G.R.; KURT, E.; SINCLAIR, L.A.; WILKINSON,R.G.: Fatty acid composition and eating quality of lamb types derived from four diverse breed x production systems, Meat Science 55 (2000), 2, FOLCH, J.; LEES, M.; STANLEY, G.H.S.: A simple method for the isolation and purification of total lipids from animal tissues, J. Biol. Chem. 226 (1957), GRUSZECK,I T.M.; KLEWIEC, J.; LIPIEC, A.; LIPECKA,CZ.; JUNKUSZEW, A.; BARANOWSKI, A.: Composition of the lipid fraction in muscles of lambs fattened accrodign to the feeding system (in Polish), Rocz. Nauk. Zoot., Supl. 11 (2001),

7 274 KĘDZIOR, W.: Genetic determinants of fatty acid composition in lamb meat (in Polish), Zesz. Nauk. AE, Kraków, 644 (2004), KĘDZIOR,W.: Sheep food products (in Polish), PWE, (2005), Warszawa KĘDZIOR, W.: Effect of single-stage crossing of Pogórza sheep on lamb meat quality (in Polish). Rocz. Przem. Mięs. Tłuszcz., 28: (1991) NAWARA, W.; OSIKOWSKI, M.; KLUZ I.; MODELSKA, M.: Cost evaluation of rams based on progeny testing in ram testing stations (In Polish), Instytut Zootechniki, 166: (1963), NÜRNBERG, K.; GRUMBACH, S.; PAPSTEIN, H.J.; MATTHES, H.D.; ENDER, K.; NÜRBERG, G.: Fetzusammensetzung von Lammfleisch. Fett/Lipid 98 (1996), 2, OSTASIEWICZ, W.: Statistical methods of data analysis (in Polish).: AE, Wrocław, (2001) PN-ISO 1442 Meat and meat products. Determination of moisture content (in Polish) (2000). PN-ISO 1444 Meat and meat products. Determination of free fat content (In Polish) (2000). PN-75A Agri-food products. Nitrogen determination with Kjeldahl s method and conversion into protein (In Polish) (1975). PN-A Meat and meat products. Determination of ph (In Polish) (1977). ROBORZYŃSKI, M.; KIEĆ, W.; KĘDZIOR, W.; KNAPIK, J.; KRUPIŃSKI, J.: Results of pasture rearing, slaughter value and meat quality of Polish Mountain Sheep and alpine ram crossbred lambs (in Polish). Rocz. Nauk. Zoot., Supl., z. 8: (2000), TYSZKIEWICZ, S.: Studying the physical properties of meat (in Polish). WNT, Warszawa. (1969) VERORDNUNG: Deutsches Ministerium für Ernährung, Landwirtschaft und Forsten über gesetzliche Handelsklassen für Schafsfleisch vom 21 Juni 1993, Nr. 3 Tag der Ausgabe: Bonn, den 26 Juni 1993 und Verordnung (EWG) Nr 461/93 der Kommission vom 26. Februar 1993 mit Bestimmung zum gemeinschaftlichen Handelklassenschema für Schlachtkörper von Schafen. Amtsblatt der Europäischen Gemeinschaft. Nr. L 49/74 ( ). VLACIL, R.; MARGETIN, M.: Ecological aspects of dairy utilization of sheep in Slovakia (in Polish), Symposium on Sheep and the Environment, Grodziec Śląski, (1999), VOLK, W.: Applied statistics for engineers (in Polish): WNT, Warszawa, (1973) Author, s addresses Prof. Dr habil. MACIEJ POMPA ROBORZYŃSKI ul. Dauna 18, KRAKÓW, POLAND Prof. Dr. habil. WŁADYSŁAW KĘDZIOR Cracow University of Economics, Department of Food Science KRAKÓW, POLAND