Slaughter value and quality of meat from Pomeranian lambs and crossbreds by Blackface and Charolaise rams

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1 Animal Science Papers and Reports vol. 24 (2006) Supplement 2, Institute of Genetics and Animal Breeding, Jastrzębiec, Poland Presented at the III Conference Genetic and environmental possibilities of adjusting the slaughter value and meat quality of animals to consumers requirements 7-8 September 2006, Lublin-Krasnobród, Poland Slaughter value and quality of meat from Pomeranian lambs and crossbreds by Blackface and Charolaise rams Henryk Brzostowski, Janina Sowińska, Zenon Tański Faculty of Animal Bioengineering, University of Warmia and Mazury in Olsztyn, Oczapowskiego 5, Olsztyn, Poland Selected indicators were compared of the slaughter value and quality of meat in 50-day-old pure Pomeranian lambs (P) and F1 lambs (P ewe x Blackface ram and P eve Charolaise ram - PB and PCh crossbreds, respectively). The slaughter value was determined based on live body weight, intestinal fat weight, dressing percentage, loin eye length and area, thickness of fat cover over the ribs and loin, proportions of valuable cuts in a carcass, and tissue composition of the leg. Meat quality was evaluated based on the chemical composition as well as the physico-chemical and sensory properties of quadriceps femoris muscle. PB and PCh lambs, as compared with P lambs, had higher live weight, a higher dressing percentage, a higher proportion of valuable cuts in a carcass, as well as more desirable lean-to-bone and lean-to-fat ratios in the leg. The length and area of loin eye were also greater in PCh lambs. Meat from PCh lambs, as compared to meat from lambs P, contained more protein and less collagen, and was characterized by a better water holding capacity, a lighter color, a greater diameter of muscle fibers, as well as worse tenderness and juiciness. Meat from PB lambs showed a lower collagen content and a smaller diametre of muscle fibers than meat from P lambs, as well as a higher fat content, better tenderness and juiciness than meat from PCh lambs. KEY WORDS: cholesterol / collagen / crossing / lambs / meat / slaughter value 53

2 Henryk Brzostowski et al. The principles of human nutrition change along with the progress of civilization. It follows that food products of animal origin, including lamb meat, have to meet higher and higher expectations. A high protein content accompanied by a low fat content, as well as the optimum fatty acid profile and good flavor characteristics, fulfilling the requirements of modern dietetics and prophylactic treatment, decide about consumer acceptance and interest in a given product [Hoffman et al. 2003, Kłobukowski et al. 2003]. Milk-fattened lambs (12-30 kg live weight) characterized by high meat content of carcasss, low fatness and health-promoting properties of meat, can satisfy these requirements [Borys et al. 2003, Brzostowski et al. 2004]. Taking into account the present breed structure of the sheep population in Poland, it seems that lamb meat quality can be improved through commercial crossing of ewes of regional breeds, perfectly adjusted to local environmental conditions, with rams of meat breeds. The results of such crossing are greatly affected by the proper choice of breed components [Pieniak-Lendzion et al. 1998, Brzostowski et al. 1999, Ciuryk i Kaczor 2001]. In the Pomeranian region an important role may be played in this respect by early-maturing Pomeranian ewes used for wool and meat production. Professional literature on the subject provides no information on the crossing ability of Pomeranian ewes with rams of mutton breeds, directed primarily towards the production of light slaughter lambs. Facing the above, the aim of this study was to determine the slaughter value and quality of meat from 50-day-old Pomeranian (P) ewes and F 1 crossbreeds of P ewes with Charolaise and Blackface rams. 54 Material and methods The investigation was performed on three groups of 50-day-old ram lambs. Group 1 were 12 pure Pomeranian lambs (P), group 2 were 12 F 1 PB lambs coming from crossing of P ewes with Blackface rams (B) and group 3 were 12 F 1 PCh lambs from crossing of P ewes with Charolaise rams. Apart from mother s milk, the lambs of all groups were offered mixed feed composed of meadow hay, maize silage and CJ concentrate, in accordance with lamb nutrient requirements [Ryś 1998]. The slaughter value was determined with the method recommended by the National Research Institute of Animal Production [Nawara et al. 1963], based on live body weight, intestinal fat weight, dressing percentage, loin eye length and area, thickness of fat cover over the last rib and loin, proportions of valuable cuts in a carcass and tissue composition of the leg. Meat quality was assessed based on the chemical composition as well as on the physico-chemical and sensory properties of quadriceps femoris muscle. The following determinations were made: dry matter by sample drying at 105 o C, crude protein by the Kjeldahl method, crude fat by the Soxhlet method, crude ash by sample ashing at 550 o C, gross energy with a KL 10 adiabatic bomb calorimeter, water holding capacity by the Grau and Hamm method [1953], color lightness with a Specol spectrocolorimeter with an R 045 remission attachment at a wavelength of

3 Adjusting the slaughter value and meat quality of animals to consumers requirements 560 nm, ph 24 hours post mortem with a Radiometr PHM 22 ph-meter, cholesterol with the method proposed by Komprda et al. [2000] with an EPOLL 20 colorimeter, collagen based on the amount of hydroxyproline [Blomfield and Farrar 1964]. Meat samples were hydrolyzed as described by Dzierżyńska-Cybulko and Kijowski [1982], following the removal of the outer collagen membrane (epimysium) containing less hydroxyproline and having a slightly different amino acid composition. Muscle fibre thickness was measured on samples of longissimus lumborum muscle taken immediately after slaughter, fixed in neutralized (ph 7.4) 10% formalin and paraffinembedded. Microtome sections were hematoxylin- and eosin-stained. Thickness measurements were performed by computer image analysis, using LUCIA 3.52a software. Sensory evaluation of meat was preceded by thermal treatment, as described by Baryłko-Pikielna [1975]. A five-point scale was applied, taking into account the following quality attributes of cooked meat: aroma (intensity and desirability), taste (intensity and desirability), tenderness and juiciness. The results were verified statistically by the analysis of variance in a one-factor orthogonal design, using STATISTICA 7 software. Results and discussion Rams of meat breeds mated to Pomeranian ewes had a positive effect on the live body weight and some carcass quality indicators in F 1 crossbred lambs (Tab. 1). Lambs by Blackface and Charolaise sires (PB and PCh crossbreds, respectively) had a significantly higher dressing percentage (48.21% and 48.16%, respectively) than purebred P lambs (46.83%). The proportion of valuable cuts was highly significantly lower (40.76%) in P lambs, as compared to PB (42.45%) and PCh (42.73%) lambs. These differences resulted primarily from significantly lower leg weight in the carcasses of P lambs. The leg tissue composition was also less desirable in P lambs. In comparison with the legs of PB and PCh lambs, the legs of P lambs contained by 2.39 and 2.09 per cent points (pp) less lean (P 0.01) and by 1.29 and 1.15 pp more bones. As a result, the values of the lean-to-bone and lean-to-fat ratios were also lower (P 0.05). The length and area of loin eye were also greater in PCh lambs than in P lambs. Borys et al. [2003] also demonstrated that the genotype affected the leg tissue composition and loin eye area in lambs. The above results show that both slaughter value and carcass quality of Pomeranian ewes, although satisfactory, can be substantially improved through crossing with properly selected rams of meat breeds. Also Lipecka et al. [2001] found that lambs with Charolaise genes had higher live weights and muscular tissue content than lowland lambs. The beneficial influence of Blackface sires on the slaughter quality of crossbred lambs was confirmed also by Brzostowski et al. [2001]. 55

4 Henryk Brzostowski et al. Table 1. Live body weight at slaughter and carcass quality indicators in lambs Trait Pomeranian Lamb group Pomeranian Blackface Pomeranian Charolaise mean V(%) mean V(%) mean V(%) Slaughter weight (kg) b a a Intestinal fat (%) Dressing percentage b a a 3.14 Loin length (cm) b a 8.49 Loin eye area (cm 2 ) b a 7.14 Fat over the loin (mm) Fat over the ribs (mm) a b Valuable cuts (%) B A A 3.97 Leg weight (kg) 1.14 b a a Leg composition lean (kg) lean (%) B A A 2.02 fat (kg) fat (%) bone (kg) bone (%) Lean to bone ratio 3.95 b a a 5.89 Lean to fat ratio 6.03 b a a aa... Means within rows bearing different superscripts differ significantly at: small letters P 0.05; capitals P Sire breed had a significant effect on some chemical and physico-chemical properties of meat (Tab. 2). Meat from PCh crossbred lambs, contained more protein and less fat and collagen (P 0.05), and was characterized by a better water holding capacity (P 0.05), a lighter color (P 0.01), and a greater diameter of muscle fibres (P 0.01) than P lambs meat. A significantly better W/P ratio, indicating better ripeness of meat from PCh lambs, results from a higher content of protein and a lower content of water. This confirms the opinion that protein is the main water-biding component, which was reflected by the best water holding capacity of meat from PCh lambs. A higher protein concentration in meat from crossbreds was also observed by Hoffman et al. [2003]. Meat from PB lambs contained less collagen, showed a lighter color (P 0.05), a smaller diameter of muscle fibres and a higher fat content than meat from PCh lambs. The lamb genotype had no effect on cholesterol level of meat. As 56

5 Adjusting the slaughter value and meat quality of animals to consumers requirements Table 2. Chemical composition and physico-chemical properties of meat in lambs Trait Pomeranian Lamb group Pomeranian Blackface Pomeranian Charolaise mean V(%) mean V(%) mean V(%) Dry matter (%) Crude protein (%) b a 3.27 Fat (%) a b Ash (%) Ratio W/P (Water/Protein) 4.36 A B 3.25 ph GE/100g Colour Aa b B 9.40 Water holding capacity (cm 2 ) 9.55 a b Cholesterol (mg/100 g) Collagen (mg/100 g) A Bb a 8.12 Muscle fibre thickness (µm) b B Aa 5.88 aa... Means within rows bearing different superscripts differ significantly at: small letters P 0.05; capitals P compared to meat from lambs aged 70 and 90 days, in a study conducted by Borys et al. [2003], the cholesterol content of meat from the lambs described in the present report can be considered low (P 52.43, PB 54.35, PCh mg/100 g). A sensory evaluation, including aroma, consistency (tenderness, juiciness) and palatability (Tab. 3), revealed that the genotype had a considerable effect on some quality characteristics of cooked lamb meat. Meat from PB lambs received the highest scores for tenderness (4.59 points) and juiciness (4.59 points), and that from PCh lambs the lowest (4.37 and 4.29 points respectively), P It seems that a significantly higher intramuscular fat content was responsible for the fact that meat from PB lambs got higher scores for the above quality attributes. According to Dankowski and Zielińska [8], intramuscular fat contributes to loosening of the muscular tissue microstructure, thus improving tenderness, juiciness and other sensory properties of lamb meat. A higher collagen content and a greater diameter of muscle fibres also deteriorated the tenderness and juiciness of meat from PCh lambs. Thinner muscle fibres, containing less collagen (the main component of connective tissue) are easier and faster digested by proteolytic enzymes in the stomach, and better utilized by humans [Oprządek and Oprządek 2000, Kłobukowski et al. 2003]. Due to a high protein content, low levels of cholesterol and collagen, as well as low calorific value, 57

6 Henryk Brzostowski et al. Table 3. Sensory evaluation of lamb meat (points) Trait Lamb group Pomeranian Pomeranian Pomeranian Blackface Charolaise mean V(%) mean V(%) mean V(%) Aroma intensity Aroma desirability Tenderness b 9.16 Juiciness a b 7.69 Taste intensity Taste desirability Overall evaluation ab Means within rows bearing different superscripts differ significantly at P meat from lambs of all genotypes analyzed in the present study can be recommended as a valuable component of a well-balanced healthy diet. Higher live body weight, a higher dressing percentage, a higher proportion of valuable cuts in a carcass, better meat content of carcass, a higher protein content and a lower collagen content, as well as a better water holding capacity and a lighter colour of meat, recorded in crossbred lambs indicate that Pomeranian ewes should be mated to Blackface, and especially to Charolaise rams. References BARYŁKO-PIKIELNA N., 1975 Zarys analizy sensorycznej żywności (An outline of the sensory evaluation of food). In Polish. PWN, Warszawa. BLOMFIELD L. J., FARRAR F., 1964 Factors affecting the determination of hydroksyproline. Analytical Chemistry. 20 (1964), BORYS B., JARZYNOWSKA A., BORYS A., 2003 Jakość zdrowotna mięsa lekkich jagniąt rzeźnych w zależności od wieku i genotypu (Dietary attributes of light slaughter lambs meat depending on age and genotype). In Polish, summary in English. Zeszyty Naukowe Przeglądu Hodowlanego 68, BRZOSTOWSKI H., TAŃSKI Z., SOWIŃSKA J., 1999 Jakość mięsa tryczków mlecznych owcy pomorskiej, ile de france oraz ich mieszańców (Meat quality in milk-fattened ram lambs of the Pomeranian and Ile de France breeds and their crosses). In Polish, summary in English. Zeszyty Naukowe Przeglądu Hodowlanego 43, BRZOSTOWSKI H., SOWIŃSKA J., TAŃSKI Z., 2001 The slaughter value and the quality of meat obtained from pomeranian sheep lambs and crossbreds of pomeranian ewes with meat-type rams. Polish Journal of Food and Nutrition Science 10/51, No. 3, BRZOSTOWSKI H., TYWOŃCZUK J., TAŃSKI Z., 2004 Indexes of nutritive value of meat obtained from Pomeranian lambs and crossbreeds of Pomeranian ewes with meat breed rams. Archiv fuer Tierzucht, Dummerstorf 47, Special Issue,

7 Adjusting the slaughter value and meat quality of animals to consumers requirements CIURYK S., KACZOR U., 2001 Wpływ standardu wagowego na wybrane parametry użytkowości mięsnej tryczków mieszańców po maciorkach polskiej owcy długowełnistej i trykach rasy Charolais (The effect of body weight at slaughter on selected slaughter parametres in crossbred (Polish Longwool ewes x Charolaise rams) ram lambs Roczniki Naukowe Zootechniki, Supplement, z. 11, DANKOWSKI A., ZIELIŃSKA M., 1999 Problem otłuszczenia jagniąt rzeźnych Cz. I. Zagadnienia ogólne (Fattness in slaughter lambs. Part I. General). In Polish. Przegląd Hodowlany 12, DZIERŻYŃSKA-CYBULKO B., KIJOWSKI J., 1982 Zarys przetwórstwa surowców zwierzęcych (Outline of Processing Animal Raw Products). In Polish. Published by the Agricultural University of Poznań. GRAU R., HAMM R., 1953 Űber das Wasserbindung vermőgen des toten Saugetiermuskels. J. Mitteilung. Der Einfluss des ph-wertes auf die Wasserbindung von der kleinertem. Rind der Muskel Biochemie 1-3, 325. HOFFMAN L. C., MULLER M., CLOETE S. W. P., SCHMIDT D., 2003 Comparison of six crossbred lamb types: sensory, physical and nutritional meat quality characteristics. Meat Science 65, KŁOBUKOWSKI J., BRZOSTOWSKI H., TAŃSKI Z., 2003 Composition and nutritional value of the meat protein of lamb. Polish Journal of Food and Nutrition Sciences 13, KOMPRDA T., ZELENKA J., TIEFFOVÁ P., ŠTOHANDLOVÁ, M., FOLTYN J., FAJMONOVÁ E., 2000 Effect of age on total lipid, cholesterol and fatty acids content in tissues of growing chickens. Archiv fuer Gefluegelkunde 64, LIPECKA Cz., GRUSZECKI T., KAMIŃSKA A., JANKUSZEW A., 2001 Growth and slaughter value of hybrid lambs with suffolk and charolaise share in genotype. Polish Journal of Food and Nutrition Sciences 3, NAWARA W., OSIKOWSKI M., KLUZ J., MODELSKA M., Wycena tryków na podstawie badania wartości potomstwa w Stacjach Oceny Tryków Instytutu Zootechniki za rok 1962 (The 1962 results of progeny-testing of rams in Ram Evaluation Stations). In Polish. Published by the National Research Institute of Animal Production, Cracow. Publication No OPRZĄDEK J., OPRZĄDEK A., 2000 Czynniki wpływające na jakość mięsa wołowego (Factors affecting beef quality). In Polish. Przegląd Hodowlany 8, PIENIAK-LENDZION K., NIEDZIÓŁKA R., SZELIGA W., 1998 Przydatność do tuczu i wartość rzeźna jagniąt polskiej owcy nizinnej oraz jej mieszańców z trykami ras mięsnych (Fattening ability and slaughter value of lambs of Polish Lowland sheep and its crosses with mutton rams) Zeszyty Naukowe Przeglądu Hodowlanego 37, PEISKER K.V., 1964 A rapid semi-mikro method for preparation of methyl esters from triglycerides using chloroform, methanol and sulphuric acid. Journal of American Oil Chemistry Science 41, RYŚ S., 1998 Normy żywienia bydła i owiec systemem tradycyjnym.(feeding standards for cattle and sheep according to traditional system). In Polish. Published by the National Research Institute of Animal Production, Kraków, Poland. 59

8 Henryk Brzostowski et al. Henryk Brzostowski, Janina Sowińska, Zenon Tański Wartość rzeźna i jakość mięsa jagniąt rasy pomorskiej i jagniąt mieszańców owcy pomorskiej z czarnogłówką i owcą rasy charolaise St r e s z c z e n i e Oceniano wybrane wskaźniki wartości rzeźnej i jakości mięsa 50. dniowych jagniąt owcy pomorskiej (P) i jej mieszańców po trykach rasy czarnogłówka (PB) i charolaise (PCh). W ocenie wartości rzeźnej uwzględniono: masę ciała przed ubojem, masę łoju okołojelitowego, wydajność rzeźną, długość i powierzchnię oka polędwicy, grubość tłuszczu nad żebrami i nad polędwicą, udział wartościowych wyrębów w tuszy oraz skład tkankowy udźcca. W ocenie jakości mięsa przeprowadzonej na mięśniu czterogłowym uda (m. quadriceps femoris) przeanalizowano skład chemiczny oraz właściwości fizykochemiczne i sensoryczne mięsa. Jagnięta PB i PCh charakteryzowały się wyższą niż jagnięta P masą ciała przed ubojem i wydajnością rzeźną, wyższym udziałem wartościowych wyrębów w tuszach, korzystniejszym stosunkiem mięsa do kości i mięsa do tłuszczu w udźcach, a jagnięta PCh także dłuższą i o większej powierzchni oka polędwicą. Mięso jagniąt PCh w stosunku do mięsa jagniąt P zawierało więcej białka, mniej kolagenu oraz charakteryzowało się lepszą wodochłonnością, jaśniejszą barwą, mniejszą średnicą włókien mięśniowych oraz gorszą kruchością i soczystością. Mięso jagniąt PB odznaczało się niższą zawartością kolagenu i mniejszą średnicą włókien mięśniowych niż mięso jagniąt P oraz wyższą zwartością tłuszczu, lepszą kruchością i soczystością niż mięso jagniąt PCh. 60