Evaluation of carcass and meat quality in Polish Landrace fatteners slaughtered at 128 kg live body weight

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1 Animal Science Papers and Reports vol. 24 (2006) Supplement 2, Ititute 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 coumers requirements 7-8 September 2006, Lublin-Krasnobród, Poland Evaluation of carcass and meat quality in Polish Landrace fatteners slaughtered at 128 kg live body weight Tadeusz Barowicz 1, Mariusz Pietras 1, Marek Pieszka 1, Władysław Migdał 2 1 Department of Feed Science, National Research Ititute of Animal Production, Krakowska 1, Balice, Poland 2 Department of Animal Products Technology, Agricultural University of Kraków, Balicka 122, Kraków, Poland The aim of the study was to evaluate the carcasses and meat obtained from Polish Landrace fatteners slaughtered at the live weight exceeding that being a common standard in pork production. The study involved 24 fatteners kept under the same conditio and fed a standard diet. Animals were slaughtered at 100 or 128 kg live body weight, their carcasses being dissected and meat samples taken from the longissimus dorsi (LD) muscle to determine its physico-chemical and seory traits, fatty acids profile, total cholesterol and TBARS value. The slaughter weight of pigs was found to affect the quality of the carcasses obtained. As the carcass weight increased, there were significant increase in backfat thickness, weight of loin and ham, and ham meat percentage. Meat content of carcass declined. No effect of carcass weight on dressing percentage and loin eye area was observed. Heavier carcasses were characterized by a higher content of fat, lower lightness (L) and less attractive aroma (P<0.05). There was no effect of slaughter weight on the fatty acid profile of LD muscle lipids or on the cholesterol content of the muscle. The ratio of n-6 to n-3 fatty acids was observed to be lower while TBARS to be higher in fatteners slaughtered at higher body weight (P<0.05). 29

2 Tadeusz Barowicz et al. It is believed that the decrease in meat content of carcass accompanying the increase in the fatteners weight at slaughter is mainly caused by the increasing carcass fatness. However, these animals produce much heavier loi and hams. KEY WORDS: cholesterol / carcass / fatty acids / meat quality /pig / slaughter value Modern pig breeding is driven by a desire to achieve high live weight gain and a relatively low feed intake. However, coumers are increasingly concerned with the quality of pork, especially its dietetic value (fat content, cholesterol level, and composition of fatty acids). In recent years, a growing trend has been observed in most European countries towards the slaughter of fattening pigs at higher body weight than common standard. Approximate data indicate that the weight of a typical pig carcass from the European Union increased over the last 5 years by 12%. A new system is being introduced in Germany, in which fatteners are slaughtered at 8-10 kg higher body weights than previously [Korytowska 1997]. It was found that slaughtering pigs at rather than kg body weight has no significant effect on growth rate, feed conversion or meat content of carcass [Kratz et al. 2000]. Some positive aspects of prolonged fattening of pigs were also observed. Dressing percentage and daily gain were at a similar level, with an approximately 2 mm thicker backfat and by 0.6 per cent points (pp) lower meat content of carcass. However, studies carried out by the Meat and Fat Research Ititute using large numbers of fatteners traported to abattoirs indicate that meatiness decreases by an average of 1.7 pp with each 10 kg increase in carcass weight within the kg range [Borzuta and Lisiak 2001]. This value is coidered representative of the mass population of Polish fatteners originating mostly from 2 different crossbreds. The aim of the present study was to compare the quality of carcasses and meat obtained from Polish Landrace fatteners heavier than standard. 30 Material and methods The experiment was carried out on 24 Polish Landrace fatteners with the mean body weight of 70 kg and assigned to two groups. Animals were kept in cages (4 animals per cage) and fed according to the feeding standards for pigs published by the Ititute of Animal Physiology and Nutrition [1993] with a pelleted, complete standard diet containing per kg of diet: 12.7 MJ metabolizable energy, 160 g crude protein, 65 g ether extract, 65 g crude fibre, 7.8 g lysine, 5.1 g methionine and cystine, 5.5 g total calcium and 1.8 g total phosphorus. Daily ratio were given in two feedings and animals were given cotant access to water. At the end of the experiment, the fatteners were slaughtered at 100 or 128 kg body weight (group 1 and 2, respectively. The dissection of right carcass-sides was carried out in accordance with the Pig Testing Station (SKURTCh) procedure presented by [Różycki 1996]. Meatiness was estimated on live animals using a Piglog-105 device during the weighing of animals on the day preceding slaughter. Meat samples were taken

3 Adjusting the slaughter value and meat quality of animals to coumers requirements from the longissimus dorsi (LD) muscle in the area between the last thoracic vertebra and the first lumbar vertebra. Meat samples were assayed for chemical composition [Budsławski and Drabent 1972], ph was measured in water homogenates according to the Polish Standard PN-77/A [1977], meat colour in the Lab system [CIE 1976] was measured using a Minolta CR-310 reflectance spectrophotometer, water binding capacity was measured in accordance with Grau and Hamm method [1953], and thermal loss (loss of meat juices) was determined during preparation of the meat for seory analysis. Meat samples were also subjected to lipid extraction using the method of Folch et al. [1957], followed by determination of the composition of fatty acids using gas chromatography (Varian 3400). Moreover, the lipid extracts of LD muscle samples were analysed for total cholesterol using the method of Rhee et al. [1982] and for the malondialdehyde (TBARS) as described by Salih et al. [1987] and modified by Pikul [1993] after 60-day storage at -19 C. The meat was also subjected to seory analysis after cooking to an internal temperature of 85 C, on a 5-point scale [Baryłko-Pikielna [1975]. Proximate chemical composition of feeds and meat was determined conventionally with the AOAC [1990] procedures.. The results obtained were evaluated statistically using analysis of variance and Student s t-test in the STATGRAPHICS Plus 4.0 software. Results and discussion The optimum slaughter weight of fattening pigs is determined by a number of factors such as genotype, feeding, sex, growth rate, production costs, requirements of the meat industry and purchase price [Borzuta and Lisiak 2001].The problem of optimum slaughter weight is complicated by a conflict of interest between producers and processors. Early termination of fattening to maximize production profitability is beneficial for the producer, while processors prefer higher slaughter weights to obtain commercially attractive products such as large loi or large hams and smoked baco [Migdał et al. 2004]. In the present study mean body weight of the slaughtered pigs was ±0.79 and ±4.26 kg for group 1 and 2, respectively, with respective daily gai reaching 780±15 g and 752±17 g. Feed conversion ratio (kg feed/kg gain) in group 1 and 2 amounted to 3.30±0.09 and 3.79±0.22 kg. Differences in slaughter weight had a significant effect on the quality of carcasses obtained (Tab. 1). As the weight of carcass increased (P<0.05), backfat thickness, weight of loin and ham, and meat content of ham increased significantly being accompanied by a decrease in meat content of carcass. Carcass weight had no effect on dressing percentage or loin eye area. Heavier carcasses were characterized by a higher content of crude fat, lower lightness (L) of meat and poorer meat aroma (P<0.05) - Table 2. The meat of heavier pigs showed a tendency towards better tenderness, juiciness and palatability. However, the inter-group differences were not found significant. The body weight at slaughter affected neither the fatty acid composition nor the level of cholesterol of LD (Tab. 31

4 Tadeusz Barowicz et al. Table 1. Carcass quality traits in fatteners slaughtered at different body weight Trait Slaughter weight 101 kg 129 kg Significance of difference Cold carcass weight (kg) Cold dressing percentage (%) Meat content of carcass (%) Mean backfat thickness from five measurements (mm) Weight of loin (kg) Loin muscle area (cm 2 ) Weight of ham (kg) Meat content of ham (%) 77.23± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±0.29 P<0.05; P<0.01; P>0.05. Table 2. Physico-chemical traits and seory properties of meat in fatteners slaughtered at different body weight Trait Slaughter weight 101 kg 129 kg Significance of difference Dry matter (%) Crude protein (%) Crude fat (%) ph 24 Water binding capacity (%) Colour L a b Cooking loss (%) Tenderness (points) Juiciness (points) Flavour inteity (points) quality (points) Palatability inteity (points) quality (points) 26.17± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±0.14 P<0.05; P>

5 Adjusting the slaughter value and meat quality of animals to coumers requirements Table 3. Composition of fatty acids (% of the sum), total cholesterol and malondialdehyde (TBARS) contents of the longissimus dorsi muscle after 60 days of storage at -19 C Item Slaughter weight 101 kg 129 kg Significance of difference Saturated fatty acids (SFA) Uatureted fatty acids (UFA) Monouaturated fatty acids (MUFA) Polyuaturated fatty acids (PUFA) n-3 PUFA n-6/n-3 PUFA Total cholesterol (mg/100 g fresh tissue) TBARS (mg/kg) 39.70± ± ± ± ± ± ± ± ± ± ± ± ± ± ± ±0.030 P<0.05; P> ). Narrowing of the n-6 to n-3 fatty acid ratio and an increased TBARS value were observed in fatteners slaughtered at higher body weights (P<0.05). Economic arguments seem to speak in favour of fattening pigs to higher slaughter weights [Płonka and Paschma 1975, Kondracki and Żebrowski 1991, Korytowska 1997]. One of these is the high price of piglets due to much poorer sow prolificacy than in the other European Union countries. The increase in the body weight of growing pigs is related to changes in digestion, absorption and nutrient and energy metabolism. Studies by Fandrejewski [1999], Fandrejewski et al and Raj et al. [2000] show that as the body weight of pigs increases the growth rate and carcass protein deposition decrease, and fat deposition increases. Our studies showed significant differences for most slaughter traits between the carcasses of pigs slaughtered at different body weight. The increase in carcass weight was accompanied by increased carcass fatness, loin and ham weight and decreased meat content of carcass. Similar findings were reported by Bąk et al. [1996], Migdał et al. [1999], Łyczyński et al. [2000], Gardzińska [2003] and Correa et al. [2006]. Orcutt et al.[1990] who slaughtered pigs weighing from 88 to kg, observed increased backfat thickness and loin eye area with increasing body weight. Body weight and carcass quality modify the chemical composition of meat and fats. Meller [1992] observed increased fat and dry matter content of the LD muscle with increased body weight of pigs. Correa et al. [2006] failed to observe the effect of the slaughter body weight of pigs (107, 115 and 125 kg) on meat ph. A their studies the higher fat content was characteristic of the meat of castrated males, while the protein content of muscle increased with the weight of carcasses and was higher in castrated males than in gilts. Surdacki et al. [1990] reported that the composition of depot fats depends on the breed of pigs. Puławska pigs are characterized by more saturated fat than white breeds. Likewise, in pigs characterized by greater meatiness, loin and ham 33

6 Tadeusz Barowicz et al. fat contain more uaturated fatty acids (UFA). As the slaughter weight increases, increases the degree of fat saturation and decreases the share of polyuaturated fatty acids (PUFA) - Gardzińska [2003]. Castrated males fat is more saturated than gilts fat [Piedrafita et al. 2001]. In the study presented here a tendency appeared towards increased degree of saturation and a decreased level of PUFA in the lipids of the LD muscle of fatteners slaughtered at higher body weight (129 vs 101 kg). Despite the many studies on the cholesterol content of pork, there are no conclusive data concerning the effect of age, weight, sex, breed and degree of carcass fatness on the level of cholesterol in meat and depot fat. Korzeniowski et al.[1992] showed that the meat of Polish Large White fatteners, characterized by a relatively high fat content compared to fatteners with different share of Duroc blood, also contained more cholesterol. The present report does not confirm these observatio. The increase in the fat content of the meat of pigs slaughtered at 129 kg body weight was not found related to the level of total cholesterol. In conclusion, the increase in slaughter weight of Polish Landrace pigs is accompanied by a significant decrease in meat content of carcass, mainly due to the increasing carcass fatness. Heavier animals gave significantly heavier loi and hams. There was no significant effect of the higher slaughter weight of pigs on most of the physico-chemical and seory traits, total cholesterol content and the fatty acid profile of meat lipids References AOAC., Official Methods of Analysis of Association of Official Analytical Chemists. Kenneth Helrich, 15 th edition, Arlington, Virginia, USA. BARYŁKO-PIKIELNA N., Zarys analizy seorycznej żywności. In Polish. WNT, Warszawa, BĄK T., WAJDA S., DASZKIEWICZ T., Grubość słoniny i skład szynek z tusz tuczników i macior o różnej masie. Materiały Konferencji Naukowej: Zootechniczno-ekonomiczne uwarunkowania mięsności świń. Rzeszów, , BORZUTA K., LISIAK D., Problemy z określeniem optymalnej masy ubojowej tuczników. Trzoda Chlewna 39, BUDSŁAWSKI J., DRABENT Z., Metody analizy żywności. WNT, Warszawa, CIE CIE Publication No. 15 (E-1.3.1, 1971/tc-1-1), Suppl. 2. Recommendatio on uniform colour spaces-colour difference equatio. Psychometric Color Terms, Commission Internationale de l Eclairage, Paris. CORREA J.A., FAUCITANO L., LAFOREST J.P., RIVEST J., MARCOUX M., GARIEPY C., Effects of slaughter weight on carcass composition and meat quality in pigs of two different growth rates. Meat Science 72, FANDREJEWSKI H., Rasy świń w świetle badań nad przemianą energii. Roczniki Naukowe Zootechniki Suplement, z. 3, FANDEREJEWSKI H., RAJ S., WEREMKO D., BURACZEWSKA L., SKIBA G., Protein and energy metabolism in pigs of two genotypes. In: Energy Metabolism of Farm Animals. EAAP Publ. (A. Chwalibóg and K. Christeen Eds.), EAAP publication, Wageningen Pers, Wageningen. FOLCH J., LEES M., STANLEY G.H.S., A simple method for the isolation and purification of total lipids from animal tissues. Journal of Biological Chemistry 226,

7 Adjusting the slaughter value and meat quality of animals to coumers requirements GARDZIŃSKA A., Wartość rzeźna tuczników mieszańców o różnej masie ciała (Slaughter value of crossbred fatteners of different body weight) Rozprawa doktorska (Thesis), Akademia Rolnicza w Krakowie, GRAU R., HAMM R., Eine einfache Methode zur Bestimmung der Wasserbindung im Muskel. Naturwissechaften 40, 29. KONDRACKI S., ŻEBROWSKI Z., Zawartość tłuszczu w mięśniu najdłuższym grzbietu tuczników rasy puławskiej i polskiej białej zwisłouchej ubijanych przy masie ciała od 90 do 140 kg (Content of fat in longissimus dorsi muscle in Pulawska and Polish Landrace fatteners slaughtered at different body weight). In Polish, summary in English. Roczniki Naukowe Zootechniki 18, KORYTOWSKA D., Czy ubijać w wyższej wadze? Slaugter at higher body weight? In Polish. Trzoda Chlewna 35, KORZENIOWSKI W., OSTOJA H., JARCZYK A., Zawartość cholesterolu w tkance tłuszczowej i mięśniowej świń czystych ras i ich krzyżówek (Cholesterol content of musle and fat of purebred and crossbred pigs) In Polish. Medycyna Weterynaryjna 48, KRATZ R., SCHULZ E., FLACHOWSKY G., GLODEK P., Soybean oil, sex, slaughter weight, cross-breeding - influence on fattening performance and carcass traits of pigs. In: Quality of meat and fat in pigs affected by genetics and nutrition (C. Wenk, J.A. Fernandez and M. Dupuis, Eds.) Wageningen Pers, Wageningen, ŁYCZYŃSKI A., POSPIECH E., URBANIAK M., FRANKIEWICZ A., RZOSIŃSKA E., BARTKOWIAK Z., Cechy rzeźne świń ubijanych przy różnej masie ciała (Slaughter traits in pigs slaughtered at different body weight) In Polish, summary in English. Roczniki Naukowe Zootechniki Supplement, z. 6, MELLER Z., Wpływ masy ciała i otłuszczenia tuczników na jakość mięsa wieprzowego (The effect of body weight and fatness of porkers on the quality of pork. In Polish, summary in English. Acta Academiae Agriculturae ac Technicae Olsteneis Zootechnika 35, MIGDAŁ W., GARDZIŃSKA A., KOCZANOWSKI J., KLOCEK C., TUZ R., STAWARZ M., Wartość tuczna i rzeźna tuczników mieszańców ubijanych przy różnej masie ciała (Fattening and slaughter performance in porkers of different body weights Roczniki Naukowe Zootechniki Suplement, z. 3, MIGDAŁ W., PAŚCIAK P., GARDZIŃSKA A., BAROWICZ T., PIESZKA M., WOJTYSIAK D., Wpływ czynników genetycznych i środowiskowych na jakość wieprzowiny (The effect of genetic and environmental factors on the quality of pork) Prace i Materiały Zootechniczne Zeszyt Specjalny, 15, Ititute of Animal Pysiology and Nutrition of the Polish Academy of Sciences, Normy żywienia świń i wartość pokarmowa pasz (Feeding standards for pigs and nutritive values of feeds). In Polish. Omnitech Press, Warszawa, ORCUTT M.W., FORREST J.C., JUDGE M.D., SCHINCKEL A.P., KUEI C.H., Practical mea for estimating pork carcass composition. Journal of Animal Science 68, PIEDRAFITA J., CHRISTIAN L., LONERGAN S.M., Fatty acids profiles in three stress genotypes of swine and relatiohips with performance carcass and meat quality traits. Meat Science 57, PIKUL J., Ocena technologiczna surowców i produktów przemysłu drobiarskiego (Technological assessment of raw materials and products of poultry industry. In Polish. Published by the Agricultural University of Poznań, PŁONKA S., PASCHMA J., Różnice w użytkowości tucznej i rzeźnej świń typu mięsnego ubijanych przy ciężarze 85, 100, 115 i 130 kg (Differences in fattening and slaughter performance between pork pigs slaughtered at the 85, 100, 115 and 130 kg live weight). In Polish, summary in English. Roczniki Naukowe Zootechniki 2,

8 Tadeusz Barowicz et al Polish Standard PN-77/A , Meat and Meat Products - determination of ph. Polska Norma PN-77/A RAJ S., FANDREJEWSKI H., WEREMKO D., SKIBA G., BURACZEWSKA L., ŻEBROWSKA T., HAN I.K., Growth performance, body composition and protein and energy utilization of pigs fed ad libitum diets formulated according to digestible amino acid content. Asian-Australian Journal of Animal Science 13, RHEE K.S., DUTSON T.R., SMITH G.C., HOSTETLER R.L., REISER R., Effects of changes in intermuscular and subcutaneous fat level on cholesterol content of raw and cooked beef steaks. Journal of Food Science 47, RÓŻYCKI M., Zasady postępowania przy ocenie świń w stacjach kontroli użytkowości rzeźnej trzody chlewnej (Rules and principles in evaluating pigs in pig testing statio). In: The present situation in pig breeding and evaluation. In Polish. Published by the National Research Ititute for Animal Production, XIV, SALIH M., SMITH D.M., PRICE J.F., DAWSON L.E, Modified extraction 2-thiobarbituric acid method for measuring lipid oxidation in poultry. Poultry Science 66, SURDACKI Z., WIELBO E., STASIAK A., BURDZANOWSKI J., WÓJCIK S., GRELA E., Jakość mięsa i charakterystyka chemiczna tłuszczu zapasowego świń ras czystych i mieszańców (Meat quality and chemical traits of store fat in purebred and crossbred pigs. In Polish, summary in English. Roczniki Nauk Rolniczych seria B, 106, Tadeusz Barowicz, Mariusz Pietras, Marek Pieszka, Władysław Migdał Ocena jakości tusz i mięsa tuczników pbz ubijanych przy masie ciała zwiększonej do 128 kg S t r e s z c z e n i e Celem prezentowanych badań była próba oceny tusz oraz mięsa uzyskanego od tuczników pbz cięższych niż standardowe. Badania przeprowadzono na 24 tucznikach utrzymywanych w jednakowych warunkach oraz żywionych standardową paszą. Zwierzęta ubito po przekroczeniu przez nie 100 lub 128 kg masy ciała, przeprowadzono dysekcję tusz oraz pobrano próbki mięsa z mięśnia najdłuższego grzbietu, w których określono cechy fizykochemiczne, seoryczne, skład kwasów tłuszczowych, cholesterol całkowity oraz liczbę TBARS. Wraz ze wzrostem masy tuszy istotnie rosła grubość słoniny, masa schabu i szynki, oraz zawartość mięsa w szynce. Następował spadek zawartości (%) mięsa w tuszy. Nie stwierdzono wpływu masy tuszy na wydajność rzeźną ani powierzchnię oka polędwicy. Cięższe tusze cechowały się wyższą zawartością tłuszczu surowego, ciemniejszym mięsem (L) oraz gorszym zapachem (P<0,05). Nie obserwowano wpływu masy ubojowej tuczników na skład kwasów tłuszczowych w lipidach mięśnia najdłuższego grzbietu ani na zawartość cholesterolu w tym mięśniu. Obserwowano zawężenie proporcji kwasów tłuszczowych z grupy n-6 do n-3 oraz wzrost liczby TBARS w przypadku tuczników ubitych przy wyższej (128 kg) masie ciała (P<0,05). Uważa się, że spadek zawartości mięsa w tuszy wraz ze wzrostem masy ciała ubijanych tuczników wynika głównie z rosnącego jej otłuszczenia. Od zwierząt takich pozyskuje się jednak polędwice i szynki o istotnie większej masie. 36