Análise térmica da carne de coelhos

O objetivo deste trabalho foi avaliar o efeito da adição de condimentos na carne de coelho, sobre a estabilidade térmica de suas proteínas miofibrilares. Retalhos de 24 músculos Longissimus dorsis foram moídos e misturados, para a obtenção de um lote homogêneo. Foram adicionados, em alíquotas dessa carne: 1,0; 2,0 ou 3,0% de sal; 2,5; 5,0 ou 7,5% de sacarose e 1,5; 3,0 ou 4,5% de ácido acético 3% em solução aquosa, e uma mistura perfazendo 3% de sal, 5% de sacarose e 3% da mesma solução de ácido acético. Após homogeneização manual, as amostras foram mantidas em repouso sob refrigeração, por 30 minutos. Alíquotas da ordem de 10mg foram usadas para análise térmica e o restante, para análises de pH, proteínas e umidade. As análises térmicas foram realizadas em um calorímetro diferencial de varredura DSC-TA2010, a 10ºC/min, entre 0 e 100ºC. As curvas de DSC da carne pura apresentaram endotermas nas temperaturas de (Td) 58,4(0,7ºC (miosina) e 78,2(0,2ºC (actina), envolvendo entalpia (DHd) de 17,5J/g de proteínas. O sal e o ácido acético desestabilizaram as proteínas, provocando redução da Td da miosina e actina, contrariamente à sacarose, que apresentou efeito estabilizante. A adição da mistura dos condimentos desestabilizou as proteínas miofibrilares. Apenas o ácido, adicionado acima de 1,5%, provocou desnaturação das proteínas.

Efeito do método de abate e do sexo sobre a qualidade da carne de capivara (Hydrochaeris hydrochaeris)

O presente trabalho teve como objetivo avaliar o efeito de dois métodos de abate (MA) e do sexo sobre a qualidade de carne de capivaras. Os métodos de abate avaliados foram o humanitário (MH) e por tiro (MT), sendo utilizados 2 lotes de 10 animais, um deles contendo 5 machos e 5 fêmeas e outro com 8 machos e 2 fêmeas, nos quais foram avaliados os valores de pH na 1ª, 3ª, 5ª, 7ª, 9ª, 11ª e 24ª horas após o abate e a perda de peso por cozimento (PPC), a cor e a força de cisalhamento (FC), em porções do músculo longissimus dorsi, retiradas entre a 10ª e 12ª vértebras. Os resultados obtidos indicaram que as médias de pH não foram influenciadas pelo MA e pelo sexo. Os valores médios foram: 6,24; 6,05; 6,01; 6,01; 6,03; 6,04 e 5,96 às 1, 3, 5, 7, 9, 11 e 24 horas, respectivamente. Em relação à cor, o MT apresentou valor de L* (32,40) superior (P<0,05) ao MH (29,59), não sendo observado o efeito de sexo sobre esse parâmetro. Nos demais parâmetros de cor e na PPC não foram observadas diferenças entre os lotes. A FC foi influenciada pelo MA, sendo observado maiores valores (P<0,05) para MT do que para MH com médias de 5,04 e 3,97kgf, respectivamente.

Influência do sexo e faixas de peso ao abate nas características físico-químicas da carne de capivara

Este trabalho objetivou avaliar o efeito dos fatores sexo e faixas de peso ao abate (30-40, 40-50, 50-60kg) sobre o declínio de pH, pH final, cor, capacidade de retenção de água (CRA), perda de peso por cozimento (PPC) e força de cisalhamento (FC) da carne de capivara (Hydrochaeris hydrochaeris). As amostras do músculo longissimus dorsi (LD) foram obtidas de 28 capivaras (16 machos e 12 fêmeas), provenientes de um zoocriadouro. Não houve influência dos fatores sexo e faixas de peso ao abate sobre o pH as 2h (6,29), 5h (6,29), 8h (6,25) e 24h (6,01) post mortem; na cor (Sistema CIE LAB) para luminosidade (34,28), teor de vermelho (10,74) e teor de amarelo (1,74); CRA (0,47), PPC (32,27%) e FC (5,20kgf/g). Comparando com espécies domésticas, a carne de capivara apresentou pH final elevado; índice de luminosidade baixo e teor de vermelho elevado, assemelhando-se à carnes de bovinos e ovinos (carnes vermelhas); CRA e PPC dentro dos limites considerados normais; e, textura (FC) considerada macia.

Efeitos do sexo e do tempo de maturação sobre a qualidade da carne ovina

Foi realizado um estudo para verificar os efeitos do sexo e do tempo de maturação sobre a qualidade da carne de alguns cortes de ovinos. Foram utilizados os músculos Longissimus dorsi e Semimembranosus de cinco machos inteiros, cinco machos castrados e cinco fêmeas, com peso aproximado de 35kg. As variáveis pH, índice de fragmentação miofibrilar, perdas na cocção, força de cisalhamento, gordura intramuscular, cor e maciez sensorial foram determinadas após 1, 3, 7 e 14 dias de maturação da carne em refrigeração a 2ºC. A carne dos machos castrados e a das fêmeas apresentaram menor força de cisalhamento e maior maciez sensorial do que as de macho inteiro. Na carne de animais castrados foi observado um maior nível de gordura e menores perdas na cocção que na dos animais inteiros. O tempo de maturação da carne não afetou significativamente (p>0,05) a força de cisalhamento e maciez sensorial, indicando que a comercialização da carne destes animais, principalmente a dos machos castrados, poderá ser realizada com um dia (24 horas) de acondicionamento sob refrigeração a 2ºC.

Efeitos do grupo genético, sexo e peso ao abate sobre as propriedades físico-químicas da carne de cordeiros em crescimento

O objetivo desse trabalho foi avaliar a evolução do pH post mortem, cor, perda de peso por cozimento e força de cisalhamento dos músculos Longissimus dorsi (LD) e Semimembranosus (SM) de 49 cordeiros provenientes de cruzamentos entre as raças Bergamácia com Santa Inês (BgxSI) e Ile de France com Santa Inês (IFxSI), machos inteiros e fêmeas, distribuídos nos grupos pesos ao abate de 15, 25, 35 e 45kg. Os grupos genéticos apresentaram diferenças (P<0,05) sobre o pH dos músculos LD e SM, sendo que BgxSI apresentou média de pH mais elevada, do que IFxSI. O fator sexo não afetou a cor, entretanto o grupo genético influenciou (P<0,001) o valor L* e o valor a*; o valor L* de 35,25 e 32,89, para IFxSI e BgxSI, respectivamente; e o valor a* de 16,09 e 14,64, para BgxSI e IFxSI, respectivamente. A perda de peso por cozimento não foi influenciada pelos fatores grupos genéticos, sexos e grupos de peso. A maciez no músculo SM não foi afetada pelos fatores estudados. Entretanto no LD, os grupos de peso afetaram a maciez (P<0,05). Os grupos de 15 e 25kg apresentaram força de cisalhamento mais elevada (13,57 e 10,98kgf, respectivamente), do que os cordeiros de 35 e 45kg (8,56 e 7,97kgf, respectivamente).

Medições instrumentais e sensoriais de dureza e suculência na carne caprina

Foi avaliado o efeito do tipo de músculo e da maturação sobre algumas propriedades funcionais e sensoriais da carne caprina. Utilizaram-se os músculos longissimus dorsi, semimembranosus e biceps femoris de cabras com aproximadamente 20 meses de idade. A carne, sem maturar e maturada por sete dias, foi avaliada para perdas por cocção (PPC) e força de cisalhamento (FC), por métodos instrumentais, e para dureza sensorial (DS) e suculência sensorial (SS), por provadores treinados. As PPC não sofreram efeito significativo (p > 0,05) do tipo de músculo e da maturação da carne. A carne sem maturar do músculo semimembranosus apresentou maior FC que aquelas dos músculos longissimus dorsi e biceps femoris. Em relação ao tipo de músculo, após a maturação, as carnes dos músculos semimembranosus e biceps femoris se apresentaram mais macias que a do longissimus dorsi. Quanto ao efeito da maturação, a FC da carne do músculo semimembranosus diminuiu significativamente. A FC apresentou correlação positiva com DS e correlação negativa com SS. Dureza e suculência avaliadas de forma sensorial apresentaram correlação negativa. A maturação por 7 dias diminuiu a dureza, mas não afetou as PPC da carne dos músculos semimembranosus e bíceps femoris.

Carnes PSE (Pale, Soft, Exudative) e DFD (Dark, Firm, Dry) em lombo suíno numa linha de abate industrial

A necessidade para uma maior produção de carne magra em suínos tem acarretado modificações nas características bioquímicas do músculo conduzindo ao desenvolvimento das anomalias nas suas cores, as denominadas carnes PSE e DFD. Estas carnes por apresentarem alterações de suas propriedades funcionais, resultam em grandes perdas econômicas. Nesse experimento, foram utilizadas 946 amostras de Longissimus dorsi m., lombos de suínos da linhagem Dalland, machos castrados e fêmeas, com 100 dias de idade, em um Frigorífico localizado na Região Sul do País. Os lombos foram classificados com base no valor de L*24 h e pH24 h. Foi constatada uma incidência de 22,8% de carnes PSE, 1,0% de DFD e 76,2% de normal. Esses valores relativamente altos de carnes PSE mostram a necessidade de se realizar controles no seu manejo pré e pós-abate para a manutenção da qualidade da carne e evitar o excessivo prejuízo econômico dos frigoríficos decorrentes dessas anormalidades.

Effect of genotype, finishing system, and sex on physiochemical characteristics of goat meat

Seventy-eight kids of both sexes and five genotypes were used: Alpine, ½ Boer + ½ Alpine (½ BA), ¾ Boer + ¼ Alpine, ½ Anglo-nubian + ½ Alpine and "tricross" (½ Anglo-nubian + ¼ Boer + ¼ Alpine) with initial average weight of 14.1 ± 2.5. The objective was to evaluate the effect of genotype, finishing system, and sex on the physiochemical characteristics of goat meat. Finishing systems were: ST1 - kid + dam in pasture and ST2 - weaned kid and feedlot. Kids in ST1 were kept in an area with Panicum maximum cv. Tanzania, and after grazing, water and mineral salt/mix were fed ad libitum to the animals. The animals in ST2 were confined in collective pens distributed according to genotypes and received diet with 16% CP and 73% TDN. The values of pH, a* (red content), Cooking Loss (CL), and Ether Extract (EE) percentage were influenced by genotype. Values for red content (a*) and L* (brightness), CL and percentages of moisture, protein, EE, and ash were influenced by the finishing system. Longissimus dorsi muscle from animals ½ BA exhibited better physiochemical characteristics. For greater tenderness and higher percentages of fat, consumers should choose female kid goat meat.

Meat quality characteristics of exotic and SPRD crossbred goats from the semiarid region

Thirty-two intact male goats from four genetic groups (eight pure-bred Boers, eight ¾ Boer + ¼ SPRD crossbreeds, eight ½ Boer + ½ SPRD crossbreeds, and eight ½ Anglo Nubian + ½ SPRD crossbreeds) were evaluated for meat quality. The goats were reared in confinement and slaughtered at the average live weight of 29 kg. Temperature and pH decrease in the longissimus dorsi muscle was determined for 24 hours, and analyses of colour, cooking loss, water-holding capacity, and sensory attributes were also performed. Genotype significantly (P < 0.05) influenced the confinement period; ½ Boer + ½ SPRD crossbreeds required the most time in confinement to reach the target weight, while the pure-bred Boers required the least time. Genotype also significantly influenced (P < 0.05) the weight loss due to cooking, shearing force, colour (intensity of yellowness and luminescence), and the sensory attributes of flavour, odour, and raw colour of the meat. The crossing of exotic Boer and Anglo Nubian breeds with the native SPRD resulted in a goat meat of high quality.

Cassava root peel as a replacement for maize in diets for growing pigs: effects on energy and nutrient digestibility, performance and carcass characteristics

Two experiments were conducted to evaluate cassava root peel (CRP) as diet component for fattening pigs. In the first experiment, ten male pigs were used to investigate the nutrient digestibility and the nutritive value of CRP as replacement for maize in the diet at 0 %, 30 %, 40 %, 50 % and 60 %, while supplementing free amino acids (fAA). During two experimental periods, faeces were quantitatively collected and analysed for chemical composition. In the second experiment, 40 pigs received the same diets as in Experiment 1, and daily feed intake and weekly weight changes were recorded. Four pigs per diet were slaughtered at 70 kg body weight to evaluate carcass traits. Digestibility of dry and organic matter, crude protein, acid detergent fibre and gross energy were depressed (p<0.05) at 60 % CRP; digestible energy content (MJ kg^(−1) DM) was 15.4 at 0 % CRP and 12.7 at 60 % CRP. In the second experiment, CRP inclusion had only a small impact on feed intake, weight gain and feed conversion ratio (p>0.05) as well as on the length of the small intestine and the Longissimus dorsi muscle area. The missing correlation of daily weight gain and feed-to-gain ratio up to a CRP inclusion of 40 % indicates that negative effects of CRP on pig growth can be avoided by respecting upper feeding limits. Hence, a combined use of CRP and fAA can reduce feeding costs for small-scale pig farmers in countries where this crop-by product is available in large amounts.

Effect of magnesium sulphate and L-tryptophan and genotype on the feed intake, behaviour and meat quality of pigs

Sixty-nine entire male pigs with different halothane genotype (homozygous halothane positive – nn-, n=36; and homozygous halothane negative – NN-, n=33) were fed with a supplementation of magnesium sulphate (Mg) and/or L-tryptophan (Trp) in the diet for 5 days before slaughter. Animals were housed individually and were submitted to stressful ante mortem conditions (mixed in the lorry according to treatments and transported 1h on rough roads). Individual feed intake was recorded during the 5-day treatment. At the abattoir, pig behaviour was assessed in the raceway to the stunning system and during the stunning period by exposure to CO2. Muscle pH, colour, water holding capacity, texture and cathepsin activities were determined to assess meat quality. The number of pigs with an individual feed intake lower than 2kg/day was significantly different among diets (P<0.05; Control: 8.7%; Mg&Trp: 43.5%; Trp: 17.4%) and they were considered to have inadequate supplement intake. During the ante mortem period, 15.2% of pigs included in the experiment died, and this percentage decreased to 8.7% in those pigs with a feed intake > 2kg/day, all of them from the stress-sensitive pigs (nn). In general, no differences were observed in the behaviour of pigs along the corridor leading to the stunning system and inside the CO2 stunning system. During the stunning procedure, Trp diet showed shorter periods of muscular excitation than control and Mg&Trp diets. The combination of a stressful ante mortem treatment and Mg&Trp supplementation led to carcasses with high incidence of severe skin lesions. Different meat quality results were found when considering all pigs or considering only those with adequate supplement intake. In this later case, Trp increased pH45 (6.15) vs Control diet (5.96) in the Longissimus thoracis (LT) muscle (P<0.05) and pH at 24h (Trp: 5.59 vs C: 5.47) led to a higher incidence of dark, firm and dry (DFD) traits in SM muscle (P<0.05). Genotype affected negatively all the meat quality traits. Seventy-five percent of LT and 60.0% of the SM muscles from nn pigs were classified as pale, soft and exudative (PSE), while none of the NN pigs showed these traits (P<0.0001). No significant differences were found between genotypes on the incidence of DFD meat. Due to the negative effects observed in the Mg&Trp group in feed intake and carcass quality, the utilization of a mixture of magnesium sulphate and tryptophan is not recommended

Effect of high dose selenium enriched yeast diets on the distribution of total selenium and selenium species within lamb tissues

The objective of this study was to determine the distribution of total selenium (Se) and of the proportion of total Se comprised as the selenized amino acids selenomethionine (SeMet) and selenocysteine (SeCys) within the post mortem tissues of lambs that were fed high dose selenized enriched yeast (SY), derived from a specific strain of Saccharomyces cerevisae CNCM (Collection Nationale de Culture de Micro-organism) I-3060. Thirty two Texel X Suffolk lambs (6.87 ± 0.23 kg BW) were offered both reconstituted milk replacer and a pelleted diet, both of which had been either supplemented with high SY (6.30 ± 0.18 mg Se/kg DM) or unsupplemented (0.13 ± 0.01 mg Se/kg of DM), depending on treatment designation, for a continuous period of 91 d. At enrollment and 28, 56 and 91 d following enrollment lambs were blood sampled. At the completion of the treatment period, five lambs from each treatment group were euthanased and samples of heart, liver, kidney and skeletal muscle (Longissimus Dorsi and Psoas Major) were retained for Se analysis. The inclusion of high SY increased (P < 0.001) whole blood Se concentration, reaching a maximum mean value of 815.2 ± 19.1 ng Se/mL compared with 217.8 ± 9.1 ng Se/mL in control animals. Tissue total Se concentrations were significantly (P < 0.001) higher in SY supplemented animals than in controls irrespective of tissue type; values were 26, 16, 8 and 3 times higher in skeletal muscle, liver, heart and kidney tissue of HSY lambs when compared to controls. however, the distribution of total Se and the proportions of total Se comprised as either SeMet or SeCys differed between tissue types. Selenocysteine was the predominant selenized amino acid in glandular tissues, such the liver and kidney. irrespective of treatment, although absolute values were markedly higher in HSY lambs. Conversely selenomethionine was the predominat selenized amino acid in cardiac and skeletal muscle (Longissimus Dorsi, and Psoas Major) tissues in HSY animals, although the same trend was not apparent for control lambs in which SeCys was the predominant selenized amino acid. It was concluded that there were increases in both whole blood and tissue total Se concentrations as a result of dietary supplementation with high dose of SY. Furthermore, distribution of total Se and Se species differed between both treatment designation and tissue type.

Selenium persistency and speciation in the tissues of lambs following the withdrawal of dietary high-dose selenium-enriched yeast

The objective was to determine the concentration of total selenium (Se) and the proportion of total Se comprised as selenomethionine (SeMet) and selenocysteine (SeCys) in post mortem tissues of lambs in the six weeks period following the withdrawal of a diet containing high dose selenized yeast (SY), derived from a specific strain of Saccharomyces cerevisae CNCM (Collection Nationale de Culture de Micro-organism) I-3060. Thirty Texel x Suffolk lambs used in this study had previously received diets (91 days) containing either high dose SY (HSY; 6.30 mg Se/kg DM) or an unsupplemented control (C; 0.13 mg Se/kg DM). Following the period of supplementation all lambs were then offered a complete pelleted diet, without additional Se (0.15 mg Se/kg DM), for 42 days. At enrollment and 21 and 42 days later, five lambs from each treatment were blood sampled, euthanased and samples of heart, liver, kidney and skeletal muscle (Longissimus Dorsi and Psoas Major) tissue were retained. Total Se concentration in whole blood and tissues was significantly (P < 0.001) higher in HSY lambs at all time points that had previously received long term exposure to high dietary concentrations of SY. The distribution of total Se and the proportions of total Se comprised as SeMet and SeCys differed between tissues, treatment and time points. Total Se was greatest in HSY liver and kidney (22.64 and 18.96 mg Se/kg DM, respectively) and SeCys comprised the greatest proportion of total Se. Conversely, cardiac and skeletal muscle (Longissimus Dorsi and Psoas Major) tissues had lower total Se concentration (10.80, 7.02 and 7.82 mg Se/kg DM, respectively) and SeMet was the predominant selenized amino acid. Rates of Se clearance in HSY liver (307 µg Se/day) and kidney (238 µg Se/day) were higher compared with HSY cardiac tissue (120 µg Se/day) and skeletal muscle (20 µg Se/day). In conclusion differences in Se clearance rates were different between tissue types, reflecting the relative metabolic activity of each tissue, and appear to be dependant upon the proportions of total Se comprised as either SeMet or SeCys.

Effects of dietary supplementation with selenium enriched yeast or sodium selenite on selenium tissue distribution and meat quality in lambs

The objective was to determine the concentration of total selenium (Se) and the proportion of total Se comprised as selenomethionine (SeMet) and selenocysteine (SeCys), as well as meat quality in terms of oxidative stability in post mortem tissues of lambs offered diets with an increasing dose rate of selenized enriched yeast (SY), or sodium selenite (SS). Fifty lambs were offered, for a period of 112 d, a total mixed ration which had either been supplemented with SY (0, 0.11, 0.21 or 0.31 mg/kg DM to give total Se contents of 0.19, 0.3, 0.4 and 0.5 mg Se/kg DM for treatments T1, T2, T3 and T4, respectively) or SS (0.11 mg/kg DM to give 0.3 mg Se/kg DM total Se [T5]). At enrolment and at 28, 56, 84 and 112 d following enrolment, blood samples were taken for Se and Se species determination, as well as glutathione peroxidase (GSH-Px) activity. At the end of the study lambs were euthanased and samples of heart, liver, kidney, and skeletal muscle were retained for Se and Se species determination. Tissue GSH-Px activity and thiobarbituric acid reactive substances (TBARS) were determined in Longissimus Thoracis. The incorporation into the diet of ascending concentrations of Se as SY increased whole blood total Se and the proportion of total Se comprised as SeMet, and erythrocyte GSH-Px activity. Comparable doses of SS supplementation did not result in significant differences between these parameters. With the exception of kidney tissue, all other tissues showed a dose dependant response to increasing concentrations of dietary SY, such that total Se and SeMet increased. Selenium content of Psoas Major was higher in animals fed SY when compared to a similar dose of SS, indicating improvements in Se availability and retention. There were no significant treatment effects on meat quality assessments GHS-Px and TBARS, reflecting the lack of difference in the proportion of total Se that was comprised as SeCys. However, oxidative stability improved marginally with ascending tissue Se content, providing an indication of a linear dose response whereby TBARS improved with ascending SY inclusion.

Effect of plasma insulin and branched-chain amino acids on skeletal muscle protein synthesis in fasted lambs

The increase in fractional rate of protein synthesis (K-s) in the skeletal muscle of growing rats during the transition from fasted to fed state has been explained by the synergistic action of a rise in plasma insulin and branched-chain amino acids (BCAA). Since growing lambs Also exhibit an increase in K-s with level of feed intake, the objective of the present study was to determine if this synergistic relationship between insulin and BCAA also occurs in ruminant animals. Six 30 kg fasted (72 h) lambs (8 months of age) received each of four treatments, which were based on continuous infusion into the jugular vein for 6 h of: (1) saline (155 mmol NaCl/l); (2) a mixture of BCAA (0.778 mumol leucine, 0.640 mumol isoleucine and 0.693 mumol valine/min.kg); (3) 18.7 mumol glucose/min.kg (to induce endogenous insulin secretion): (4) co-infusion of BCAA and glucose. Within each period all animals received the same isotope of phenylalanine, (Phe) as follows: (1) L-[1-C-13]Phe; (2) L-phenyl-[ring H-2(5)]-alanine; (3) L-[N-15]Phe; (4) L-[ring 2,6-H-3]Phe. Blood was sampled serially during infusions to measure plasma concentrations of insulin, glucose and amino acids, and plasma free Phe isotopic activity; biopsies were taken 6 h after the beginning of infusions to determine K-s in in. longissimus dorsi and vastus muscle. Compared with control (saline-infused) lambs, K-s was increased by an average of 40% at the end of glucose infusion, but this effect was not statistically significant in either of the muscles sampled. BCAA infusion, alone or in combination with glucose, also had no significant effect on K-s compared with control sheep. K-s was approximately 60% greater for vastus muscle than for m. longissimus dorsi (P<0.01), regardless of treatment. It is concluded that there are signals other than insulin and BCAA that are responsible for the feed-induced increase in K-s in muscle of growing ruminant animals.