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Master's Dissertation
DOI
Document
Author
Full name
Annelise Aila Gomes Lobo
Institute/School/College
Knowledge Area
Date of Defense
Published
Pirassununga, 2019
Supervisor
Committee
Silva, Saulo da Luz e (President)
Rotta, Polyana Pizzi
Gomes, Marina de Nadai Bonin
Pesce, Domingos Marcelo Cenachi
Title in Portuguese
Estudo da relação entre indicadores de estresse pré-abate com características qualitativas e metabolismo muscular pós-morte de bovinos terminados a pasto
Keywords in Portuguese
Corte escuro
Cortisol
Pastagem
pH
Potencial glicolítico
Qualidade de carne
Abstract in Portuguese
O objetivo do presente estudo foi avaliar a relação entre indicadores de estresse pré-abate com características de qualidade e metabolismo pós-morte de bovinos terminados em pastagem. Foram colhidas amostras do músculo Longissimus de 55 bovinos da raça Nelore (Bos indicus), não castrados, terminados exclusivamente em pasto. Do total de animais abatidos, foram selecionadas 29 carcaças, de acordo com o pH e classificadas em dois tratamentos: DFD (pH ≤ 5.8; n=13) e normal (pH > 5.8; n=16). Durante a sangria, foram colhidas amostras de sangue para as análises de cortisol e de lactato plasmáticos. Foram colhidas amostras do músculo Longissimus thoracis no dia do abate para as análises de metabólitos e pH e 48h após foram retirados dois bifes de 2,5 cm de espessura cada um, para análises instrumentais de qualidade de carne após 0 ou 14 dias de maturação. Não foi observada diferença entre os tratamentos para lactato e cortisol sanguíneos. O pH reduziu com o tempo pós-morte para ambos o tratamentos, porém o tratamento DFD apresentou maiores valores em relação a carne com pH normal. Foi observada uma interação entre os tratamentos e os tempos avaliados para glicogênio (P = 0,006), lactato (P < 0,0001), G-6-P (P < 0,0001) e glicose (P < 0,0001). A concentração de glicogênio diminuiu ao longo do tempo. Os valores de perdas por cocção e força de cisalhamento foram maiores para o tratamento DFD (P = 0,01). Com relação à cor, foi observado maiores valor de L* (P = 0,01) e b* (P = 0,01) para carne DFD. O valor de a* foi maior para a carne normal na carne não maturada, porém após 14 dias o tratamento DFD apresentou maior valor. Foram observadas maiores concentrações de glicogênio muscular nos tempos 8h e 24h, assim como maiores valores de glicose, glicose-6-fosfato e menores concentrações de lactato para o tratamento DFD (P < 0,01). Os indicadores de estresse pré-abate não foram adequados para diferenciar carnes pelo pH final. Diferenças nos valores de pH final não recapitulam o mecanismo esperado de cortes mais escuros para as amostras de alto pH, enquanto que os metabólitos foram associados com diferenças encontradas no pH final, porém o mecanismo responsável por essa diferença não foi determinado.
Title in English
Study of the relationship between pre-slaughter stress indicators with qualitative characteristics and postmortem muscle metabolism of beef cattle
Keywords in English
Cortisol
Dark cutting
Glycolytic potential
Meat quality
Pasture
pH
Abstract in English
The objective of the present study was to evaluate the relationship between pre-slaughter stress indicators with quality characteristics and post-mortem metabolism of cattle grazing. Samples of the Longissimus muscle were collected from 55 Nellore (Bos indicus) bovines, non-castrated, exclusively grassfed. From the total of slaughtered animals, 29 carcasses were selected according to pH and classified into two treatments: DFD (pH ≤ 5.8, n = 13) and normal (pH> 5.8, n = 16). During slaghter, blood samples were collected for plasma cortisol and lactate analyzes. Samples of the Longissimus thoracis muscle were collected on the day of slaughter for metabolite and pH analyzes and 48 hours after two steaks of 2.5 cm thickness were removed for instrumental analyzes of meat quality after 0 or 14 days of maturation. No difference was observed between treatments for blood lactate and cortisol. The pH reduced with the time after death for both treatments, however the DFD treatment presented higher values in relation to the meat with normal pH. It was observed an interaction between the treatments and the times evaluated for glycogen (P = 0.006), lactate (P <0.0001), G-6-P (P <0.0001) and glucose (P <0.0001). The glycogen concentration decreased overtime. The values of cooking losses and shear force were higher for DFD treatment (P = 0.01). Regarding color, a higher value of L * (P = 0.01) and b * (P = 0.01) was observed for DFD meat. The value of a * was higher for normal meat in the unmated meat, but after 14 days the DFD treatment presented higher value. Higher concentrations of muscle glycogen were observed in 8h and 24h times, as well as higher glucose, glucose-6-phosphate and lower lactate concentrations for DFD treatment (P < 0.01). The pre-slaughter stress indicators were not adequate to differentiate meats by the final pH. Differences in the final pH values did not recapitulate the expected mechanism of darker cuts for the high pH samples, while the metabolites were associated with differences found in the final pH, but the mechanism responsible for this difference was not determined.
 
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Publishing Date
2019-08-29
 
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