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1.
Ann Oncol ; 31(12): 1746-1754, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-32866624

RESUMO

BACKGROUND: Immune checkpoint inhibitors (ICIs) have demonstrated significant overall survival (OS) benefit in lung adenocarcinoma (LUAD). Nevertheless, a remarkable interpatient heterogeneity characterizes immunotherapy efficacy, regardless of programmed death-ligand 1 (PD-L1) expression and tumor mutational burden (TMB). KEAP1 mutations are associated with shorter survival in LUAD patients receiving chemotherapy. We hypothesized that the pattern of KEAP1 co-mutations and mutual exclusivity may identify LUAD patients unresponsive to immunotherapy. PATIENTS AND METHODS: KEAP1 mutational co-occurrences and somatic interactions were studied in the whole MSKCC LUAD dataset. The impact of coexisting alterations on survival outcomes in ICI-treated LUAD patients was verified in the randomized phase II/III POPLAR/OAK trials (blood-based sequencing, bNGS cohort, N = 253). Three tissue-based sequencing studies (Rome, MSKCC and DFCI) were used for independent validation (tNGS cohort, N = 289). Immunogenomic features were analyzed using The Cancer Genome Atlas (TCGA) LUAD study. RESULTS: On the basis of KEAP1 mutational co-occurrences, we identified four genes potentially associated with reduced efficacy of immunotherapy (KEAP1, PBRM1, SMARCA4 and STK11). Independent of the nature of co-occurring alterations, tumors with coexisting mutations (CoMut) had inferior survival as compared with single-mutant (SM) and wild-type (WT) tumors (bNGS cohort: CoMut versus SM log-rank P = 0.048, CoMut versus WT log-rank P < 0.001; tNGS cohort: CoMut versus SM log-rank P = 0.037, CoMut versus WT log-rank P = 0.006). The CoMut subset harbored higher TMB than the WT disease and the adverse significance of coexisting alterations was maintained in LUAD with high TMB. Significant immunogenomic differences were observed between the CoMut and WT groups in terms of core immune signatures, T-cell receptor repertoire, T helper cell signatures and immunomodulatory genes. CONCLUSIONS: This study indicates that coexisting alterations in a limited set of genes characterize a subset of LUAD unresponsive to immunotherapy and with high TMB. An immune-cold microenvironment may account for the clinical course of the disease.


Assuntos
Carcinoma Pulmonar de Células não Pequenas , Neoplasias Pulmonares , Adenocarcinoma de Pulmão/genética , Adenocarcinoma de Pulmão/terapia , Ensaios Clínicos Fase II como Assunto , Ensaios Clínicos Fase III como Assunto , Humanos , Imunoterapia , Proteína 1 Associada a ECH Semelhante a Kelch/genética , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/terapia , Mutação , Fator 2 Relacionado a NF-E2 , Ensaios Clínicos Controlados Aleatórios como Assunto , Microambiente Tumoral
2.
Oncology ; 81(3-4): 230-6, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-22094540

RESUMO

OBJECTIVE: To evaluate two docetaxel-based regimens as first-line treatment in advanced breast cancer patients. METHODS: Patients were randomly assigned to docetaxel/gemcitabine (arm A: docetaxel 75 mg/m(2) on day 1, gemcitabine 1,000 mg/m(2) on days 1 and 8) or docetaxel/capecitabine (arm B: docetaxel 75 mg/m(2) on day 1, capecitabine 1,250 mg/m(2) twice daily on days 1-14); both chemotherapy regimens were repeated every 21 days. The primary objective of the study was to evaluate the response rate. RESULTS: Seventy-two patients were enrolled (36 each in arms A and B). Responses according to intention-to-treat analysis were as follows: arm A, 41.7% [95% confidence interval (CI) 25.6-57.8]; arm B, 38.9% (95% CI 23-54.8). Median progression-free survival was 10.9 months (95% CI 8.1-13.7) in arm A and 10 months (95% CI 8.8-11.2) in arm B. Overall survival was 26 months (95% CI 22.0-30.0) in arm A and 28 months (95% CI 23.4-32.6) in arm B. Both treatments were well tolerated; myelosuppression was the dose-limiting toxicity, with grade 3-4 neutropenia in 13.8 and 19.4% of the patients in arms A and B, respectively. No relevant differences in other toxicities were observed in the two arms, except for diarrhea (13.9%) and hand-foot syndrome (11.1%), which occurred only in arm B. CONCLUSIONS: Both regimens were active and well tolerated in advanced breast cancer.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Neoplasias da Mama/tratamento farmacológico , Adulto , Idoso , Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Capecitabina , Intervalos de Confiança , Desoxicitidina/administração & dosagem , Desoxicitidina/efeitos adversos , Desoxicitidina/análogos & derivados , Intervalo Livre de Doença , Feminino , Fluoruracila/administração & dosagem , Fluoruracila/efeitos adversos , Fluoruracila/análogos & derivados , Seguimentos , Humanos , Análise de Intenção de Tratamento/métodos , Pessoa de Meia-Idade , Gencitabina
3.
Animal ; 15(2): 100089, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33712220

RESUMO

In general, calf production occurs in less intensive systems. The limitation of nutrients during the gestation phase of beef cows can have negative impacts on the consequent productivity of females. Therefore, this study aimed to evaluate the effects of nutritional levels in the third trimester of pregnancy on the productive performance of beef cows kept in a natural pasture (NP). Eighty-three Charolais × Nelore cows were used, ranging in age from 4 to 12 years, which were divided according to their nutritional levels during the third trimester of pregnancy: NP, cows supplemented with 100% of their energy and protein requirements (SP100) and cows supplemented with 150% of their energy and protein requirements (SP150). The experimental design was completely randomized with three treatments and a varied number of repetitions. The SP100 and SP150 cows presented better body condition at calving (2.92 and 2.99 vs 2.81 points) and at the start of the breeding season (2.90 and 2.95 vs 2.80 points) than did NP cows. The nutritional level of the cows in the third trimester of gestation did not influence the blood metabolite concentrations. The plasma levels of albumin and total proteins were 3.11 and 8.18 g/dl, respectively. Glucose and cholesterol showed values of 74.96 and 166.50 mg/dl. The lowest concentration of blood metabolites was observed in the first postpartum weeks. The SP100 and SP150 cows showed faster follicular growth and, consequently, a higher percentage of females with ovulatory follicles at 21 days postpartum than did NP cows (45.68, 41.11, and 11.00%, respectively). The SP150 cows had a higher pregnancy rate (40.74%), total calf production (295.88 kg/cow), and consequently, offspring sale value. An increased nutritional level in the third trimester of pregnancy improves the postpartum metabolic condition and productive efficiency of beef cows kept on NP.


Assuntos
Suplementos Nutricionais , Período Pós-Parto , Ração Animal/análise , Fenômenos Fisiológicos da Nutrição Animal , Animais , Bovinos , Dieta/veterinária , Feminino , Lactação , Gravidez , Taxa de Gravidez , Estações do Ano
4.
Biomark Res ; 9(1): 57, 2021 Jul 13.
Artigo em Inglês | MEDLINE | ID: mdl-34256855

RESUMO

BACKGROUND: In Western countries, ovarian cancer (OC) still represents the leading cause of gynecological cancer-related deaths, despite the remarkable gains in therapeutical options. Novel biomarkers of early diagnosis, prognosis definition and prediction of treatment outcomes are of pivotal importance. Prior studies have shown the potentials of micro-ribonucleic acids (miRNAs) as biomarkers for OC and other cancers. METHODS: We focused on the prognostic and/or predictive potential of miRNAs in OC by conducting a comprehensive array profiling of miRNA expression levels in ovarian tissue samples from 17 non-neoplastic controls, and 60 tumor samples from OC patients treated at the Regina Elena National Cancer Institute (IRE). A set of 54 miRNAs with differential expression in tumor versus normal samples (T/N-deregulated) was identified in the IRE cohort and validated against data from the Cancer Genoma Atlas (TCGA) related to 563 OC patients and 8 non-neoplastic controls. The prognostic/predictive role of the selected 54 biomarkers was tested in reference to survival endpoints and platinum resistance (P-res). RESULTS: In the IRE cohort, downregulation of the 2 miRNA-signature including miR-99a-5p and miR-320a held a negative prognostic relevance, while upregulation of miR-224-5p was predictive of less favorable event free survival (EFS) and P-res. Data from the TCGA showed that downregulation of 5 miRNAs, i.e., miR-150, miR-30d, miR-342, miR-424, and miR-502, was associated with more favorable EFS and overall survival outcomes, while miR-200a upregulation was predictive of P-res. The 9 miRNAs globally identified were all included into a single biologic signature, which was tested in enrichment analysis using predicted/validated miRNA target genes, followed by network representation of the miRNA-mRNA interactions. CONCLUSIONS: Specific dysregulated microRNA sets in tumor tissue showed predictive/prognostic value in OC, and resulted in a promising biological signature for this disease.

5.
J Hematol Oncol ; 12(1): 111, 2019 10 29.
Artigo em Inglês | MEDLINE | ID: mdl-31665051

RESUMO

Breast cancer (BC) is a complex disease with primary or acquired incurability characteristics in a significant part of patients. Immunotherapeutical agents represent an emerging option for breast cancer treatment, including the human epidermal growth factor 2 positive (HER2+) subtype. The immune system holds the ability to spontaneously implement a defensive response against HER2+ BC cells through complex mechanisms which can be exploited to modulate this response for obtaining a clinical benefit. Initial immune system modulating strategies consisted mostly in vaccine therapies, which are still being investigated and improved. However, the entrance of trastuzumab into the scenery of HER2+ BC treatment was the real game changing event, which embodied a dominant immune-mediated mechanism. More recently, the advent of the immune checkpoint inhibitors has caused a new paradigm shift for immuno-oncology, with promising initial results also for HER2+ BC. Breast cancer has been traditionally considered poorly immunogenic, being characterized by relatively low tumor mutation burden (TMB). Nevertheless, recent evidence has revealed high tumor infiltrating lymphocytes (TILs) and programmed cell death-ligand 1 (PD-L1) expression in a considerable proportion of HER2+ BC patients. This may translate into a higher potential to elicit anti-cancer response and, therefore, wider possibilities for the use and implementation of immunotherapy in this subset of BC patients. We are herein presenting and critically discussing the most representative evidence concerning immunotherapy in HER2+ BC cancer, both singularly and in combination with therapeutic agents acting throughout HER2-block, immune checkpoint inhibition and anti-cancer vaccines. The reader will be also provided with hints concerning potential future projection of the most promising immutherapeutic agents and approaches for the disease of interest.


Assuntos
Neoplasias da Mama/terapia , Predisposição Genética para Doença , Imunoterapia , Receptor ErbB-2/genética , Antineoplásicos/uso terapêutico , Neoplasias da Mama/genética , Feminino , Humanos
6.
Breast ; 29: 96-101, 2016 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-27476084

RESUMO

PURPOSE: The everolimus and exemestane combination represents a treatment option for the endocrine sensitive metastatic breast cancer (MBC) patients. The toxicity profile reported in the Bolero 2 trial showed the feasibility in the selected patients. Few data are available for the unselected population. METHODS: In order to evaluate the safety in the unselected population of the clinical practice and to evaluate a possible association of toxicities with previous treatments, clinical data from 181 consecutive patients were retrospectively collected. RESULTS: Due to toxic events, everolimus dosage was reduced to 5 mg in 27% of patients. No association was found in the analysis between toxicity and number of prior therapies, neither between toxicity and response. In the multivariate analysis the previous exposure to anthracyclines for advanced disease represents the only predictive factor of developing grade ≥2 toxicity (OR = 2.85 CI 95% 1.07-7.59, p = 0.036). CONCLUSIONS: The association of everolimus and exemestane has confirmed to be a safe and effective treatment for endocrine sensitive MBC patients even in routine clinical practice. The rate of treatment discontinuation due to toxicity is low and none association between previous number of treatments and response or between toxicity and response was found.


Assuntos
Androstadienos/efeitos adversos , Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Neoplasias da Mama/tratamento farmacológico , Efeitos Colaterais e Reações Adversas Relacionados a Medicamentos/etiologia , Everolimo/efeitos adversos , Adulto , Idoso , Idoso de 80 Anos ou mais , Androstadienos/administração & dosagem , Antraciclinas/efeitos adversos , Protocolos de Quimioterapia Combinada Antineoplásica/administração & dosagem , Neoplasias da Mama/química , Neoplasias da Mama/patologia , Everolimo/administração & dosagem , Feminino , Humanos , Itália , Pessoa de Meia-Idade , Metástase Neoplásica , Modelos de Riscos Proporcionais , Receptor ErbB-2/análise , Análise de Regressão , Estudos Retrospectivos , Resultado do Tratamento
7.
Expert Rev Vaccines ; 15(10): 1327-36, 2016 10.
Artigo em Inglês | MEDLINE | ID: mdl-27063030

RESUMO

Human papillomavirus (HPV) is widely known as a cause of cervical cancer (CC) and cervical intraepithelial neoplasia (CIN). HPVs related to cancer express two main oncogenes, i.e. E6 and E7, considered as tumorigenic genes; their integration into the host genome results in the abnormal regulation of cell cycle control. Due to their peculiarities, these oncogenes represent an excellent target for cancer immunotherapy. In this work the authors highlight the potential use of therapeutic vaccines as safe and effective pharmacological tools in cervical disease, focusing on vaccines that have reached the clinical trial phase. Many therapeutic HPV vaccines have been tested in clinical trials with promising results. Adoptive T-cell therapy showed clinical activity in a phase II trial involving advanced CC patients. A phase II randomized trial showed clinical activity of a nucleic acid-based vaccine in HPV16 or HPV18 positive CIN. Several trials involving peptide-protein-based vaccines and live-vector based vaccines demonstrated that these approaches are effective in CIN as well as in advanced CC patients. HPV therapeutic vaccines must be regarded as a therapeutic option in cervical disease. The synergic combination of HPV therapeutic vaccines with radiotherapy, chemotherapy, immunomodulators or immune checkpoint inhibitors opens a new and interesting scenario in this disease.


Assuntos
Vacinas Anticâncer/administração & dosagem , Vacinas Anticâncer/imunologia , Infecções por Papillomavirus/complicações , Neoplasias do Colo do Útero/terapia , Ensaios Clínicos como Assunto , Descoberta de Drogas/tendências , Feminino , Humanos
8.
J Cancer Res Clin Oncol ; 140(2): 221-6, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24292401

RESUMO

PURPOSE: Diarrhea in relation to the lapatinib-capecitabine regimen is a common and debilitating side effect which may interfere with optimal treatment delivery. We performed a post hoc analysis in human epidermal growth factor receptor 2-positive advanced breast cancer patients treated with a modified schedule in its administration, aimed primarily to evaluate grade (G) ≥ 2 diarrhea incidence and, secondarily, treatment efficacy. PATIENTS AND METHODS: Treatment schedule consisted of lapatinib 1,250 mg daily for the first 10 days, then in combination with capecitabine, 2,000 mg/m(2), starting day 11 for the first cycle, and thereafter from day 8, for 14 days of a 21-day cycle, in 3 daily administrations. Lapatinib was dissolved in water, and cholestyramine was continuously given twice a day. RESULTS: Among 38 patients treated and analyzed, the incidence of G ≥ 2 diarrhea was 13.2 %. In 28 patients diarrhea was not observed, while G1-2 diarrhea was reported in 9 (23.7 %) patients; a single episode of G3 diarrhea was observed in 1 (2.6 %) patient. Overall response rate was 34.2 %, clinical benefit 55.3 %, and median progression-free survival 10 months. CONCLUSION: The results of the present post hoc analysis are very encouraging, both in terms of tolerability and treatment efficacy, and all data compare favorably with previous reports of "conventional" administration of the lapatinib-capecitabine regimen.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/mortalidade , Adulto , Idoso , Idoso de 80 Anos ou mais , Neoplasias da Mama/patologia , Capecitabina , Desoxicitidina/administração & dosagem , Desoxicitidina/análogos & derivados , Feminino , Fluoruracila/administração & dosagem , Fluoruracila/análogos & derivados , Seguimentos , Humanos , Lapatinib , Dose Máxima Tolerável , Pessoa de Meia-Idade , Metástase Neoplásica , Estadiamento de Neoplasias , Prognóstico , Quinazolinas/administração & dosagem , Receptor ErbB-2/metabolismo , Taxa de Sobrevida
9.
J Cancer Res Clin Oncol ; 139(5): 853-60, 2013 May.
Artigo em Inglês | MEDLINE | ID: mdl-23411686

RESUMO

PURPOSE: Recurrences and deaths are known to occur, even if less frequently, in small, node-negative breast cancer patients, and decision on adjuvant treatments remains controversial. In the present analysis, we evaluate recurrence risk in patients with pT1 a, b, c, node-negative, breast cancer, accordingly with some prognostic biological factors. METHODS: We retrospectively evaluated 900 node-negative patients (pT1a, b, c) surgery treated between 2000 and 2009 in four Italian oncologic centers. We defined 3 different cohorts: ER positive (ER+); Her-2 positive (Her-2+); and triple negative (TN). RESULTS: pT1a was seen in 7.6% of patients, 37.7 % pT1b, 54.8 % pT1c. Concerning the 3 different cohorts, 58.2 % were ER+; 10.8 % were Her-2+; 8.2 % were TN. Overall, chemotherapy was given to 3.0 %, 27.2 %, 69.8 % of pT1a, b, c, respectively, and to 22.7 %, 58.8 %, 68.9 % of ER+, Her-2+, TN subgroups. At a median follow-up of 67 months, 5-year DFS was 96.3 %, 89.2 %, 89.4 % in pT1a, b, c, respectively (100 %, 93.6 %, 89.8 % in ER+; 100 %, 78.7 %, 85.0 % in Her-2+; 100 %, 76.8 %, 85.2 % in TN) (p = ns). At multivariate analysis, histologic grade and Ki-67 resulted independent prognostic factors. Overall, 5-year OS was 98 %, without differences among pT1a, b, c, or among the 3 cohorts. CONCLUSIONS: Overall, 5-year DFS was very favorable in this series of small, node-negative breast cancers, but Her-2+ and TN cohorts have a higher recurrence rate than ER+ cohort (p < 0.0001); pT1c, but also pT1b, in Her-2+ and TN subgroups, have a worse outcome, and effective chemotherapy treatment should be considered in these unfavorable subgroups.


Assuntos
Neoplasias da Mama/epidemiologia , Neoplasias da Mama/patologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/metabolismo , Feminino , Humanos , Pessoa de Meia-Idade , Gradação de Tumores , Estadiamento de Neoplasias , Prognóstico , Receptor ErbB-2/metabolismo , Receptores de Estrogênio/metabolismo , Receptores de Progesterona/metabolismo , Recidiva , Estudos Retrospectivos , Risco , Análise de Sobrevida , Adulto Jovem
10.
Clin Ter ; 162(4): 297-9, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21912815

RESUMO

The classic view of tumor progression is that genetic mutation introduced in differentiated or progenitor cells causes tumors, through the acquisition of advantages for survival, and leading to phenotypic heterogeneity. Another theory (stem cell hypothesis) considers that tumor progression derives from cells within the tumor with stem cell characteristics of self-renewal and multiple differentiation potential. It is still unknown the timing of expression of various biological characteristics of breast cancer during the progression cascade, and the existence of clonal heterogeneity within primary tumor and synchronous or asynchronous distant metastases contributes to treatments failures.


Assuntos
Neoplasias da Mama/patologia , Neoplasias da Mama/genética , Diferenciação Celular , Células Clonais/patologia , Progressão da Doença , Estrogênios , Feminino , Genes erbB-2 , Humanos , Metástase Neoplásica , Neoplasias Hormônio-Dependentes/genética , Neoplasias Hormônio-Dependentes/patologia , Células Neoplásicas Circulantes , Células-Tronco Neoplásicas/patologia , Progesterona
11.
Clin Ter ; 162(2): 137-49, 2011.
Artigo em Italiano | MEDLINE | ID: mdl-21533321

RESUMO

Since the first cancer chemotherapy use, efforts have been made in identifying drugs with an antitumor specific action, but cancer is a very complex situation to be cured with a single agent, and to increase drugs selective cytotoxicity new agent combinations, or innovative cellular cycle related schedule, or the use of pro-drugs have been developed. Notwithstanding some relevant improvements in results, chemotherapy remains often a palliative approach. The improved knowledge of the biology of cancer, and of molecular mechanisms and specific targets, has recently modified the approach to various tumors. In particular, the identification of a single and specific genetic alteration in some tumors such as myeloid chronic leukaemia or gastrointestinal stromal tumors (GIST) led to the development of imatinib, a "target" drug with a multikinase inhibitor activity towards the specific genetic alteration; this unique opportunity is not applicable to other tumors, because usually tumors have multiple genetic alterations with very complex molecular pathways. The development of drugs with a multitarget action is probably the best approach to the majority of human cancers, but other possibility are the combination of multiple agents, each with known selective activity towards a specific molecular target, or the choice of a chemotherapic drug in combination with one or more molecularly targeted drugs. The knowledge of the multiple and extremely complex molecular pathways of the neoplastic cells will hopefully drive oncologic science towards a more "exact" science, with the use of "personalized" treatment in each cancer patient.


Assuntos
Antineoplásicos/uso terapêutico , Neoplasias/tratamento farmacológico , Antineoplásicos/farmacocinética , Previsões , Humanos , Modelos Teóricos , Terapia de Alvo Molecular , Neoplasias/metabolismo , Distribuição Tecidual
12.
Contrast Media Mol Imaging ; 5(4): 190-200, 2010.
Artigo em Inglês | MEDLINE | ID: mdl-20812287

RESUMO

The identification of genetic and biochemical mechanisms underlying tumor growth and progression along with the unraveling of human genoma provided a plethora of new targets for cancer detection, treatment and monitoring. Simultaneously, the extraordinary development of a number of imaging technologies, including hybrid systems, allowed the visualization of biochemical, molecular and physiological aberrations linked to underlying mutations in a given tumor. In vivo evaluation of complex biological processes such as proliferation, apoptosis, angiogenesis, metastasis, gene expression, receptor-ligand interactions, transport of substrates and metabolism of nutrients in human cancers is feasible using PET/CT and radiolabeled molecular probes. Some of these compounds are in preclinical phases of evaluation whereas others have been already applied in clinical settings. Here we provide prominent examples on how some biological processes and target expression can be visualized by PET/CT in animal tumor models and cancer patients for the noninvasive detection of well-known markers of tumor aggressiveness, invasiveness and resistance to treatment and for the evaluation of tumor response to therapy.


Assuntos
Neoplasias/diagnóstico , Tomografia por Emissão de Pósitrons/métodos , Tomografia Computadorizada por Raios X/métodos , Animais , Humanos , Neoplasias/diagnóstico por imagem
13.
Arq. bras. med. vet. zootec ; 61(2): 467-474, abr. 2009. tab
Artigo em Português | LILACS | ID: lil-518724

RESUMO

Avaliaram-se a composição física da carcaça e a qualidade da carne de 22 novilhos contemporâneos, com média de idade de 22 meses, das raças Charolês ou Nelore, terminados em confinamento, e que receberam diferentes proporções de concentrado na dieta. A fração volumosa da dieta foi composta pelas silagens de milho e sorgo em partes iguais. Os animais foram distribuídos em três tratamentos constituídos por 35, 50 ou 65 por cento de concentrado na matéria seca. Não houve efeito (P>0,05) da porcentagem de concentrado na dieta sobre a composição física da carcaça. A proporção de inclusão do concentrado influenciou (P=0,0013) positivamente a maciez da carne, aumentando em 0,026 pontos a cada ponto percentual de aumento do concentrado. As demais características qualitativas da carne não foram influenciadas (P>0,05) pelo aumento do concentrado na dieta. A carne dos novilhos Charolês apresentou textura mais fina, 4,15 x 3,14 pontos, foi mais macia, 6,85 x 5,71 pontos, mais suculenta, 7,17 x 5,77 pontos, e apresentou menor resistência das fibras ao cisalhamento, 3,79 x 5,79kgF. A carcaça dos novilhos Charolês apresentou maior deposição muscular, 65,5 x 61,5 por cento, e a dos novilhos Nelore apresentou maior percentagem de gordura, 23,3 x 20,3 por cento.


The physical compositionof carcass and meat quality of 22 Charolais (C) and Nellore (N) steers, feedlot finished and fed different levels of concentrate in the diet, were evaluated. The roughage fraction of the diet was made up by equal parts of corn and sorghum silages. The animals were distributed in three treatments constituted by 35, 50, or 65 percent of concentrate, in dry matter basis. Concentrate level did not affect carcass physical composition (P>0.05). Meat tenderness was positively affected (P=0.0013) by the concentrate level, increasing 0.026 points for each percent point increase of concentrate. The other meat qualitative characteristics were not affected by the concentrate level in the diet (P>0.05). Charolais steers showed meat with lighter color (4.44 x 2.89; P=0.0013), finer texture (4.15 x 3.14 points), better tenderness (6.85 x 5.71 points; P=0.0010), higher juiciness (7.17 x 5.77 points), lower Shear force (3.79 x 5.79kgf), and carcasses with higher muscle deposition (65.5 x 61.5 percent) in relation to N steers. Carcasses of Nellore steers showed higher fat percentage (23.3 x.20.3 percent).


Assuntos
Animais , Composição Corporal , Bovinos , Dieta , Qualidade dos Alimentos
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