The Effects of Castration, Implant Protocol, and Supplementation of Bos indicus-Influenced Beef Cattle under Tropical Savanna Conditions on Growth Performance, Carcass Characteristics, and Meat Quality.

The effects of castration, supplementation, and implant protocol (IP) on growth, carcass characteristics, and meat quality of grass-fed cattle were evaluated. Two experiments followed a two-way ANOVA and a 2 × 2 factorial arrangement. Experiment-I, 99 bulls were evaluated for: (a) supplementation (mineral (MS) or strategic protein-energy supplementation (SS), and (b) IP (repeated (day-0 and day-90) Zeranol-72 mg implantation (Zeranol-Zeranol) or Trenbolone Acetate-140 mg/Estradiol-20 mg (day-0) followed by Zeranol-72 mg (day-90) (TBA/E2-Zeranol). Experiment II, 50 animals were evaluated for: (a) IP (like Experiment-I), and (b) male class (steers vs. bulls). In Experiment-I, SS bulls had greater growth rate, carcass yield, and yield of high-valued boneless lean cuts than MS bulls, while decreasing (p < 0.05) time to harvest. Steaks from SS-bulls on TBA/E2-Zeranol IP were more (p = 0.05) tender than SS/Zeranol-Zeranol counterparts. Experiment-II bulls had greater growth than steers, but decreased (p < 0.05) carcass quality aspects. Zeranol-Zeranol increased (p < 0.01) meat tenderness of steers. Interactions (p < 0.05) affected cutability (Experiment-II) and meat sensory traits (Experiment-I/II). The SS improved growth, carcass yield, and shortened days until harvest of bulls, while TBA/E2-Zeranol IP positively affected tenderness in bull meat only. Castration improved carcass quality while the implant effects on cutability and tenderness were male-class dependent.

Effects of Sex Class, a Combined Androgen and Estrogen Implant, and Pasture Supplementation on Growth and Carcass Performance and Meat Quality of Zebu-Type Grass-Fed Cattle.

Forty-seven Zebu calves were used to determine the effects of class (bull or steer), supplementation (SUPPL, a poultry litter-based supplement or mineral supplementation), and implant (20 mg estradiol combined with 120 mg of trenbolone acetate or no implant) on growth and carcass performance and beef eating quality. The average daily gain (ADG) of implanted cattle significantly increased for steers, but not for bulls. The SUPPL treatment increased ADG by 8.63% from day 0 to end, and shortened in 73.3 d the time to reach 480 kg BW (p < 0.01). Compared to bulls, the steer carcasses exhibited more desirable maturity and finish scores, thicker back fat (p < 0.05), and yielded greater (p < 0.01) percentages of high-value boneless subprimals (HVBLS) (+1.64%) and total cuts (1.35%). The SUPPL bulls dressed 2.63 and 1.63% greater than non-supplemented bulls and SUPPL steers, respectively (p < 0.05). Meat sensory quality was subtly affected (p < 0.05) by sex class or supplementation. The implant did not affect (p > 0.05) shear force or sensory ratings. The supplementation improved key growth performance traits while it adversely affected tenderness-related sensory traits. The implant enhanced the rate of gain of steers only, without improving cut-out yields or inducing adverse effects on palatability traits in both steers and bulls.

Effect of Dietary Brown Seaweed (Macrocystis pyrifera) Additive on Meat Quality and Nutrient Composition of Fattening Pigs.

The objective of this study was to evaluate the effects of dietary brown seaweed (Macrocystis pyrifera) additive (SWA) on meat quality and nutrient composition of commercial fattening pigs. The treatments were: Regular diet with 0% inclusion of SWA (CON); Regular diet with 2% SWA (2%-SWA); Regular diet with 4% SWA (4%-SWA). After slaughtering, five carcasses from each group were selected, and longissimus lumborum (LL) samples were taken for meat quality and chemical composition analysis. Meat quality traits (except redness intensity) were not affected (p > 0.05) by treatments. Samples from the 4%-SWA treatment showed the lowest a value than those from the 2%-SWA and CON treatments (p = 0.05). Meat samples from the 4%-SWA group contained 3.37 and 3.81 mg/100 g more of muscle cholesterol than CON and 2% SWA groups, respectively (p < 0.05). The SWA treatments affected (p ≤ 0.05) the content of ash, Mn, Fe, and Cu. The LL samples from 4%-SWA had the highest content of ash; however, they showed 0.13, 0.45, and 0.23 less mg/100 g of Mn, Fe, and Zn, respectively, compared to samples from CON (p ≤ 0.05). Fatty acids composition and macro minerals content (Na, Mg, and K) did not show variation due to the SWA treatments. Further studies are needed to understand the biological effects of these components on adipogenesis, cholesterol metabolism, and mineral deposition in muscle.

Multivariate Relationships among Carcass Traits and Proximate Composition, Lipid Profile, and Mineral Content of Longissimus lumborum of Grass-Fed Male Cattle Produced under Tropical Conditions.

Hierarchical cluster (HCA) and canonical correlation (CCA) analyses were employed to explore the multivariate relationships among chemical components (proximate, mineral and lipidic components) of lean beef longissimus dorsii lumborum (LDL) and selected carcass traits of cattle fattened on pasture under tropical conditions (bulls, n = 60; steers, n = 60; from 2.5 to 4.0 years of age, estimated by dentition). The variables backfat thickness (BFT), Ca, Mn, Cu, C14:0, C15:0, and C20:0 showed the highest coefficients of variation. Three clusters were defined by the HCA. Out of all carcass traits, only BFT differed significantly (p < 0.001) among clusters. Clusters significantly (p < 0.001) differed for total lipids (TLIPIDS), moisture, dry matter (DM), fatty acid composition, cholesterol content, and mineral composition (except for Fe). The variables that define the canonical variate "CARCASS" were BFT and degree of marbling (MARBLING). TLIPIDS was the main variable for the "PROXIMATE" canonical variate, while C16:0 and C18:1c had the most relevant contribution to the "LIPIDS" canonical variate. BFT and MARBLING were highly cross-correlated with TLIPIDS which, in turn, was significantly affected by the IM lipid content. Carcass traits were poorly correlated with mineral content. These findings allow for the possibility to develop selection criteria based on BFT and/or marbling to sort carcasses, from grass-fed cattle fattened under tropical conditions, with differing nutritional values. Further analyses are needed to study the effects of sex condition on the associations among carcass traits and lipidic components.

Temperature, but not excess of glycogen, regulates "in vitro" AMPK activity in muscle samples of steer carcasses.

Postmortem muscle temperature affects the rate of pH decline in a linear manner from 37.5°C to 0-2°C. The pH decline is correlated with the enzymatic degradation of glycogen to lactate and this process includes the metabolic coupling between glycogenolysis and glycolysis, and that are strongly upregulated by the AMPK. In this study, we used 12 samples previously characterized by have different muscle glycogen concentration, lactate and AMPK activity, selected from 38 steers that produced high final pH (>5.9) and normal final pH (<5.8) carcasses at 24 h postmortem. Moreover, we evaluated changes in the AMPK activity in samples from both categories incubated at 37, 25, 17 and 5°C and supplemented with exogenous glycogen. Finally, we analysed if there were structural differences between polymers from both categories. Our results showed that "in vitro" enzymatic AMPK activity evaluated at both 0.5 or 24 h was greater in samples from normal then high pH categories (p <0.01), and in all temperature of incubation analysed (17, 25 and 37°C). For other hand, a greater AMPK activity were obtained in samples incubated at 17 that 25 or 37°C, in normal carcasses at both 0.5 or 24 h (p < 0.01), as also in samples from carcasses categorized as high pH, but at 24 h (p < 0.05). Interestingly, AMPK activity was totally abolished at 5°C, independent of final pH category of carcasses, and was confirmed that the incubation temperature at which the maximum activity was obtained (p < 0.01), at least in carcasses with a normal pH is at 17°C. The enzymatic AMPK activity did not change in relation to excess glycogen (p > 0.05) and we did not detect structural differences in the polymers present in samples from both categories (p > 0.05), suggesting that postmortem AMPK activity may be highly sensitive to temperature and not to in vitro changes in glycogen concentration (p > 0.05). Our results allow concluding that normal concentrations of muscle glycogen immediately at the time of slaughter (0.5 h) and an adequate cooling managing of carcasses are relevant to let an efficient glycogenolytic/glycolytic flow required for lactate accumulation and pH decline, through the postmortem AMPK signalling pathway.

Attitudinal Determinants of Beef Consumption in Venezuela: A Retrospective Survey.

Consumer surveys were conducted in the Western, Central, and Eastern regions of Venezuela to determine buying expectations, motivations, needs, perceptions, and preferences of beef consumers, and their acceptance of domestic (and foreign) beef, as affected by different intrinsic and extrinsic factors. Data (n = 693) were gathered by face-to-face interviews on the way out of fresh markets, butcher stores, supermarkets, and, in some cases, at home by using a 45-question structured questionnaire. Responses were subjected to factorial analysis of correspondence (FA) and hierarchical cluster analysis. From the FA, the first two factors explain 74% of the common variance. Factor 1 comprises intrinsic attributes such as color, smell, tenderness, flavor, juiciness, and freshness; while Factor 2 contains extrinsic attributes, mostly related to the origin. The FA profiling data showed that it is possible to concentrate on the traits that consumers usually use as a criterion to perceive beef quality, and to purchase beef. Using cluster analysis, four groups of consumers were mainly distinguished by region, intrinsic attributes, and credence attributes related to production system, aging, traceability, and hygiene. Results from this study will be helpful in designing strategies for recovering and enhancing the future, domestic beef demand.

Early differential gene expression in beef Longissimus thoracis muscles from carcasses with normal (<5.8) and high (>5.9) ultimate pH.

The objective of this study was to investigate early postmortem (0.5 h) gene expression in beef Longissimus thoracis (LT) muscles from carcasses with NORMAL (<5.8) and HIGH (>5.9) ultimate pH (pHu). A total of 53 transcripts were differentially expressed (P-value <.05): 40 showed up-regulation and 13 showed down-regulation in HIGH pHu carcasses. Four up-regulated (PDK4, GADD45B, MAOA, METTL21C) genes were confirmed (P < .05) by q-PCR. HIGH pHu samples resulted with lower values in glycolytic potential and AMP-activated protein kinase activity compared to NORMAL at 0.5 and 24 h postmortem (P < .05). Functional pathway analysis showed that calcium transport and GADD45 signaling pathways are associated with the development of HIGH pH meat. Genes involved in stress-related signaling, such as GADD45B, METTL21C and MAOA were overexpressed. These genes are involved in stress signaling that might be affecting Ca2+ transport and oxidative metabolism pathways in HIGH pH muscles.

Predictability of lean product, bone, and fat trim in beef carcasses from Costa Rica.

Data from 292 hot fat trimmed carcasses derived from Costa Rican cattle were used to predict yield of fabricated boneless, closely-trimmed, high-valued cuts (BVS, by weight and percentage); yield of total saleable product (TSP, by weight and percentage); and percentage yields of bone and trim fat. Backfat thickness was not significantly associated with weight of BVS or TSP. Carcass weight explained 93.7% and 95.9% of the total variation in weight of BVS and TSP, respectively. Equations for predicting percentage yields of BVS and TSP showed little predictive efficacy. Conversely, the greater precision of the equations selected to predict the quantity (kg) of BVS or TSP, offers a practical alternative of using them in hot fat trimmed carcasses.

Evaluation of Digestible lysine levels in diets with high energy density for finishing pigs / Evaluación de niveles de lisina digestible en dietas con alta densidad energética para cerdos en finalización

Objective. To evaluate the effects of different levels of digestible lysine in diets with high energy density on productive performance and carcass characteristics of finishing pigs. Materials and Methods. Seventy crossbred barrows (initial body weight of 83.36 kg) were used and allotted in a randomized block design with five treatments, seven replications and two pigs per experimental unit. Pigs were fed ad libitum with diets containing 3.5 kcal/kg of ME and five levels of digestible lysine (0.46, 0.52, 0.58, 0.64 and 0.70%) during four weeks. Final live weight (FLW), daily feed intake (DFI), daily weight gain (DWG), feed conversion (FC), daily lysine intake (DLI), and the amount of lysine per body weight gain (DLI/DWG), were evaluated. At the end of the experiment, blood samples were taken from each pig to determine urea nitrogen concentration (UN) in serum and slaughtered to evaluate quantitative and qualitative carcass characteristics. Results. The FLW increased linearly (p<0.05).There were no differences among treatments for DFI, DWG, FC, carcass characteristics and UN. The DLI and DLI/DWG varied significantly (p<0.001) and increased linearly (p<0.001) with each lysine level. Pigs that consumed the limiting diet in lysine (0.46%) showed less DLI and DLI/DWG (p<0.001) than pigs fed the other diets. Conclusions. The amount of DLI/DWG increased with the evaluated levels of digestible lysine in diets with high energy density, without effects on productive performance and carcass characteristics of finishing pigs.

Objetivo. Evaluar los efectos de diferentes niveles de lisina digestible en dietas con alta densidad energética sobre el desempeño productivo y características de la canal de cerdos en finalización. Materiales y métodos. Se utilizaron 70 cerdos (peso inicial de 83.36 kg) mestizos castrados, distribuidos en un diseño de bloques al azar con cinco tratamientos, siete repeticiones y dos cerdos por unidad experimental. Los cerdos fueron alimentados ad libitum con dietas que contenían 3.5 Mcal/kg de energía metabolizable y cinco niveles de lisina digestible (0.46, 0.52, 0.58, 0.64 y 0.70%) durante cuatro semanas. Se evaluaron: peso vivo final (PVF), consumo diario de alimento (CDA), ganancia diaria de peso (GDP), conversión de alimento (CA), consumo diario de lisina (CDLis) y la cantidad de lisina por peso ganado (CDLis/GDP). Al final de experimento, se extrajeron muestras de sangre de todos los cerdos para determinar la concentración de nitrógeno ureico (NU) en suero sanguíneo y luego se sacrificaron para evaluar las características cualitativas y cuantitativas de la canal. Resultados. No se observaron diferencias significativas entre tratamientos para CDA, GDP, CA, características de la canal y NU. El PVF incrementó linealmente (p<0.05). El CDLis y la CDLis/GDP variaron significativamente (p<0.001) e incrementaron linealmente (p<0.001) con cada nivel de lisina. Los cerdos que consumieron la dieta limitante en lisina (0.46%) mostraron menor consumo y CDLis/GDP (p<0.001) que los cerdos alimentados con las otras dietas. Conclusiones. Los niveles de lisina digestible evaluados en dietas con alta densidad energética aumentan la CDLis/GDP, sin efectos sobre el desempeño productivo y las características de la canal de los cerdos en finalización.

[Proximal composition, lipid and cholesterol content of meat from pigs fed peach-palm meal (Bactris gasipaes Kunth) and synthetic lysine]. / Composición proximal y contenido de lípidos y colesterol de la carne de cerdos alimentados con harina de pijiguao (Bactris gasipaes Kunth) y lisina sintética.

Two experiments were conducted to evaluate the proximal composition, lipids and cholesterol content of meat from pigs fed diets with peach-palm meal (PPM), with or without addition of synthetic lysine (LYS). In experiment 1, 24 pigs were randomly allotted into six treatments with three levels of PPM (0.16 and 32%) and two levels of LYS (0 and 0.27%). In experiment II, 16 finishing pigs were fed with two levels of PPM (0 and 17.50%) and two levels of LYS (0 and 0.27%). At the end of each experiment (42 and 35 d, respectively), pigs were slaughtered and loin samples were obtained to determine crude protein, dry matter, moisture, ash, total lipids, and cholesterol content. In experiment I, pork loin from 16% PPM had more dry matter (26.45 g/100 g) and less moisture (73.49 g/100g) than pork loin from 32% PPM (25.11 y 75.03 g/100g, respectively). Meat samples from pigs without LYS had higher (p < 0.05) content of lipids (2.11 g/100 g) than meat from pigs that consumed LYS (1.72 g/100 g). In experiment II, the proximal, lipids and cholesterol content were similar among treatments. The PPM addition to pig diets did not affect the proximal composition of pork, while LYS addition indicated a reduction of total lipids, which could result as an alternative to obtain leaner meat.

Composición proximal y contenido de lípidos y colesterol de la carne de cerdos alimentados con harina de pijiguao (Bactris gasipaes Kunth) y lisina sintética

Se condujeron dos experimentos para evaluar la composición proximal y el contenido de lípidos y colesterol de la carne de cerdos alimentados con dietas en las que se añadió harina de pijiguao (HP) con y sin adición de lisina sintética (LIS). En el experimento I, se utilizaron 24 cerdos en crecimiento distribuidos al azar en seis tratamientos con tres niveles de HP (0, 16 y 32%) y dos niveles de LIS (0 y 0,27%). En el experimento II se utilizaron 16 cerdos en engorde alimentados con dos niveles de HP (0 y 17,50%) y dos niveles de LIS (0, y 0,27%). Al final de cada experimento (42 y 35 días, respectivamente), los cerdos fueron sacrificados y se obtuvieron muestras de lomo para determinar el contenido de proteína cruda, materia seca, humedad, cenizas, lípidos totales y colesterol. En el experimento I, las carnes provenientes de animales con 16% HP, presentaron más materia seca (26,45 g/100 g) y menos humedad (73,49 g/100 g) que las carnes de 32% HP (25,11 y 75,03 g/100g), respectivamente). Las carnes de los cerdos sin LIS presentaron mayor (p.

Two experiments were conducted to evaluate the proximal composition , lipids and cholesterol content of meat from pigs fed diets with peach-palm meal (PPM), with or without addition of synthetic lysine (LYS). In experiment I, 24 pigs were randomly allotted into six treatments with three levels of PPM (0, 16 and 32%) and two levels of LYS (0 and 0.27%). In experiment II, 16 finishing pigs were fed with two levels of PPM (0 and 17.50%) and two levels of LYS (0 and 0.27%). At the end of each experiment (42 and 35 d, respectively), pigs were slaughtered and loin samples were obtained to determine crude protein, dry matter, moisture, ash, total lipids, and cholesterol content. In experiment I, pork loin from 16% PPM had more dry matter (26.45 g/100 g) and less moisture (73.49 g/100g) than pork loin from 32% PPM (25.11 y 75.03 g/100g, respectively). Meat samples from pigs without LYS had higher (p.

Efecto de la Sobrealimentación sobre las Características de la Canal y la Degradación Postmortem de la Vinculina y Troponina-T en Carne de Novillos Doble Propósito / Overfeeding Effects on Beef Carcass Traits and Postmortem Degradation of Vinculin and Troponin-T in Dual Purpose Steers

El efecto de sobrealimentación sobre las características de la canal y la degradación de la vinculina y la troponina-T a tres tiempos postmortem (0, 24 y 48 h), fue evaluado en 10 novillos doble propósito de 21 m de edad. Los animales fueron segregados al azar en dos tratamientos durante 12 m, como sigue: Tratamiento 1 (T1): cinco (5) novillos (grupo testigo) alimentados con heno (Cynodon nlemfuensis), más 20% de concentrado (relación heno:concentrado = 80:20, para una ganancia diaria de peso (GDP) de 100 g/d). Tratamiento 2 (T2): cinco (5) novillos alimentados con heno (Cynodon nlemfuensis), más 40% de concentrado (relación heno: concentrado = 60:40, para una GDP de 500 g/d). Las canales fueron evaluadas, para las características cualitativas y cuantitativas a las 24 h postmortem. Para evaluar la degradación de vinculina y troponina-T mediante la técnica de Western Blot, se colectaron 0,5 g del músculo longissimus dorsi de cada media canal al beneficio (0, 24 y 48 h postmortem). El análisis de varianza(ANAVAR) incluyó el peso de los animales al inicio del ensayo como covariable. Los resultados indicaron que las canales de los novillos sobrealimentados mejoraron sus características en canal, presentando mayor área del ojo costal, mayor espesor de grasa y mayor madurez ósea (P<0,05), sin alcanzar niveles adecuados de acabado de grasa. Se observó que la sobrealimentación no varió el patrón de degradación de la vinculina y la troponina-T a ningún tiempo postmortem. La vinculina se degradó a partir de las 24 h postmortem; sin embargo, no se detectó degradación de la troponina-T. Estos resultados deben ser confirmados con un número mayor de animales junto con la evaluación cuantitativa de la expresión de las proteínas.

The effect of overfeeding on carcass characteristics and on degradation of vinculin and troponin-T at three different postmortem times (0, 24, and 48 h) were evaluated in dual purpose steers. A total of 10 steers, 21 months of age was used. The animals were randomly selected and allocated to two different treatment protocols for 12 months, as follows: Treatment 1 (T1): Five steers (Control Group) fed with a diet consistent of hay (Cynodon nlemfuensis) plus concentrate, with a hay/concentrate ratio of 80:20, to reach a daily weight gain (DWG) of 100 g/d; Treatment 2 (T2); five steers fed with hay (Cynodon nlemfuensis) plus concentrate with a hay/concentrate ratio of 60:40, to obtain a DWG of 500 g/d. Carcasses were assessed for both qualitative and quantitative characteristics at 24 h postmortem. To evaluate the degradation of vinculin and troponin-T at three different times (0, 24, and 48 h postmortem), 0.5 g of the longissimus dorsi muscle was collected from each half carcass and subjected to a Western blot analysis. Samples were analyzed by ANOVA. The analysis included the weight of the animals as a covariance. The results of the present investigation indicate that the carcasses of overfed steers exhibited better carcass traits, showing larger loin eye areas, back fat thickness, and a skeletal maturity (P≤0.05), without reaching adequate levels of fat finish. It was also observed that overfeeding did not change the pattern of degradation of vinculin and troponin-T at any postmortem time. Vinculin showed degradation at 24 h postmortem while troponin-T was not degraded. These results must be confirmed using a greater number of animals and a quantitative evaluation of protein expression.

Composición proximal, mineral y contenido de colesterol del músculo Longissimus dorsi de novillos criollo limonero suplementados a pastoreo / Proximate composition, mineral and cholesterol content of the Longissimus dorsi muscle of criollo limonero steers supplemented on pasture

Las muestras de músculo longissimus dorsi fueron obtenidas de 23 novillos Criollo Limonero (CL), que a los 36 meses de edad se distribuyeron aleatoriamente en cada uno de los siguientes tratamientos de suplementación, durante un período de 158 días: T1= Pastoreo (Echinochloa polystachia) no suplementado; T2= Pastoreo más 1.0Kg./animal/día de concentrado al 11 por ciento Proteína Cruda (PC) y T3= Pastoreo más 1 h/día ramoneando Leucaena leucocephala. A las 48 horas postmortem, le fue retirado un bistec del músculo longissimus dorsi para determinar el efecto de la suplementación sobre la composición proximal y mineral (Ca, Mg, Na, K, Fe, Zn, Mn, Cu, y P), y contenido de colesterol. El análisis de varianza por el método de mínimos cuadrados no indicó efectos significativos (P>0,05) de los tratamientos de suplementación sobre las variables estudiadas. Los bajos niveles de lípidos totales y contenido de colesterol de las muestras para todos los tratamientos, incluyendo la suplementación con concentrado, evidenciaron una alta magrez, lo que indica que las carnes de los novillos Criollo Limonero pudieran ser comercializadas como carnes ligeras o bajas en grasas.

Longissimus dorsi samples were obtained from 23 Criollo Limonero (CL) steers, that were subjected to supplementation treatments (at 36 months of age), during 158 d of fattening on pasture, as follows: T1= a non-suplemented (control) group, grazing on Echinochloa polystachia grass; T2= grazing plus 1 Kg/d/head of a concentrate to 11% Crude Protein (CP), and T3= grazing plus 1h/d of pruning an arboreal legume (Leucaena leucocephala). After postmortem, muscles samples were removed from their carcasses to study the effects of supplementation on the proximal (content of protein, moisture, total lipids and ash) and mineral composition (Ca, Mg, Na, K, Fe, Zn, Mn, Cu, and P), cholesterol content. Analysis of variance was conducted by the least squares method. The variance analysis did not reveal significant effect (P>0.05) of the supplementation treatments on the proximal composition, cholesterol and mineral content in the longissimus dorsi muscle. Meat derived from Criollo Limonero steers showed low levels of total lipids and cholesterol, which indicated that meat derived from these animals could be marketed as light meat or low in fat.

Efecto de la suplementación estratégica, régimen de implantes y condición sexual sobre la composición proximal y mineral de carne de bovinos cruda y cocida / Effect of strategic supplementation, implant regime and gender on the proximate and mineral composition of raw and cooked bovine meat

Se evaluó el efecto de suplementación, régimen de implantes (RI) y condición sexual (CS) sobre la composición proximal y mineral del longissimus dorsi crudo y cocido, de 89 animales (77 toros y 12 novillos) alimentados al azar con pasto (NSUE) o con suplementación estratégica (SUE). Un grupo (n= 49) fueron implantado con una doble dosis de Ralgro® (2Ralgro), con reimplante a los 90 d.; a otro (n=40), con un tratamiento mixto: Revalor® por 90 d., luego 2Ralgro (Revalor-2Ralgro). El análisis de varianza (ANOVA) reveló que la carne cruda de los toros SUE, mostró mayor contenido de humedad (HUM) (P<0,05) (74,23 vs. 73,88 g/100g de muestra), mientras que el Na fue el único mineral afectado (P<0,05) en las muestras cocidas de los NSUE (71,32 vs. 69,16 mg/100g de muestra). RI sólo afectó el contenido de Na y Cu observándose un aumento (P<0,05) en la carne cocida de toros implantados con Revalor-2Ralgro. CS afectó a HUM (P<0,05), mostrando la carne cocida de novillos el mayor contenido. La SUE x RI incrementó(P<0,05) el contenido de proteínas (PC) en la carne cocida de los toros SUE implantados con Revalor-2Ralgro, mientras que la CS x RI incrementó el contenido de lípidos (LIP) y la concentración de K de la carne cruda de novillos. Se observó que ni SUE ni IR produjeron los resultados esperados, es decir, un aumento del PC, y la disminución en LIP en las muestras de carne consideradas; los incrementos observados en la carne cocida se debieron probablemente a la pérdida del agua durante la cocción. Los resultados sugieren que la suplementación estratégica, la administración de implantes hormonales y la castración utilizados para maximizar los índices productivos del ganado, si bien no produjeron un beneficio adicional en lacomposición química de las carnes, tampoco disminuyeron la calidad nutricional de las mismas.

The effect of supplementation, implant regime (IR) and gender (G) on the proximal and mineral composition of the raw and cooked longissimus dorsi muscle, from 89 animals (77 bulls and 12 steers) was studied. A randomly selected group of animals was grass-fed (NSUE) and other was strategically supplemented (SUE). One group (n= 49) was implanted with one double dose of Ralgro® (2Ralgro) and then reimplanted to the 90 d. Another one (n= 40) was treated with a mixture: Revalor® for 90 d. then 2Ralgro before the slaughter (Revalor-2Ralgro). The analysis of the variance (ANOVA) detected a higher moisture (M) content in the raw SUE bull meat (74.23 vs. 73.88 g/100g of sample), while only Na from NSUE was the mineral affected in the cooked meat (71.32 vs. 69.16 g/100g of sample). IR only affected (P<0.05) the Na and Cu content; an increase in the cooked bull meat reimplanted with Revalor-2Ralgro was observed. Gender (G) affected (P<0.05) M, being higher in the cooked steers meat samples. SUE x IR interaction significantly (P<0.05) increased the protein content (PC) in the cooked bull meat (SUE) implanted with Revalor-2Ralgro, while G x IR interaction had provoked an increase in LIP and K contents of the raw steers meat. It is inferred that neither SUE nor IR caused the expected results, it is to say, an increase in PC nor a decrease in LIP in the meat samples considered; the increments observed in the cooked meat was probably due to loss of the water during cooking. Results suggest of SUE, IR and castration used for maximize the cattle productive index, although they did not produce an additional benefit in the chemical composition of the meat samples, did not diminish their nutritional quality either.

Fine mapping of a QTL region with large effects on growth and fatness on mouse chromosome 2.

We combined the use of a congenic line and recombinant progeny testing (RPT) to characterize and fine map a previously identified region of distal mouse chromosome 2 (MMU2) harboring quantitative trait loci (QTL) with large effects on growth and fatness. The congenic line [M16i.B6-(D2Mit306-D2Mit52); MB2] was created using an inbred line (M16i) derived from a line that had undergone long-term selection for rapid weight gain (M16) as the recipient for an approximately 38-cM region on MMU2 from the inbred line C57BL/6J. A large F2 cohort (1,200 mice) originating from a cross between MB2 and M16i was created, and 40 F2 males with defined recombinations within the QTL region were used to produce 665 segregating progeny. Linkage analysis of the F2 population detected QTL with very large effects on body weight, body fat, lean tissue mass, bone mineral density, and liver weight. Confidence intervals of the QTL were narrowed to regions of 1.5-4.5 cM. Analysis of progeny of the recombinant F2 males confirmed the existence of the QTL and further contributed to localization of their map positions. These efforts confirmed the presence of QTL with major effect on MMU2, narrowed the estimated region harboring the QTL from 38 to 12 cM, and further characterized phenotypic effects of the QTL, effectively culminating in a significantly decreased pool of positional candidate genes potentially representing these genes controlling predisposition to growth and fatness.

Characterization of QTL with major effects on fatness and growth on mouse chromosome 2.

OBJECTIVE: To isolate and characterize a region on mouse chromosome 2 harboring quantitative trait loci with large influences on growth and fatness. RESEARCH METHODS AND PROCEDURES: A congenic line [M16i.B6-(D2Mit306-D2Mit52); MB2] was created using the polygenic obese M16i selection line as the recipient for an approximately 38-centimorgan region from C57BL/6J. Males and females from M16i and MB2 were compared for body weight, body composition, feed consumption, and additional traits at 6, 15, and 24 weeks. Interactions of genotype and environment (low and high dietary fat) were investigated. Males (8 weeks) were evaluated for fatty acid profiles in liver and for transcriptional profiles in liver and adipose. RESULTS: Consequences of replacing M16i alleles with C57BL/6J alleles in MB2 were maximized at 15 weeks. MB2 mice were up to 15% lighter than M16i at this age, with no differences in feed consumption. As a percentage of body weight, MB2 had dramatically less epididymal (males) or perimetrial (females) fat (1.17% vs. 2.79% pooled across sex) and lower total lipids (16.1% vs. 23.3%) than M16i. Decreased adiposity in MB2 was not dependent on gender or diet. MB2 mice also had significant decreases in levels of leptin, insulin, and glucose, decreased de novo synthesis of hepatic fatty acid, and transcriptional changes for many genes both within, and external to, the congenic region. DISCUSSION: Results confirm the presence and large effects of mouse chromosome 2 quantitative trait loci and further define their phenotypic consequences related to energy balance. The MB2 congenic line is a powerful resource for eventual identification of pathways and mutations within genes regulating predisposition to growth and obesity.

Contenido de humedad, lípidos totales y ácidos grasos del músculo longissimus crudo de bovinos en Venezuela / Moisture, total lipids and fatty acids in raw longssimus muscle from Venezuelan cattle

Grupos de bovinos mestizos para sacrificio (n=145), seleccionados al azar, con predominancia fenotípica lechera (n=14) o cebú (n=131), se clasificaron por edad dentaria (2.5,3.0,3.5 y 4.0 años) y según el grado de gordura, descrita en canal por varios criterios, incluyendo la grasa visible intramuscular (marmoleo), para estudiar la variación en contenido de humedad (H), lípidos (L) y de ácidos grasos (AG) en el músculo longssimus dorsi, sin cubierta de grasa. Las medias generales de desviaciones estándar (g/100g de tejido fresco) para H y L fueron 73.9 ñ 1.36 y 2.9 ñ 1.04, respectivamente. El análisis de varianza por cuadrados mínimos indicó que el perfil de AG fue afectado por edad dentaria, tipo racial, marmoleo, gordura del lomo y acabado general de la canal (p<0.05). Animales de mayor edad (4 años o más), con tendencia a un menor tenor graso (2,72 g/100g) intramuscular, presentaron el mayor índice (2.04) de insaturación (AG instaurados/saturados). El tipo racial tuvo poco efecto sobre el perfil de AG. La comparación de medidas cuadráticas mostró concentraciones intramusculares de ácidos mirístico (C14:0) y linolénico (C18:3) mayores (p<0.05) en muestras de mestizos lecheros. Canales con pobre distribución de grasa subcutánea (acabado "en parches") mostraron el índice más alto (0.16) de AG polinsaturados/saturados en el músculo (p<0.05). Los índices de insaturación para muestras de carnes limpias de grasa con los niveles prevalentes de marmoleo (de 1.76 para el nivel "Trazas" a 1.92 para el nivel "Nada") muestran la predominancia de AG insaturados, en proporción relativamente mayor a la estimada para el mismo corte de carne en los Estados Unidos

Contenido de colesterol en el músculo longissimus de bovinos venezolanos / Cholesterol content of beet longissimus from slaughter cattle of venezuelan

Se seleccionó una muestra de 149 bovinos sacrificados en un matadero venezolano. Después de la evaluación y clasificación de las canales, se tomaron bistéks del solomo, con el objeto de estudiar el efecto de la clase de animal, por su condición sexual (62 toros, 67 novillos, 20 novillas), la edad dentaria (2.5, 3.5, 4.0 años), el tipo racial (17 mestizos lecheros y 132 mestizos Cebú), madurez fisiológica (A o B), categoría oficial en canal (optima, Excelente, Selecta o Superior), marmoleo (cuatro niveles desde "Nada" hasta "Pequeña cantidad"), grado de acabado ("Uniforme"; "Desuniforme", "En parches" y "Desprovisto") y el espesor de grasa de cobertura del solomo (1=0,1-0,2 cm; 2=0,3-0,4 cm; 3=0,5-0,9 cm and 4=>1,0 cm) sobre la concentración (mg/100 g de tejido fresco) de colesterol, determinar, la condición sexual, la clasificación de la canal, el nivel de marmoleo, el grado de acabado o el espesor de la grasa de cobertura sobre el solomo no tuvieron efecto significativo sobre el contenido de colesterol del longissimus. Sin embargo, los mestizos lecheros superaron a los mestizos Cebú en 12,2 mg/100 g de colesterol muscular (P=0,08). La media general de la muestra y su dispersión (66,6 ñ 16 mg/100 g) no muestra valores distintos a los obtenidos con ganado igual o mejor cebado en otras latitudes

Factores que afectan la culinaria de bistés del músculo longissimus de bovinos venezolanos / Factors affecting cookery traits of longissimus beef steaks derived from venezuelan cattle

Se realizaron 274 pruebas de cocción, del músculo longissimus, de reses evaluadas en un matadero industrial y provenientes de distintas regiones venezolanas, para determinar el efecto de condición sexual (toros, novillos, novillas). tipo racial (mellizos cebú, mestizos doble propósito), edad (2,3 y 4 años). madurez fisiológica (A, B y C) y marmoleo (nada, trazas y ligero) sobre tiempo y mermas de cocción. El análisis de varianza reveló efectos de marmoleo y madurez fisiológica sobre la culinaria de la carne (P<0.05). Carne con "trazas" de marmoleo se cocinaron más rápido y tuvieron las mayores mermas por cocción. La carne de animales jóvenes ("A") tardaron 14 min más en cocinarse y perdieron 3 g/100 g más de su peso crudo que la de animales maduros "C". Las interacciones de la condición sexual con el tipo racial o la edad cronológica sólo afectaron el tiempo de cocción. Las carnes de novillos y toros doble propósito se cocinaron más lentamente que las de aquellos tipificados como Cebú. Las carnes de novillas, independientemente de la edad o el tipo racial, fueron las que se cocinaron más rápido. De acuerdo a la variación y magnitud de las diferencias detectadas, se concluye que para mejorar la eficacia en los servicios de comida, los administradores deberían tomar en cuenta los factores intrínsecos que afectan la culinaria de la carne de res

Experiencias en el entrenamiento de un panel de degustación de carne vacuna a nivel de un matadero frigorífico industrial venezolano / Experience during training of a descriptive taste panel at a packing house of Venezuela

Se describen las experiencias en el entrenamiento de un panel descriptivo para degustación de carne vacuna. El adiestramiento constó de cuatro pasos: entrevista persona, selección, entrenamiento y evaluación del desempeño. Previo al entrenamiento se evaluaron 37 bistés por los siete candidatos potenciales de un grupo de 12 que fueron los que asistieron regularmente a sesiones preliminares de degustación. Luego se entrevistaron todos los 12 candidatos potenciales. Para medir su habilidad natural durante la selección se realizaron pruebas de triángulo que permitieron la selección de diez candidatos. Durante el entrenamiento el líder instruyó las técnicas de degustación y se uniformizaron criterios en la asignación de puntuaciones. Una vez entrenados, se realizó una primera prueba de desempeño, de 12 sesiones distribuidas en 4 días, con 3 sesiones por día, 3 muestras por sesión para un total de 9 muestras diferentes. Se calculó el valor F con un análisis de varianza por panelista, para medir la habilidad de los panelistas en acertar y ser consistentes en las puntuaciones de las nueve muestras, durante las 4 repeticiones, para cada atributo. Los resultados fueron satisfactorios; en la primera prueba de desempeño se descartaron 2 candidatos con los menores valores F, quedando el panel constituido por 8 catadores. Después de 300 pruebas de degustación se realizó una segunda prueba de desempeño para conocer su nivel de mejora, obteniéndose cambios en el ordenamiento por habilidad de los panelistas y una mayor uniformidad del panel en sus evaluaciones. El efecto panelista fue detectado antes (P<0.05) y después (P<0.001) del entrenamiento con muestras de longissimus (N=37 y N=40, respectivamente). Sin embargo, las medidas para panelistas entrenados fueron menos variables y sólo difirieron en décimas dentro de una escala de ocho puntos para cinco diferentes atributos. Los resultados validan las metodologías utilizadas para entrenamiento y la adecuación del panel para la evaluación sensorial de carnes no procesadas