Abstract Carcass quality traits and the Longissimus thoracis (LT) and semitendinosus (ST) muscles, aged for 2 or 14 d, from sixty castrated (CM) and non-castrated (NCM) Brangus males, slaughtered at 16 (M16) or 20 (M20) mo of age (391 and 434 kg live weight; 3.81 and 4.25 mm backfat thickness respectively), were evaluated. The carcasses of castrated and younger animals weighed less than those of non-castrated and older ones (P<0.001). Castration produced more subcutaneous fat and lower rib eye areas (P<0.05). Temperature and pH decline was faster in younger animals, and final pH was lower in castrated (P< 0.05). While the Warner Bratzler Shear Force (WBSF) of LT was 9 % lower in castrated, and 7 % higher in younger animals (P<0.05); it decreased with a longer aging period (P<0.001). The WBSF of LT was positively associated with total collagen content (r= 0.54; P<0.01) and negatively with myofibrillary fragmentation index (r= -0.39; P<0.05). The WBSF of ST was not affected by animal castration or slaughter age (P>0.05), but decreased with a longer aging period (P<0.001), and was positively associated with total collagen content (r= 0.61; P<0.05). Both muscles from castrated slaughtered at younger ages had the higher L* values. It is concluded that castration and age at slaughter on Brangus males produced differences on WBSF values only on LT muscle where collagen is not the main determinant of shear force.

Resumen Se evaluaron los rasgos de calidad de la canal y los músculos Longissimus thoracis (LT) y semitendinoso (ST), madurados durante 2 o 14 días, de sesenta machos Brangus castrados (MC) y no castrados (MNC), sacrificados a los 16 (M16) o 20 (M20) meses de edad (391 y 434 kg de peso vivo; 3.81 y 4.25 mm de grosor de la grasa dorsal, respectivamente). Las canales de los animales castrados y más jóvenes pesaron menos que las de los no castrados y de mayor edad (P<0.001). La castración produjo más grasa subcutánea y áreas del ojo de la costilla menores (P<0.05). La disminución de la temperatura y el pH fue más rápida en los animales más jóvenes, y el pH final fue menor en los castrados (P<0.05). Mientras que la Fuerza de Cizalla de Warner-Bratzler (FCWB) de LT fue 9 % menor en los castrados, y 7 % mayor en animales más jóvenes (P<0.05); disminuyó con un período de maduración más largo (P<0.001). La FCWB de LT se asoció positivamente con el contenido de colágeno total (r= 0.54; P<0.01) y negativamente con el índice de fragmentación miofibrilar (r= -0.39; P<0.05). La FCWB de ST no se vio afectada por la castración o la edad de sacrificio del animal (P>0.05), pero disminuyó con un período de maduración más largo (P<0.001), y se asoció positivamente con el contenido de colágeno total (r= 0.61; P<0.05). Ambos músculos de castrados sacrificados a edades más tempranas presentaron los valores más altos de L*. Se concluye que la castración y la edad de sacrificio en machos Brangus produjeron diferencias en los valores de FCWB solo en el músculo LT, donde el colágeno no es el principal determinante de la fuerza de cizalla.

Abstract Cattle ranching, transportation, and utilization are issues associated with resource endowment, distance traveled, and types of markets. The structure of the livestock mobilization network by market at the municipal and state level in Mexico during the 2017-2021 period was investigated. The data were analyzed using measures of economic structure and Social Network Analysis. During the period under analysis, an annual average of 8.9 million heads of cattle were moved in Mexico: 57.9 % interstate and 42.1 % intrastate. The most important markets were for slaughter and fattening, the rest corresponded to beef breeding, reproduction, fairs, and shows. The average market and state specialization were low, with a higher specialization in the entertainment market. The structure of the state network of all markets showed a high degree of average market and density, but low centrality of output and input. These measures mean that, on average, states can connect in 1.2 steps to the national network and in 1.7 steps to the network per purpose. The authors conclude that the state structure of the livestock market in Mexico is composed of 32 origins, 32 destinations, six markets, and major interstate mobilization from the south to the north of the country.

Resumen La ganadería, el transporte y el aprovechamiento de bovinos son problemas asociados con la dotación de recursos, la distancia recorrida y los tipos de mercado. Se investigó la estructura de la red de movilización de ganado bovino por mercado a nivel municipal y estatal en México durante el periodo 2017-2021. Los datos se analizaron con medidas de estructura económica y de Análisis de Redes Sociales. En el periodo de análisis, un promedio anual de 8.9 millones de cabezas de ganado fueron movilizadas en México: 57.9 % interestatal y 42.1 % intra estatal. Los mercados más importantes fueron para rastro y engorda, el resto correspondió a repasto, reproducción, ferias y espectáculos. La especialización promedio de los mercados y de los estados fue baja, con mayor especialización en el mercado para espectáculos. La estructura de la red estatal de todos los mercados presentó un alto grado promedio y de densidad, pero baja centralidad de salida y entrada. Estas medidas hacen que, en promedio, los estados puedan conectarse en 1.2 pasos a la red nacional y 1.7 en la red por motivo. Se concluye que la estructura estatal del mercado de bovinos en México se compone de 32 orígenes, 32 destinos, seis mercados y mayor movilización interestatal de sur al norte del país.

ABSTRACT This study aimed to investigate the effects of animal type, on-farm handling, and transport conditions on temperament of beef cattle pre-slaughter. The study evaluated 4,061 cattle batches, averaging 49 animals, with a total of 199,026 cattle. Temperament was evaluated through a behavioral assessment carried out based on the temperament shown by cattle when approached by humans. One of three different temperament scores were assigned to each batch: calm, anxious, or excitable. Excitable temperament was reported in animals subjected to long transport time and distance and high loading density. The degree of carcass fatness was higher in calm animals, followed by anxious animals, with the excited temperament animals having the lowest carcass fatness degree. Older animals showed more excitable temperament, while younger animals showed calmer temperament. The excitable temperament was more evident in horned animals in relation to polled animals. Animal temperament was more reactive in batches with older cattle, low carcass fatness degree, and with more than 20% horned animals. Good handling and loading facilities and procedures at the farm contributed to adequate cattle temperament expression prior to slaughter. type onfarm preslaughter. preslaughter pre slaughter pre-slaughter 4061 4 061 4,06 199026 199 026 199,02 humans batch density 20 406 06 4,0 19902 19 02 199,0 2 40 0 4, 1990 1 199,

RESUMO O trabalho teve por objetivo avaliar a influência de variáveis relacionadas às condições de manejo e de transporte na expressão do temperamento pré-abate de bovinos de corte. Foram avaliados 4.061 lotes, com média de 49 animais, totalizando 199.026 bovinos. O temperamento foi avaliado por meio da expressão comportamental dos lotes diante da aproximação humana. Foram atribuídas três diferentes classificações de temperamento: “calmo”, “ansioso” ou “excitável”. Verificou-se temperamento excitável em animais submetidos a longos tempos de transporte, a grandes distâncias e à alta densidade de carga. O grau de gordura na carcaça foi mais elevado em animais “calmos”, seguidos dos animais “ansiosos”, e menor em animais de temperamento “excitado”. Os animais com temperamento excitável eram mais velhos, e aqueles com temperamento calmo eram mais jovem. O temperamento excitável foi mais evidente em animais com a presença de chifres. O temperamento animal foi mais reativo em lotes de bovinos mais velhos, com baixo grau de gordura de carcaça e com mais de 20% de animais com presença de chifres. Boas instalações e condições apropriadas de manejo e de carregamento dos animais contribuem para a expressão adequada do temperamento dos bovinos no pré-abate. préabate pré abate corte 4061 4 061 4.06 199026 199 026 199.02 humana calmo, , “calmo” ansioso “ansioso excitável. . “excitável” Verificouse Verificou se carga calmos, calmos “calmos” ansiosos, ansiosos “ansiosos” excitado. excitado “excitado” velhos jovem chifres 20 préabate. abate. 406 06 4.0 19902 19 02 199.0 “calmo “excitável “calmos “ansiosos “excitado 2 40 0 4. 1990 1 199.

ABSTRACT. The influence of harvest method on proximate composition, protein oxidation, and texture profile of beef from Nellore cattle were investigated. Longissimus lumborum (LL) muscles were obtained from twelve grain-fed Nellore carcasses. The animals were slaughtered after stunning (STU; n=6) or without stunning (WST; n=6) and after 24 hours postmortem, the LL was sliced into 2.54-cm steaks, packed under aerobic conditions, and stored at 4°C for nine days. Proximate composition was analyzed on day 0, whereas protein oxidation (carbonyl content) and texture profile (hardness, chewiness, cohesiveness, and springiness) were evaluated on days 0, 3, 6, and 9. STU and WST steaks exhibited similar proximate composition, hardness, and chewiness (p > 0.05). WST steaks exhibited greater protein oxidation and lower cohesiveness than their STU counterparts on day 0 (p < 0.05). Concerning the storage period, WST steaks demonstrated a decrease in springiness and a more pronounced increase in cohesiveness than their STU counterparts (p < 0.05). These results indicated that the harvest method influenced LL protein oxidation and texture profile from Bos indicus cattle. ABSTRACT investigated (LL grainfed grain fed carcasses (STU n=6 n6 n 6 (WST 2 postmortem 2.54cm 254cm cm 2.54 54 conditions 4C C 4 carbonyl content hardness (hardness 3 9 p 0.05. 005 0.05 . 05 0.05) period n= 54cm 254 2.5 5 00 0.0 25 2. 0.

The main characteristics of the beef production chain are set out in order to identify the chain links that hamper its development. The Uruguayan experience is shown. The importance of the time devoted to the productive process as to biological particularities of the biological cycle of beef production and the multiplicity of products generated during the industrial stage are two of the traits that should be taken into account to design a strategy addressed to the development of this process. The application of production technologies that fasten cattle growth and fattening, as well as market differentiation to efficiently sell products (high- and low-quality meat cuts) and byproducts (hide, viscera, fat) are two alternatives that encourage beef production. The strategy implemented in Uruguay has permitted a significant reduction in slaughter age by including supplementation in enclosure feeding for cattle production systems. The development of a public policy based on obtainment of sanitary status, on total cattle traceability, and on an electronic information system in the beef industry has allowed gaining international confidence, reflected in entering the most demanding markets, besides fulfilling the domestic market intake.

Se exponen las principales características de la cadena productiva de la carne de res, a los efectos de identificar los eslabones que limitan su desarrollo. Se presenta la experiencia de Uruguay. La importancia del tiempo invertido en el proceso productivo, en cuanto a las particularidades biológicas del ciclo de producción de carne bovina y la multiplicidad de productos generados durante la fase industrial, son dos características que se deben considerar para diseñar una estrategia encaminada al desarrollo de dicho proceso. La aplicación de tecnologías de producción que aceleren el proceso de crecimiento y engorde, así como la diferenciación de mercados, que permitan la colocación eficiente de productos (cortes de carne de alta y baja calidad) y subproductos (cuero, vísceras, sebo) son dos alternativas que posibilitan traccionar el proceso productivo de la carne de res. La estrategia implementada por Uruguay ha permitido una significativa reducción en la edad de faena mediante la incorporación de la suplementación combinada con la alimentación a corral en los sistemas de producción ganaderos. El desarrollo de una política pública, basada en la obtención de un estatus sanitario, en la trazabilidad total del ganado y en un sistema de información electrónica en la industria cárnica, le han permitido generar una confianza internacional, que se refleja en el ingreso a los mercados más exigentes, además de satisfacer el consumo del mercado doméstico.

Abstract The animal welfare concept must be considered in every cattle life phases. Its preservation is not just integrated by ethical aspects, but by the possibility of improving productivity and meat quality. It is important that every person involved in the raising process, transportation and slaughter of cattle understands the importance of animal care. It is necessary know the mechanisms by which the conditions provided affect the sensorial and nutritional characteristics of the meat. It is known that meat composition begins to be defined in the primary production stage. Intensive production systems that aim to maximize production must guarantee animal welfare. This is because animals depend entirely on man’s will to agreement adequate food, water and environmental conditions. The animal comfort food and genetics contribute to obtaining an excellent carcass. While acute and chronic stress events negatively affect the characteristics and preservation of meat products. The objective of this review is to evaluate the effects of animal welfare on production and meat quality. In addition, a fattening system developed by the National Agricultural Technology Institute (INTA) is presented, where management and feeding conditions are considered to contribute to animal welfare.

Resumen El bienestar de los animales es un concepto que debe abordarse en todas las etapas de la vida de los bovinos. Su preservación no solo está integrada por aspectos éticos, sino también por la posibilidad de mejorar los niveles de producción y la calidad de la carne. Es importante que todos los sujetos que intervienen en la crianza, traslado y faena de los bovinos para producción de alimentos entiendan la importancia del cuidado de los animales. Para ello, es necesario conocer los mecanismos por los cuales las condiciones brindadas afectan las características sensoriales y nutritivas de la carne. Ello se debe a que la composición de la carne comienza a definirse en la etapa de producción primaria. Los sistemas de producción intensiva que se orientan a maximizar la producción deben garantizar el bienestar animal. En este sentido, es responsabilidad del hombre encargado de los animales garantizar alimento, agua y condiciones ambientales adecuadas. El confort de los animales, la alimentación y la genética contribuyen a la obtención de una res bien conformada. Mientras que los eventos de estrés agudo y crónico repercuten negativamente sobre las características y la conservación de los productos cárnicos. El objetivo de la presente revisión es abordar los efectos del bienestar animal sobre la producción y calidad de la carne. Además, se presenta un modelo de engorde intensivo desarrollado por el Instituto Nacional de Tecnología Agropecuaria (INTA) donde se consideran las condiciones de manejo y alimentación para contribuir al bienestar animal.

Resumo: A pecuária de corte no Brasil tem se tornado cada vez mais competitiva, levando o país a ser o segundo maior produtor e o maior exportador mundial de carne bovina. Dessa forma, é relevante analisar o comportamento do preço da arroba do boi gordo, assim como dos fatores que o influenciam, pois tal compreensão auxilia no planejamento estratégico e nas tomadas de decisões dos stakeholders desse setor. O presente estudo aborda o comportamento do preço da arroba do boi gordo no estado de São Paulo no período de janeiro de 2005 a janeiro de 2020, com o objetivo de estimar a projeção da tendência desse preço por meio dos modelos lineares dinâmicos (MLD). Além disso, selecionaram-se previamente, com base na literatura existente, variáveis de mercado para a análise da correlação delas com o valor da arroba do boi gordo. Verificou-se uma forte correlação positiva com o preço do bezerro, a relação de troca boi gordo/boi magro, o abate de bovinos e a importação de carne brasileira pela China. Houve também uma correlação positiva moderada quanto ao volume de exportação de carne bovina pelos Estados Unidos e uma correlação negativa moderada do preço da arroba em reais com a taxa de câmbio do dólar americano.

Abstract: Beef cattle in Brazil has become increasingly competitive, as the country is the second-largest producer and the largest exporter of beef in the world. It is relevant to analyze the behavior of the price of the cattle arroba in this sector, as well as the factors that influence it, considering that such knowledge helps in the strategic planning and decision-making of the parties involved. This study addresses the verification of the behavior of arroba prices in the state of São Paulo from January 2005 to January 2020 to estimate the projection of the trend of this indicator inquiring the use of the Dynamic Linear Models (DLM). In addition, market variables were previously selected based on the existing literature for the analysis of their correlation with the value of the arroba. There was a strong positive correlation with the price of the calf, the exchange ratio of fat cattle/lean cattle, the slaughter of cattle, and the importation of Brazilian meat by China. There was also a moderate positive correlation regarding the volume of beef exports by the United States and a moderate negative correlation between the arroba price in Brazilian reais and the US dollar exchange rate.

Resumo Uma vez que o sistema calpaína é central para o amaciamento da carne e dada a importância da atividade de calpastatina na determinação da maciez de bifes de bovinos Bos taurus indicus, o objetivo do presente estudo foi determinar se a expressão do gene de μ-calpaína (CAPN1), calpastatina total (CAST T), e suas variantes (CAST I e II) foi induzido pela inclusão de vitamina D3 na dieta. Os animais receberam nenhuma ou 2 × 106 UI dose de vitamina D3 por 2 ou 8 dias antes do abate, e foram submetidos a diferentes condições durante o confinamento: exposição solar ou sombreamento artificial. Bifes do Longissimus lumborum foram fabricados e submetidos a maturação por 1, 7, e 21 dias post-mortem e posteriormente usados para determinação da força de cisalhamento e do índice de fragmentação miofibrilar. Vitamina D3 não influenciou a abundância de RNAm, exceto para maior abundância de transcritos de CAST II em animais que foram suplementados por 8 dias antes do abate. Foi encontrada associação negativa entre a abundância de CAST II e a força de cisalhamento. Essa contradição revela uma importante modulação da expressão do sistema calpaína resultado da suplementação com vitamina D que pode ser importante na determinação de estratégias para melhorar a maciez da carne.

ABSTRACT The calpain system is the central player for meat tenderization and the calpastatin activity plays an important role in beef tenderness of Bos taurus indicus cattle. This study investigated whether dietary vitamin D3 induced gene expression of μ-calpain (CAPN1), total calpastatin (CAST T), and their variants (CAST I and II). Animals received none or 2 × 106 IU of vitamin D3 for either 2 or 8 days before slaughter and were submitted to different conditions during feedlot: sun exposure or artificial shade. Steaks from Longissimus lumborum were fabricated, aged for 1, 7, and 21 days post-mortem, and later used for the analyses of shear force and the myofibrillar fragmentation index. Vitamin D3 did not influence mRNA abundance; however, it induced a greater CAST II transcript in animals supplemented 8 days before slaughter. There was a negative association between CAST II abundance and the shear force, which revealed an important modulation of the calpain system expression due to vitamin D supplementation. This result is an important tool for strategies to improve beef tenderness.

Resumen Con el objeto de evaluar el rendimiento y la calidad de la carne en bovinos de la raza Blanco Orejinegro (BON), se utilizaros 77 machos (castrado y entero) y dos rangos de edad (20-30 y 30-36 meses). Se evaluó la ganancia de peso (GDP), área de ojo del lomo (AOL), espesor de grasa de la cadera (EGC), rendimiento de la canal caliente y fría, longitud de la canal (LC), perímetro de pierna, grado de osificación y acabado. Adicionalmente, se evaluó la calidad de la carne a diferentes días de maduración. Se utilizó ANOVA de efectos mixtos y componentes principales para el análisis de la información. Los resultados mostraron que la condición fisiológica, edad y la interacción de estos factores no afectaron significativamente (p > 0,05) la GDP, peso beneficio, AOL y EGC. La edad afectó significativamente (p < 0,05) el peso de la canal. Así mismo, la condición fisiológica afectó significativamente (p < 0,05) la LC, favoreciendo los animales castrados (+17cm). La edad de maduración tuvo efecto significativo sobre la terneza y el porcentaje de pérdidas por cocción (p < 0,05), con mejores registros a 21 días (2,75 kilogramo-fuerza) y 37 días (17 %), respectivamente. La carne de novillos BON presentó alta terneza, baja presencia de tejido conectivo y alta puntuación en jugosidad. Los resultados del presente trabajo evidencian un buen desempeño de la raza BON para la cadena cárnica.

Abstract Aiming at evaluating the performance and beef quality in the Blanco Orejinegro (BON) breed, 77 males (castrated and non-castrated) and two age ranges (20-30 and 30-36 months) were used. Weight gain (ADG), ribeye area (RA), hip fat thickness (HFT), hot and cold carcass yield, carcass length (CL), leg circumference, carcass ossification, and fat cover grade were evaluated. Additionally, the beef quality was assessed at different days of meat ageing. A mixed-effects ANOVA and a principal component analysis were used to analyze the information. The results showed that the physiological condition, age, and the interaction of these factors did not significantly affect (p > 0.05) ADG, slaughter weight, RA, or HFT. Age significantly (p < 0.05) affected carcass weight. Likewise, the physiological condition significantly affected (p < 0.05) CL, favoring the castrated animals (166 cm vs. 149 cm). The maturation age had a significant effect on tenderness and the percentage of cooking losses (P < 0.05), with better records at 21 days (2.75 kilogram-force) and 37 days (17%), respectively. The BON beef showed high tenderness, low presence of connective tissue, and a high juiciness score. The results of this work show a good performance of the BON breed for the meat chain.

RESUMO O objetivo deste trabalho foi avaliar o efeito da substituição da silagem de sorgo por diferentes proporções de silagem de triticale no desempenho e na carcaça de novilhas Braford. A silagem de sorgo foi substituída em 0%, 30%, 60% e 100% pela silagem de triticale como fonte de volumoso na alimentação de 24 novilhas da raça Braford, em um sistema de confinamento. O período experimental total foi de 63 dias para a avaliação do consumo dos componentes da ração, a conversão alimentar e o ganho médio diário. Ao final do experimento, os animais foram abatidos e avaliados em relação às características de carcaça. A substituição da silagem de sorgo pela silagem de triticale não apresentou efeito no consumo dos componentes da ração e no ganho médio diário entre as novilhas (P>0,05). A conversão alimentar foi melhor para as novilhas que receberam menores proporções de silagem de triticale (0% e 30%) em substituição à silagem de sorgo (P<0,05). As características das carcaças foram semelhantes entre os animais independentemente da fonte de volumoso. A silagem de triticale apresenta-se como alimento alternativo à silagem de sorgo em regiões de transição climática para a terminação de novilhas de corte, proporcionando o mesmo desempenho animal e as mesmas características de carcaça.

ABSTRACT The aim of this study was to evaluate the effect of sorghum silage substitution with different proportions of triticale silage on the performance and carcass of Braford heifers. Twenty-four Braford heifers were randomly assigned to four diets where sorghum silage was replaced at 0%, 30%, 60%, and 100% for triticale silage in a feedlot system. During sixty-tree days of the experiment, the feed intake, feed ratio conversion, and average daily gain were measured. The heifers were slaughtered and the effects of the sorghum and triticale silage in carcass characteristics were evaluated. The replacement of sorghum silage with triticale silage did not affect the feed intake and average daily gain (P> 0.05). Feed gain ratio was higher for the heifers that received lower proportions of triticale silage (0% and 30%) in replace sorghum silage (P <0.05). Eye loin area and fat thickness were similar among treatments (P<0.05). Other carcass characteristics, such as slaughter live weight, dressing percentage, conformation and fat classification were similar among experimental treatments (P<0.005). Triticale silage can replace sorghum silage for finishing beef heifers in feedlot system and provides similar carcass characteristics.

Abstract: The analysis of the value chain in beef cattle of Mexico has focused mainly on production and final consumer; however, slaughter centers represent the main link between producers and consumers. The objective was to analyze the demand for live beef cattle in the slaughter centers of Mexico, 2000-2018. The sample considered 50 slaughterhouses, in 26 of 32 states and the demand models were estimated using the ordinary least squares method. It was possible to estimate the four best demand models by product; the price explained 43.4 % of the variability in the quantity of beef in the slaughter centers; 60.4 % for cull cows, 37.7 % steers, 33.5 % cull bulls and 28.8 % heifers. All products behaved inelastic in price (-0.17), but the demand for steers had the lowest elasticity (-0.06). The beef market presented a low average density of connections between the producers and slaughter centers analyzed (25.2 ± 43.4 %), which indicates its inefficiency. The state of Jalisco represented the main slaughter center in steers and cull cows, while Aguascalientes in heifers and cull bulls.

Resumen: El análisis de la cadena de valor en bovinos carne de México se ha centrado en la producción y consumidor final, principalmente; sin embargo, los centros de sacrificio representan el eslabón principal entre productores y consumidores. El objetivo fue analizar de la demanda de bovinos carne en pie en los centros de sacrificio de México, 2000-2018. La muestra consideró 50 casas de matanza, en 26 de 32 entidades federativas y los modelos de demanda fueron estimados mediante el método de mínimos cuadrados ordinarios. Fue posible estimar los cuatro mejores modelos de demanda por producto; el precio explicó 43.4 % de la variabilidad en la cantidad de carne de bovino en los centros de sacrificio; 60.4 % para vacas de desecho, 37.7 % novillos, 33.5 % toros de desecho y 28.8 % novillas. Todos los productos se comportaron inelásticos al precio (-0.17), pero la demanda de novillos tuvo la menor elasticidad (-0.06). El mercado de la carne de bovino presentó una baja densidad media de las conexiones entre productores y centros de sacrificio analizados (25.2 ± 43.4 %), que indica una ineficiencia del mismo. El estado de Jalisco representó el principal centro de sacrificio en novillos y vacas de desecho, mientras que Aguascalientes en novillas y toros de desecho.

Abstract A total of 27 management variables (before, during and after slaughter) in 394 bovines were analyzed and used to determine their association and explanatory value with the presence of DFD (Dark, Firm, Dry) beef, using probability ratios in a multiple logistic regression model. The study was conducted from November 2016 to August 2017 on a Federal Inspection Type slaughterhouse located in northeastern Mexico. The presence of DFD beef was 13.45%. A contrast was made between classes for the factors evaluated by means of Student’s t and Chi-square according to the nature of the variable as a criterion for inclusion in logistic modeling. Ten of the variables showed statistical significance (P<0.05) in these tests, but only four of them presented explanatory value in the final multiple logistic model (P<0.01), which were: the waiting time prior to death, poor desensitization, the thickness of the subcutaneous fat and pH differential of the carcass established with 24 h of difference. The first two increased the possibility in the presence of DFD beef, on the contrary, the fat thickness and pH differential were inversely proportional. The four variables included in the final model were present at different stages and are of a different nature. For this reason, to effectively prevent this problem, a multicausal evaluation is needed throughout the slaughter process.

Resumen Un total de 27 variables de manejo (antes, durante y después del sacrificio) en 394 bovinos fueron analizadas y utilizadas para determinar su asociación y valor explicativo con la presencia de carne DFD (Dark, Firm, Dry, por sus siglas en inglés), mediante las razones de probabilidad en un modelo de regresión logística múltiple. El estudio se realizó de noviembre de 2016 a agosto de 2017 en un rastro Tipo Inspección Federal localizado en el noreste de México. La presencia de carne DFD fue del 13.45 %. Se realizó un contraste entre clases para los factores evaluados mediante t Student y Ji cuadrada en función de la naturaleza de la variable como criterio de inclusión en la modelación logística. Diez de las variables mostraron significación estadística (P<0.05) en estas pruebas, pero solo cuatro de ellas presentaron valor explicativo en el modelo logístico múltiple final (P<0.01), las cuales fueron: el tiempo de espera previo a la muerte, un mal insensibilizado, el espesor de la grasa subcutánea y diferencial de pH de la canal establecido con 24 h de diferencia. Las dos primeras aumentaron la posibilidad en la presencia de carne DFD, por el contrario, el espesor de grasa y el diferencial de pH fueron inversamente proporcionales. Las cuatro variables incluidas en el modelo final estuvieron presentes en diferentes etapas y son de naturaleza distinta. Por esta razón, para prevenir de manera efectiva este problema se necesita una evaluación multicausal en todo el proceso de matanza.

The aim of this study was to evaluate the effects of various dietary energy levels on the carcass and meat characteristics of feedlot-finished steers. A total of 27 purebred and crossbred Charolais and Nellore steers were used, with a mean initial age of 22 months and weight of 253 kg. The animals were allotted to a completely randomized design with three treatments and nine replicates each. Dietary treatments were arranged so that the average forage to concentrate ratio (FCR) was equivalent to that of a constant FCR treatment. The treatments consisted of CT (constant FCR at 60 to 40), CT5 (starting with 70: 30 FCR and finishing with 50: 50 FCR, that is, a mean overall FCR of 60: 40), and CT10 (starting with 80: 20 FCR and finishing with 40: 60, that is, a mean overall FCR of 60: 40). The dietary treatments did not affect slaughter weight, carcass weight, carcass conformation, physiological maturity, subcutaneous fat thickness, ribeye area, marbling score, and carcass measurements or the yield of commercial cuts. Chilling loss was higher in CT10 steers (2.41%) than in CT (2.26%) and CT5 (2.15%).

Resumen Introducción. La preferencia al riesgo es la situación en la que un productor agropecuario decide invertir dinero y existe la probabilidad de obtener beneficios distintos a los deseados. Objetivo. Evaluar la preferencia al riesgo y la utilidad de la producción intensiva de carne de bovino Angus y Hereford en el Rancho Teseachic, La Posta, Chihuahua, México a través de la utilidad monetaria. Materiales y métodos. El experimento se realizó del 24 de marzo al 11 de agosto de 2017. Se evaluaron 52 bovinos, los cuales se alimentaron por un periodo de 141 días a base de maíz rolado (53,3 %) y granos de destilería (37,8 %). Los animales se dividieron en dos lotes: uno con 32 cabezas de Angus con 226,28±28,69 kg de peso vivo inicial y el otro con 20 cabezas de Hereford con 191,58±24,23 kg de peso vivo. Se ajustó un modelo econométrico, mediante Mínimos Cuadrados Ordinarios, para determinar la preferencia al riesgo absoluta y relativa de la utilidad monetaria en la engorda de los bovinos. Resultados. Al final del periodo, el peso fue de 371,7±43,96 kg para Angus y 320,9±37,99 en Hereford. El modelo de producción indicó un peso vivo óptimo al sacrificio de 375,5 kg para Angus y 321,5 kg para Hereford. Conclusión. El productor rechazó la preferencia sin riesgo a la preferencia con riesgo. La producción de carne con terneros Angus presentó una menor preferencia por el riesgo (20 %) que en terneros Hereford (44 %) y por ende menor utilidad.

Abstract Introduction. Risk preference is the situation in which an agricultural producer decides to invest money and there is a probability of obtaining benefits from those desired. Objective. To evaluate risk preference and utility of intensive Angus and Hereford beef production in Rancho Teseachic, La Posta, Chihuahua, Mexico through monetary utility. Materials and methods. The experiment was conducted from March 24th to August 11th 2017. 52 cattle were evaluated and fed for a period of 141 days with rolled corn (53,3 %) and distillers’ grain (37,8 %). The animals were divided into two lots: one with 32 Angus heads with 226.28±28.69 kg of initial live weight and the other with 20 Hereford heads with 191.58±24.23 kg of initial live weight. An econometric model was adjusted, using Ordinary Minimums Squares, to determine the absolute and relative risk preference of the monetary utility in cattle fattening. Results. At the end of the period, the weight was 371.7±43.96 kg for Angus and 320.9±37.99 for Hereford. The production model indicated an optimum live weight at slaughter of 375.5 kg for Angus and 321.5 kg for Hereford. Conclusion. The producer rejected the risk-free preference to the risky preference. Meat production with Angus calves showed a lower risk preference (20 %) than Hereford calves (44 %) and therefore less utility.

Abstract This study aimed to determine the frequency of contamination and serovar diversity of Salmonella enterica (SE) and Escherichia coli (EC) in different stages of cattle slaughtering and deboning processes. Fecal, carcass, and primal cut (100 of each type) samples were collected in a Federally Inspected slaughterhouse in Mexicali, Baja California. EC was not analyzed in fecal samples because it is part of the gut microbiota. Strain identity was confirmed by biochemical methods and PCR, using the taxonomic genes invA and gadA for SE and EC, respectively. In EC, the presence of genes associated with the main pathotypes was also investigated. SE had a 34 % frequency in fecal samples, 3% in carcasses, and 2% in cuts, while Montevideo was the predominant serovar (72.5 % of the total strains). EC was detected in carcasses (34 %) and cuts (11 %) at an average concentration of 0.012 and 0.33 log CFU cm-2, respectively. Although several of the identified EC serovars were associated with enterotoxigenic or Shiga toxin-producing strains, none carried the virulence factors typically observed in these pathotypes. In summary, beef carcasses and cuts are not a relevant source of EC pathogenic strains. However, beef is an important reservoir of SE, which represents a public health risk. Genomic studies are required on the virulence profile and genes of SE strains commonly associated with subclinical infections and isolated from apparently healthy animals.

Resumen El objetivo fue determinar la frecuencia de contaminación y la diversidad de serotipos de Salmonella enterica (SE) y Escherichia coli (EC) en diferentes etapas de los procesos de matanza y deshuese de bovinos. Se tomaron muestras de heces, canales y cortes primarios (100 de cada tipo) en un rastro Tipo Inspección Federal ubicado en Mexicali, Baja California. EC no se analizó en heces, por ser esta bacteria parte de la microbiota intestinal. La identidad de las cepas se confirmó por métodos bioquímicos y por PCR: genes taxonómicos invA y gadA, para SE y EC, respectivamente. En EC se investigó también la presencia de genes asociados con los principales patotipos. SE tuvo una frecuencia de 34 % en heces, 3 % en canales y 2 % en cortes, siendo Montevideo el serotipo predominante (72.5 % del total de cepas). EC se detectó en canales (34 %) y en cortes (11 %), en concentraciones promedio de 0.012 y 0.33 log UFC cm-2, respectivamente. Aunque varios de los serotipos de EC identificados están asociados con cepas enterotoxigénicas o productoras de toxinas tipo Shiga, ninguno portaba factores de virulencia característicos de estos patotipos. En resumen, las canales y cortes de bovino no son una fuente relevante de cepas patógenas de EC. En contraste, los bovinos constituyen un importante reservorio de SE, lo cual representa un riesgo para la salud pública. Se requieren estudios genómicos sobre el perfil de virulencia y los genes asociados con infecciones subclínicas en cepas de SE provenientes de animales aparentemente sanos.