Resumen: Se observaron desgarros y desprendimientos de piel en un ternero recién nacido, luego de la revisión umbilical. El diagnóstico presuntivo de dermatosparaxis se realizó con base en la anamnesis y los signos clínicos típicos de la enfermedad, como alta fragilidad y desprendimientos totales de fragmentos de piel. Para la confirmación se realizaron estudios histopatológicos mediante tinciones HE, PAS y tricrómica de Masson sobre muestras de piel del animal afectado, usando como control muestras de piel de la misma región de un animal sano de igual edad y cruza, proveniente del mismo establecimiento de origen. Se complementó el diagnóstico con técnicas moleculares mediante la extracción de ADN, PCR y electroforesis. Finalmente, los resultados histopatológicos confirmaron compatibilidad con la enfermedad de colágeno planteada. No se pudo comprobar que la mutación fuera la misma ya descrita en bovinos. Según lo investigado, este es el primer reporte de dermatosparaxis en esta especie en Uruguay.

Abstract: Tears and skin detachments were observed in a newborn calf after umbilical revision. The presumptive diagnosis of Dermatosparaxis was based on the anamnesis and the typical clinical signs of the disease, such as high fragility and total detachment of skin fragments. Three staining techniques (HE, PAS and Masson’s trichrome) were performed on skin samples from the affected animal, using skin samples from the same region of a normal animal with the same age and crossbreed, and from the same ranch used as control. The diagnosis was complemented with molecular techniques through DNA extraction, PCR, and electrophoresis. Finally, the histopathological results confirmed compatibility with this collagen disease. It could not be possible to confirm that the mutation was the same described in other cases of this clinical disease in cattle. As investigated, this is the first Dermatosparaxis report in calves in Uruguay.

Resumo: Pele rasgada e descamação foram observadas em um bezerro recém-nascido após revisão umbilical. O diagnóstico presuntivo de Dermatosparaxia foi feito com base na anamnese e nos sinais clínicos típicos da doença, como alta fragilidade e descolamento total de fragmentos de pele. Para confirmação, foram realizados estudos histopatológicos por meio das colorações HE, PAS e tricrômico de Masson em amostras de pele do animal afetado, utilizando como controle amostras de pele da mesma região de um animal sadio da mesma idade e cruzamento, do mesmo estabelecimento de origem. O diagnóstico foi complementado com técnicas moleculares por meio de extração de DNA, PCR e eletroforese. Por fim, os resultados histopatológicos confirmaram a compatibilidade com a doença do colágeno proposta. Não foi possível verificar que a mutação era a mesma já descrita em bovinos. De acordo com o que foi investigado, este é o primeiro relato de Dermatosparaxis nesta espécie no Uruguai.

ABSTRACT: Heterosis plays an important role on yield and profitability of beef production systems. This study evaluates the morphometrics of purebred Nellore (N) and Charolais (C) animals and of the second (G2) and third (G3) generations of their alternating crosses, regarding the effects of genetic group and heterosis from birth to 365 days of age. The experiment comprised 159 calves (C = 29, N = 22, G2 - 3/4C 1/4N = 21, 3/4N 1/4C = 9, G3-5/8C 3/8N = 44 and 5/8N 3/8C = 34). The foreshank girth (FG), thoracic girth (TG), body length (BL), and hip height (HH) were measured after birth, and at 63, 210, and 365 days of age, and the total increases were calculated. The Charolais animals had greater FG, TG, and BL values than Nellore, while the latter had greater HH. For the offspring generations, the predominance of Charolais genes in the genotypes resulted in greater measurements for FG and TG in G2, whereas the predominance of Nellore genes resulted in higher HH values in both generations. The crossbred animals had greater values for all measurements than the purebreds, with more significant differences in FG, TG, and BL compared to Nellore purebreds and in HH compared to Charolais. Charolais animals show higher values for muscularity; while, Nellore animals are taller. Crossbred animals show greater development compared to purebreds, indicating a significant effect of heterosis.

The study investigated the effect of crossbreeding Charolais bulls with Nguni cows on carcass and lean yield and meat quality characteristics. The intact Charolais bulls (n=10) served as control group against the Charolais x Nguni (n=10). The Nguni dam proved a good option for a dam line because of the hardiness of the breed, its mothering ability, ease of calving, and low maintenance cost. In contrast, the Charolais had excellent growth and carcass characteristics. It was a late maturing breed with better growth performance and higher yields than Charolais x Nguni, which could be classified as a medium maturing beef breed. Over the same duration and conditions of feeding the Charolais calves had better feed conversion and growth rates and produced larger carcasses than Charolais x Nguni calves. Owing to the large difference in carcass size, the Charolais had better meat to bone ratio than the Charolais x Nguni (P <0.001). Both breeds produced meat with a desirable appearance and good eating quality and no differences were recorded in the related traits. It could be concluded that Charolais and Charolais x Nguni weaned calves were well suited to the grain-fed market and would produce meat of acceptable quality.

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%).

Abstract The National Institute of Forestry, Agricultural and Livestock Research in Mexico has been active for decades in researching genetic improvement in beef cattle. This review uses master theses, congress papers and scientific articles published from 1987 to 2020 to summarize much of the relevant research, and addresses research challenges and outlook over the short-, medium- and long-term in this area. Research done over the last 34 yr has evaluated the productive and reproductive performance of Bos indicus and Bos taurus x Bos indicus beef cattle raised under tropical conditions. Multibreed genetic evaluations have been done for Simmental-Simbrah and Charolais-Charbray populations in Mexico. Analyses have quantified the importance of maternal effects on growth traits, and estimated heritability and genetic correlations for growth and reproductive traits in male and female Bos taurus and Bos indicus animals. The genotype-environment interaction has been confirmed to influence expression of weaning weight in Simmental cattle. Age adjustment factors have been developed for maternal age for weights at birth and weaning, and prototypes of national genetic evaluation were developed for stayability and heifer fertility. Genetic diversity has been quantified for Simmental, Charolais and Simbrah populations, and SNPs identified that are associated with growth traits in Simmental and Simbrah populations. Short-term goals include development of selection indices and prediction of the genetic merit of carcass traits. Over the medium-term, emphasis is needed on genomic evaluations for tolerance to heat stress, residual feed intake and health traits, while in the long-term the goal is to make inter-breed genomic predictions.

Resumen El objetivo fue presentar resultados de investigación sobre mejoramiento genético de bovinos productores de carne realizados por el Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias, así como los retos y perspectivas de investigación a corto, mediano y largo plazo en dicha área del conocimiento. Se utilizaron tesis de maestría, trabajos de congresos y artículos científicos publicados de 1987 a 2020. En los últimos 34 años, se logró caracterizar productiva y reproductivamente animales Bos indicus y Bos taurus x Bos indicus en condiciones tropicales, implementar evaluaciones genéticas multirraciales para las poblaciones Simmental-Simbrah y Charolais-Charbray, determinar la importancia de los efectos maternos en características de crecimiento y estimar la heredabilidad y correlaciones genéticas para características de crecimiento y reproductivas de machos y hembras en animales Bos taurus y Bos indicus, comprobar que la interacción genotipo-ambiente es un factor importante en la expresión de peso al destete en Simmental, desarrollar factores de ajuste de edad de la madre para pesos al nacimiento y destete, desarrollar un prototipo de evaluación genética nacional para permanencia productiva y otro para fertilidad de vaquillas, estimar la diversidad genética de las poblaciones Simmental, Charolais y Simbrah, e identificar SNP asociados a características de crecimiento en Simmental y Simbrah. En el corto plazo, se espera desarrollar índices de selección y predecir el mérito genético de características de canal; en el mediano, realizar evaluaciones genómicas para tolerancia al estrés calórico, consumo de alimento residual y características de salud; y a largo plazo, realizar predicciones genómicas a través de razas.

Abstract A full understanding of how specific genes affect live weight variables is required for their incorporation into genetic improvement programs. An analysis was done of the allelic frequencies of 28 single nucleotide polymorphisms (SNP) located in candidate genes for growth in cattle to identify their effect on live weight traits in Charolais and Simmental herds in the state of Tamaulipas, Mexico. Hair samples were collected from 313 animals and genotyped using the Sequenom MassARRAY system. Genotype analysis showed that all the markers were polymorphic in the evaluated populations and their allelic frequencies were significantly different between the two breeds (P<0.05). An association analysis found that in the Charolais population the marker PRL + 2723 had a significant effect (P= 0.0350) on birth weight and the marker GHR-6.1 affected weaning weight (P= 0.0226). In the Simmental population GHR-6.1 was associated with yearling weight and the marker LEP-3100 (P=0.0249) had a significant effect on weaning weight. The tested 28 SNP panel is polymorphic in both breeds and three of the markers had a significant effect on the evaluated live weight parameters. They can therefore be potentially validated for use as tools in the selection and breeding of beef cattle in Tamaulipas.

Resumen El objetivo del estudio fue analizar las frecuencias alélicas de 28 Polimorfismos de un solo nucleótido (SNP) localizados en genes candidatos para crecimiento en bovinos, así como determinar su efecto sobre rasgos de peso vivo en hatos de las razas Charolais y Simmental. Se tomaron muestras de pelo de 313 animales provenientes de cinco hatos ubicados en cuatro municipios de Tamaulipas y se genotipificaron con la tecnología de Sequenom Mass Array. Todos los marcadores resultaron ser polimórficos en las poblaciones evaluadas y sus frecuencias alélicas fueron significativamente diferentes entre razas (P<0.05). El análisis de asociación determinó que en los animales de la raza Charolais, el marcador PRL+2723 tiene un efecto significativo (P=0.0350) sobre el peso al nacimiento y el marcador localizado en el gen GHR (GHR-6.1), sobre peso al destete (P=0.0226). El GHR-6.1 también se asoció con el peso al año en los animales de la raza Simmental. El marcador LEP-3100 (P=0.0249) también tuvo un efecto significativo sobre el peso al destete en los animales Simmental. El panel probado es polimórfico en las dos razas evaluadas y tres de los marcadores tuvieron efecto significativo en los parámetros de peso vivo evaluados, por lo que tienen el potencial de validarse y usarse como una herramienta adicional en la selección y mejoramiento genético del ganado de carne en Tamaulipas.

Resumo: O objetivo deste trabalho foi avaliar o efeito do grupo genético e da heterose na relação entre peso corporal e medidas morfométricas, em bezerros puros e mestiços das raças Nelore e Charolesa de segunda (G2) e terceira (G3) gerações. Peso corporal (PC), ganho de peso médio diário (GMD), circunferência da perna dianteira (CPD), circunferência torácica (CT), comprimento corporal (CC) e altura da garupa (AG) foram medidos ao nascimento e aos 63, 210 e 365 dias de idade, nos animais de G2 e G3. Os animais da raça Charolesa foram superiores aos da Nelore quanto aos ganhos de PC, GMD, CC e CT, e para a razão entre o ganho de PC e o de AG; os animais Nelore foram superiores quanto aos ganhos de AG. Animais mestiços de ambas as gerações foram superiores aos animais puros quanto aos ganhos de PC, CC e AG. Na G2, a predominância dos genes da raça Charolesa resultou em maiores ganhos de PC, GMD, CPD e CT. Os animais da G3 foram superiores aos puros quanto a GMD, CPD e CT. Não se encontraram diferenças na proporção entre os ganhos nas medidas de peso e morfometria. Heterose e complementaridade são aparentes para as medidas de peso e corporais de bezerros mestiços de cruzamentos rotacionais.

Abstract: The objective of this work was to assess the effect of genetic group and heterosis on the relationship between body weight and morphometric measurements, in purebred and crossbred animals from the second (G2) and third (G3) generations of Nellore and Charolais calves. Body weight (BW), average daily weight gain (ADG), foreleg circumference (FC), thoracic girth (TG), body length (BL), and croup height (CH) were measured at birth and at 63, 210, and 365 days of age in animals from G2 and G3. Charolais animals were superior to Nellore ones for gains BW, ADG, BL, and TG, as well as for the ratio between BW gain and CH gain; Nellore animals were superior for CH gains. Crossbred animals of both generations were superior to the purebred animals for gains of BW, BL, and CH. In G2, the predominance of Charolais genes resulted in greater gains of BW, ADG, FC, and TG. The G3 animals were superior to the purebred animals for ADG, FC, and TG. No differences were found for the ratio between gains of weight and morphometric measurements. Heterosis and complementarity are apparent for weight and body measurements of crossbred calves from rotational crossings.

ABSTRACT In this study, we reported the evaluation of ruminal parameters and the rate and degree of degradation of biogenic amines (BA) in vitro, using ruminal fluid from sheep fed two different diets (meadow hay and silage of Medicago sativa L.). Herein, the Charolais sheep breed with a ruminal cannula was used to gather samples. Multiple rumen parameters were evaluated after 10 days of the feeding period. Samples were processed using fermenters inoculated by BA (histamine, tyramine, putrescine, cadaverine, spermine, and spermidine) during 8-h fermentation. Levels of BA were determined using ion-exchange chromatography, and volatile fatty acids (VFA) were determined using gas chromatography. More rapid BA degradation was noticed in hay than in haylage. Overall, VFA levels increased with duration of the fermentation, while pH lowered. The rapid increase was observed after 4 h of fermentation. Ammonia concentration had a decreasing trend in silage and increasing in the hay. Hypotheses on BA degradation were accepted. Important knowledge of the development of ruminal parameters in time was obtained, and based on gathered information, it is possible to say that other parameters and their impacts on BA in rumen need to be examined further.

ABSTRACT The objective was to evaluate factors that influence calving probability in the first and second reproductive years of beef heifers that reached the minimum recommended body weight (BW) in the first breeding season. Two hundred twenty-seven 24-month-old Charolais × Nellore heifers that mated between 2003 and 2012 were analyzed. The parameters evaluated were: year effect; individual and maternal heterozygosis; percentage of Charolais genotype; average daily gain (ADG) from weaning to the end of the first breeding season; BW at 18 and 24 months of age, end of breeding season, parturition, and weaning; Julian date of calving; and adjusted calf weight at weaning. These variables were subjected to logistic regression. Calving rates in the first and second reproductive years were 58.1 and 49.5%, respectively. Performance until the end of the first breeding season, BW before the first breeding season, and individual heterozygosis affected the calving probability in the first breeding season. In the second breeding season, BW variation from the first breeding season and calving, Julian date of calving, and BW at the end of the second breeding season influenced calving probability. Until the end of the first breeding season, ADG of beef heifers responded positively to the calving probability, even after reaching the usually recommended BW for the first breeding season. Primiparous cows calving at the beginning of the breeding season and gaining more BW between the first and second breeding season are more likely to give birth in the second breeding season.

Abstract We investigated whether a panel of molecular markers previously associated with temperament has an effect on live growth traits. Phenotypic data from 412 Charolais cows categorized according to their age in adult and young cows were used to determine Pearson's correlations between birth (BW), weaning (WW), and yearling live (YW) weight and temperament traits (measured as exit velocity [EV] and temperament score [TS]). For association analysis, selective genotyping of a group of 80 cows identified as the most docile and temperamental were genotyped with a 151-SNP (single-nucleotide polymorphisms) panel of molecular markers previously associated with temperament. Significant Pearson's correlations between birth weight and weaning weight and the two temperament measurements (EV and TS) were observed only in the young cow group. Significant effects of ten SNP on BW and WW were observed. Four markers located on candidate genes for temperament traits also had an effect on birth weight and weaning weight in Charolais cows, which indicates that both traits could be influenced by the same genes.

Resumo O objetivo desta pesquisa foi mensurar o comportamento ingestivo de novilhos terminados exclusivamente com concentrado contendo casca do grão de soja (moída) e/ou grão de aveia branca. Foram utilizados 32 novilhos, com predominâncias raciais Charolês ou Nelore. Os animais foram distribuídos ao acaso nos tratamentos, bloqueados conforme predominância genética e alocados em baias individuais. As dietas foram isonitrogenadas, sendo os tratamentos: Casca do grão de soja; Grão de aveia branca e a Mistura (partes iguais), acrescidos de calcário calcítico e núcleo proteico. Os animais que receberam dieta à base de casca de soja permaneceram mais tempo em ócio, comparados aos que receberam a mistura; estes, por sua vez, permaneceram mais tempo em ócio em relação aos que tiveram acesso à dieta à base de aveia branca. Os novilhos que consumiram dieta à base de casca de soja ruminaram menos tempo que os da mistura e estes, por sua vez, menos tempo que os novilhos alimentados à base de aveia branca. Dietas exclusivamente com concentrado à base de casca de soja, embora apresentem elevado teor de fibra solúvel em detergente neutro, não são suficientes para promover adequado comportamento ingestivo de novilhos de predominância racial Charolês ou Nelore.

Abstract The objective of this research was to measure the ingestive behavior of steers finished exclusively with concentrate containing soybean hulls (ground) and/or white oat grain.We used 32 steers with Charolais or Nellore predominance.The animals were randomly distributed in the treatments, blocked according to genetic predominance, and allocated in individual pens. Diets were isonitrogenous, being the treatments: Soybean hulls; White oat grain or the Mixture (equal parts), plus limestone and protein nucleus. Steers that received the diet based on soybean hulls remained more time in idle compared to the ones that received the mixture, and these remained more time in idle than the steers that received the diet based on white oat grain. Steers that received the diet based on soybean hulls ruminated less time than the steers fed the mixture, and these less time than those fed white oat grain. Exclusively concentrate diets based on soybean hulls although presenting high soluble fiber content in neutral detergent, are not sufficient to promote an appropriate ingestive behavior of steers of Charolais or Nelore racial predominance.

ABSTRACT The effect of three localized genetic markers in growth hormone (GH), Insulin-like growth factor 1 (IGF-1) and leptin (LEP) genes on feed efficiency indicators was evaluated using records from 136 young bulls of the Charolais, Angus and Brangus breeds during a productive behavior test. The analysis of association between the genotypes obtained and the productive traits evaluated showed a significant effect of the GH-Alu marker on CRA (p = 0.032) in the Angus breed, and in the Charolais one; this result shows that its inclusion in the initial efforts for the determination of efficiency phenotypes in Mexico and its consequent application in selection and breeding strategies are possible.

RESUMEN Se evaluó el efecto de tres marcadores genéticos localizados en los genes de hormona de crecimiento (GH), factor de crecimiento semejante a insulina-1 (IGF-1) y leptina (LEP) sobre indicadores de eficiencia alimenticia, utilizando registros de 136 toretes de las razas Charolais, Angus y Brangus durante una prueba de comportamiento productivo. El análisis de asociación entre los genotipos obtenidos y los rasgos productivos evaluados mostró un efecto significativo del marcador GH-Alu sobre CRA (p = 0.032) en la raza Angus, y sobre el peso final ajustado (p = 0.041), en la Charolais; este resultado muestra que es posible su inclusión en los esfuerzos iniciales para la determinación de fenotipos de eficiencia en México y su consecuente aplicación en las estrategias de selección y mejoramiento genético.

Abstract The objective of this study was to evaluate the effect of live weight and body condition score, measured at different growth stages, on the rebreeding of first-calf heifers. A total of 120 Nellore and Charolais crossbred heifers born between 2004 and 2008 were assessed. Their average age was 26±1 months, they were all from the same herd, and they received the same management from birth. To conduct this study, pre- and postpartum measurements of first-calf heifers were taken. The data were submitted to analysis of variance, and the means were compared using Student’s t-test at a significance level of α=0.05. A higher live weight of the heifer at 24 months enabled early calving within the first calving season (r=-0.30). First-calf heifers that rebred had a higher live weight at weaning (361 kg vs. 333 kg) than those that did not, although their live weights at calving were similar (344 kg vs. 332 kg). The rebreeding of first-calf heifers that gave birth with the same body condition score as in the first calving was dependent on positive live weight gain until the end of the following breeding season, especially during the calving-weaning period.

Resumen El objetivo de este estudio fue evaluar el efecto del peso vivo y la puntuación de condición corporal, medido en diferentes fases de crecimiento, sobre la repetición de la cría en primíparas. Se evaluaron 120 novillas cruzadas Nellore con Charoles nacidas entre los años 2004 y 2008, con edad media de 26±1 meses siendo todas oriundas del mismo rebaño y que reciben idéntico manejo desde el nacimiento. Para la realización de este estudio se utilizaron de la base de datos a las mediciones de la primípara en el pre y post-partos. Los datos fueron sometidos al análisis de varianza y las medias comparadas a través del test “t” de Student, a α=0,05 de probabilidad. El mayor del peso vivo de la novilla a los 24 meses proporciona que el parto ocurra por adelantado dentro de la primera estación de parición (r=-0,30). Primíparas que repetían crea presentaron mayor peso vivo al destete (361 kg vs. 333 kg) de las que no repitieron crea, aunque hubiera peso vivo al parto semejante entre sí (344 kg vs. 332 kg). La repetición de la cría de primíparas que paren con la misma puntuación de condición corporal, en el primer parto, es dependiente de la ganancia de peso vivo positivo hasta el final de la estación de montaje siguiente, principalmente en el período parto-destete.

The aim is of the study was to identify novelty traits that could be used as breeding objectives to improve cow-calf efficiency and describe cow efficiency in extensive systems in support of climate-smart production in beef cattle. The traits that were investigated were 'weaning weight of the calf as a trait of the dam' (K205) and 'kilogram calf weaned per large stock unit' (KgC/LSU. The latter trait is a value that expresses performance (calf weaning weight) per constant unit, namely per LSU. This may be a useful breeding objective or goal to increase production efficiency, which may reduce the carbon footprint of extensive beef cow-calf production systems. The investigation of the novel traits was conducted on three diverse breeds, namely Afrikaner, Angus and Charolais, with 6104, 7581 and 2291 complete cow-calf records, respectively. Only cows with all three first parities recorded were used to investigate KgC/LSU and K205, as breeding objectives to improve cow-calf efficiency. The heritabilities for KgC/LSU were 0.52, 0.24 and 0.21 for the Afrikaner, Angus and Charolais, respectively, and for K205 were 0.40, 0.17 and 0.13 respectively. The genetic relationship between KgC/LSU and K205 for Angus and Charolais varied substantially. In Charolais cows a strong negative correlation (-0.75) was found, while a strong positive correlation (+0.84) was estimated in Angus cows. These results indicate that a 'cow efficiency index' in which several traits (production, fertility and efficiency) are included may be a more effective alternative breeding strategy. Breeding strategies and production systems to improve the production efficiency of beef cattle could play a significant role in reducing the carbon footprint and would enhance climate-smart beef production.

Resumo O estudo avaliou o comportamento ingestivo de bovinos terminados em confinamento com dieta de alto grão. Foram utilizados 45 animais do cruzamento das raças Charolês e Nelore, com peso e idade média inicial de 310 kg e 20 meses para os novilhos e 350 kg e 32 meses para as novilhas. Os animais foram distribuídos ao acaso nos tratamentos e bloqueados conforme a categoria. Foram utilizados 15 animais (8 novilhos e 7 novilhas) por tratamento, compostos por: Arroz (85% de arroz); Aveia (85% aveia) e Milho (85% milho), cada ingrediente acrescido de 15% de núcleo proteico, além de calcário calcítico e ureia. Os animais que receberam dieta à base de milho permaneceram mais tempo em ócio, menos tempo se alimentando e obtiveram maior número de refeições diárias, quando comparada aos outros tratamentos. Em relação ao tempo de ruminação, observa-se que os animais que consumiram dieta à base de aveia ruminaram mais tempo do que os demais que receberam os outros alimentos. O nível de FDN na dieta de bovinos confinados com dieta sem volumoso exerce influência sobre os tempos despendidos pelos animais em ruminação e ócio. No entanto, as dietas não alteram o tempo de alimentação.

Abstract The study evaluated the ingestive behavior of bovines finished in feedlot with high grain diet. Forty-five Charolais and Nelore crossbreds were used, with initial average weight and age of 310 kg and 20 months for the steers and 350 kg and 32 months for the heifers. The animals were randomly distributed in the treatments and blocked according the category. Fifteen animals (8 steers and 7 heifers) were used per treatment, composed by: Rice (85% of rice); Oat (85% oat) and Corn (85% corn), each ingredient plus 15% protein nucleus in addition to calcitic limestone and urea. The animals that received the diet based on corn remained more time in idle, less time on feeding and obtained a higher number of daily meals, when compared to the other treatments. Regarding the rumination time, it was observed that the animals that consumed the diet based on oat spent more time ruminating than the other treatments. The level of NDF in the diet of cattle confined with a non-roughage diet exerts an influence on the time spent by the animals in rumination and leisure, however, the diets do not alter feeding time.