Abstract The objective of this work was to evaluate, through meta-analysis, the impact of subcutaneous fat thickness on beef qualitative traits. Combined data from 13 studies were used, comprising 245 carcasses of male bovines slaughtered in Brazil. Effect size for all parameters was calculated as mean difference or standardized mean difference, at 95% probability. The meta-analysis of random and fixed effects was carried out when I2>50% and I2<50%, respectively, for each indicator separately, with means for fat thickness, classified in the “control” (3–6 mm), “low” (<3 mm), and “high” (>6 mm) groups. Carcasses in the “high” group showed greater intramuscular fat deposition, whereas those in the “low” group presented an intramuscular fat deposition similar to that of the control. When the fat thickness was below the recommended threshold of 3 mm, shear force increased. Subcutaneous fat thickness values greater than 6 mm induced a positive change in the perception of tenderness by the panel of evaluators. Beef carcasses with a subcutaneous fat thickness over 6 mm tend to accumulate more intramuscular fat content and are tenderer for consumers’ acceptance. Carcasses with a fat thickness less than 3 mm produce tougher meat.

Resumo O objetivo deste trabalho foi avaliar, por meio de meta-análise, o impacto da espessura de gordura subcutânea nas características qualitativas de carne bovina. Foram utilizados dados combinados de 13 estudos, compreendendo 245 carcaças de bovinos machos abatidos no Brasil. O tamanho do efeito para todos os parâmetros foi calculado como diferença média ou diferença média padronizada, a 95% de probabilidade. A meta-análise de efeitos aleatórios e fixos foi realizada quando I2>50% e I2<50%, respectivamente, para cada indicador separadamente, com as médias para espessura de gordura classificadas nos grupos “controle” (3–6 mm), “baixo” (<3 mm) e “alto” (>6 mm). As carcaças do grupo “alto” apresentaram maior deposição de gordura intramuscular, enquanto as do grupo “baixo” apresentaram deposição de gordura intramuscular semelhante à do controle. Quando a espessura da gordura estava abaixo do limite recomendado de 3 mm, a força de cisalhamento aumentou. Valores de espessura de gordura subcutânea maiores que 6 mm induziram mudança positiva na percepção de maciez pelo painel de avaliadores. As carcaças bovinas com espessura de gordura subcutânea superior a 6 mm tendem a acumular maior teor de gordura intramuscular e são mais macias para aceitação do consumidor. As carcaças com espessura de gordura inferior a 3 mm produzem carne mais dura.

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.

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.

Resumo: O objetivo deste trabalho foi analisar os efeitos da imunocastração sobre o desempenho e a qualidade de carcaça de novilhos em terminação, em comparação à não castração e à castração cirúrgica. Analisaram-se dados de dez estudos, com registros de 1.261 bovinos machos. Os estudos incluídos na meta-análise continham, necessariamente, tratamentos com imunização ativa contra o hormônio liberador de gonadotrofinas. Cada estudo foi considerado como efeito aleatório no modelo estatístico utilizado. Os dados foram testados quanto à homogeneidade de variâncias e à normalidade dos resíduos, e, posteriormente, submetidos à análise de variância. As médias foram comparadas pelo teste t de Student. Os novilhos não castrados apresentaram maiores ganho de peso diário, eficiência alimentar, pesos ao abate e de carcaça quente, e área de olho de lombo, além de menor espessura de gordura que os castrados cirurgicamente e menores valores de a* e b*, para coloração da carne. No geral, os novilhos imunocastrados foram inferiores aos não castrados, mas superiores aos castrados cirurgicamente. Novilhos submetidos à imunocastração apresentam características de desempenho e de carcaça superiores aos castrados cirurgicamente, mas qualidade de carne similar.

Abstract: The objective of this work was to analyze the effects of immunocastration on the performance and carcass quality of steers in the finishing phase, compared with non-castration and surgical castration. Data from ten studies with records of 1,261 male bovines were analyzed. The studies included in the meta-analysis necessarily contained treatments with immunocastration specifically against the gonadotropin-releasing hormone. Each study was considered as a random effect in the statistical model used. The data were tested for homogeneity of variances and residue normality, and then subjected to the analysis of variance. Means were compared by Student’s t-test. Non-castrated steers showed greater daily weight gain, feed efficiency, slaughter and hot carcass weights, and loin eye area, besides lower fat thickness than surgically-castrated animals and the lowest a* and b* meat coloration values. Overall, immunocastrated steers were inferior to the non-castrated ones, but superior to those surgically-castrated. Immunocastrated steers present performance and carcass traits superior to those of surgically-castrated animals, but similar meat quality.

Resumo Objetivou-se avaliar as características dos componentes do corpo vazio que não integram a carcaça de novilhos castrados cirurgicamente ou imunologicamente. Foram utilizados 48 bezerros Aberdeen Angus, monitorados a partir de idade média inicial de seis meses e peso médio inicial de 160 kg. Os animais foram distribuídos nos seguintes tratamentos: castrados cirurgicamente ao nascimento; castrados cirurgicamente à desmama; imunocastrados com três doses de vacina (6º, 9º e 14º meses de idade dos animais) e imunocastrados com quatro doses (6º, 7º, 10º e 15º meses de idade dos animais). O delineamento experimental foi o inteiramente casualizado. Durante o abate, todos os componentes internos e externos do corpo do animal foram separados e pesados individualmente. O total de órgãos internos expressos em percentual do peso de corpo vazio diferiu entre os dois protocolos de imunocastração, com superioridade quando aplicou-se quatro doses (3,61 vs. 3,39 kg). Novilhos castrados ao nascer depositaram mais gordura cardíaca, renal e pélvica, e gordura do trato gastrintestinal que imunocastrados com três doses, independentemente da forma como foi expressa. A castração cirúrgica ao nascimento promove maior deposição de gordura visceral, em novilhos abatidos em idade jovem, em relação à imunocastração com dosagem definitiva com nove meses de idade.

Abstract The objective was to evaluate the characteristics of empty body components that are not part of the carcass of steers surgically or immunologically castrated. Forty-eight Aberdeen Angus calves were used and monitored since six months of age and 160 kg of average weight. The animals were divided into the following treatments: surgically castrated at birth; Surgically castrated at weaning; Immunocastrated with three doses immunocastrated of vaccine (6th, 9th and 14th months of age of the animals) and immunocastrated with four doses (6th, 7th, 10th and 15th months of age of the animals). The experimental design used was the completely randomized. During the slaughter, all internal and external components of animal body were separated and weighed individually. The total internal organs, expressed in percentage of empty body weight, differed between the two protocols of immunocastration, with superiority when it was applied four doses (3.61 vs. 3.39 kg). Steers castrated at birth deposited more cardiac, kidney and pelvic fat, and fat of the gastrointestinal tract that immunocastrated with three doses, regardless of how it was expressed. Surgical castration at birth promotes greater deposition of visceral fat at the slaughtered in young steers in relation to immunocastration with definitive dosage at nine months of age.

RESUMO. Este trabalho foi realizado para avaliar a substituição do farelo de soja por fontes de nitrogênio não proteico, em combinação com milho moído ou inteiro para bovinos confinados. Foram utilizados 54 novilhos, mestiço Charolês x Nelore com 22 ± 0,23 meses e 250 ± 15,80 kg. O delineamento experimental foi o inteiramente casualizado, com arranjo fatorial 3 x 2. Os tratamentos consistiram em diferentes combinações de formulação do concentrado: farelo de soja com milho grão ou moído; ureia convencional com milho grão ou moído, e ureia protegida com milho grão ou moído. Houve interação entre fonte nitrogenada e data de coleta para albumina sérica, com elevação crescente para o farelo de soja, enquanto houve elevação do dia 0 para o dia 84, estabilizando até o abate, para as ureias. Maiores consumos de matéria seca e proteína bruta, ganho de peso diário e eficiência de ruminação foram observadas para farelo de soja. Novilhos que receberam ureia protegida destinaram mais tempo à alimentação, em relação ao farelo de soja. Maior tempo de ócio foi verificado para o farelo de soja, enquanto a ureia convencional foi superior à ureia protegida. Substituir o farelo de soja por fontes de nitrogênio não proteico limita os resultados de metabólitos sanguíneos, desempenho e comportamento ingestivo.

ABSTRACT. This study evaluated the substitution of soybean meal with non-protein nitrogen sources, in combination with ground or whole corn for feedlot cattle. Fifty-four Charolais x Nellore steers with 22 ± 0.23 months and 250 ± 15.80 kg were assigned to a 3 x 2 factorial completely randomized experimental design. The treatments consisted of different combinations of concentrate formulation: soybean meal with whole or ground corn, conventional urea with whole or ground corn, and protected urea with whole or ground corn. There was interaction between nitrogen source and collection date for serum albumin, with increasing elevation for soybean meal; while there was elevation from day 0 to day 84, stabilizing until the slaughter, for urea. Higher intakes of dry matter and crude protein, daily weight gain and rumination efficiency were observed for soybean meal. Steers that received protect urea spent more time to feed, in comparison to soybean meal. Longer idle time was verified for soybean meal; while conventional urea was superior to protected urea. Replacing soybean meal by sources of non-protein nitrogen limits the results of blood metabolites, performance and ingestive behavior.

The response of energy supplementation was evaluated on the development and reproductive performance of beef heifers on temperate grasslands. Twenty-eight Charolais × Nellore heifers, with initial average age of 18 months and initial live weight of 274.9 kg were utilized. The animals were maintained on oat + ryegrass pasture and distributed in the following treatments: no supplementation (NS): heifers kept exclusively on pasture; MEG: supplementation with protected fat Megalac®; BRM: supplementation with brown rice meal; BRM+MEG: supplementation with BRM + protected fat. The average final weight of the heifers was of 403.4 kg and corresponded to 89.5% of the adult weight. The body condition of heifers increased linearly with daily increase of 0.012 points, correlating positively with the final weight. There was interaction between treatment and period for average daily weight gain. The highest daily weight gain, 1.395 kg, occurred in the first period when the animals were supplemented with BRM+MEG. In the last period, the NS animals presented the lowest daily weight gain, 0.888 kg. Supplementation with brown rice meal and/or protected fat does not interfere in the intake of pasture by heifers or increase the total intake of dry matter, not changing, therefore, the average daily weight gain at the end of the period of grazing. The daily weight gain does not change during supplementation. The use of temperate pasture with and without supplementation promotes the proper development of the structure and reproductive tract of heifers, benefiting the animal performance indexes in the first mating at 25-27 months of age.