ABSTRACT The aim of this study was to evaluate intake, digestibility and performance in dairy heifers fed diets containing increasing levels of babassu cake (0, 100, 200 and 300 g kg-1 dry matter - DM) as a substitute for sugarcane treated with calcium oxide. Twenty-four heifers with an initial mean weight of 190.8 + 40.8 kg were used, distributed in a completely randomised design. The dry matter intake (DMI), neutral detergent fibre intake (NDFI) and acid detergent fibre intake (ADFI), as %BW and g BW-0.75 , showed an increasing linear response. The organic matter intake (OMI) showed a linear increase of 40 g day-1, 0.017%BW and 0.66 g BW-0.75 for each 10 g kg-1 increase in babassu cake in the diet. The apparent digestibility of the dry matter (ADDM) and organic matter (ADOM) showed a quadratic response (P < 0.05), with a minimum of 493 g kg-1 DM for 150 g kg-1 DM and 526.5 g kg-1 DM for 320 g kg-1 DM as a substitute for the sugarcane, respectively. The final mean weight was not altered, presenting a value of 299.7 + 45.5 kg. Daily weight gain (DWG) showed a quadratic response, with the highest value at a substitution level of 190 g kg-1 DM. The feed conversion rate of the DM was not affected by the addition of babassu cake, with an average of 4.6 + 0.74 kg DM kg-1 in weight gain. Babassu cake can substitute hydrolysed sugarcane in heifer diets up to 300 g kg-1 DM, with the greatest weight gain seen at a substitution level of 190 g kg-1 DM.

RESUMO A utilização de subprodutos agroindustriais na alimentação de ruminantes apresenta vantagens nutricionais, ambientais e econômicas, contribuindo para a sustentabilidade do sistema de produção. Assim, objetivou-se avaliar o valor nutritivo de dietas contendo torta de babaçu em substituição ao feno de Tifton-85 (70; 140; 210; 280 e 350 g kg-1 de matéria seca; MS). Foram utilizados 25 ovinos machos castrados, com peso corporal médio de 49,6 ± 9,4 kg, alocados em gaiolas metabólicas em delineamento inteiramente casualizado. O consumo voluntário foi obtido pela subtração da quantidade de alimento fornecido pela sobra pesada na manhã seguinte. Para avaliação da digestibilidade dos nutrientes e balanço de nitrogênio (N), amostras de urina e fezes foram coletadas separadamente. O consumo de MS não foi influenciado, contudo o consumo de proteína bruta (PB) e extrato etéreo aumentaram linearmente. A inclusão da torta de babaçu não afetou a digestibilidade da MS (média de 604,6 ± 272,8 g kg-1). A digestibilidade aparente da PB e os teores de nutrientes digestíveis totais apresentaram comportamento linear crescente, enquanto a digestibilidade da fibra em detergente ácido decresceu linearmente. O teor de N retido variou de 9,72 ± 1,12 a 15,51 ± 1,84 g dia-1 e sua relação com o N ingerido variou entre 521,0 ± 26,7 e 578,4 ± 31,8 g kg-1 de N. A inclusão da torta de babaçu, em substituição ao volumoso, incrementou o valor nutritivo da dieta, podendo ser incluída em até 350 g kg-1 da MS na dieta, em substituição ao feno de Tifton-85.

ABSTRACT The use of agro-industrial by-products in feeding ruminants has nutritional, environmental and economic advantages, and helps to sustain the production system. The aim of this study was to evaluate the nutritional value of diets containing babassu cake as a substitute for Tifton-85 hay (70, 140, 210, 280 and 350 g kg-1 dry matter: DM). Twenty-five castrated male sheep with a mean body weight of 49.6 ± 9.4 kg were used, distributed in metabolic cages in a completely randomised design. Voluntary intake was obtained from the difference between the amount of feed provided and the leftovers the following morning. To evaluate nutrient digestibility and nitrogen (N) balance, samples of urine and faeces were collected separately. There was no effect on DM intake; however, crude protein (CP) and ether extract intake increased linearly increased linearly. The addition of babassu cake had no effect on DM digestibility (mean value of 604.6 ± 272.8 g kg-1). Apparent CP digestibility and total digestible nutrient content showed increasing linear behaviour, while the digestibility of acid detergent fibre decreased linearly. The level of retained N varied from 9.72 ± 1.12 to 15.51 ± 1.84 g day-1 with the ratio to ingested N ranging from 521.0 ± 26.7 to 578.4 ± 31.8 g kg-1 N. The addition of babassu cake to replace the roughage, increased the nutritional value of the diet. Babassu cake can be included up to a total of 350 g kg-1 DM in the diet as a substitute for Tifton-85 hay.

ABSTRACT The objective of this study was to evaluate the production performance of feedlot cattle fed diets containing chopped sugarcane ratios (580 or 380 g/kg of diet dry matter) as roughage and levels of inclusion of babassu mesocarp bran (BMB; 420 to 620 g/kg of concentrate dry matter). Twenty-four young Nellore bulls with 321±23 kg initial body weight, at 22 months of age, were used in a completely randomized experimental design with treatments in a 2 × 2 factorial arrangement and six replicates. Dry matter intake (21.71 g/kg of body weight), average daily gain (1.46 kg/day), and cold carcass weight (232.59 kg) were not changed by proportion of sugarcane or BMB level. The proportions of sugarcane and BMB levels did not change the apparent digestibility of the diets, except the digestibility of neutral detergent fiber, which was lower in the diet associating the lowest levels of sugarcane and BMB. Increasing proportions of sugarcane reduced subcutaneous fat thickness from 2.89 to 1.91 mm. Carcass commercial primal cuts were not affected by variation factors. Inclusion of babassu mesocarp bran enables the use of larger proportions of sugarcane as a result of the increased digestibility of the fiber fraction of feedlot cattle diets without changing the performance and main carcass traits of these animals.

ABSTRACT The objective of the study was to assess the effects of including 0, 79.8, 159.8, and 240.0 g kg-1 crude glycerin in the total diet dry matter on the 84 days feedlot performance, nutrient digestibility, blood parameters, and carcass characteristics of crossbred dairy steers. Experimental diets were composed of 98.5 g kg-1 of sorghum silage and 901.5 g kg-1 of concentrate. Twenty-four crossbred dairy steers (337.3±39.8 kg body weight and 15 months of age) were distributed in a completely randomized design with four treatments and six replicates. The intake and digestibility of the dry matter and nutrients were not altered by including crude glycerin in the diet. Crude glycerol levels did not affect the final weight (430.2 kg), daily weight gain (1.38 kg day-1), total weight gain (97.2 kg), hot carcass weight (218.9 kg), cold carcass weight (215.2 kg), hot carcass yield (0.50 kg 100 kg-1 BW), longissimus dorsi area (62.86 cm²), subcutaneous fat thickness (4.05 mm), and carcass physical composition. Concentrations of serum glucose, triglycerides, total cholesterol, high-density lipoprotein cholesterol, and creatinine were not altered by including crude glycerin in the diet. Crude glycerin can be added to high concentrate diet up to 240 g kg-1 without changing the animal performance, apparent digestibility of nutrients, the main carcass characteristics, and blood parameters of finishing crossbred dairy steers.

ABSTRACT The objective of this study was to assess the effects of including crude glycerin in the diet on intake, performance, rumen development, and carcass traits of dairy crossbred veal calves fed starter concentrate containing 0, 80, 160, and 240 g kg−1 crude glycerin. Twenty-eight calves with an average weight of 38.03±6.7 kg and five days of age were distributed in a completely randomized design with four treatments with seven replications. Calves were individually housed in covered stalls equipped with feeders and drinkers for 56 days. The calf response to inclusion of crude glycerin in the concentrate changed over the weeks and the inclusion level of 240 g kg−1 resulted in greater dry matter intake and average daily gain. There was no effect on the final weight and total weight gain of the animals, with mean values of 73.60 and 35.16 kg, respectively. The weight of the rumen-reticulum adjusted for body weight, empty body weight, and total stomach weight increased linearly with the inclusion of crude glycerin. Blood total protein, globulin, urea, cholesterol, gamma glutamyl transferase, aspartate aminotransferase, and alkaline phosphatase concentrations did not differ among treatments. Carcass traits and meat color were not affected. Crude glycerin can be added to dairy calf starter concentrate up to 240 g kg−1 dry matter because it benefits concentrate intake, performance, and rumen development without affecting animal health.

ABSTRACT - The objective of this study was to find the best level of inclusion of crude glycerin (0, 60, 120, and 240 g kg−1 of dry matter of diet) in substitution of pearl millet in a feedlot diet. Twenty-eight Nellore young bulls with mean age of 18 months and average weight of 357±23.56 kg were used. The animals were distributed in a completely randomized design with four treatments and seven replications. The intakes of dry matter, crude protein, neutral detergent fiber, and total digestible nutrients were similar among the dietary levels of crude glycerin. The ether extract intake decreased with increase in the levels of crude glycerol in the diets. Apparent digestibility of dry matter, crude protein, and extract ether was similar among the dietary crude glycerin levels. Apparent digestibility of neutral detergent fiber was lower in the diets with inclusion of crude glycerin in relation the other diets. The increase in the levels of crude glycerin did not affect the total digestible nutrients content of the diets. Average daily gain increased linearly with the increase in crude glycerin. Feed conversion was not altered by the increase in the levels of crude glycerin in the diets. The dietary increase in crude glycerin level did not affect the carcass characteristics. The inclusion of up to 240 g kg−1 of crude glycerin in pearl millet grain-based diets for feedlot-finished Nellore young bulls increases average daily gain, but does not change the main carcass characteristics of economic importance.

ABSTRACT The objective of this study was to evaluate the feeding behavior and feedlot productive performance of dairy-origin steers fed for 84 days ground pearl millet grain-based diets with 0, 120, 240, 360, and 480 g kg-1 of babassu mesocarp bran (BMB) and a standard diet based on ground corn. Thirty Holstein-Zebu steers with average initial body weight of 371.02±27 kg were used. The experimental design was completely randomized, with five replications. Dry matter intake showed better fit with the quadratic regression equation with the inclusion of BMB, reaching a maximum value in diets with 360 g of this by-product. There was no difference for dry matter intake between pearl millet- and corn-based diets. There was no difference in total digestible nutrients intake between diets. The digestibility coefficient of organic matter decreased linearly with the increase in the dietary level of BMB. The digestibility coefficient of organic matter was not different between corn and millet diets. There was no difference in feeding time between diets. Total requirement of metabolizable energy increased linearly with inclusion of BMB. However, total requirements of metabolizable energy did not differ between the corn- and pearl millet-based diets. Average daily gain decreased linearly with the increase in BMB, with adjustment forced by the sharp decline of this variable in diets with 480 g of BMB. There was no difference in average daily gain between corn- and pearl millet-based diets. The inclusion of levels above 360 g of babassu mesocarp bran in pearl millet-based diets reduces the supply of metabolizable energy and the productive performance of feedlot dairy steers.

The objective of the present study was to evaluate the effects of corn milling and the inclusion of babassu mesocarp bran (BMB) on productive performance, digestibility of dietary nutrients, and blood parameters of dairy crossbred (Holstein-Gyr) bulls finished in confinement. Twenty-four bulls were fed four different experimental diets, containing two levels of inclusion of BMB (0 and 41.24%) and corn supplied in two different forms (ground and whole), for 98 days (77 days of data collection and 21 days of adaptation). The intakes and digestibility coefficients of the dry matter (DM) and nutrients were determined. There were no significant interaction effects of the BMB inclusion level and the form of corn used on the performance and digestibility variables. The intakes of DM, crude protein (CP), and neutral detergent fibre (NDF) increased with the inclusion of BMB in the diets. However, the inclusion of BMB in the diets decreased the ether extract intake, the NDF apparent digestibility, and the feed efficiency of DM and CP. Dry matter and NDF intakes also increased with the use of ground corn in the diet, which promoted an increase in the intake of total digestible nutrients (TDN), digestibility of non-fibrous carbohydrates, and average daily gain. However, the supply of ground corn reduced the feed efficiency of TDN. The remaining measured variables did not vary with the tested diets. The levels of plasma protein and albumin remained normal, but glucose concentrations were always high, irrespective of the tested diet. The form of corn supplied and the level of BMB inclusion had a significant interaction effect on the levels of triglycerides, urea, aspartate aminotransferase, and alkaline phosphatase. Babassu mesocarp bran can be included up to 41.24% in the diet of confined bulls without a negative effect on the animal weight gain. Corn should be supplied ground because this form improves the performance of crossbred bulls

The objective of this study was to evaluate the effect of grinding corn and inclusion of babassu mesocarp bran (BMB) in the diet of crossbred dairy young bulls finished in feedlot on their carcass and meat characteristics. Twenty-four young bulls were fed four experimental diets containing two BMB inclusion levels (0 and 41.24%) and corn in two forms of processing (ground and whole grains) for 98 days, and then slaughtered in a commercial packing plant. Among the quantitative carcass characteristics, there was interaction only in fat trimmings/whole hot carcass weight and cold carcass yield. The whole hot carcass and hot carcass weights showed reduced means with the use of whole corn. The other quantitative variables were not separately affected by BMB inclusion levels or by the form corn was processed. There was interaction between the factors for pistol cut weight, edible portion and weight of the cuts of the pistol cut, in which the use of whole corn and BMB promoted reduction in the mean values. The use of the whole corn grain reduced the participation of flank cut and elevated the participation of the bone fraction in the carcass. Inclusion of 41.24% of BMB did not change the qualitative meat characteristics, but the use of corn grain resulted in darker meat. The use of whole corn resulted in alteration in the weight of cuts like eye of rump and striploin, which have a high commercial value. There was interaction between factors for the percentages of moisture and minerals of the meat, whereas the crude protein content was affected by the two factors. The use of diets with whole corn or with babassu mesocarp bran may modify the carcass and meat characteristics of finishing crossbred young bulls.

The objective of the present study was to evaluate the effect of the use of babassu mesocarp meal (BMM) and corn in different physical forms on the feeding behavior of crossbred young bulls of a dairy breed. Twenty-four crossbred (Nellore vs. Holstein) steers (307.35 kg) were fed four experimental diets containing two levels of inclusion of the babassu mesocarp meal (0 and 412.4 g/kg) and corn in two physical forms (kernels or ground) for 98 days. Data was collected on three days during the finishing phase, with observations every five minutes, for 24 hours. When the activities performed by the animals were evaluated as a function of the period of the day, the physical form of the corn showed interaction with the BMM inclusion level on the time spent feeding and on other activities. When the activities were evaluated over the day, the defecation frequency was affected and decreased as BMM was included. The feeding time was longer at the moments that followed feed supply, whereas the time used for other activities increased during the morning period, regardless of the diet utilized. Rumination and idle times were affected by the period of the day and remained high during the night and morning periods. There was increase in feeding time and dry matter rumination efficiencies and neutral detergent fiber as BMM was added to the diet. The number of rumination chews per bolus, however, decreased as BMB was included. Inclusion of babassu mesocarp meal increases the animal feeding time but the physical form of corn does not change its feeding behavior.

Objetivou-se avaliar o comportamento ingestivo durante 24 horas em oito períodos do dia, de 24 tourinhos Limousin x Nelore terminados em confinamento, alimentados com quatro níveis do subproduto gérmen de milho integral na dieta (0, 15, 30, 45%). O fornecimento de alimento (25% de volumoso e 75% de concentrado) foi realizado diariamente às 9:00 e 16:30 horas. A adição de gérmen de milho integral às dietas não influenciou os tempos despendidos em alimentação, dormindo e em outras atividades, nem as frequências de procura por água, micção e defecação. Os animais alimentaram-se mais nos períodos em que foram arraçoados, gastando em média 137,10 minutos por dia. Os animais dormiram mais à noite, das 2 às 5 horas, enquanto, o tempo despendido em outras atividades foi maior das 17 às 20 horas. Os níveis de gérmen de milho integral influenciaram o tempo de ruminação e de ócio de forma quadrática, com o nível de 30% apresentando maior tempo de ruminação (28,30% do tempo diário) e menor de ócio (42,24% do tempo diário). As atividades ruminação, ócio, alimentação, dormindo e outras atividades, além das frequências de ingestão de água, micção e defecação, comportaram-se de forma distinta para os diferentes períodos do dia. A inclusão de gérmen de milho integral à dieta de bovinos proporciona maior tempo de ruminação e modifica a distribuição desta atividade durante o dia.

This research was conducted to assess the ingestive behavior during 24 hours in eight periods of the day of 24 Limousin x Nellore young bulls in feedlot, fed with diets containing 0; 15; 30 and 45% of whole corn germ. At 9 a.m. and 4:30 p.m., the animals were fed with a roughage:concentrate ration of 25:75. The inclusion of whole corn germ in the diets did not affect the time spent with food intake, sleeping and other activities, neither the frequencies of water drinking, urination and defecation. Food intake occurred more often during the periods when animals were fed, spending in average 137.10 minutes with this activity. Animals slept more during the night, from 2 to 5 a.m., whereas the time spent with other activities was higher from 5 to 8 p.m. Whole corn germ levels affected the rumination and leisure time in a quadratic form, with the 30% level showing higher rumination time (28.3% of the daily time), and lower leisure time (42.24% of the daily time). Animals submitted to different levels of whole corn germ showed distinct behavior for rumination, leisure, food intake, sleeping and other activities, and frequencies of water drinking, urination and defecation, during the different periods of the day. The inclusion of whole corn germ to the diet of bovines provides greater rumination time and modifies the distribution of this activity during the day.

Nutrient intake and digestibility and productive performance of 30 feedlot young bulls fed diets containing babassu mesocarp bran in replacement of corn were evaluated. Animals were distributed in a completely randomized design with five levels of replacement of corn by babassu mesocarp bran (BMB): 0, 250, 500, 750 and 1000 g/kg of dry matter, and six replications. The dry matter (DM) intake in kg/day, g/kg body weight (BW) and g/kgBW0.75 increased as the corn was replaced by BMB. The intake of neutral detergent fiber (NDF) and crude protein (CP) increased linearly, whereas the intake of non-fibrous carbohydrates (NFC) had quadratic behavior. The digestibility of DM, CP, NDF and NFC and the total digestible nutrients (TDN) showed quadratic behavior with points of minimum digestibility of 850.0, 638.0, 867.0, 638.0 and 833.0 g/kg dry matter of replacement of corn by BMB, respectively. The final weight (476.82 kg) and average daily gain (1.55 kg/day) were not affected by experimental diets. The feed efficiencies of DM and CP decreased with increase in the levels of BMB, but the feed efficiency of TDN was not changed. Babassu mesocarp bran enables satisfactory performance, and depending on the price and opportunity cost, it can be utilized in the feeding of feedlot cattle totally replacing the corn of the diet.

Objetivou-se avaliar o consumo, a digestibilidade aparente de nutrientes e o balanço de nitrogênio de dietas contendo farelo de mesocarpo de babaçu (FMB) em substituição à silagem de capim elefante (0; 21; 38; 62 e 78%). Utilizaram-se 20 ovinos alojados em gaiolas metabólicas individuais e distribuídos em delineamento inteiramente casualizado com quatro repetições. Foram coletados e registrados o consumo de alimentos e excreções de fezes e urina. Os consumos de matéria seca, matéria orgânica, proteína bruta, cinzas, fibra em detergente neutro, fibra em detergente ácido, hemicelulose e carboidratos totais não foram influenciados pelas dietas experimentais. Foi observada alteração nos consumos de carboidratos não fibrosos (CCNF) e redução nos consumos de extrato etéreo em % do PV e em gramas por unidade de tamanho metabólico (g UTM-1). O consumo de nutrientes digestíveis totais (CNDT) teve comportamento quadrático com pontos de máximo em 37,3 e 37,9% de FMB expressos em %PV e g UTM-1, respectivamente. As digestibilidades aparentes da matéria orgânica, fibra em detergente neutro, fibra em detergente ácido, proteína bruta e carboidratos não fibrosos reduziram na medida em que o FMB aumentou nas dietas. As digestibilidades aparentes da matéria seca (DAMS), extrato etéreo e carboidratos não fibrosos tiveram comportamento quadrático, com máxima DAMS estimada em 10% de FMB. O NDT reduziu 0,28% para cada ponto percentual de inclusão de FMB nas dietas. A adição do FMB reduziu a digestibilidade das frações fibrosas e aumentou o CCNF e o CNDT, o que indica que este subproduto pode ser utilizado como fonte energética em dietas para ruminantes.

The objective of this study was to evaluate the intake, apparent digestibility of nutrients and the nitrogen balance of diets containing babassu-mesocarp meal (BMM) as a replacement for elephant-grass silage (0, 21, 38, 62 and 78%). Twenty sheep were used, housed in individual metabolic cages and distributed in a completely randomized design with four replications. Food intake was noted and faeces and urine excretions were collected and recorded. Intake of dry matter, organic matter, crude protein, ash, neutral-detergent fibre, acid-detergent fibre, hemicellulose, and total carbohydrate was not affected by the experimental diets. Changes were observed in the non-fibrous carbohydrates intake (INFC) and a reduction in the intake of ether extract as a % of live weight (LW) and grams per unit of metabolic body size (g MBS-1). Total digestible nutrient intake (ITDN) presented quadratic behaviour, with maximum points at 37.3% and 37.9% of BMM expressed as %LW and g MBS-1 respectively. The apparent digestibility of organic matter, neutral-detergent fibre, acid-detergent fibre, crude protein and non-fibrous carbohydrate decreased with the increase in BBM in the diet. The apparent digestibility of dry matter (ADDM), ether extract and non-fibrous carbohydrates showed a quadratic response, with maximum ADDM estimated at 10% of BMM. The TDN decreased by 0.28% for each percentage point of BMM added to the diet. The addition of BMM reduced digestibility of the fibres and increased both INFC and ITDN, indicating that this byproduct can be used as an energy source in ruminant diets.

Foram avaliadas a composição tecidual da carcaça e as características qualitativas da carne de 30 tourinhos mestiços (18,9 meses e 346,8kg iniciais) alimentados com dietas formuladas com diferentes proporções de farelo de mesocarpo de babaçu (Orbygnia sp.) em substituição ao milho: 0; 25; 50; 75 e 100% de substituição. Os animais foram abatidos com peso médio de 476,7kg. A porcentagem de músculo na carcaça aumentou de forma linear: 0,022% para cada ponto percentual de inclusão de farelo de mesocarpo de babaçu (FMB). Por sua vez, os percentuais de gordura e osso da carcaça variaram de forma quadrática, sendo a maior proporção de gordura observada quando a substituição de milho por FMB na dieta foi de 25% e a menor proporção de osso obtida com 50% de substituição. A relação porção comestível:osso foi maior com 42,5% de substituição do milho por FMB. À medida que se elevou a proporção de FMB nas dietas, houve decréscimo na espessura do coxão, escore muscular e compacidade da carcaça. A força de cisalhamento da carne teve acréscimos de 44kgf para cada ponto percentual de substituição do milho por FMB. Quanto à composição química da carne, verificou-se aumento no teor de matéria mineral. O uso de FMB em dietas de terminação de bovinos reduziu a maciez da carne, não alterando as demais características qualitativas.

We evaluated the carcass composition and meat qualitative characteristics, of 30 young crossbred bulls (18.9 months and 346.8kg) fed with diets with different proportion of babassu mesocarp bran (BMB) (Orbygnia sp.); replacing corn: 0, 25, 50, 70 and 100% substitution. The percentage of muscle in the carcass increased linearly, 0.022% for each percentage point of including BMB and the percentages of fat and bone had a quadratic response in which adipose tissue has increased until the replacement of 25% and bone tissue decreased to 50% substitution. The ratio of edible portion: bone increased up to 42.5%. As the levels of BMB increased, a decrease in cushion thickness, muscle score and carcass compactness occurred. The shear force of meat was increased by 44kgf for each percentage point of corn replacement. For the physical-chemical composition we observed an increase in the meat mineral matter. The use of BMB in finishing diets for beef cattle reduced the tenderness of the meat, not altering the other qualitative characteristics.

Foram avaliadas as carcaças de 800 novilhos oriundos do cruzamento rotativo entre as raças Charolesa e Nelore abatidos aos 2 anos de idade. As características avaliadas foram: conformação, espessura de coxão, perímetro de braço, área de olho-de-lombo e área de olho-de-lombo dividida por 100 kg de peso da carcaça fria (AOL100). Na análise dos dados, consideraram-se dois modelos: o Modelo 1 incluiu os efeitos genéticos de sistema de acasalamento e grupo genético do novilho aninhado em sistema de acasalamento e o Modelo 2 correspondeu ao Modelo 1, porém o sistema de acasalamento e o grupo genético foram substituídos pelas covariáveis representativas da porcentagem da raça Charolesa no indivíduo e na sua mãe e da porcentagem de heterozigose no indivíduo e na sua mãe. Pela análise do Modelo 1, novilhos charoleses foram superiores aos nelores em todas as características avaliadas. A heterose retida foi significativa para conformação (4,2%), espessura de coxão (3,2%), perímetro de braço (4,2%), área de olho-de-lombo (7,3%) e AOL100 (-6,7%). O efeito genético aditivo individual da raça Charolesa em relação à Nelore foi de 1,89 pontos para conformação, 1,37 cm para espessura de cochão, 2,55 cm para perímetro de braço, 12,70 cm² para área de olho-de-lombo e 3,13 cm² para AOL100. O efeito genético heterótico individual (em relação à média dos definidos) foi de 3,9% para conformação, 3,8% para espessura de cochão, 3,1% para perímetro de braço e 9,8% para área de olho-de-lombo. A heterose materna é significativa apenas para perímetro de braço (1,6%) e AOL100 (-5,4%). Os efeitos genéticos não-aditivos, representados por epistasia e ligação gênica, não influenciam as características avaliadas.

The carcasses of 800 steers derived from rotational crossbreeding between Charolais and Nellore breeds, slaughtered at two years of age, were evaluated. The evaluated characteristics were the following: conformation, cushion thickness, arm perimeter, Longissimus dorsi area, Longissimus dorsi area divided by 100 kg of cold carcass weight (AOL100). Two models were used for the data analyses: Model 1 included the genetic effects of the breeding system and steer genetic group nested within the breeding system and Model 2 corresponded to Model 1, but the breeding and genetic group were substituted by the covariables corresponding to the percentage of Charolais breed of the individual and its mother and the percentage of heterozygosis of the individual and its mother. From the analysis in Model 1, Charolais steers were superior to the Nelores in all assessed traits. The retained heterosis was significant for conformation (4.2%), cushion thickness (3.2%), arm perimeter (4.2%), Longissimus dorsi area (7.3%) and AOL100 (-6.7%). The individual additive genetic effect of Charolais breed regarded to Nelore was 1.89 points for conformation, 1.37 cm for cushion thickness, 2.55 cm for arm perimeter, 12.70 cm² for Longissimus dorsi area and 3.13 cm² for AOL100. The individual heterotic genetic effect (regarded to the straightbred mean) was 3.9% for conformation, 3.8% for cushion thickness, 3.1% for arm perimeter and 9.8% for Longissimus dorsi area. Maternal heterosis is significant only for arm perimeter (1.6%) and AOL100 (-5.4%). The nonadditive genetic effects, represented by epistasis and linkage, do not influence the evaluated characteristics.