ABSTRACT. The objective of this work was to evaluate the performance, carcass traits and economic indicators of Santa Inês lambs and their crossings finished in feedlot. Thirty whole lambs (10 Santa Inês, 10 ½ Dorper + ½ Santa Inês and 10 – Dorper + ¼ Santa Inês) were used, with 115 days of age and initial live weight of 20.07 kg. The lambs were kept for 60 days receiving sorghum silage and concentrate, after which they were slaughtered. The – Dorper + ¼ Santa Inês lambs and the ½ Dorper + ½ Santa Inês lambs showed higher of dry matter intake and water intake, greater daily weight gain and body score in relation to Santa Inês lambs. The carcasses of – Dorper + ¼ Santa Inês lambs showed better conformation, finishing and marbling. The gross profit margin showed positive values for all genetic groups, covering the effective operating cost. Dorper crossbred lambs had a higher gross margin compared to Santa Inês lambs. The cost of the diet represented on average 61.35% of the price paid per kilo of sheep meat. In the sheep meat production system, the genetic group influences the zootechnical and economic indicators of finishing feedlot of lambs.

RESUMO Este estudo avaliou as características de cortes de carcaça e comerciais de cordeiros Santa Inês de diferentes biótipos (tradicional e moderno) abatidos com 32 kg e 34 kg. As trinta e seis ovelhas Santa Inês utilizadas, das quais 18 biótipos tradicionais e 18 modernos, tinham em média 180 dias e pesavam inicialmente 16 kg. Os animais foram mantidos em baias individuais (0,80 × 1,20 m) até atingirem o peso de abate. O delineamento experimental foi inteiramente casualizado, fatorial 2×2 (dois biótipos x dois pesos de abate). O biótipo tradicional influenciou significativamente (P<0,05) os rendimentos de carcaça, conformação e marmoreio, em comparação ao biotipo moderno. O biótipo não influenciou (P>0,05) as medidas morfométricas da carcaça e os cortes comerciais. Por outro lado, o peso de abate de 34 kg afetou a maioria das características de carcaça. O biótipo tradicional apresentou maior rendimento, melhor conformação e maior quantidade de gordura intramuscular na carcaça. O maior peso de abate influenciou as características de carcaça e a quantidade de gordura. Em geral, as carcaças apresentaram alta proporção muscular e quantidade de gordura adequada ao consumidor.

SUMMARY This study evaluated the characteristics of carcass and commercial cuts of Santa Ines lambs of different biotypes (traditional and modern) slaughtered at 32 kg and 34 kg. The thirty-six Santa Ines sheep used, of which 18 traditional and 18 modern biotypes were on average 180 days old and weighed 16 kg initially. The animals were kept in individual stalls (0.80 × 1.20 m) until they reached the slaughtering weight. The experimental design was completely randomized, factorial 2×2 (two biotypes x two slaughtering weights). The traditional biotype influenced significantly (P<0.05) the carcass yields, conformation, and marbling, compared to the modern biotype. The biotype did not influence (P> 0.05) carcass morphometric measurements and commercial cuts. On the other hand, the 34-kg slaughtering weight affected most of carcass characteristics. The traditional biotype displayed higher yield, better conformation and greater amount of intramuscular fat in the carcass. The higher slaughtering weight influenced carcass characteristics and the amount of fat. Generally, the carcasses presented high muscle proportion and fat amount appropriate to the consumer.

RESUMO Objetivou-se avaliar o desempenho e características de cordeiros Santa Inês e suas cruzas desmamados aos 75 dias de vida e terminados em confinamento. Foram utilizados 30 cordeiros não castrados, 10 Santa Inês, 10 ½Dorper × ½Santa Inês e 10 ¾Dorper × ¼Santa Inês, com idade e peso vivo médio no início do experimento de 82 dias e 19,40 kg, respectivamente. Foi utilizada dieta única contendo 169,0 g/kg de proteína bruta e 2,80 Mcal/kg MS. Não houve efeito do genótipo sobre o desempenho dos cordeiros, exceto para escore corporal final, em que os mestiços Dorper alcançaram os maiores escores. As carcaças dos cordeiros ½Dorper × ½Santa Inês e ¾Dorper × ¼Santa Inês apresentaram maior largura da garupa, área de olho de lombo e percentual de lombo do que as carcaças dos cordeiros Santa Inês. As carcaças dos cordeiros ¾Dorper × ¼Santa Inês alcançaram maior largura do tórax e do anterior quando comparadas com as carcaças dos cordeiros Santa Inês, tendo obtido também melhor conformação e acabamento de carcaça quando comparadas com as carcaças dos demais genótipos. Entretanto, as carcaças dos cordeiros Santa Inês e ½Dorper × ½Santa Inês apresentaram maior percentual de pescoço em relação às carcaças dos cordeiros ¾Dorper × ¼Santa Inês.

SUMMARY This study evaluated the performance and carcass traits of Santa Ines sheep and crosses weaned at 75 days old and finished in feedlot. Thirty uncastrated sheep, 10 Santa Ines, 10 ½Dorper × ½Santa Ines, and 10 ¾Dorper × ¼Santa Ines were used. The sheep were 82 days old average and 19.40 kg average initial weight. The diet used contained 169.0 g/kg crude protein and 2.80 Mcal/kg DM. No effect of genotype was observed on the performance of lambs, except for the higher final body condition scores achieved by the Dorper crossbreds. The carcasses of the ½Dorper × ½Santa Ines and ¾Dorper × ¼Santa Ines crossbreds lambs had greater rump and loin eye area and higher loin percentage compared to Santa Ines. Carcasses of ¾Dorper × ¼Santa Ines crossbreds lambs had greater chest and anterior width compared to Santa Ines and better carcass conformation and finish compared to other genotypes. Furthermore, the carcasses of Santa Ines and ½Dorper × ½Santa Ines lambs had higher neck percentage compared to carcasses of ¾Dorper × ¼Santa Ines.

The effect of the substitution of Tifton hay (0, 33, 66, 100 g/100 g) for pineapple (Ananas comosus L.) stubble hay was evaluated in the characteristics of the carcasses of goats of an unknown breed (UB) in feedlot. Thirty-two bucks with an average initial live weight of 17.5±1.3 kg, at approximately 150 days of age, were housed in individual stalls provided with feeding and drinking troughs. The animals were distributed in a completely randomized design with four treatments and eight replications. There was a quadratic effect on the weights of hot carcass and cold carcass, empty body, and loin eye area. A linear increase was observed for losses by carcass cooling. The weights of commercial cuts and the weights of total muscle, total bone, intramuscular fat, and total fat decreased linearly. All morphometric measurements were influenced by the inclusion of pineapple stubble hay in the .diets. Substitution of Tifton hay for pineapple stubble hay at the level of 33 g/100 g improves the carcasses of UB goats qualitatively and quantitatively

The objective of this study was to evaluate the performance, qualitative, morphometric and quantitative carcass traits of Santa Inês lambs of different frame sizes finished in a feedlot. Twenty 120-day-old intact lambs with a 25.0±3.1 kg average body weight at the beginning of the experiment were used. Lambs received a diet containing 17% crude protein and 2.70 Mcal/kg dry matter. Frame size influenced performance and tissue composition in the carcasses of the lambs. Lambs with large frame sizes showed better carcass conformation compared with those of medium-sized frames. Frame size was found to have a significant effect on rump perimeter. Large-framed lambs showed higher compactness on the carcass index and carcass dressing area compared with medium-framed lambs. The cuts of large-framed lambs weighed more than those of mediumframed lambs. However, no significant differences were found in dressing.

The objective of this study was to evaluate performance, carcass dressing and gross profit margin of lambs of different genotypes finished in feedlot with diets containing two levels of energy (2.40 Mcal/kg dry matter - DM or 2.90 Mcal/kg DM). Fifty-four non-castrated lambs of the following genotypes were used: Santa Inês, F1 Dorper × Santa Inês and F1 Santa Inês × undefined breed at approximately 150 d of age averaging 22.6 kg of live body weight. Lambs subjected to the diet containing 2.90 Mcal/kg DM stayed in feedlot for a shorter period of time. Moreover, they showed lower intake of dry matter and water in addition to greater daily weight gain and corporal score. There was interaction of feed conversion, carcass dressing yield and gross profit margin. The Dorper × Santa Inês lambs showed similar feed conversion in the two diets. However, Santa Inês lambs and Santa Inês × undefined breed lambs showed better feed conversion with the diet containing 2.90 Mcal/kg DM. The carcass dressings of the Santa Inês × undefined breed lambs were similar for both diets. Furthermore, the carcass dressing values were higher for the Santa Inês and Dorper × Santa Inês which received the diet with higher energy density. The gross profit margin is higher for Dorper × Santa Inês lambs in relation to genotype Santa Inês × undefined breed lambs when subjected to the diet with 2.40 Mcal/kg DM.

The present study aimed to assess the effect of supplementation on the performance of F1 (Boer × females of no defined breed) goats finished in native pasture. The experiment was conducted at the Universidade Federal de Campina Grande, Patos Campus, Paraíba, Brazil, with twenty-four 120-day-old non-castrated F1 (Boer × NDB) male goats, with a 15.52 kg live weight (LW). Animals were distributed in four levels of supplementation (0.0; 0.5; 1.0; 1.5% of body) and six replicates. In order to perform the evaluation of dry matter availability, the herbaceous vegetation was divided into grass and herbaceous dicotyledon and evaluated at the beginning (5/28/2007), in the middle (7/9/2007) and at the end (8/6/2007) of the experiment. In the beginning of the experiment, the availability of grass dry matter was 1,102.89 kg/ha, and at the end of the experiment, the availability of the referred matter was greater (1,494.81); on the other hand, the opposite occurred for the dicotyledons, with a dry matter content of 1,759.46 kg/ha in the beginning of the experiment, and only 236.76 kg/ha at the end of the experiment. Supplementation made it possible to estimate the increase in dry matter intake of 257.15 g/day and of 20.79 g/kg0.75/day, as well as the daily weight gain of 103 g for each percentage point increase that resulted from supplementation. The availability and nutritional quality of forage had a strong influence on the effect of supplementation on dry matter intake, with a negative response for supplementation levels of up to 0.74% of the live weight Consequently, the finishing of F1 crossbred goats in a grazing area in the Caatinga can be improved with the supplementation of concentrate at levels 1.0 to 1.5% of the live weight.

The objective of this study was to evaluate the effect of the replacement of a ground corn diet by a forage cactus meal diet on the carcass characteristics and body components of Santa Inês lambs finished in feedlot. This study was carried out at Estação Experimental de Pendência, belonging to Empresa de Pesquisa Agropecuária da Paraíba S.A. (EMEPA-PB). Forty Santa Inês male lambs in feedlot were used in the experiment. Treatments were randomly assigned to the animals according to a completely randomized design, with four treatments, which consisted of growing replacement levels of ground corn by forage cactus meal: 0, 33, 66 and 100% of substitution and ten replications (lambs). Animals were slaughtered, and the following characteristics were evaluated: body weight, empty body weight, hot carcass weight, cold carcass weight, non-carcass components (NCC), hot carcass yield, cold carcass yield, biological yield, revenue of non components of carcass, revenues of non-carcass components, relative weight and relative value of the commercial cuts, viscera and organs' yield. Averages were submitted to analysis of variance and regression analyses at a 5% level of probability. The replacement levels of ground corn by forage cactus meal had no influence on biological yield, revenue of the non components of carcass, relative weight and relative value of the prime and choice cuts or on the relative weight of viscera and organs. The replacement of ground corn by forage cactus meal, on the ration given to Santa Ines lambs in feedlot does not impact the biological yield, relative weight and relative value of prime and choice cuts or the relative weight of viscera and other organs.

Objetivou-se avaliar as características quantitativas de carcaça de cordeiros de diferentes genótipos recebendo diversos níveis de energia na dieta. Foram utilizados 54 cordeiros não-castrados, sendo 18 Santa Inês (SI), 18 F1Dorper × Santa Inês (Dp × SI) e 18 F1 Santa Inês × Sem Raça Definida (SI × SRD), com idade média de 150 dias e peso médio de 22,60 kg no início do experimento. As dietas continham 17% de proteína bruta e 2,40 Mcal/kg MS ou 2,90 Mcal/kg MS. Os cordeiros alimentados com a dieta contendo 2,90 Mcal/kg MS apresentaram maior peso corporal e de carcaça, área de olho-de-lombo, percentual de gordura interna, índice de musculosidade, índice de compacidade da carcaça, percentual de gordura e menor relação músculo:gordura. As carcaças desses cordeiros obtiveram também menores perdas por resfriamento e maior peso e percentual de paleta e perna. As carcaças dos cordeiros Dorper × Santa Inês foram superiores em espessura de gordura subcutânea, medida GR (gordura sobre a 12ª costela a 11 cm de distância da linha média lombo), percentual de gordura, relação músculo:osso, índice de musculosidade, peso e percentual de lombo. Os cordeiros Santa Inês apresentaram maior relação músculo:gordura. A dieta e o genótipo influenciam as características quantitativas de carcaça de cordeiros.

The objective of this study was to evaluate the quantitative carcass traits of lambs from different genotypes receiving different levels of energy in the diet. Fifty-four non-castrated lambs - 18 Santa Inês (SI), 18 F1Dorper × Santa Inês (Dp × SI) and 18 F1Santa Inês × No defined breed (SI × NDB) - of average 150 days old and 22.6-kg BW were used in the beginning of the experiment. Diets contained 17% crude protein and 2.40 Mcal/kg DM or 2.90 Mcal/kg DM. Lambs fed the diet containing 2.90 Mcal/kg DM showed higher final live and carcass weight, loin eye area, percentage of internal fat, muscularity index, compactness of the carcass index, percentage of fat and lower muscle:fat relation. These lambs' carcasses also presented lower percentage of cold loss and higher weight and percentage of shoulder and leg. Carcasses of Dp × SI lambs were superior in fat thickness, GR site, percentage of fat, muscle:bone relation, muscularity index, weight and percentage of loin. Santa Inês sheep showed higher muscle:fat relation. Both diet and genotype influence quantitative carcass traits of lambs.

The objective of this study was to evaluate the effect of the levels of replacement of ground corn by forage cactus meal in the diet on the muscularity and adiposity of carcass of Santa Inês lambs finished at feedlot. This study was carried out at Estação Experimental de Pendência, belonging to Empresa de Pesquisa Agropecuária da Paraíba S.A. (EMEPA-PB). Forty male Santa Inês lambs in feedlot were used in the experiment. Treatments were randomly assigned to the animals according to a completely randomized design, with four treatments, that consisted of growing substitution levels of ground corn for forage cactus meal: 0, 33, 66 and 100% of substitution and ten replications (lambs). Animals were slaughtered and carcasses cooled for 24 hours for later assessment of conformation, morphometry, loin eye-muscle area, fatness, perirenal fat, marbling and subcutaneous fat thickness. Legs were separated for dissection of muscle, bone, subcutaneous fat, intermuscle fat and total fat, which were weighed for the determination of the muscle:bone and muscle:fat relation and the relative weight of tissue components. Averages were submitted to variance and regression analyses at a 5% level of probability. Diets had no effect on carcass conformation. However, a negative linear effect on weights and yields of fats was observed with the increased levels of forage cactus meal in the diet, and the opposite was observed in the muscle yield behavior. Forage cactus meal is biologically as efficient as ground corn, because it increases the muscularity and reduces the adiposity of the carcass of Santa Inês lambs in feedlot.

The objective of this study was to evaluate the characteristics of carcass and non-carcass components in Brazilian semi-arid native goats of different genotypes in feedlot system. It was used 30 non-castrated Azul, Graúna and Moxotó goats with average initial weight of 15.93 ± 2.4, distributed in a completely randomized design with 3 genotypes and 10 replicates. The experimental diet used had a roughage:concentrate ratio of 47:53. There was a significant effect for weight gain and subcutaneous fat thickness according to genotype. Retail cut yields did not differ among the studied breeds. The percentage of non-carcass components in relation to live weight and empty body weight were not different among genotypes. Graúna and Azul genotypes showed daily gain greater than Moxotó genotype. The subcutaneous fat thickness presented by Azul and Moxotó genotypes was greater than that of Graúna genotype. All genotypes have good quantitative and morphometric carcass traits in addition to satisfactory yields of cut and non-carcass components, but for subcutaneous fat thickness (carcass finishing), Azul and Moxotó genotypes stand out.

Objetivou-se estimar a composição tecidual da carcaça a partir da composição física dos cortes comerciais de caprinos mestiços F1 (Boer com fêmeas de padrão racial não definido) terminados em pastagem nativa com quatro níveis de suplementação com concentrado (0,0; 0,5; 1,0 e 1,5% do PC em matéria seca). Utilizaram-se 24 animais não-castrados com peso corporal inicial de 15,52 kg e 120 dias de idade. A carcaça foi seccionada ao meio, e da meia-carcaça esquerda foram separados os cortes: perna, lombo, costilhar, paleta e pescoço, os quais foram dissecados em músculo, osso e gordura. O peso e rendimento da carcaça foram preditos a partir do peso e o rendimento dos tecidos nos cortes comerciais, por meio de análise de regressão. Todos os cortes podem ser utilizados para predizer os pesos de músculo e de gordura na carcaça. Para músculo, a relação foi linear e positiva nos cortes perna, costilhar, paleta e pescoço e cúbica no lombo; para todos os cortes, a gordura manteve relação linear com a carcaça. O rendimento de músculo e de gordura dos cortes comerciais apresentou relação linear positiva com o da carcaça, exceto para gordura do costilhar, para o qual a relação foi cúbica. Considerando todos os resultados e utilizando a relação com o maior coeficiente de determinação, o costilhar foi o corte que possibilitou melhor estimativa do rendimento de músculo e de gordura da carcaça de caprinos mestiços F1 (Boer com fêmeas de padrão racial não definido) terminados em pastagem nativa.

The objective of this study was to estimate tissue composition of the carcass from physical composition of commercial cuts of F1 crossbred goats (Boer with females of non-defined racial standard) finished on native pasture with four levels of supplementation with concentrate (0.0; 0.5; 1.0 and 1.5% of BW in dry matter). It was used 24 non-castrated animals at initial body weight of 15.52 kg and at 120 days of age. The carcass was sectioned in the half, and from the lefthalf carcass, the following cuts were detached: leg, loin, ribs, shoulder and neck, which were dissected in muscle, bone and fat. Carcass weight and yield were predicted from the weight and yield of tissues in the commercial cuts by regression analysis. All the cuts can be used to predict muscle and fat weight in the carcass. For the muscle, the relationship was linear and positive in the cuts leg, ribs, shoulder and neck, and cubic in the loin; for all the cuts, fat kept a linear relationship with the carcass. Muscle and fat yield of all the commercial cuts showed a positive linear relationship with carcass yield, except for rib fat, for which a cubic relationship was found. Considering all the results obtained and using the relationship with the highest determination coefficient, the ribs were the cut that provided the best estimate of the carcass muscle and fat yields of F1 crossbred goats (Boer with females of non-defined racial standard) finished on native pasture.

Objetivou-se avaliar as características de carcaça por ultrassonografia em tempo real e após o abate e a relação entre essas características e os rendimentos de carcaça de cordeiros de diferentes genótipos terminados em confinamento com diversos níveis de energia na dieta. Foram utilizados 54 cordeiros não-castrados - 18 Santa Inês puros (SI), 18 ½Dorper x ½Santa Inês (Dp x SI) e 18 ½Santa Inês x ½Sem Raça Definida (SI x SRD) - com média de 150 dias de idade e peso médio de 22,60 kg no início do experimento. As dietas continham 17% de proteína bruta e 2,40 Mcal/kg MS e 2,90 Mcal/kg MS. As mensurações realizadas por ultrassonografia e diretamente na carcaça dos cordeiros apresentaram resultados similares. Os cordeiros alimentados com a dieta contendo 2,90 Mcal/kg apresentaram maior área de olho-de-lombo, melhor conformação e acabamento de carcaça e maior quantidade de gordura pélvico-renal. Os cordeiros Dp x SI apresentaram maior área de olho-de-lombo e musculosidade por 100 kg de PV em comparação aos SI x SRD e foram superiores a todos os genótipos quanto à espessura de gordura subcutânea, à conformação e ao acabamento de carcaça. O marmoreio observado nos cordeiros Dp x SI foi superior aos dos Santa Inês. As correlações das medidas tomadas por ultrassonografia e na carcaça foram altas e significativas, exceto o marmoreio. Houve correlação significativa entre conformação da carcaça e acabamento, marmoreio, espessura de gordura subcutânea e gordura pélvico-renal. As gorduras de cobertura avaliadas subjetivamente e objetivamente apresentaram correlações altas e significativas. A dieta e o genótipo influenciam as características de carcaça de cordeiros.

The objective of this study was to evaluate carcass traits through ultrasonography in real time and after slaughter and the relationship between these traits and carcass yields of lambs with different genotypes finished in feedlot with several levels of energy in the diet. It was used 54 non-castrated lambs: 18 pure Santa Inês (SI), 18 ½Dorper x ½Santa Inês (Dp x SI) and 18 ½Santa Inês x ½ Without Standard Defined Breed (SI x WSDB), at an average age of 150 days and at an average body weight of 22.6 kg at the beginning of the experiment. Diets contained 17% of crude protein, 2.40 Mcal/kg DM and 2.90 Mcal/kg DM. Measurements made by ultrasonography and directly on carcass of the lambs showed similar results. Lambs fed diets containing 2.90 Mcal/kg showed larger loin eye area, better carcass conformation and finishing and higher amount of pelvic-renal fat. Lambs Dp x SI showed larger loin eye areas and muscularity per 100 kg of body weight in comparison to SI x SRD lambs and they were superior to all genotypes regarded to subcutaneous fat thickness, conformation and finishing carcass. Marbling observed in Dp x SI lambs were superior than in Santa Inês lambs. Correlations of measures taken by ultrasonography and on the carcass were high and significant, except marbling. There was a significant correlation among carcass conformation and finishing, marbling, subcutaneous fat thickness and pelvic-renal thickness. Backfat subjectively and objectively evaluated showed high and significant correlations. Diet and genotype influence characteristics of carcass of lambs.

Com o objetivo de avaliar o efeito dos níveis de suplementação com concentrado na composição tecidual dos cortes comerciais de caprinos terminados em pastagem nativa utilizaram-se 24 animais, não-castrados, mestiços F1 (Boer × SPRD), com peso vivo (PV) médio inicial de 15,52 kg e 120 dias de idade, distribuídos em quatro níveis de suplementação com concentrado (0,0; 0,5; 1,0 e 1,5% do PV em matéria seca) e abatidos aos 25,12 g; 26,62; 28,56 e 29,19 kg, respectivamente, correspondentes a 218 dias de idade. A carcaça foi seccionada ao meio e da meia-carcaça esquerda, foram separados os cortes perna, lombo, costilhar, paleta e pescoço, os quais foram dissecados em músculo, osso e gordura e os resultados expressos em peso e em rendimento dos tecidos em relação ao peso do corte. A suplementação aumentou o peso de músculo e o peso e rendimento de gordura e reduziu a relação músculo:gordura, mas não influenciou a proporção de músculo dos cinco cortes. Assim, para obtenção de cortes comerciais de melhor acabamento, recomenda-se suplementação de 1,0 e 1,5% do PV, mas, se a finalidade for cortes mais leves e com boa proporção de músculo, a suplementação e desnecessária.

The present study aimed to assess the effect of levels of supplementation with concentrate on the tissue composition of commercial cuts of goats finished in native pasture. It was used 24 non-castrated cross-bred F1 (Boer × SPRD) goats at the age of 120 days, with initial average body weight (BW) of 15.52 kg distributed in four levels of supplementation with concentrated feed (0.0; 0.5; 1.0 and 1.5% of body weight in dry matter) and slaughtered at 25.12 kg; 26.62 kg; 28.56 kg and 29.19 kg, respectively, corresponding to 218 days of life. The carcass was sectioned in the half, and from the left half of the carcass, the following cuts were separated: leg, loin, ribs, shoulder and neck, which were dissected into muscle, bone and fat, with the results expressed in weight and yield of the tissues in relation to the weight of the cut. Supplementation incresead the muscle weight, as well as the fat weight and yield and decreased the muscle:fat relationship; however there was no influence on the proportion of muscle in the five studied cuts. Therefore, in order to obtain better finished commercial meat cuts, supplementation of 1.0 and 1.5% of body weight is recommended. Nevertheless, supplementation is unnecessary for obtaining lighter meat cuts with a good proportion of muscle.

Este trabalho foi realizado com os objetivos de avaliar os efeitos da alimentação e do genótipo sobre as características quantitativas de carcaça de cordeiros terminados em confinamento e estimar sua margem bruta. Foram utilizados 18 cordeiros de cada genótipo: Morada Nova, Santa Inês e mestiços Dorper × Santa Inês. As rações foram constituídas de 2,5 Mcal EM/kg MS e 2,94 Mcal EM/kg MS. Utilizou-se um delineamento inteiramente casualizado, em esquema fatorial 3 × 2. As dietas influenciaram o ganho de peso diário, o peso de corpo vazio, o escore corporal, a eficiência alimentar e o tempo de confinamento, enquanto o genótipo promoveu diferenças em todas as variáveis estudadas. A densidade calórica das dietas influenciou os rendimentos biológicos, de carcaça quente e fria, esses dois últimos influenciados pelos genótipos. A dieta mais energética (2,94 Mcal EM/kgMS) proporcionou maiores pesos absolutos de pescoço, paleta, costela, lombo e perna, porém, em valores relativos, cordeiros alimentados com diferentes níveis energéticos não diferiram quanto a essas características, independentemente do nível energético da dieta. Os rendimentos percentuais dos cortes foram influenciados pelos genótipos, exceto o corte pescoço. Os pesos de todos os cortes foram influenciados pelos genótipos. A maior margem bruta de carcaça foi obtida com ração de maior nível energético.

This study was performed with the objective of assessing the effects of feed and genotype on the quantitative characteristics of carcasses of lambs finished in a feedlot and estimate gross margins. Eighteen lambs of each genotype were used: Morada Nova, Santa Inês and cross-breed Dorper × Santa Inês. Feeds with low and high energetic levels consisted of 2.5 Mcal ME/kg DM and 2.94 Mcal ME/kg DM, respectively. A randomized complete design was used, with a 3 × 2 factorial scheme. The diets influenced daily weight gain, empty body weight, body score, feed efficiency and feedlot days, whilst the genotype promoted differences in all the variables studied. The caloric density of the diets influenced the biological hot and cold carcass yields, and the latter two were influenced by genotype. The more energetic diet (2.94 Mcal EM/kgDM) resulted in higher absolute weights of neck, shoulder, rib, loin and leg, but, in relative values, lambs fed with different energetic levels did not differ for these characteristics, regardless of the energetic level of the diet. The percentage yield of the cuts was influenced by the genotypes, except for the neck. The weights of all the cuts were influenced by genotypes. The treatment with the highest energy level resulted in the largest gross margin.