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Item Body chemical composition, tissue deposition rates and gain composition of young Nellore cattle selected for postweaning weight(2014) Bonilha, Eduardo Figueiredo Martins; Branco, Renata Helena; Bonilha, Sarah Figueiredo Martins; Araújo, Fabiana Lana de; Cyrillo, Joslaine Noely dos Santos Gonçalves; Magnani, ElaineEmpty body and carcass chemical composition were determined in 67 Nellore bulls from Selection Nellore (NeS) and Control Nellore (NeC) herds of an animal breeding program for growth, slaughtered at 570 days of average age, after 100 days of feedlot. Selection Nellore animals had, respectively, 360 and 430 kg of initial and slaughter body weight, and NeC animals had 318 and 373 kg for the same traits. Animals were slaughtered and empty body composition was determined by chemical analysis of the components blood, hide, head and feet, viscera and carcass. Tissue deposition rates and gain chemical composition were also determined based on gains estimated by comparative slaughter technique. Significant differences were detected between NeS and NeC animals for slaughter body weight, empty body weight, empty body gain rate, and contents of water, protein, ash and retained energy in empty body, showing that selected animals had greater body sizes and growth rates. There were no significant differences in fat contents in empty body and carcass, suggesting that selected animals had higher growth rates as compared with the control, and were slaughtered with good body and carcass fat contents in the same feedlot time. Control Nellore animals showed a 10% higher gain in fat percentage than NeS in the period. This shows that the growth of bone and muscle ceased earlier and NeC group accumulated more fat. Animals selected for growth have heavier carcasses and greater tissue deposition rates with proportional composition similar to unselected animals.Item Development and evaluation of models to estimate body chemical composition of young Nellore bulls(2017) Silva, Luiz Henrique Oliveira; Bonilha, Sarah Figueiredo Martins; Branco, Renata Helena; Cyrillo, Joslaine Noely dos Santos Gonçalves; Mercadante, Maria Eugênia ZerlottiABSTRACT The objective of this study was to develop accurate regression equations to predict body composition of Nellore cattle using chemical composition of the 9th, 10th, and 11th ribs and to evaluate the models proposed by analyzing mean and linear bias. Sixty-seven Nellore bulls were slaughtered and slaughter body weight (SBW), hot carcass weight (HCW), and 9th-, 10th-, and 11th-rib-cut weight (RCW) were measured. Empty body composition was obtained after grinding, homogenizing, sampling, chemical analysis, and pooling (blood, skin, head + feet, viscera, and carcass). Chemical components were determined in rib cut, carcass, and empty body: protein (RCP, HCP, and EBP), fat (RCF, HCF, and EBF), ash (RCA, HCA, and EBA), and water (RCWt, HCWt, and EBWt). Stepwise options were used to determine variables to be included and excluded from regressions. Predictive ability of equations was verified using standard error of prediction, coefficient of determination, and Cp statistic. Regression estimates were tested to evaluate the models in a database different from that used for equation development. The best equations found to predict carcass components, in kg, were: HCF = -0.994 + 0.123 × SBW - 9.201 × RCW + 34.249 × RCF (R² = 0.86) and HCWt = 2.733 - 0.172 × SBW + 0.821 × HCW - 23.939 × RCF + 12.186 × RCWt (R² = 0.96). For empty body, the best equations, in kg, were: EBF = -1.4 + 0.166 × SBW - 10.073 × RCW + 40.202 × RCF (R² = 0.90) and EBWt = 3.524 + 0.272 × SBW + 0.373 × HCW - 11.727 × RCW + 31.079 × RCWt (R² = 0.98). Body weight has a high predictive power and should be included in equations to estimate body composition of Nellore cattle. Unbiased models are valid as an indirect method for determining body composition in beef cattle.Item Development and evaluation of models to estimate body chemical composition of young Nellore bulls(2017) Silva, Luiz Henrique Oliveira; Bonilha, Sarah Figueiredo Martins; Branco, Renata Helena; Cyrillo, Joslaine Noely dos Santos Gonçalves; Mercadante, Maria Eugênia ZerlottiABSTRACT The objective of this study was to develop accurate regression equations to predict body composition of Nellore cattle using chemical composition of the 9th, 10th, and 11th ribs and to evaluate the models proposed by analyzing mean and linear bias. Sixty-seven Nellore bulls were slaughtered and slaughter body weight (SBW), hot carcass weight (HCW), and 9th-, 10th-, and 11th-rib-cut weight (RCW) were measured. Empty body composition was obtained after grinding, homogenizing, sampling, chemical analysis, and pooling (blood, skin, head + feet, viscera, and carcass). Chemical components were determined in rib cut, carcass, and empty body: protein (RCP, HCP, and EBP), fat (RCF, HCF, and EBF), ash (RCA, HCA, and EBA), and water (RCWt, HCWt, and EBWt). Stepwise options were used to determine variables to be included and excluded from regressions. Predictive ability of equations was verified using standard error of prediction, coefficient of determination, and Cp statistic. Regression estimates were tested to evaluate the models in a database different from that used for equation development. The best equations found to predict carcass components, in kg, were: HCF = -0.994 + 0.123 × SBW - 9.201 × RCW + 34.249 × RCF (R² = 0.86) and HCWt = 2.733 - 0.172 × SBW + 0.821 × HCW - 23.939 × RCF + 12.186 × RCWt (R² = 0.96). For empty body, the best equations, in kg, were: EBF = -1.4 + 0.166 × SBW - 10.073 × RCW + 40.202 × RCF (R² = 0.90) and EBWt = 3.524 + 0.272 × SBW + 0.373 × HCW - 11.727 × RCW + 31.079 × RCWt (R² = 0.98). Body weight has a high predictive power and should be included in equations to estimate body composition of Nellore cattle. Unbiased models are valid as an indirect method for determining body composition in beef cattle.Item Development and evaluation of prediction equations for methane emission from Nellore cattle(2019) Pires Sobrinho, Tatiana Lucila; Branco, Renata Helena; Magnani, Elaine; Berndt, Alexandre; Canesin, Roberta Carrilho; Mercadante, Maria Eugênia ZerlottiABSTRACT. Dry matter intake (DMI), nutrient intake and enteric CH4 emission were evaluated in 48 Nellore cattle (392 ± 27 days of age). Equations were generated from intake data and evaluated using root mean square prediction error (RMSPE), and validated by cross-validation. Equations that included DMI and hemicellulose intake (HEMI) [ C H 4 M J d - 1 = 4.08 ± 1.65 + 11.6 ± 2.34 D M I k g d - 1 - 33.4 ± 7.21 H E M I ( k g d - 1 ) ]; DMI and total carbohydrate intake (TCHI) [ C H 4 M J d - 1 = 5.26 ± 1.69 - 6.3 ± 1.47 D M I k g d - 1 + 8.8 ± 1.81 T C I k g d - 1 ]; metabolizable energy intake (MEI) and cellulose intake (CELI) [ C H 4 M J d - 1 = 5.16 ± 1.72 - 0.13 ± 0.048 M E I M J d - 1 + 7.37 ± 1.53 C E L I k g d - 1 ], and non-fiber carbohydrate intake (NFCI) [ C H 4 M J d - 1 = 3.14 ± 1.48 + 3.65 ± 1.05 N F C I k g d - 1 ] resulted in the lowest RMSPE (14.3, 14.1, 14.3 and 14.7%, respectively). When literature equations were evaluated using our database, the most accurate predictions were obtained with equations that included DMI and lignin intake (RMSPE = 15.27%) and MEI, acid detergent fiber intake and lignin intake (RMSPE = 15.7%). The mean error of predicting enteric CH4 emission with the equations developed in this study based on DMI and nutrient intake is 17% and the most accurate predictions are obtained with equations including DMI, carbohydrate intake and MEI.Item Feed efficiency of Nellore cattle selected for postweaning weight(2010) Castilhos, André Michel de; Branco, Renata Helena; Corvino, Tatiana Lucila Sobrinho; Razook, Alexander George; Bonilha, Sarah Figueiredo Martins; Figueiredo, Leopoldo Andrade deTwo Nellore herds were compared, one selected for greater postweaning weight and the other, control, selected for average postweaning weight, to evaluate the effects of 29 years of selection on feed efficiency. Sixty Nellore males (41 selected and 19 control) averaging 205 kg and 267 days of age were evaluated in individual pens during performance test. Performance and dry matter intake were used to determine the following feed efficiency traits: feed conversion; residual feed intake; residual gain; partial growth efficiency; relative growth rate and Kleiber ratio. After the 112-day experimental period, control animals showed lower body weight when compared to selected animals, however, they did not differ for dry matter intake (% of body weight), rib-eye area and fat thickness at the 12th rib subcutaneous region and on the rump region. Dry matter intake (kg/day) and average daily weight gain from selected animals were, respectively, 19.4% and 26.4% higher than the control ones. The highest average daily weight gain by selected animals promoted significant improvement, around 6%, on feed conversion; 70 g/day on residual gain; and 17% on Kleiber rate. The other feed efficiency traits (residual feed intake, partial growth efficiency and relative growth rate) did not differ between herds. The 29-year selection for post-weaning weight did not affect feed efficiency of Nellore cattle. Foram comparados dois rebanhos Nelore, um selecionado para maior peso pós-desmame e outro controle, selecionado para a média de peso pós-desmame, para avaliar os efeitos de 29 anos de seleção sobre a eficiência alimentar. Sessenta machos Nelore com 205 kg e 267 dias de idade (41 selecionados e 19 controle), foram avaliados em baias individuais durante a prova de ganho de peso. O desempenho e o consumo de matéria seca foram utilizados para determinar as seguintes medidas de eficiência: conversão alimentar; consumo alimentar residual; ganho residual; eficiência parcial de crescimento; taxa de crescimento relativo; e taxa de Kleiber. Após o período experimental de 112 dias, os animais controle apresentaram menor peso vivo final em comparação aos selecionados, contudo, não diferiram quanto ao consumo de matéria seca (% do peso vivo), à área de olho-de-lombo e às espessuras de gordura subcutânea na altura da 12ª costela e na região da picanha. O consumo de matéria seca (kg/dia) e o ganho médio diário dos animais selecionados foram, respectivamente, 19,4 e 26,4% superiores aos dos controle. O maior ganho médio diário dos animais selecionados promoveu melhora significativa, em torno de 6%, na conversão alimentar; 70 g/dia no ganho residual; e de 17% na taxa de Kleiber. As demais medidas de eficiência (consumo alimentar residual, eficiência parcial de crescimento e taxa de crescimento relativo) não diferiram entre os rebanhos. Os 29 anos de seleção para peso pós-desmame não afetaram a eficiência alimentar de bovinos Nelore.Item Feedlot performance, feed efficiency and carcass traits in Nellore cattle selected for postweaning weight(2013) Lucila Sobrinho, Tatiana; Bonilha, Sarah Figueiredo Martins; Gonçalves, Heraldo Cesar; Castilhos, André Michel de; Magnani, Elaine; Razook, Alexander George; Branco, Renata HelenaThe objective of this study was to evaluate the correlated responses to selection for growth in feed efficiency and carcass traits of Nellore animals. A total of 121 animals of the Nellore control (NeC) and selection herds were subjected to performance testing and classified regarding residual feed intake (RFI). Sixty-seven of these animals were selected and finished until reaching 4 mm of subcutaneous fat thickness between the 12th and 13th ribs. The animals were slaughtered at a mean age of 541 days and mean live weight of 423 kg for NeS and of 363 kg for NeC, and carcass traits were measured. Animals in NeS presented higher initial and slaughter weights, dry matter intake, hot and cold carcass weight, weight of retail cuts, and carcass yield than NeC animals for the same slaughter age and feedlot time. No significant differences in RFI were observed between herds, showing that the weight gain from selection for growth did not cause changes in the energy efficiency of the animals.Item Genetic and non-genetic effects on calf vigor at birth and preweaning mortality in Nellore calves(2013) Schmidek, Anita; Costa, Mateus José Rodrigues Paranhos da; Mercadante, Maria Eugênia Zerlotti; Toledo, Luciandra Macedo de; Cyrillo, Joslaine Noely dos Santos Gonçalves; Branco, Renata HelenaThe objective of the present study was to evaluate the genetic and non-genetic effects that influence vigor at birth and preweaning mortality in Nellore calves. A total of 11,727 records of births that occurred between 1978 and 2006, offspring of 363 sires, were analyzed. Poor calf vigor at birth (VB) and preweaning mortality divided into stillbirth (SB), early mortality (EM) and total mortality (TM) were analyzed as binary variables. Generalized linear models were used for the evaluation of non-genetic effects and generalized linear mixed models for genetic effects (sire and animal models). The incidences were 4.75% for VB, 2.66% for SB, 5.28% for EM, and 7.99% for TM. Birth weight was the effect that most influenced the traits studied. Calves weighing less than 22 kg (females) and less than 24 kg (males) were at a higher risk of low vigor and preweaning mortality. Preweaning mortality was higher among calves born from cows aged <3 and >11 years at calving compared with cows aged 7 to 10 years. Male calves presented less vigor and higher preweaning mortality than female calves. Selection for postweaning weight did not influence preweaning mortality. The heritability estimates ranged between 0.01 and 0.09 for VB, 0.00 and 0.27 for SB, 0.03 and 0.17 for EM and 0.02 and 0.10 for TM. Stillbirth should be included as a selection criterion in breeding programs of Nellore cattle, alone or as part of a selection index, aiming to reduce preweaning mortality.Item Phenotypic association between feed efficiency and feeding behavior, growth and carcass traits in Senepol cattle(2017) Guimarães, André Lasmar; Mercadante, Maria Eugênia Zerlotti; Canesin, Roberta Carrilho; Branco, Renata Helena; Lima, Maria Lucia Pereira; Cyrillo, Joslaine Noely dos Santos GonçalvesABSTRACT The objective of this study was to evaluate the associations between feed efficiency and feeding behavior, growth and carcass traits in Senepol cattle. A total of 137 animals were evaluated. Of these animals, 36 males were evaluated in a second test, totaling 173 records (initial age of 466±96 days and initial weight of 426±104 kg). Residual feed intake (RFI) was calculated as the difference between observed and expected dry matter intake, estimated by regression of dry matter intake on average daily gain and metabolic body weight (BW0.75), and the animals were classified as negative (high efficiency) and positive RFI (low efficiency). The mean RFI was -0.838±0.078 and 0.797±0.075 kg DM day-1 for negative and positive RFI animals, respectively, with a difference of 1.63 kg dry matter day-1. The dry matter intake of negative RFI animals, expressed as kg day-1 and percentage of mean body weight, was 11.3% and 13.1% lower than that of positive RFI animals. Negative RFI animals spent less time at the feed bunk and ingested less dry matter per visit than positive RFI animals, but did not differ in terms of chest girth, scrotal circumference, or hip height. However, negative RFI animals had lower rump fat deposition (7.13±0.477 mm) than positive RFI animals (7.83±0.473 mm). The Spearman correlation between RFI estimated in the first and second tests was 0.69, indicating that RFI is consistent when evaluated during two different periods of the life of the animal. Senepol animals with low residual feed intake (high efficiency) deposit less subcutaneous rump fat, but this reduction is not accompanied by a reduction in backfat thickness and longissimus muscle area.Item Relationship between residual feed intake and enteric methane emission in Nellore cattle(2015) Mercadante, Maria Eugênia Zerlotti; Caliman, Ana Paula de Melo; Canesin, Roberta Carrilho; Bonilha, Sarah Figueiredo Martins; Berndt, Alexandre; Frighetto, Rosa Toyoko Shiraishi; Magnani, Elaine; Branco, Renata HelenaFeed intake and average daily gain (ADG) in Nellore cattle were determined to calculate residual feed intake in two performance tests: first during the growth phase (RFIgrowth) and then during a measurement of the methane emission phase (RFImet). During the RFIgrowth test, 62 males and 56 females were classified as low-, medium-, and high-RFI. Enteric methane emission was measured in 46 animals; 23 males used for RFImet measurement plus 23 females (22 low-RFIgrowth and 24 high-RFIgrowth). Diet consisted of Brachiaria brizantha cv. Marandu hay (445 g/kg DM) and concentrate (555 g/kg DM). During the RFIgrowth and RFImet phases, DMI was lower in the animals with low RFI, with no difference in ADG. Residual feed intake was -0.359 and 0.367 kg DM/d for low- and high-RFI animals. Enteric methane emission (g/d, g/kg BW0.75 and g/kg ADG) did not differ between RFIgrowth classes. Enteric methane emission (g/d) was higher in high RFImet and lower in low RFImet males. Spearman correlations among traits obtained during both tests, which were high between metabolic BW (r = 0.959) and between DMI (r = 0.718), and zero between ADG (r = -0.062), resulted in moderate correlation between RFIgrowth and RFImet (r = 0.412). However, it is not possible to confirm that high-efficiency animals release less enteric methane, since different results were obtained when enteric methane was compared between the RFIgrowth and RFImet classes.Item Test post-weaning duration for performance, feed intake and feed efficiency in Nellore cattle(2011) Castilhos, André Michel de; Branco, Renata Helena; Razook, Alexander George; Bonilha, Sarah Figueiredo Martins; Mercadante, Maria Eugênia Zerlotti; Figueiredo, Leopoldo Andrade deThis study was conducted to determine optimum test duration for measuring performance, feed intake and feed efficiency. Sixty young Nellore bulls were submitted to feeding performance test and fed in individual pens to determine feed intake and performance over 112 days. Body weight was determined every 28 days, after fasting of water and feed for 16 hours. Changes in variance, relative variance and Pearson and Spearman correlations among data from shortened test periods (28, 56 and 84 days) and full test period (112 days) were used to determine optimum test duration. Test duration for average daily gain, dry matter intake, feed:gain ratio and residual feed intake could be shortened to 84, 28, 84 and 84 days, respectively, without reducing significantly the reliability of measurements for animals fed in individual pens. O objetivo neste estudo foi determinar o melhor período de avaliação para medidas de desempenho, consumo e eficiência alimentar. Durante 112 dias, 60 machos da raça Nelore, recém-desmamados, submetidos à prova de ganho de peso, foram alimentados em baias individuais para determinação do consumo alimentar e do desempenho. O peso corporal dos animais foi determinado a cada 28 dias, depois de jejum de 16 horas de líquidos e sólidos. As alterações na variância, variância relativa e correlações de Pearson e Spearman entre os dados dos períodos de avaliação reduzidos (28, 56 e 84 dias) e período total (112 dias) foram usados para determinar a melhor duração do período de avaliação. A duração do período de avaliação para ganho médio diário, consumo de matéria seca, conversão alimentar e consumo alimentar residual pode ser reduzida para 84, 28, 84 e 84 dias, respectivamente, pois tal redução não diminui significativamente a confiabilidade das avaliações em animais alimentados em baias individuais.