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Proteomics studies can be used to identify proteins that affect feed efficiency traits, related to cost and profitability of meat production. We used a proteomic approach based on two-dimensional electrophoresis (2D-PAGE) in combination with mass spectrometry (ESI-MS) to study liver samples of Nellore bulls divergently ranked according to residual feed intake (RFI). The study showed that 71 protein spots were expressed differentially (P < 0.05) among RFI groups and 47 were identified by ESI-MS. In RFI, efficient animals (low RFI) eat less than predictions, based on their weights and growth rate, while inefficient animals (high RFI) that eat more than predicted. Data from 18 animals (9 high vs. 9 low RFI) aged 24-26 months in feedlot finishing were used. Immediately after slaughter, liver samples were collected and protein extracts were separated. The gels of RFI groups were scanned and the images analyzed, whereby we found 279 and 215 liver protein spots in high and low RFI bulls, respectively. The proteins identified were related to the following biological functions: (I) oxygen transport and blood flow; (II) mitochondrial function and energy metabolism; (III) amino acid metabolism, ion transport, and cell survival. The study suggests hemoglobin subunit beta and heat shock protein 71 kDa and as molecular markers to study FE in Nellore cattle. Moreover, proteins such as 3-ketoacyl-CoA thiolase and glutamate dehydrogenase 1 were found in liver from high and low RFI animals, respectively. Such protein expression could be associated with changes in the oxidative capacity of RFI phenotypes.

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Evaluation of the body chemical composition of beef cattle can only be measured postmortem and those data cannot be used in real production scenarios to adjust nutritional plans. The objective of this study was to develop multiple linear regression equations from in vivo measurements, such as ultrasound parameters [backfat thickness (uBFT, mm), rump fat thickness (uRF, mm), and ribeye area (uLMA, cm2)], shrunk body weight (SBW, kg), age (AG, d), hip height (HH, m), as well as from postmortem measurements (composition of the 9th to 11th rib section) to predict the empty body and carcass chemical composition for Nellore cattle. Thirty-three young bulls were used (339 ± 36.15 kg and 448 ± 17.78 d for initial weight and age, respectively). Empty body chemical composition (protein, fat, water, and ash in kg) was obtained by combining noncarcass and carcass components. Data were analyzed using the PROC REG procedure of SAS software. Mallows' Cp values were close to the ideal value of number of independent variables in the prediction equations plus one. Equations to predict chemical components of both empty body and carcass using in vivo measurements presented higher R2 values than those determined by postmortem measurements. Chemical composition of the empty body using in vivo measurements was predicted with R2 > 0.73. Equations to predict chemical composition of the carcass from in vivo measurements showed R2 lower (R2< 0.68) than observed for empty body, except for the water (R2 = 0.84). The independent variables SBW, uRF, and AG were sufficient to predict the fat, water, energy components of the empty body, whereas for estimation of protein content the uRF, HH, and SBW were satisfactory. For the calculation of the ash, the SBW variable in the equation was sufficient. Chemical compounds from components of the empty body of Nellore cattle can be calculated by the following equations: protein (kg) = 47.92 + 0.18 × SBW - 1.46 × uRF - 30.72 × HH (R2 = 0.94, RMSPE = 1.79); fat (kg) = 11.33 + 0.16 × SBW + 2.09 × uRF - 0.06 × AG (R2 = 0.74, RMSPE = 4.18); water (kg) = - 34.00 + 0.55 × SBW + 0.10 × AG - 2.34 × uRF (R2 = 0.96, RMSPE = 5.47). In conclusion, the coefficients of determination (for determining the chemical composition of the empty body) of the equations derived from in vivo measures were higher than those of the equations obtained from rib section measurements taken postmortem, and better than coefficients of determination of the equations to predict the chemical composition of the carcass.

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A total of 127 Nellore bulls classified as low and high residual feed intake (RFI), from three selection lines, were evaluated in five experiments aiming to identify associations between RFI, carcass, and meat quality traits. Feedlot performance, carcass traits, and meat quality of Longissimus muscle were evaluated. A mixed model including the fixed effects of RFI class, selection line, interaction between RFI class and selection line, and age at slaughter as a covariate, and the random effects of diet within experiment and experiment was used, with means compared by the t-test. Feed intake average difference was 0.962kg/day; low RFI animals consumed 0.479kg/day less feed and high RFI animals consumed 0.483kg/day more feed than expected. No differences between RFI classes were detected for most of studied variables, demonstrating the absence of unfavorable associations between RFI and carcass and meat quality traits. Low RFI Nellore animals use feed efficiently and produce good quality carcasses and meat.

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The objective of this research was to characterize the chemical composition and digestibility of aerial part and cuttings of four cassava cultivars grown in five different levels of soil fertilization and three plant densities, in order to use the residues for ruminant feeding. The experiment was conducted using a randomized complete block design, in strip-split-plot scheme, with four replicates. The plots were composed of IAC14, IAC15, IAC90, and Cascuda cultivars; the subplots consisted of five fertilization categories, one fertilization with poultry litter (3000 kg.ha-1) and four chemical fertilization rates (0, 150, 450, 900 kg.ha-1) with NPK 4-20-20; and with the sub-subplots consisted of three plant densities (7,500, 12,500, 17,500 plants.ha-1). During the experiment, aerial part and cuttings were sampled for chemical and in vitro digestibility analyzes. There were differences between the varieties of cassava and fertilization rates on fiber fractions, chemical composition, in vitro digestibility, total digestible nutrients (TDN), and dry matter yield (kg / ha) of aerial part (P

RESUMO

The objective of this research was to characterize the chemical composition and digestibility of aerial part and cuttings of four cassava cultivars grown in five different levels of soil fertilization and three plant densities, in order to use the residues for ruminant feeding. The experiment was conducted using a randomized complete block design, in strip-splitplot scheme, with four replicates. The plots were composed of IAC14, IAC15, IAC90, and Cascuda cultivars; the subplots consisted of five fertilization categories, one fertilization with poultry litter (3000 kg.ha-1 ) and four chemical fertilization rates (0, 150, 450, 900 kg.ha-1 ) with NPK 4-20-20; and with the sub-subplots consisted of three plant densities (7,500, 12,500, 17,500 plants.ha-1 ). During the experiment, aerial part and cuttings were sampled for chemical and in vitro digestibility analyzes. There were differences between the varieties of cassava and fertilization rates on fiber fractions, chemical composition, in vitro digestibility, total digestible nutrients (TDN), and dry matter yield (kg / ha) of aerial part (P < 0.05) and cuttings (P < 0.05). Cassava aerial part and cuttings have considerable amounts of nutrients that can be used for ruminant feeding on small farms and for animal categories with low nutritional requirements. From all treatments, variety IAC15, with chemical fertilization of 900 kg.ha-1, as well as fertilization with poultry litter, with the highest plant density, were those with better nutritional composition and greater amount of available nutrients. (AU)

O objetivo desta pesquisa foi quantificar e estudar a composição química e a digestibilidade da parte aérea e da manivamãe de quatro cultivares de mandioca, cultivadas sob cinco diferentes níveis de adubações e três densidades de plantio, com a finalidade de utilização destes coprodutos na alimentação de ruminantes. O experimento foi realizado no Pólo Regional de Desenvolvimento do Médio Paranapanema utilizando o delineamento experimental em blocos casualizados, em esquema de parcelas sub-subdivididas, com quatro repetições. As parcelas foram compostas pelas cultivares IAC 14, IAC 15, IAC 90 e Cascuda; as subparcelas compostas por doses de 4-20-20 (0, 150, 450, 900 kg/ha) ou adubação com cama de frango (3.000 kg/ha de cama de frango) e as sub-subparcelas compostas por densidades de plantio de 7.500, 12.500, 17.500 plantas/ha. Foram feitas amostragens de parte aérea e maniva-mãe e realizadas análises químicas para determinação dos nutrientes e digestibilidade in vitro. Houve diferença entre as variedades de mandioca e níveis de fertilização sobre as frações da fibra; composição química; digestibilidade in vitro; nutrientes digestíveis totais (NDT), e rendimento de matéria seca (kg/ha) da parte aérea (P < 0,05) e da maniva-mãe (P < 0,05). A parte aérea e a maniva-mãe oriundas das sobras da colheita de variedades de mandiocas selecionadas para a produção de raiz possuem cons

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The objective of this research was to characterize the chemical composition and digestibility of aerial part and cuttings of four cassava cultivars grown in five different levels of soil fertilization and three plant densities, in order to use the residues for ruminant feeding. The experiment was conducted using a randomized complete block design, in strip-splitplot scheme, with four replicates. The plots were composed of IAC14, IAC15, IAC90, and Cascuda cultivars; the subplots consisted of five fertilization categories, one fertilization with poultry litter (3000 kg.ha-1 ) and four chemical fertilization rates (0, 150, 450, 900 kg.ha-1 ) with NPK 4-20-20; and with the sub-subplots consisted of three plant densities (7,500, 12,500, 17,500 plants.ha-1 ). During the experiment, aerial part and cuttings were sampled for chemical and in vitro digestibility analyzes. There were differences between the varieties of cassava and fertilization rates on fiber fractions, chemical composition, in vitro digestibility, total digestible nutrients (TDN), and dry matter yield (kg / ha) of aerial part (P < 0.05) and cuttings (P < 0.05). Cassava aerial part and cuttings have considerable amounts of nutrients that can be used for ruminant feeding on small farms and for animal categories with low nutritional requirements. From all treatments, variety IAC15, with chemical fertilization of 900 kg.ha-1, as well as fertilization with poultry litter, with the highest plant density, were those with better nutritional composition and greater amount of available nutrients.

O objetivo desta pesquisa foi quantificar e estudar a composição química e a digestibilidade da parte aérea e da manivamãe de quatro cultivares de mandioca, cultivadas sob cinco diferentes níveis de adubações e três densidades de plantio, com a finalidade de utilização destes coprodutos na alimentação de ruminantes. O experimento foi realizado no Pólo Regional de Desenvolvimento do Médio Paranapanema utilizando o delineamento experimental em blocos casualizados, em esquema de parcelas sub-subdivididas, com quatro repetições. As parcelas foram compostas pelas cultivares IAC 14, IAC 15, IAC 90 e Cascuda; as subparcelas compostas por doses de 4-20-20 (0, 150, 450, 900 kg/ha) ou adubação com cama de frango (3.000 kg/ha de cama de frango) e as sub-subparcelas compostas por densidades de plantio de 7.500, 12.500, 17.500 plantas/ha. Foram feitas amostragens de parte aérea e maniva-mãe e realizadas análises químicas para determinação dos nutrientes e digestibilidade in vitro. Houve diferença entre as variedades de mandioca e níveis de fertilização sobre as frações da fibra; composição química; digestibilidade in vitro; nutrientes digestíveis totais (NDT), e rendimento de matéria seca (kg/ha) da parte aérea (P < 0,05) e da maniva-mãe (P < 0,05). A parte aérea e a maniva-mãe oriundas das sobras da colheita de variedades de mandiocas selecionadas para a produção de raiz possuem cons

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Data from 156 Nellore males were used to develop equations for the prediction of retail beef yield and carcass fat content, expressed as kilograms and as a percentage, from live animal and carcass measurements. Longissimus muscle area and backfat and rump fat thickness were measured by ultrasound up to 5 d before slaughter and fasted live weight was determined 1 d before slaughter. The same traits were obtained after slaughter. The carcass edible portion (CEP in kg and CEP% in percentage; n = 116) was calculated by the sum of the edible portions of primal cuts: hindquarter, forequarter, and spare ribs. Trimmable fat from the carcass boning process, with the standardization of about 3 mm of fat on retail beef, was considered to be representative of carcass fat content. Most of the variation in CEP was explained by fasted live weight or carcass weight (R(2) of 0.92 and 0.96); the same occurred for CEP% (R(2) of 0.15 and 0.13), and for CEP, the inclusion of LM area and fat thickness reduced the equation bias (lower value of Mallow's Cp statistics). For trimmable fat, most variation could be explained by weight or rump fat thickness. In general, the equations developed from live animal measurements showed a predictive power similar to the equations using carcass measurements. In all cases, the traits expressed as kilograms were better predicted (R(2) of 0.39 to 0.96) than traits expressed as a percentage (R(2) of 0.08 to 0.42).

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Empty body and carcass chemical compositions, expressed as content of water, ether extract, protein, minerals, and energy, were evaluated in Nellore bulls with different residual feed intakes (RFI). Forty-nine not castrated males, with 343 kg of average initial BW and 398 kg of average slaughter BW, were studied. Animals were divided in two subgroups: reference group (RG) and ad libitum feeding group. At the end of the adaptation period, animals of subgroup RG were slaughtered and the other animals were finished in individual pens for approximately 100 d, until they reached a subcutaneous fat thickness over the LM of 4 mm, and were slaughtered at an average age of 540 d. Body composition was obtained after grinding, homogenizing, sampling, analyzing, and combining blood, hide, head + feet, viscera, and carcass. Tissue deposition rates and chemical composition of gain were also measured based on gains estimated by comparative slaughter technique. No significant differences in slaughter BW (P = 0.8639), empty BW (P = 0.7288), HCW (P = 0.6563), or empty body and carcass rates of gain were observed between RFI groups, demonstrating that the low (-0.331 kg DM/d) and high (+0.325 kg DM/d) RFI animals presented similar body sizes and growth rates. No significant differences in empty body or carcass content of water, ether extract, protein, minerals, and energy were observed between the low and high RFI animals. And also there were no significant differences in empty BW or carcass gain, demonstrating that low and high RFI animals had a similar growth potential. More efficient animals (low RFI) consumed less feed than less efficient animals (high RFI) but presented similar body sizes, growth rates, and empty body and carcass chemical composition.

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Fifty-nine Nellore bulls from low and high residual feed intake (RFI) levels were studied with the objective of evaluating meat quality traits. Animals were slaughtered when ultrasound-measured backfat thickness reached 4mm, and samples of Longissimus were collected. A mixed model including RFI as fixed effect and herd and diet as random effects was used, and least square means were compared by t-test. More efficient animals consumed 0.730 kg dry matter/day less than less efficient animals, with similar performance. No significant differences in carcass weight, prime meat cuts proportion, chemical composition, pH, sarcomere length, or color were observed between RFI groups. Shear force, myofibrillar fragmentation index and soluble collagen content were influenced by RFI, with a higher shear force and soluble collagen content and a lower fragmentation index in low RFI animals. Feedlot-finished low RFI young Nellore bulls more efficiently convert feed into meat, presenting carcasses within quality standards.

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Relationships between the chemical composition of the 9th- to 11th-rib section and the chemical composition of the carcass and empty body were evaluated for Bos indicus (108 Nellore and 36 Guzerah; GuS) and tropically adapted Bos taurus (56 Caracu; CaS) bulls, averaging 20 to 24 mo of age at slaughter. Nellore cattle were represented by 56 animals from the selected herd (NeS) and 52 animals from the control herd (NeC). The CaS and GuS bulls were from selected herds. Selected herds were based on 20 yr of selection for postweaning BW. Carcass composition was obtained after grinding, homogenizing, sampling, and analyzing soft tissue and bones. Similarly, empty body composition was obtained after grinding, homogenizing, sampling, analyzing, and combining blood, hide, head + feet, viscera, and carcass. Bulls were separated into 2 groups. Group 1 was composed of 36 NeS, 36 NeC, 36 CaS, and 36 GuS bulls and had water, ether extract (EE), protein, and ash chemically determined in the 9th- to 11th-rib section and in the carcass. Group 2 was composed of 20 NeS, 16 NeC, and 20 CaS bulls and water, EE, protein, and ash were determined in the 9th- to 11th-rib section, carcass, and empty body. Linear regressions were developed between the carcass and the 9th- to 11th-rib section compositions for group 1 and between carcass and empty body compositions for group 2. The 9th- to 11th-rib section percentages of water (RWt) and EE (RF) predicted the percentages of carcass water (CWt) and carcass fat (CF) with high precision: CWt, % = 29.0806 + 0.4873 × RWt, % (r(2) = 0.813, SE = 1.06) and CF, % = 10.4037 + 0.5179 × RF, % (r(2) = 0.863, SE = 1.26), respectively. Linear regressions between percentage of CWt and CF and empty body water (EBWt) and empty body fat (EBF) were also predicted with high precision: EBWt, % = -9.6821 + 1.1626 × CWt, % (r(2) = 0.878, SE = 1.43) and EBF, % = 0.3739 + 1.0386 × CF, % (r(2) = 0.982, SE = 0.65), respectively. Chemical composition of the 9th- to 11th-rib section precisely estimated carcass percentages of water and EE. These regressions can accurately predict carcass and empty body compositions for Nellore, Guzerah, and Caracu breeds.

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We analyzed the polymorphisms TFAM HaeIII, TFAM MboI and FABP4 MspA1I in three Nellore lines selected for growth in order to evaluate how selection affects the frequencies of these polymorphisms and evaluate their association with growth and carcass traits in Zebu cattle. Birth, weaning and yearling weights, rump height, longissimus muscle area, backfat thickness, and rump fat thickness were analyzed. The sample was constituted of animals from two lines selected for yearling weight (NeS and NeT), and a control line (NeC), established in 1980, at the São Paulo Instituto de Zootecnia. Two hundred and seventy-two heifers were genotyped for TFAM gene SNPs, and 325 heifers were genotyped for the FABP4 SNP. High frequencies were observed for the alleles A (TFAM HaeIII), C (TFAM MboI) and C (FABP4 MspA1I). Significant differences in allele frequencies between NeS and NeT were observed for the TFAM HaeIII, and between the line NeT and lines NeC and NeS for the FABP4 MspA1I SNP. Five haplotypes were observed for the two polymorphisms in the TFAM gene, haplotype AACC being the most frequent. None of the markers separately or according to haplotype was significantly associated with the growth and carcass traits. The low frequencies of alleles that are associated with high marbling scores and thick subcutaneous fat in taurine breeds might explain the low means for these traits in Nellore cattle.

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