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Objective: Objectives were to estimate energy and protein requirements of dairy crossbred steers, as well as to evaluate equations previously described in the literature (HH46 and CS16) to predict the carcass and empty body chemical composition of crossbred dairy cattle.Methods: Thirty-three Holstein × Zebu steers, aged 19 ± 1 months old, with an initial shrunk body weight of 324 ± 7.7 kg, were randomly divided into three groups: reference group (n = 5), maintenance level (1.17% BW; n = 4), and the remaining 24 steers were randomly allocated to 1 of 4 treatments. Treatments were: intake restricted to 85% of ad libitum feed intake for either 0, 28, 42, or 84 d of an 84-d finishing period.Results: The net energy and the metabolizable protein requirements for maintenance were 0.083 Mcal/EBW0.75/d and 4.40 g/EBW0.75, respectively. The net energy (NEG) and protein (NPG) requirements for growth can be estimated with the following equations: NEG (Mcal/kg EBG) = 0.2973(± 0.1212) × EBW0.4336(± 0.1002) and NPG (g/d) = 183.6(± 22.5333) × EBG – 2.0693(± 4.7254) × RE, where EBW = empty body weight, EBG = empty body gain, and RE = retained energy. Crude protein (CP) and ether extract (EE) chemical contents in carcass, and all the chemical components in the empty body were precisely and accurately estimated by CS16 equations. However, water content in carcass was better predicted by HH46 equation.Conclusion: The equations proposed in this study can be used for estimating the energy and protein requirements of crossbred dairy steers. The CS16 equations were the best estimator for CP and EE chemical contents in carcass, and all chemical components in the empty body of crossbred dairy steers, whereas water in carcass was better estimated using the HH46 equations.

This study assessed the capability of dual-energy X-ray absorptiometry (DEXA) to predict intramuscular fat (IMF) content of beef longissimus steaks against chemical IMF as the gold standard. DEXA performance of fat% prediction was assessed using a leave-one-out cross validation method among Angus and Nellore steaks, which generated a chemical fat% range of 14.05-36.82% and 2.46-7.84%, respectively, and using pooled data. There was a significant positive association between DEXA predicted fat and chemical fat content. However, higher precision was found for pooled data (R

Aboveground biomass (AGB) data are important for profitable and sustainable pasture management. In this study, we hypothesized that vegetation indexes (VIs) obtained through analysis of moderate spatial resolution satellite data (Landsat-8 and Sentinel-2) and meteorological data can accurately predict the AGB of Brachiaria (syn. Urochloa) pastures in Brazil. We used AGB field data obtained from pastures between 2015 and 2019 in four distinct regions of Brazil to evaluate (i) the relationship between three different VIs?normalized difference vegetation index (NDVI), enhanced vegetation index 2 (EVI2) and optimized soil adjusted vegetation index (OSAVI)?and meteorological data with pasture aboveground fresh biomass (AFB), aboveground dry biomass (ADB) and dry-matter content (DMC); and (ii) the performance of simple linear regression (SLR), multiple linear regression (MLR) and random forest (RF) algorithms for the prediction of pasture AGB based on VIs obtained through satellite imagery combined with meteorological data. The results highlight a strong correlation (r) between VIs and AGB, particularly NDVI (r = 0.52 to 0.84). The MLR and RF algorithms demonstrated high potential to predict AFB (R2 = 0.76 to 0.85) and DMC (R2 = 0.78 to 0.85). We conclude that both MLR and RF algorithms improved the biomass prediction accuracy using satellite imagery combined with meteorological data to determine AFB and DMC, and can be used for Brachiaria (syn. Urochloa) AGB prediction. Additional research on tropical grasses is needed to evaluate different VIs to improve the accuracy of ADB prediction, thereby supporting pasture management in Brazil. Made available in DSpace on 2021-09-24T12:00:47Z (GMT). No. of bitstreams: 1 Prediction-aboveground-biomass.pdf: 1252337 bytes, checksum: 8c28255d14a371fd12b83ab37a62467a (MD5) Previous issue date: 2021

Background Vitamin A has been reported as a factor influencing marbling deposition in meat from animals. Although the mechanisms by which vitamin A regulates lipid metabolism in mature adipocytes are already well-established, information regarding molecular mechanisms underlying the effects of vitamin A on the regulation of intramuscular fat deposition in beef cattle still remains limited. The present study aimed to assess the molecular mechanisms involved in the intramuscular fat deposition in beef cattle supplemented with vitamin A during the fattening phase using a proteomic approach. Results Vitamin A supplementation during the fattening phase decreased intramuscular fat deposition in beef cattle. Proteome and phospho-proteome analysis together with biological and networking analysis of the protein differentially abundant between treatments indicated that Vitamin A supplementation affects the overall energy metabolism of skeletal muscle, impairing lipid biosynthesis in skeletal muscle. Conclusion Vitamin A supplementation at fattening phase impairs intramuscular fat deposition in beef cattle likely by changing the energy metabolism of skeletal muscle. The interaction of retinoic acid and heat shock 70-kDa protein may play a pivotal role in intramuscular fat deposition as a consequence of vitamin A supplementation by impairing de novo fatty acid synthesis as a result of a possible decrease in insulin sensitivity in the skeletal muscle. © 2020 Society of Chemical Industry.

Made available in DSpace on 2022-04-28T19:49:20Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-11-01 This study was designed to evaluate the timing of administration of the bovine appeasing substance (BAS) on performance and physiological responses of Bos indicus feedlot cattle. Nellore bulls (n = 100) were ranked by initial body weight (BW; 341 ± 18.5 kg) and assigned to receive BAS (n = 50) or placebo (CON; n = 50) on day -2 of the experiment. Treatments (5 mL) were applied topically to the nuchal skin area of each bull. Bulls were loaded into commercial livestock trailers immediately after treatment administration, transported for 880 km, and unloaded on day -1 at a commercial feedyard. On day 0, bulls within each treatment were again assigned to receive, in a 2 × 2 factorial arrangement, BAS or CON as described previously (25 bulls/treatment combination). Upon treatment administration on day 0, bulls were housed in 12 feedlot pens (3 pens/treatment) for a 108-d feeding period, which was divided into an adaptation (days 0-19), growing (days 20-60), and finishing (days 61-108) phases. Dry matter intake (DMI) was measured daily from days 0 to 108, whereas blood samples and hair from the tail switch were collected on days -2, 0, 19, 60, and 108. Administration of BAS prior to loading (day -2) improved ADG, FE, and DMI during adaptation and across the 108-d feeding period (P ≤ 0.08), resulting in greater (P = 0.03) hot carcass weight and dressing percentage upon slaughter on day 109. A treatment × day interaction was detected for serum glucose concentrations (P = 0.05), which was greater (P = 0.03) on day 60 of the feeding period in bulls receiving CON prior to loading. Administration of BAS at feedlot entry (day 0) improved DMI, ADG, and FE during adaptation (P ≤ 0.05), but it did not impact (P ≥ 0.18) performance and carcass traits during the 108-d feeding period. Bulls administered BAS prior to loading and at feedlot entry had less (P ≤ 0.05) mean serum cortisol concentrations across the 108-d feeding period (loading × feedlot entry interaction; P = 0.10) and greater (P ≤ 0.05) serum insulin concentration on day 60 (loading × feedlot entry × day interaction; P = 0.05). In summary, BAS administration prior to loading increased the overall feedlot performance of Nellore bulls. These outcomes were noted in bulls that received or not a second BAS administration at feedlot entry, suggesting that the benefits of BAS are exploited when this substance is administered before transport to the feedlot. Department of Animal Science Universidade Federal de Viçosa Faculdade de Medicina Veterinária e Zootecnia Universidade Estadual Paulista (UNESP) Universidade Federal de Goiás Department of Animal Science Texas A&M University, College Station Faculdade de Medicina Veterinária e Zootecnia Universidade Estadual Paulista (UNESP)

Meat traceability and certification increase consumers’ confidence in making purchasing decisions. In Brazil, certified Angus beef follows specific regulation, which requires a minimum of 50% of Angus genome in its breed composition to be commercialized as certified Angus beef. Because the majority of the beef produced in Brazil is Nellore-based, the objective of this study was to estimate the Nellore genetic contribution over certified Angus beef sold in Brazil using genetic traceability. Two hundred sixty-one certified Angus ribeye steaks were obtained from four different brands in commercial establishments. DNA extraction and genotyping were performed for each sample. Genotype data from purebred Angus and Nellore were also available, generating three datasets: meat samples, Angus, and Nellore. Samples and single nucleotide polymorphism (SNP) markers with call rate lower than 0.90 and duplicated samples were excluded from the analysis for each group. Thus, 75,242 SNPs and 99 samples were unique and remained in the meat sample group. For the genotyped reference groups, Angus had 34,586 SNPs and 71 samples while Nellore had 743,665 SNPs and 1,931 samples. The software Admixture were used for the genetic composition prediction using only SNPs in common across the three groups (29563 SNPs). On average, meat samples presented 57% and 43% of Angus and Nellore genome composition, respectively, with proportions ranging from 28% to 87% of Angus genome. Additionally, a principal components analysis showed a clear separation between Nellore and Angus population, whereas the evaluated meat samples were clustered between the two groups. In conclusion, certified Angus beef sold in Brazil have a great contribution of Nellore and some samples had lower Angus contribution than the expected by the certification.

This study evaluated the effect of Licuri cake (LC) supplementation replacing soybean meal in concentrate on performance, digestibility, ingestive behavior, carcass traits and meat quality of grazing lambs. Thirty-two uncastrated Santa Ines lambs with a mean body weight (BW) of 24.7 ± 0.9 kg were distributed into 4 treatment diets in a randomized design. Lambs were fed Aruana grass (Panicum maximum cv. Aruana) as roughage and supplemented with a concentrate composed of ground corn, soybean meal and mineral premix. Licuri (Syagrus coronata) cake was added to concentrate at 0 (control), 87.0 (LOW), 174 (MED), and 260 (HIGH) g/kg of dietary DM. Lambs supplemented with LC did not affect DM Panicum maximum intake (P >0.05). However, there was a linear increase (P 0.05) by LC inclusion. However, the digestibility of NFC and NDF (P 0.05) on carcass traits, morphometric measurements, weight of commercial cuts, cooking weight loss, shear force, sarcomere length, moisture, ash and protein content of the longissimus lumborum were observed among treatments. There was a quadratic increase (P = 0.03) on the lipid content of meat lamb. The inclusion of LC in the diet of lambs linearly increased the a* (P = 0.007), b* (P=0.091) and C* (P = 0.011) color index of the meat. It is recommended the medium level of LC (174 g/kg DM) replacing soybean meal in concentrate of grazing lambs because increases the time spent eating, final weight and ADG of animals and improved the feed conversion rate without change most of the carcass traits and meat quality.

The California net energy system (CNES) was the reference for the development of most energy requirement systems worldwide, such as Nutrient Requirements of Beef Cattle (NASEM, Nutrient requirements of beef cattle, 8th Revised ed, 2016) and Brazilian Nutrient Requirements of Zebu and Crossbred Cattle (Valadares Filho, S. C., L. F. C. Silva, M. P. Gionbelli, P. P. Rotta, M. I. Marcondes, M. L. Chizzotti, and L. F. Prados, BR-CORTE: nutrient requirements of zebu and crossbred cattle, 3rd ed, 2016). This review aimed to compare methods used by NASEM and BR-CORTE to estimate the energy requirements for beef cattle. The net energy requirements for maintenance (NEm) of BR-CORTE is based on empty body weight (EBW), whereas NASEM uses shrunk body weight (SBW), but the Bos taurus indicus presents 10% to 8% lower NEm than Bos taurus taurus. We have compared animals with different EBW and SBW but with same equivalent empty body weight/standard reference weight ratio (0.75), as both systems have suggested different mature weights. Both systems predicted similar net energy requirements for gain (NEg) for animals with 1.8 kg of daily gain. However, estimated empty body gain was lower for NASEM estimations when the same metabolizable energy for gain is available. For pregnancy and lactation of beef cows, the NEm and net energy requirements for pregnancy (NEp) of a Zebu cow estimated by BR-CORTE were lower than the values estimated by NASEM. Furthermore, the magnitude of differences between these systems regarding NEp increased as pregnancy days increase. The NASEM and BR-CORTE systems have presented similar values for energy requirement for lactation (0.72 and 0.75 Mcal/kg milk, respectively).

The objective of this study was to evaluate the differential proteome and phosphoproteome between bulls and steers during conversion of muscle to meat, as well as after 14 days of aging. Twelve male Nellore (Bos taurus indicus) calves were used, and six calves were randomly selected for surgical castration. Calves were fed the same diet and were harvested after 230 days on feed. Longissimus muscle was sampled just after stunning (0d postmortem), at deboning (1d postmortem) and after aging (14d postmortem) for differential proteome analysis. Castration upregulated (P 0.05) the abundance of glycolytic enzymes, while the oxidative phosphorylation protein ATP5B was downregulated (P 0.05). In addition, abundance of troponin T fast isoform (TNNT3) was upregulated by castration (P 0.05), while the slow isoform (TNNT1) tended to be decreased (P 0.10). The creatine kinase M-type was markedly fragmented postmortem. Abundance of phosphorylated PGM1 increased during the first 24 h postmortem and was highly correlated with carcass pH. Further, abundance of the phosphorylated myofibrillar proteins ACTA1 and MYLPF were positively correlated with sarcomere shortening. Overall, our finds demonstrated that abundance and phosphorylation of glycolytic enzymes are associated with changes in beef tenderness and intramuscular fat. SIGNIFICANCE: The design of the present study allowed to clarify the key proteins related to changes during conversion of muscle to meat such as pH decline and sarcomere shortening. In addition, the correlation between some biomarker and meat quality traits were confirmed.

The work consisted of the evaluation of photosensitization in sheep grazing signal grass (Brachiaria decumbens) in a silvopastoral system or under full sunlight for 60 days in the summer. We hypothesized that shade provided by trees in the silvopastoral system prevents or alleviates the classic symptoms of photosensitization in grazing sheep and affects the concentration of the saponin protodioscin in signal grass. Twenty naive crossbred sheep (Dorper x Santa Ines) were used in a randomized block design, with two blocks and five animals per block. Animals in both silvopastoral and full sun treatments grazed B. decumbens, and animals in both treatments presented with clinical symptoms, alterations in the liver, and increased serum levels of gamma-glutamyltransferase (GGT), aspartate aminotransferase (AST), and bilirubin over the duration of the experiment. Although the protodioscin content of B. decumbens in the silvopastoral system was lower than in the full sun treatment, it was sufficient to cause secondary photosensitization in the animals. The natural shading provided by the silvopastoral system does not prevent or ameliorate photosensitization symptoms in young naive sheep grazing on B. decumbens.

Background: Rehydration of grains, such as corn and sorghum, is used to increase nutrient absorption. However, the effect of this practice on meat quality is poorly understood. Objective: To evaluate the effects of type of grain and processing on the meat quality of Nellore steers in a feedlot. Methods: Twenty-four non-castrated Nellore steers (270 ± 53 kg initial body weight) were distributed in a completely randomized 2×2 factorial design, with six replicates. The first factor was cereal type (corn or sorghum), and the second was the grain processing (dry or rehydrated and ensiled). The diets were composed of 30% corn silage and 70% concentrate. Sixty days before the beginning of the experiment, corn and sorghum grains were rehydrated and ensiled. The animals were slaughtered after 140 days of confinement. Meat quality analyses were determined in samples of fresh and aged meat (7 days) from the Longissimus lumborum muscle. Results: no difference between treatments was observed for carcass pH and L* (lightness), a* (redness), and b* (yellowness) values, shear force, thawing and cooking losses, and chemical composition of meat (p>0.05). The b* (yellowness) value of subcutaneous fat was higher in steers fed corn, regardless of grain processing (p=0.03). Sarcomere length was higher in aged meat of steers fed sorghum, regardless of processing method (p=0.01). Conclusions: the grain processing method does not affect beef quality; however, grain type can affect subcutaneous fat color and sarcomere length of aged beef. Resumen Antecedentes: La rehidratación de granos, tales como maíz y sorgo, se usa para aprovechar mejor sus nutrientes. Sin embargo, es poco conocido el efecto de esta práctica sobre la calidad de la carne. Objetivo: Evaluar los efectos del tipo de cereal y su procesamiento sobre la calidad de carne de toretes Nelore en confinamiento. Métodos: Veinticuatro novillos Nelore enteros con un peso promedio inicial de 270 ± 53 kg, se distribuyeron en un diseño factorial 2×2 completamente aleatorizado (n=6). El primer factor fue el tipo de cereal (maíz o sorgo) y el segundo fue su procesamiento (seco o rehidratado y ensilado). Las dietas estuvieron compuestas por 28,44% de ensilaje de maíz y 71,56% de concentrado. Sesenta días antes de iniciar el experimento, los granos de maíz y sorgo se rehidrataron y ensilaron. Los animales se sacrificaron después de 140 días de confinamiento. La calidad de la carne se determinó en muestras de carne fresca y madurada (7 días) obtenidas del músculo Longissimus lumborum. Resultados: No hubo diferencias entre tratamientos para el pH de las canales, ni para los valores de color (L* “luminosidad”, a* “intensidad de rojo” y b* “intensidad de amarillo”), fuerza de corte, composición química, o pérdidas de agua por descongelamiento o cocción (p>0,05). El valor de b* de la grasa subcutánea fue mayor en los novillos alimentados con maíz, independientemente del tipo de procesamiento (p=0,03). La longitud de sarcómero fue más alto en la carne madurada de novillos alimentados con sorgo, sin importar el método de procesamiento (p=0,01). Conclusiones: El método de procesamiento del grano no afecta la calidad de la carne; sin embargo, el tipo de cereal afecta el color de la grasa subcutánea y la longitud del sarcómero de la carne madurada. Resumo Antecedentes: A reidratação de grãos, como milho e sorgo, tem sido usada para aumentar a utilização de seus nutrientes. Contudo, o efeito dessa prática na qualidade da carne é pouco compreendido. Objetivo: Avaliar os efeitos do tipo de grão de cereais e seu processamento sobre a qualidade da carne de bovinos confinados. Métodos: Vinte e quatro bovinos Nelore não castrados, com peso corporal médio inicial de 270 ± 53 kg foram distribuídos em delineamento inteiramente casualizado, fatorial 2×2, com seis repetições. O primeiro fator foi o tipo de grão de cereal no concentrado (milho ou sorgo), e o segundo foi o processamento destes grãos (seco ou reidratado e ensilado). As dietas foram compostas por 28,44% de silagem de milho e 71,56% de concentrado. Sessenta dias antes do início do experimento, os grãos de milho e sorgo foram reidratados e ensilados. Os animais foram abatidos após 140 dias de confinamento. As análises de qualidade da carne foram determinadas em amostras não maturadas e maturadas (7 dias) obtidas do músculo Longissimus lumborum. Resultados: Não houve diferenças significativas (p>0,05) entre os tratamentos para pH da carcaça e L* (luminosidade), a* (intensidade de vermelho), b* (intensidade de amarelo), força de cisalhamento, perdas por descongelamento, perdas por cocção, perdas totais e composição química da carne. O valor de b* da gordura subcutânea foi maior (p=0,03) em bovinos alimentados com dietas contendo grãos de milho, independentemente do tipo de processamento. O comprimento de sarcômero foi maior na carne maturada de novilhos alimentados com sorgo, independente do método de processamento (p=0,01). Conclusões: O método de processamento dos grãos não afetou a qualidade da carne bovina, no entanto, a cor da gordura subcutânea e o comprimento de sarcômero da carne maturada foram afetados pelo tipo de grão.

The accurate supply of energy is essential to optimize livestock productivity and profitability. Furthermore, replacing empty BW gain (EBG) with carcass gain (CG) might be a suitable alternative to estimate the retained energy (RE) of beef cattle. Thus, this multi-analysis study was conducted aiming to estimate and validate new equations to predict carcass weight (CW), EBG, and RE of Zebu, beef crossbred, and dairy crossbred. A database composed by 1 112 animals encompassing bulls, steers, heifers of different genetic groups (Zebu, beef crossbred, and dairy crossbred), and two types of slaughter plants (commercial and experimental) was used for generating the new CW equation. For the development of the EBG and RE equations, a database of 636 observations composed of bulls, steers, and heifers of different genetic groups (Zebu, beef crossbred, and dairy crossbred) was assembled. The validation of new equations was performed using independent databases composed by 137 observations (80 for CW and 57 for EBG and RE). The new approaches for EBG and RE validation also included data from our research group studies (Inside) and independent data from literature publications (Outside). Furthermore, the new RE equation was compared to the current model devised by the nutritional requirements, diet formulation, and performance prediction of Zebu and crossbred cattle ( BR-CORTE, 2016 ). Validation analyses were performed by using the Model Evaluation System (MES; 3.1.13, College Station, US). The CW was accurately estimated by the new equation when using both commercial and experimental data. Also, the equations developed in this study accurately estimated EBG and RE using both inside and outside data. In conclusion, equations proposed in this study accurately and precisely estimated CW, EBG, and RE of Zebu beef cattle that composed validation data set. Therefore, we suggest the following equations to estimate CW, EBG, and RE of Zebu cattle: CW, kg = − 11.0±1.56 + P + ((0.609±0.005 + G + B) × SBW); EBG (kg) = 0.044±0.017 + 1.47±0.026 × CG; RE (MJ/d) = 4.184 × (0.082±0.002 × EQEBW0.75 × CG0.777±0.039), where P = slaughter plant effect, if commercial = − 10.98, if experimental = 0; G = gender effect, if steer = 0, if bull = 0.008169 and if heifer = − 0.00612; B = genotype effect, if Zebu = 0, if dairy crossbreds = − 0.03301 and if beef crossbreds = − 0.01595; SBW = shrunk BW; CG = carcass gain; EQEBW = equivalent empty BW.

We aimed to investigate differences in the synthesis and metabolism of intramuscular collagen in the Longissimus thoracis (LT) muscle between heifers and cull-cows fed high-energy diet. Ten cull-cows, (74.9 ± 3.2 months age, weighing 536 ± 14.55 kg) and ten heifers (18.4 ± 3.2 months age, weighting 310.5 ± 14.5 kg) were fed with high-energy diets for 150 days. The total collagen content did not differ between treatments. Greater collagen solubility was observed in heifers than cull-cows, although no differences in lysyl oxidase activity were observed between treatments. No differences were observed for mRNA expression of CO1A1, MMP2, MMP9 and TIMP2 between treatments. However, cull-cows presented greater mRNA expression of COL3A1, TIMP1 and TIMP3 than heifers. Our data give no indication that feeding a high-energy diet to cull-cows decreases the concentration of intramuscular collagen in the LT muscle or increases its solubility in respect to the collagen solubility in LT muscles from heifers on the same diet.

Made available in DSpace on 2022-04-28T19:28:06Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-03-01 Different fat ingredients and their fatty acids may influence the expression of genes responsible to encode enzymes and proteins linked to adipose tissue deposition, influencing beef quality. Therefore, the objective was to analyze the expression of PPARA, SREBF1 and genes involved in lipid metabolism in longissimus thoracis (LT) muscle of cattle fed diets containing soybean or cottonseed with or without vitamin E. Twenty-eight bulls were used in a completely randomized design using a 2 × 2 factorial arrangement. The inclusion of soybean and cottonseed in the diets provided 64.8 g kg−1 and 65.6 g kg−1 of ether extract, respectively, and vitamin E supplementation was 2500 IU per day. The PPARA expression was greater and SREBF1 expression was lower in the muscle of animals fed soybean (P

Made available in DSpace on 2020-12-10T17:29:51Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-04-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Dietary protein adjustments can reduce environmental impact and economic losses in production systems. However, we lack information regarding nitrogen (N) metabolism and protein requirements for maintenance of crossbred animals such as Red Norte breed, precluding a precise dietary management. The objective was to evaluate the effect of increasing dietary CP levels (9%, 11%, 13%, 15% and 17%) on intake, digestibility and N balance, as well as to estimate the metabolizable protein requirements for maintenance (MPm) of growing Red Norte bulls. Thirty five animals averaging 280 +/- 4.0 kg BW were fed during 45 days in a 60 : 40 forage : concentrate ratio diet in which the last 5 days were used for the digestibility trial. Intakes of CP and non-fibrous carbohydrates (NFCs) and feed efficiency linearly increased (P < 0.05) as CP levels increased, while DM, NDF, nitrogen efficiency use and ether extract were not influenced by CP levels (P > 0.05). Digestibilities of DM, organic matter, ether extract, NFC and CP as well as metabolizable energy intake linearly increased (P < 0.05), and true digestibility of CP was not affected (P > 0.05) by treatments. Urinary N and retained N linearly increased (P < 0.05) with the increase in dietary N. The MPm were estimated as 4.46 g/BW0.75 and the efficiency of use of MPm was 0.673. In conclusion, obtained MPm requirements of growing Red Norte bulls are greater than the values reported in literature for Zebu cattle and dietary CP levels of 15% and 17% exhibited great responses for growing Red Norte cattle. However, a cost-benefit evaluation should be done before its use. Univ Sao Paulo, Fac Anim Sci & Food Engn, Av Duque Caxias Norte 225, BR-13635900 Pirassununga, SP, Brazil Univ Fed Lavras, Dept Anim Sci, Ave UFLA, BR-37200000 Lavras, MG, Brazil Univ Fed Vicosa, Dept Anim Sci, Ave PH Rolfs S-N, BR-36570900 Vicosa, MG, Brazil Univ Estadual Paulista, Coll Vet Med & Anim Sci, Rua Prof Dr Walter Mauricio Correa S-N, BR-18610307 Botucatu, SP, Brazil Univ Fed Rural Rio de Janeiro, Anim Sci Inst, Dept Anim Prod, Rodovia BR 465,Km 07, BR-23897005 Seropedica, RJ, Brazil Univ Estadual Paulista, Coll Vet Med & Anim Sci, Rua Prof Dr Walter Mauricio Correa S-N, BR-18610307 Botucatu, SP, Brazil CAPES: 001

This study determined feed intake behavior, performance, feed efficiency, and maintenance requirements of bulls with high and low residual feed intake and body weight gain. Data were collected from 42 weaned Nellore bulls (initial BW 260 ± 8.1 kg; age 7 ± 1.0 mo) housed in a feedlot in a group pen that contained electronic feeders. Individual dry matter intake (DMI) was recorded daily and body weight (BW) was measured every 28 d over a 140-day period. Indexes of average daily gain (ADG), feed efficiency, and residual feed intake (RFI) were calculated. Residual feed intake and gain (RFIG) was calculated according to previously published equations. Frequency of meals, duration per visit, and time spent feeding per day were recorded as feeding behavior measures. Maintenance requirements were calculated according to the BR-CORTE system. High RFIG bulls had lower DMI (P < 0.01), lower final BW (P < 0.01), and were more feed efficient (P < 0.01) than low RFIG bulls, but both groups had similar ADG (P = 0.55). No differences in feeding behavior were observed between the two groups (P > 0.05). The net energy requirements for maintenance, metabolizable energy for maintenance, and efficiency of metabolizable energy utilization were 76.5, 122.68 kcal/EBW0.75 daily, and 62.4%, respectively for high RFIG bulls, and 89.2, 143.76 kcal/EBW0.75 daily, and 62.0% for low RFIG bulls. This study reveals that low RFIG bulls are less feed efficient and have greater maintenance requirements than high RFIG bulls (0.16 ± 0.006 and 0.18 ± 0.006, respectively). As low RFIG eat more, and in beef cattle, feeding behavior is associated with methane emissions, we suggest further research evaluating this relationship be conducted. In addition, selection for high RFIG cattle would improve feed efficiency, reduce production costs, and could potentially reduce methane emissions.

The objective of this study was to validate an electronic system for monitoring individual feeding and drinking behaviour and intake developed for young cattle housed in group. A total of 35 Holstein-Gyr crossbred heifers (BW: 180±52 kg; age: 121.5±32.5 days), fitted with an ear tag containing a unique passive transponder, were distributed in three groups of 12, 12 and 11 animals per period and had free access to 12 electronic feed bins and two electronic water bins (Intergado® Ltd). The dimensions of feed and water bins, as well as the sensors position were appropriate for young cattle. The system documented the visit frequency and duration, as well as the feed and water intakes, by recording the animal's identification tag, bin number, initial and final times of visits and the difference of feed/water weight at the start and end of each bin visit. Feed bins were monitored using time-lapse video recording over 4 days and the water bins were monitored over 6 days. For each feed bin, two feeding events were monitored using manual weighings with an external scale immediately before and after the animal's visit and the difference between them was assumed as feed intake (n=24 observations). For the water bins, 60 manual weighings were made. Video and manual weighing data were regressed on the electronic feeding and drinking behaviour and intake data to evaluate the system's precision and accuracy. The system showed high specificity (98.98% and 98.56% for the feed and water bins, respectively) and sensitivity (99.25% and 98.74%, respectively) for identifying an animal's presence or absence. Duration of feed and water bin visits as well as feed and water consumption per visit estimated by the system were highly correlated and precise compared with the observed video and manual weighing data (r 2=0.917, 0.963, 0.973 and 0.986, respectively). It was concluded that Intergado® system is a useful tool for monitoring feeding and drinking behaviour as well as water and feed intakes in young cattle housed in groups.

This study was conducted to assess the body and empty body fat physical and chemical composition through biometric measurements (BM) as well as postmortem measurements taken in 40 F1 Angus × Nellore bulls and steers. The animals used were 12.5 ± 0.51 mo of age, with an average shrunk BW of 233 ± 23.5 and 238 ± 24.6 kg for bulls and steers, respectively. Animals were fed 60:40 ratio of corn silage to concentrate diets. Eight animals (4 bulls and 4 steers) were slaughtered at the beginning of the trial, and the remaining animals were randomly assigned to a 1 + 2 × 3 factorial arrangement (1 reference group, 2 sexes, and 3 slaughter weights). The remaining animals were slaughtered when the average BW of the group reached 380 ± 19.5 (6 bulls and 5 steers), 440 ± 19.2 (6 bulls and 5 steers), and 500 ± 19.5 kg (5 bulls and 5 steers). Before the slaughter, the animals were led through a squeeze chute in which BM were taken, including hook bone width (HBW), pin bone width, abdomen width (AW), body length (BL), rump height, height at the withers, pelvic girdle length (PGL), rib depth (RD), girth circumference (GC), rump depth, body diagonal length (BDL), and thorax width. Additionally, the following postmortem measurements were obtained: total body surface (TBS), body volume (BV), subcutaneous fat (SF), internal physical fat (InF), intermuscular fat, carcass physical fat (CF), empty body physically separable fat (EBF), carcass chemical fat (CFch), empty body chemical fat (EBFch), fat thickness in the 12th rib, and 9th to 11th rib section fat. The equations were developed using a stepwise procedure to select the variables that should enter into the model. The r2 and root mean square error (RMSE) were used to account for precision and accuracy. The ranges for r2 and RMSE were 0.852 to 0.946 and 0.0625 to 0.103 m2, respectively for TBS; 0.942 to 0.998 and 0.004 to 0.022 m3, respectively, for BV; 0.767 to 0.967 and 2.70 to 3.24 kg, respectively, for SF; 0.816 to 0.900 and 3.04 to 4.12 kg, respectively, for InF; 0.830 to 0.988 and 3.44 to 8.39 kg, respectively, for CF; 0.861 to 0.998 and 1.51 to 10.98 kg, respectively, for EBF; 0.825 to 0.985 and 5.96 to 8.46 kg, respectively, for CFch; and 0.862 to 0.992 and 5.54 to 12.19 kg, respectively, for EBFch. Our results indicated that BM that could accurately and precisely be used as alternatives to predict different fat depots of F1 Angus × Nellore bulls and steers are AW, GC, or PGL for CF estimation; HBW and RD for CFch estimation; and body lengths such as BL and BDL for InF and SF estimation, respectively.

A grazing trial was carried out to evaluate the inclusion of three feed additives in supplements (crude protein, CP 230 g/kg dry matter, DM) on the performance, voluntary intake, and digestibility of beef heifers grazing Brachiaria decumbens (CP 81 and neutral detergent fiber, NDF 615 g/kg DM). Thirty-five Nellore heifers (21 months of age and 383 ± 6.29 kg of body weight, BW) were used in a completely randomized design. The treatments were as follows: no supplement (control); supplement fed at 1 kg/animal/day without additives (S); supplement with monensin (S + M); supplement with yeast culture (S + YC); and supplement with enzyme complex (S + EC). All of the supplemented heifers had greater (P < 0.1) average daily gain (∼0.186 kg/day) compared to the control treatment (0.014 kg/day). Average daily gain and final BW were similar (P > 0.1) among supplemented heifers. Monensin inclusion in the supplement decreased (P < 0.1) forage DM (expressed as g/kg BW) and NDF intake (expressed as kg/day and as g/kg BW). All of the feed additive inclusions decreased (P < 0.1) NDF digestibility. In conclusion, the heifers’ performance was improved by concentrate supplementation. However, the inclusion of additives did not enhance this effect.

Weaned Nellore bulls ( = 36; 274 ± 34 kg) were used in a randomized block design with a 2 × 2 factorial arrangement of treatments to evaluate intake, fecal excretion, and performance with different concentrations of minerals. Experimental diets were formulated with 2 concentrations of Ca and P (macromineral factor; diet supplying 100% of Ca and P according to BR-CORTE () [CaP+] or diet without limestone and dicalcium phosphate [CaP-]) and 2 concentrations of microminerals (micromineral factor; diet with supplementation of microminerals [Zn, Mn, and Cu; CuMnZn+] or diet without supplementation of microminerals [Zn, Mn, and Cu; CuMnZn-]). The factor CaP- was formulated without the addition of limestone and dicalcium phosphate, and the factor CuMnZn- was formulated without inorganic supplementation of microminerals (premix). The diets were isonitrogenous (13.3% CP). Intake was individually monitored every day. Indigestible NDF was used as an internal marker for digestibility estimates. The bulls were slaughtered (84 or 147 d on feed), and then carcass characteristics were measured and liver and rib samples were collected. Feed, feces, rib bones, and liver samples were analyzed for DM, ash, CP, ether extract (EE), Ca, P, Zn, Mn, and Cu. There were no significant interactions ( ≥ 0.06) between macro- and micromineral supplementation for any variables in the study. Calcium, P, and micromineral concentrations did not affect ( ≥ 0.20) intake of DM, OM, NDF, EE, CP, TDN, and nonfiber carbohydrates (NFC). Calcium and P intake were affected ( < 0.01) by macromineral factor. Animals fed without Ca and P supplementation consumed less of these minerals. Dry matter and nutrient fecal excretion (OM, NDF, EE, CP, and NFC) were similar ( ≥ 0.23) among all factors. Performance and carcass characteristics were similar ( ≥ 0.09) among diets. The content of ash in rib bones was not affected by diets ( ≥ 0.06). Plasma P and phosphatase alkaline concentrations were similar ( ≥ 0.52) among diets. Supplementation of microminerals decreased ( < 0.01) plasma Ca concentration; nevertheless, all analyzed blood metabolites were within the reference values. Supplementation of Ca and P increased ( < 0.01) fecal excretion of these minerals. These results indicate that mineral supplementation (Ca, P, Zn, Mn, and Cu) of conventional feedlot diets for Nellore bulls may be not necessary. Dietary reductions in these minerals would represent a decrease in the cost of feedlot diets. Dietary reduction in Ca and P content cause a decrease in fecal excretion of these minerals, which, in turn, represents an opportunity to reduce the environmental impact of feedlot operations.

The objectives of this study were to quantify the mineral balance of Nellore cattle fed with and without Ca, P, and micromineral (MM) supplementation and to estimate the net and dietary mineral requirement for cattle. Nellore cattle ( = 51; 270.4 ± 36.6 kg initial BW and 8 mo age) were assigned to 1 of 3 groups: reference ( = 5), maintenance ( = 4), and performance ( = 42). The reference group was slaughtered prior to the experiment to estimate initial body composition. The maintenance group was used to collect values of animals at low gain and reduced mineral intake. The performance group was assigned to 1 of 6 treatments: sugarcane as the roughage source with a concentrate supplement composed of soybean meal and soybean hulls with and without Ca, P, and MM supplementation; sugarcane as the roughage source with a concentrate supplement composed of soybean meal and ground corn with and without Ca, P, and MM supplementation; and corn silage as the roughage source with a concentrate supplement composed of soybean meal and ground corn with and without Ca, P, and MM supplementation. Orthogonal contrasts were adopted to compare mineral intake, fecal and urinary excretion, and apparent retention among treatments. Maintenance requirements and true retention coefficients were generated with the aid of linear regression between mineral intake and mineral retention. Mineral composition of the body and gain requirements was assessed using nonlinear regression between body mineral content and mineral intake. Mineral intake and fecal and urinary excretion were measured. Intakes of Ca, P, S, Cu, Zn, Mn, Co, and Fe were reduced in the absence of Ca, P, and MM supplementation ( < 0.05). Fecal excretion of Ca, Cu, Zn, Mn, and Co was also reduced in treatments without supplementation ( < 0.01). Overall, excretion and apparent absorption and retention coefficients were reduced when minerals were not supplied ( < 0.05). The use of the true retention coefficient instead of the true absorption coefficient provided a better estimate of mineral requirements. Dietary mineral requirements were lower for P, Cu, and Zn and greater for Fe compared with previously published recommendations. This study provides useful information about mineral requirements and mineral supplementation to obtain adequate dietary mineral supply of Nellore cattle in tropical conditions.

The use of digital images could be a faster and cheaper alternative technique to assess BW, HCW, and body composition of beef cattle. The objective of this study was to develop equations to predict body and carcass weight and body fat content of young bulls using digital images obtained through a Microsoft Kinect device. Thirty-five bulls with an initial BW of 383 (±5.38) kg (20 Black Angus, 390 [±7.48] kg initial BW, and 15 Nellore, 377 [±8.66] kg initial BW) were used. The Kinect sensor, installed on the top of a cattle chute, was used to take infrared light-based depth videos, recorded before the slaughter. For each animal, a quality control was made, running and pausing the video at the moment that the animal was standing with its body and head in line. One frame from recorded videos was selected and used to analyze the following body measurements: chest width, thorax width, abdomen width, body length, dorsal height, and dorsal area. From these body measurements, 23 indexes were generated and tested as potential predictors. The BW and HCW were assessed with a digital scale, whereas empty body fat (EBF) was estimated through ground samples of all tissues. To better understand the relationship among the measurements, the correlations between final BW (488 [±10.4] kg), HCW (287 [±12.5] kg), EBF (14 [±0.610] % empty BW) content, body measurements (taken through digital images), and developed indexes were evaluated. The REG procedure was used to develop the regressions, and the important independent variables were identified using the options STEPWISE and Mallow's Cp in the SELECTION statement. Chest width was the trait most related to weights and the correlations between this measurement and BW and HCW were above 0.85. The analysis of linear regressions between observed and predicted values showed that all models pass through the origin and have a slope of unity (null hypothesis [H]: = 0 and = 1; ≥ 0.993). The models to estimate BW and HCW of Angus and Nellore presented between 0.69 and 0.84 ( < 0.001), whereas from equations to estimate the EBF were lower ( = 0.43-0.45; ≤ 0.006). Index I5 [(chest width) × body length], related to the animal volume, was significant in all models created to estimate BW and HCW, and it explained more than 70% of the variation. This study indicates that digital images taken through a Microsoft Kinect system have the potential to be used as a tool to estimate body and carcass weight of beef cattle.

We aimed to evaluate the effects of paternal genotypes (Piau, Duroc-based, and Pietrain) and nutritional plans with different digestible lysine contents (Low, Medium, and High) on performance, carcass, and meat quality traits of pigs. Pietrain and Duroc crossbred barrows and gilts were similar in performance and carcass traits and had the greatest values when compared to Piau crossbred pigs. Regarding meat quality, drip loss was greater in pork from Pietrain crossbred barrows and gilts compared to Duroc and Piau crossbred pigs. The High nutritional plan had the greatest daily digestible lysine intake value, followed by the Medium and Low nutritional plans. Most of the performance, carcass, and meat quality traits that were evaluated in barrows and gilts were not affected by the nutritional plans. In general, Duroc and Pietrain crossbred pigs had a greater performance and carcass yield when compared to Piau crossbred pigs.

Eighteen Nellore and 18 Angus young bulls with BW of 381 ± 12 kg were randomly assigned into two feeding groups (whole shelled corn [WSC] or ground corn with silage [GC]) to evaluate the interaction of breed and diet on total nutrient digestibility, pancreatic α‐amylase, and maltase activity and SLC5A1expression in the small intestine. Experimental diets (DM basis) included (a) a diet containing 30% corn silage and 70% GC and soya bean meal‐based concentrate and (b) a diet containing 85% WSC and 15% of a soya bean meal‐ and mineral‐based pelleted supplement. The treatments were Nellore fed GC diet; Nellore fed WSC diet; Angus fed GC diet; and Angus fed WSC diet. Total faecal collection for the digestibility trial occurred from day 48 until day 50 of the experimental period. Feeding the WSC diet reduced DM and NDF intake (p < 0.01). Angus had greater DM and nutrient intake in kg/day (p < 0.01). However, there was no breed effect on DM and nutrient intakes based on percentage of BW (p > 0.19). Angus had greater starch digestibility (p = 0.03) than Nellore. Cattle fed the WSC diet had greater DM, NDF and starch digestibility (p < 0.01) compared with those fed the GC diet. The activity of pancreatic α‐amylase (U/g of protein) was greater in Nellore (p < 0.01) and was not affected by diet (p = 0.52). In duodenum, maltase activity (U/g of protein) was greater in bulls fed GC diet (p = 0.02). Expression of the gene SLC5A1was not affected by breed or diet (p > 0.05). In conclusion, Nellore had less capacity to digest starch. However, they did not have less pancreatic α‐amylase and duodenal maltase activity compared to Angus. The use of the WSC diet increases DM and total nutrient digestibility.

It is expensive and laborious to evaluate carcass composition in beef cattle. The objective of this study was to evaluate a method to predict the 9th to 11th rib section (rib) composition through empirical equations using dual energy X-ray absorptiometry (DXA). Dual energy X-ray absorptiometry is a validated method used to describe tissue composition in humans and other animals, but few studies have evaluated this technique in beef cattle, and especially in the Zebu genotype. A total of 116 rib were used to evaluate published prediction equations for rib composition and to develop new regression models using a cross-validation procedure. For the proposed models, 93 ribs were randomly selected to calculate the new regression equations, and 23 different ribs were randomly selected to validate the regressions. The rib from left carcasses were taken from Nellore and Nellore × Angus bulls from 3 different studies and scanned using DXA equipment (GE Healthcare, Madison, WI) in the Health Division at Universidade Federal de Vicosa (Vicosa, Brazil). The outputs of the DXA report were DXA lean (g), DXA fat free mass (g), DXA fat mass (g), and DXA bone mineral content (BMC; g). After being scanned, the rib were dissected, ground, and chemically analyzed for total ether extract (EE), CP, water, and ash content. The predictions of rib fat and protein from previous published equations were different ( 0.05), respectively, then the equation correctly estimated the rib composition. Comparing observed and predicted values using the new equations, Mayer's test was not significant for lean mass ( = 0.26), fat free mass ( = 0.67), EE mass ( = 0.054), and ash mass ( = 0.14). We concluded that the rib composition of Nellore and Nellore × Angus bulls can be estimated from DXA using the proposed equations.

The objectives of this study were to test the interaction of breed (Nellore or Angus) and diet (whole shelled corn [WSC] or ground corn [GC] with silage) on growth performance, carcass characteristics, and ruminal pH of young bulls. Thirty-six bulls (18 Nellore and 18 Angus) with the range in age of 18 to 22 mo and BW of 381 ± 12 kg were used in a completely randomized design experiment with a 2 × 2 factorial arrangement of treatments (2 breeds and 2 diets). Experimental diets (DM basis) included 1) a GC diet containing 30% corn silage and 70% GC- and soybean meal-based concentrate and 2) a WSC diet containing 85% WSC and 15% of a soybean meal- and mineral-based pelleted supplement. An additional 8 bulls were slaughtered at the beginning of the experimental period for determination of initial carcass weight. The treatments were Nellore fed the GC diet, Nellore fed the WSC diet, Angus fed the GC diet, and Angus fed the WSC diet. Greater DMI ( < 0.01), ADG ( < 0.01), and G:F ( < 0.01) were observed in Angus bulls compared with Nellore bulls, regardless of diet. Lower average ruminal pH ( = 0.04), maximum ruminal pH (P = 0.02), and DMI ( < 0.01) were observed in bulls fed the WSC diet than in those fed the GC diet. In addition, bulls fed the WSC diet had greater G:F ( < 0.01). The WSC diet led to greater variation in DMI compared with the GC diet ( < 0.01). Omasum and large intestine percentage was affected by diets only in the Angus breed ( < 0.02) and were greater when bulls were fed the GC diet. The WSC diet without forage may be useful for feedlots because this diet promoted greater G:F than the GC diet, regardless of breed. However, special care must be exercised in feed management during adaptation and throughout the feeding of Nellore animals to avoid digestive disorders and fluctuations in DMI.

We aimed to evaluate the expression of genes related to the regulation of muscle protein turnover in the longissimus dorsi (LD) muscle of Angus and Nellore bulls and to estimate the within-breed correlations of gene expression and performance traits. Thirteen genes related to the IGF-1 and myostatin pathways were studied. Thirteen animals, with an initial average BW of 381.2 ± 11.8 kg, from each breed were used in a completely randomized 2 × 2 factorial design (2 breeds and 2 feeding levels). The diet consisted of corn silage and a corn-soybean meal concentrate in a roughage-to-concentrate ratio of 30:70. Cattle were fed ad libitum (with 9 animals from each breed) or feed restricted (a 55% restriction of total DMI of ad libitum-fed animals, calculated as percentage of metabolic BW, with 4 animals of each breed). The experimental period lasted for 82 d and it was preceded by a 28-d adaptation period. The performance traits evaluated were slaughter body weight, total ADG (from d 1 to 82 of the trial), initial ADG (from d 1 to 41 of the trial), final ADG (from d 42 to 82 of the trial), total DMI (from d 1 to 82 of the trial), initial DMI (from d 1 to 41 of the trial), final DMI (from d 42 to 82 of the trial), HCW, LD weight (LDW), and rib eye area (REA). After slaughter, samples were taken from the LD muscle between the 12th and 13th ribs for gene expression analysis by quantitative reverse transcription PCR. There was no difference ( > 0.05) in the expression of any of the genes studied between ad libitum-fed Angus and ad libitum-fed Nellore, whereas feed restriction increased the expression of (; < 0.001), (; = 0.05), and (; = 0.04) and decreased the expression of ( < 0.01). The REA was negatively correlated to (; = 0.01), (; = 0.02), and ( = 0.05). The HCW was negatively correlated to ( = 0.01) and ( = 0.01) and tended to be negatively correlated to ( = 0.07), whereas the LDW tended to be negatively correlated to ( = 0.08). The genes , , and seem to be important for muscle growth and may be worthy of further investigation as future strategies for increasing muscle in livestock.