Carcass and meat characteristics of Nellore young bulls fed diet using cottonseed cake as a replacer of the forage fiber source.

The aim of this study was to assess the effects of substituting traditional forage fiber sources with cottonseed cake in the diet on both the quantitative and qualitative characteristics of carcass and meat in Nelore young bulls. Twenty-four Nelore steers starting with an average weight of 377.8 ± 43.5 kg, were individually housed in stalls and provided with individualized feeding over a 112-day confinement period. The study followed a completely randomized design with two treatments and 12 replications. The diets incorporated either whole plant corn silage (WPCS) and, cottonseed cake (CSC) as fiber sources, at a rate of 300 g/kg of dry matter. The CSC diet promoted higher carcass weight. Aging animal meat for seven days significantly decreased the shear force from 83.4 to 71.6 N. Although diets did not influence meat composition, WPCS diet provided higher concentrations of C16:1, C18:1n9c, C18:3n3, and C22:2 acid, and CSC diet higher concentrations of C15:0, C18:1n9t, C18:2n6c, and 20:3n3. The WPCS diet provided higher concentrations of monounsaturated fatty acids and ω9, and the CSC diet had higher concentrations of ω6 and ω6:ω3 ratio in meat. Cottonseed cake used as a fiber source increases the concentration of polyunsaturated fatty acids and ω6 fatty acids in the meat of young bulls finished in feedlot.

Nutrient intake, productive and metabolic parameters of Nellore bulls feed a forage free diet using cottonseed cake as a fiber source.

We hypothesized that cottonseed cake in confined Nellore young bulls' diet as fiber source, could maintain or improve the nutrient intake, and productive and metabolic parameters. It was evaluated the total replacement of whole plant corn silage (WPCS) by cottonseed cake (CSC) as a source of fiber in the diet. A completely randomized design with two treatments and 12 replications was used. The treatments were two experimental diets containing 300 g/kg of WPCS or CSC as roughage. All animals at 0, 15, 30, 60 and 112 days were weighed to monitor productive performance and nutrient intake. Dry matter intakes, organic matter, neutral detergent fiber, physically effective neutral detergent fiber, crude protein and non-fiber carbohydrates of the WPCS treatment cattle were higher (p < 0.05), and the ethereal extract intake of cattle fed CSC diet was higher. The BW of cattle fed WPCS was higher in the two initial periods of confinement (p < 0.05). Animals from both treatments showed linear growth during the confinement period. There was a fiber source × period interaction for total weight gain (TWG), average daily gain (ADG) and feed efficiency (FE) (p < 0.05), with the lowest in the first 15 days and the highest at 30 days, reflecting a compensatory gain in animals fed with CSC. Bulls fed with CSC showed negative TWG and ADG in the first period (p < 0.05), but recovered in the following periods, surpassing that of the SC treatment in the last two periods. There was negative EF of bulls fed with CSC in the first period (P < 0.05), but in the following periods the CSC diet did not differ from the WPCS diet. The animals fed CSC diet showed a higher concentration of cholesterol and glucose in the blood plasma (p < 0.05). The forage-free diet containing cottonseed cake as a source of fiber replacing corn silage promoted better animal performance.

In Vitro Digestibility and Models of Cumulative Gas Production of Forage-Free Diet.

Our objectives were to evaluate the use of cottonseed cake in replacing corn silage in a diet without forage and to identify the model with higher precision and accuracy of adjustment of parameters of ruminal degradation kinetics. A diet containing corn silage and another with cottonseed cake as a fiber source were formulated. Gompertz, Dual-pool Logistic, Brody, and Ørskov models were evaluated for goodness of fit to gas production. There were significant differences in dry matter (DM), organic matter (OM), and neutral detergent fiber (NDF) in the in vitro digestibility for diets and fiber sources. The estimated values of the Gompertz (6.77), Brody (6.72), and Ørskov (6.73) models were similar to the observed mean of gas production in the corn silage diet (6.73 mL/100 mg DM). Similarly, the estimated values of the Brody (5.87) and Ørskov (5.89) models were similar to the observed mean of gas production in the cottonseed cake diet (5.87 mL/100 mg DM). The roughage-free diet containing cottonseed cake as a fiber source stimulated higher gas production. Brody and Ørskov models presented higher precision and accuracy in the fitting of kinetics of degradation independent of the fiber source in the diet.

Orange peel silage in lamb feeding improves meat fatty acid profile / Silagem de bagaço de laranja na alimentação de cordeiros melhora o perfil de ácidos graxos da carne

Considering its nutritional quality and low cost compared to traditional foods, the orange peel has been used to replace grains in ruminant diets. This research was developed to evaluate the fatty acid profile of meat from lambs finished with diets containing orange peel silage (OPS) in replacement of corn (0, 33, 66 and 100%). Twenty Santa Inês lambs (five replicates per treatment), approximately five months old and body weight of 25.37 ± 1.94 kg, were distributed in a completely randomized design and the data obtained compared by the Tukey test at 0.05 of significance. There was a linear increase in the concentration of fatty acid capric (P = 0.026) and a quadratic increase for palmitic, palmitoleic, stearic, oleic, linoleic, conjugated linoleic (CLA) and α-linolenic acid, saturated, unsaturated, monounsaturated, polyunsaturated, Σn-6, Σn-3 fatty acids and desirable fatty acids in the meat of lambs fed with OPS (P<0.05). The replacement of corn by OPS in 66% in the diet of finishing lambs improves the fatty acid profile of the meat.

Considerando sua qualidade nutricional e baixo custo em relação aos alimentos tradicionais, a casca de laranja vem sendo utilizada em substituição aos grãos na dieta de ruminantes. Esta pesquisa foi desenvolvida para avaliar o perfil de ácidos graxos da carne de cordeiros terminados com dietas contendo silagem de bagaço de laranja (SBL) em substituição ao milho (0, 33, 66 e 100%). Vinte cordeiros Santa Inês (cinco repetições por tratamento), com aproximadamente cinco meses de idade e peso corporal de 25,37 ± 1,94 kg, foram distribuídos em um delineamento experimental inteiramente casualizado e os dados obtidos comparados pelo teste Tukey a 0,05 de significância. Houve aumento linear na concentração do ácido graxo cáprico (P = 0,026) e de forma quadrática (P<0,05) para o palmítico, palmitoleico, esteárico, oleico, linoleico, linoleico conjugado (CLA) e α-linolênico; dos ácidos graxos saturados, insaturados, monoinsaturados, poliinsaturados, Σn-6, Σn-3 e dos ácidos graxos desejáveis na carne de cordeiros alimentados com SBL. A substituição do milho pela SBL em 66% na dieta de cordeiros em terminação melhora o perfil de ácidos graxos da carne.

Productive characteristics, chemical composition, in vitro digestibility, and degradation kinetics of two Brachiaria grasses at different regrowth ages.

The study aimed at the effect of different regrowth ages on chemical, productive, and morphological characteristics, in addition to the kinetics of gas production and in vitro digestibility of grasses of the genus Brachiaria. The treatments consisted of two regrowth ages (21 and 35 days) and two grass species (Brachiaria brizantha and B. ruziziensis), in plat with a dimension of 10 × 10 with four replications, totaling 16 plats in a completely randomized design. The regrowth age did not change the leaf:stem ratio of the grasses. Ruziziensis-grass had higher crude protein (CP) content in leaves than Marandu-grass (14.0% versus 10.9% respectively). Marandu-grass leaf had higher NDF content than Ruziziensis-grass (65.0 and 58.3%, respectively) and ADF content (39.6 and 33.2%, respectively). The accumulation rate is high in Marandu-grass regardless of the age of regrowth; however, the in vitro digestibility of dry matter of Ruziziensis-grass is better both in the leaf and in the stem. The regrowth age did not influence the dry matter (DM) and neutral detergent fiber (NDF) in vitro digestibility (ivD) of the leaves. The ivDNDF of leaves of both types of grass were similar. There was an increase in the ivDDM of stem when the regrowth age was 21 days. The DM degradation rate was higher in Marandu-grass at both regrowth ages, and the total gas production was higher at 21 days. The parameters evaluated in the dual-pool logistic model showed interaction for age and cultivar, except for fractions λ (lag time) and total gas production. Marandu-grass presented a greater volume of gas for the rapidly degradable fraction and a lower degradation rate. There was a significant interaction for the parameters evaluated in the models between ages and grasses. The exponential model showed interaction in all fractions. Grasses had reduced CP content and increased fibrous fraction as a function of age, with no reduction in leaf DM and NDF digestibility. The Ruziziensis-grass has higher digestibility at the regrowth ages evaluated, while Marandu-grass has higher yields. We recommend adjusting the in vitro degradation kinetics by the dual-pool logistic model.

Technologies used in ruminant grazing management: an integrative review.

The objective of this study was to identify the main technologies used in the management of ruminant grazing. We developed a review protocol in which the search terms were previously tested and based on the PVO strategy to determine the guiding question (population [P]: domestic ruminants; variables [V] of interest: grazing management technologies; and outcomes [O]: intake, performance, and productivity of animals raised exclusively on pasture). The guiding question was the following: What technologies are used in the grazing management of domestic ruminants on pasture? The databases used were SCOPUS (Elsevier), SciELO Citation Index, Science Direct, and Wiley Online Library, and the search was carried out until October 15, 2021. The search identified 2683 research articles; however, only 43 were considered eligible and included due to their methodological robustness for data extraction. The most commonly used species were Lolium multiflorum and Lolium perenne (20%), Panicum maximum (18%), and Brachiaria brizantha (14%). The most widely used grazing methods were continuous grazing (53.4%) and intermittent grazing (39.5%). Among the technologies, the most widely adopted were pasture height (55.8%) and herbage allowance (11.6%). The most frequent sampling methods were the use of a ruler (37.2%) and measuring stick (13.9%) to measure the height, and clipping with a frame (18.6%) to measure herbage allowance. The animals used in the included studies were cattle (n = 1335), sheep (n = 839), and goats (n = 41). Pasture height and herbage allowance were the most widely used grazing management technologies, with the data concentrated mainly in Brazil, in studies with continuous grazing by cattle.

Cotton cake as an economically viable alternative fibre source of forage in a high-concentrate diet for finishing beef cattle in feedlots.

Cotton cake can be a sustainable and economically viable alternative to maize silage as an effective fibre source in the finishing diet of feedlot beef cattle. Thus, the objective was to evaluate the economic viability and the productive performance of Nellore steers finished in feedlots using cotton cake as a source of fibre, replacing maize silage in the diet. Twenty-four non-castrated Nellore steers, with an average weight of 377.8 kg and an age of approximately 24 months, kept in individual pens, were used. The diet was 30% roughage, in the form of maize silage, and a diet without forage containing 30% cotton cake as an effective fibre source, based on dry matter. The design used was completely randomised with two treatments and 12 replications. Effects (p < 0.05) of the dietary fibre source were observed for final body weight (BW), total weight gain, hot carcass weight (HCW) and carcass yield (CY). Revenue and net margin were higher for the treatment with cotton cake. The corn silage diet promoted higher total costs per animal (U$ 408.41 vs. U$ 336.06) and daily costs (U$ 3.65 vs. U$ 3.00). Greater differences were observed between fibre sources for the concentrate cost, and the maize silage diet had a cost U$ 98.29 higher than the treatment with cotton cake (U$ 314.04 vs. U$ 215.75). The cotton cake treatment had a higher cost of U$106.98/animal for the net margin. Cotton cake is a viable alternative and can be used as a source of fibre in forage-free diets without affecting production performance, promoting benefits in economic performance for finishing beef steers in feedlots.

Prediction of dry matter intake by meat sheep on tropical pastures.

This study was undertaken to determine whether equations for prediction of dry matter intake (DMI) by meat sheep are valid for animals raised solely on tropical pastures and to propose a new equation to predict the DMI of sheep raised on tropical pastures. The DMI prediction from published equations was evaluated by regressing the predicted and observed values, using the F test, for the identity of the parameters (ß0 = 0 and ß1 = 1) of the regression of predicted on observed data. If the null hypothesis is not rejected, the tested equation accurately estimates DMI. The proposed equation was evaluated in the same way as the published equations. The animal performance and pasture structure and chemical composition data used originated from an experiment conducted with 32 Santa Inês sheep raised on tropical pastures. In the analysis of model adequacy, the null hypothesis was rejected (P < 0.001) and the equations generated predictions that differ (ß0 = 0 and ß1 = 1) from the DMI observed under practical feeding conditions for grazing sheep. The proposed equation, DMI (%LW) = 7.16545 (± 0.76522) - 0.21799 (± 0.01812) * LW + 0.00273 (± 0.00034) * LW2-0.00688 (± 0.00299) * GT + 0.000007 (± 0.000002) * GT2 + 0.00271 (± 0.00108) * GHA, where LW is live weight (kg), GT is grazing time (min/day), and GHA is green herbage allowance (kg DM/100 kg LW), should be used to more accurately predict DMI by grazing sheep.

Prediction of Carcass Traits of Santa Inês Lambs Finished in Tropical Pastures through Biometric Measurements.

The aim of this study was to predict carcass traits of Santa Inês lambs finished in tropical pastures by using biometric measurements. Data originated from two experiments involving 56 lambs (32 in experiment I and 24 in experiment II). In both experiments, the sheep were finished in that were finished in pastures of Panicum maximum and Brachiaria brizantha, experiment I being conducted in the rainy season and experiment II in the dry season. The following biometric measurements were recorded before slaughter: body length (BL), withers height (WH), rump height (RH), thorax width (TW), rump width (RW), chest width (CW), heart girth (HG), thigh circumference (TC), rump circumference (RC) and leg length (LL), in addition to live weight at slaughter (SW). After slaughter, hot carcass weight (HCW), cold carcass weight (CCW) and the weights of primal cuts (shoulder, neck, loin, leg and rib) were recorded. In the equations generated to predict SW, HCW and CCW, R2 ranged from 0.58 to 0.91 and the measurements of WH, TC, CW, HG and RW were the most relevant. In the equations developed to predict the weight of primal cuts, in turn, R2 ranged from 0.26 to 0.99. In these models, SW, BL, CW, TC, LL and HG explained most of the variation in the weight of primal cuts. Biometric measurements can be used to accurately and precisely predict HCW, CCW and the weight of primal cuts from the carcass of Santa Inês sheep finished in tropical pastures, since the equations presented R2 and correlation coefficient and agreement above 0.8.

Use of palm bran (Nopalea cochenillifera (L.) Salm-Dyck) in partial replacement of concentrate in maintenance equine diets - a pilot study.

Forage palm is extremely suitable as animal fodder due to its high tolerance to the climatic rigors of the semiarid region and its ability to withstand the harsh physical-chemical limitations of poor soils. Thus, in this study, the effects of the partial replacement (0 %, 5 %, 10 % and 15 % replacement) of a molasses- or oat-based commercial concentrate with forage palm bran (FPB) on the acceptability, apparent digestibility and glycemic response of horses at maintenance were evaluated. The ratio of concentrate to roughage (Tifton 85 hay) was 30 : 70 , and the dry matter (DM) intake was 2 % of body weight (BW). For the preference test, 10 barren Mangalarga Marchador mares were used. The experimental diets were offered simultaneously to determine the consumption preference and the intake ratio. For the digestibility test, four mixed-breed geldings were used and were distributed in a Latin square experimental design ( 4 × 4 ). For the glycemic response, blood samples were collected 30 min before and 30, 60, 90, 120, 180 and 240 min after supplying the feed. The preference test indicated that feed containing 0 % and 5 % FPB was preferred by the animals. Nutrient digestibility coefficients did not differ among the experimental diets. Blood glucose was lower at 180 min in the 7.42 % FPB inclusion diet ( R 2 = 0.97 ); this was estimated using the following equation: Y = 115.05 - 2.75 x + 0.19 x 2 . It is concluded that the incorporation of up to 15 % of forage palm bran as a substitute for concentrate in the maintenance diet tested did not negatively influence feed intake, nutrient digestibility or glycemic index; however, inclusion values above 5 % reduced diet acceptability.

Principal component analysis of steers performance and structural and nutritional characteristics of Mombasa grass / Análise de componentes principais entre o desempenho de novilhos de corte e as características estruturais e nutricionais do capim-mombaça

ABSTRACT: There is little information about whether the increased secondary productivity observed in pastures fertilized with high nitrogen rates is attributable to fluctuations in the nutritional value or pasture structural characteristics, or both. This study aimed to identify a set of factors (structural and nutritional characteristics) that best explain the performance of beef steers grazing Mombasa grass pastures under residual effects of nitrogen fertilizer. The data were collected in Mombasa grass pastures fertilized with increasing rates of nitrogen (N) (100, 200 and 300 kg ha-1) from 2015 to 2017. In 2018, nitrogen fertilization was not used in order to characterize a residual effect of the nutrient. Variables related to pasture structural characteristics such as forage accumulation rate (FAR), canopy height, forage mass (FM) and morphological components were evaluated. The study also evaluated the nutritional value of leaf blades and the performance of beef steers based on average daily gain (ADG) and stocking rate. Principal component analysis was performed using the dataset available. Most of the variance (99.6%) was explained by only two principal components (PCs), of which 90.0% corresponded to PC1. The most influential parameters for PC1, in order of priority, were: FAR, FM, leaf blade and stem masses. These variables were positively associated with stocking rate. Conversely, ADG was not associated with any variable. ADG was the most relevant variable for the second PC; however, this PC explained less variance (9.6%). The structural characteristics of the pasture (FAR, FM and morphological components mass) better explain the fluctuations in the performance of cattle on pastures of Mombasa grass under residual effects of nitrogen fertilizer. The stocking rate is an efficient parameter to support decision-making in managed pastures with variable stocking.

RESUMO: Há pouca informação sobre se o aumento da produtividade secundária observada em pastagens fertilizadas com altas taxas de nitrogênio é atribuível a flutuações no valor nutricional ou nas características estruturais das pastagens, ou em ambas. Objetivou-se identificar grupos de caraterísticas (estruturais e nutricionais) que melhor explicassem o desempenho de novilhos de corte em pastos de capim-mombaça sob efeito residual de doses de nitrogênio. Os dados foram coletados em pastos de capim-mombaça que receberam três doses anuais de nitrogênio (N) (100, 200 e 300 kg ha-1) de 2015 a 2017. No ano de 2018 não foi utilizada adubação nitrogenada, para caracterizar o efeito residual do nutriente. As variáveis avaliadas foram relacionadas às características estruturais, taxa de acúmulo de forragem (TAF), altura do dossel, massa de forragem (MF) e dos componentes morfológicos. Também foi avaliado o valor nutritivo da lâmina foliar e o desempenho dos novilhos através do ganho médio diário (GMD) e da taxa de lotação. A partir do banco de dados foi realizada a análise de componentes principais. Os resultados demonstraram que 99,6% da variação no conjunto de dados foram explicados por apenas dois componentes principais (CPs), e 90,0% desse valor corresponde ao CP1. As características de maior magnitude para a diferenciação dos tratamentos no CP1, em ordem de prioridade foram: TAF, MF, massas de lâmina foliar e de colmo. Essas variáveis estiveram positivamente associadas com a taxa de lotação. Já o GMD não se relacionou com nenhuma variável. O GMD foi a variável de maior importância para o segundo CP, entretanto, esse CP teve pouca contribuição (9,6%) para a elucidação do resultados. As características estruturais (TAF e MF e compondes morfológicos) do pasto explicam melhor as oscilações em pastos de capim-mombaça sob efeito residual de doses de nitrogênio. A taxa de lotação é um parâmetro eficiente para apoiar a tomada de decisão em pastos manejados com lotação variável.

Mathematical models to adjust the parameters of in vitro cumulative gas production of diets containing preserved Gliricidia / Modelos matemáticos para ajuste dos parâmetros de produção cumulativa de gás in vitro de dietas contendo Gliricídia conservada

ABSTRACT: This study examined the use of the Gompertz, Groot, monomolecular, Richards and two-compartment-logistic mathematical models to investigate the kinetics of in vitro gas production of diets composed of combinations of Gliricidia hay or silage. In addition, the effects of Gliricidia hay or silage inclusion on the in vitro cumulative gas production of these diets were evaluated. Rumen fermentation kinetics were analyzed by the in vitro cumulative gas production methodology. The model parameters were estimated using the Gauss Newton method, with the exception of the Richards model, which was used by Marquardt's algorithm. Model fit was assessed using the determination coefficient, F test for parameters identity, concordance correlation coefficient, root mean square error of prediction, and decomposition of mean square error of prediction into mean error, systematic bias and random error. The models were compared for accuracy (pairwise mean square error of prediction) and precision (delta Akaike's information criterion). All model evaluation and comparison statistics were calculated using Model Evaluation System software version 3.2.2. The Groot and Richards models did not differ from each other (P>0.05) and were the most precise and accurate (P<0.05). Therefore, the Groot model was selected due to its better accuracy and precision and easier access to the parameters. The inclusion of Gliricidia silage in the diet resulted in an increase in the time to obtain the maximum rate of degradation and in the time after incubation when half of the asymptotic level was reached. The Groot model is recommended to estimate the average curve. Dietary inclusion of Gliricidia silage alters the gas production curve due to the longer time required for the diet to reach the maximum rate of degradation, this can increase the time the diet remains in rumen and promote a reduction in the consumption.

RESUMO: Objetivou-se avaliar os modelos matemáticos Gompertz, Groot, monomolecular, Richards e logístico bicompartimental para estudar a cinética de produção de gás in vitro de dietas compostas de combinações de feno ou silagem de Gliricídia. Além disso, avaliou-se os efeitos da inclusão de feno ou silagem de Gliricídia sobre a produção cumulativa de gás in vitro destas dietas. A cinética de fermentação ruminal foi avaliada pela metodologia de produção cumulativa de gás in vitro. Os parâmetros dos modelos foram estimados usando o método de Gauss Newton, com exceção do modelo de Richards, que foi usado algoritmo de Marquardt. O ajuste dos modelos foi avaliado por meio do coeficiente de determinação, teste F para a identidade dos parâmetros, coeficiente de correlação e concordância, raiz quadrada do quadrado médio do erro da predição e a decomposição do quadrado médio do erro da predição em erro médio, vício sistemático e erro aleatório. Os modelos foram comparados quanto à acurácia (quadrado médio da predição pareado) e quanto à sua precisão (critério de informação delta de Akaike). Todas as estatísticas de avaliação e comparação dos modelos foram calculadas usando o software Model Evaluation System versão 3.2.2. Os modelos de Groot e Richards não diferiram entre si (P>0.05) e foram os mais precisos e acurados (P<0.05). Portanto, modelo de Groot foi selecionado devido apresentar melhor acurácia e precisão e apresentar maior facilidade na obtenção dos parâmetros. A inclusão da silagem de Gliricídia na dieta, resultou em elevação no tempo para obtenção da máxima taxa de degradação e no tempo após a incubação em que metade do nível assintótico foi atingido. Recomenda-se a utilização do modelo de Groot para estimativa da curva média. A inclusão da silagem de Gliricídia altera a curva de produção de gás devido o maior tempo necessário para que a dieta atingisse a máxima taxa de degradação, isso pode elevar o tempo de permanência da dieta no rúmen e promover redução no consumo.

Ewe performance in the post-weaning phase and structural characteristics of Brachiaria brizantha cultivars in the dry season

The objective of this study was to examine the performance of ewes in the post-weaning phase and the structural characteristics of Brachiaria brizantha cultivars in the dry season. The treatments were represented by four Brachiaria brizantha cultivars (Piatã, Marandu, Paiaguás, and Xaraés), which were evaluated in a randomized-block design with two replicates for the forage variables and eight replicates for the animal performance variables. Canopy height, masses of forage and morphological components and chemical composition of morphological components were evaluated. Thirty-two ½ Santa Inês and ½ Dorper sheep with an initial body weight (BW) of 22.7 ± 1.2 kg were used. Average daily gain (ADG – kg animal-1 day-1), stocking rate (in animal units [AU] = 30 kg of body weight) and weight gain per area (kg ha-1 day-1) were measured. There was no cultivar effect (p > 0.05) on the structural characteristics of the pasture. The highest crude protein content in the leaf blade (11.8%) were found in cultivar Marandu. Average daily gain was higher in the animals that grazed on cultivar Marandu (0.08 kg animal-1 day-1) as compared with cultivars Xaraés (0.05 kg animal-1 day-1) and Piatã (0.04 kg animal-1 day-1), whereas the ewes that grazed on cultivar Paiaguás showed intermediate ADG values (0.06 kg animal-1 day-1). There was no difference between the cultivars for stocking rate (9.2 AU). Weight gain per area was highest in cultivar Marandu (0.33 kg ha-1 day-1) and lowest in cv. Piatã (0.16 kg ha-1 day-1). Brachiaria brizantha cultivars Piatã, Marandu, Paiaguás and Xaraés proved to be forage options for the post-weaning phase of ewes supplemented with concentrate in the dry season.

Mathematical models to adjust the parameters of in vitro cumulative gas production of diets containing preserved Gliricidia / Modelos matemáticos para ajuste dos parâmetros de produção cumulativa de gás in vitro de dietas contendo Gliricídia conservada

This study examined the use of the Gompertz, Groot, monomolecular, Richards and two-compartment-logistic mathematical models to investigate the kinetics of in vitro gas production of diets composed of combinations of Gliricidia hay or silage. In addition, the effects of Gliricidia hay or silage inclusion on the in vitro cumulative gas production of these diets were evaluated. Rumen fermentation kinetics were analyzed by the in vitro cumulative gas production methodology. The model parameters were estimated using the Gauss Newton method, with the exception of the Richards model, which was used by Marquardt’s algorithm. Model fit was assessed using the determination coefficient, F test for parameters identity, concordance correlation coefficient, root mean square error of prediction, and decomposition of mean square error of prediction into mean error, systematic bias and random error. The models were compared for accuracy (pairwise mean square error of prediction) and precision (delta Akaike’s information criterion). All model evaluation and comparison statistics were calculated using Model Evaluation System software version 3.2.2. The Groot and Richards models did not differ from each other (P>0.05) and were the most precise and accurate (P<0.05). Therefore, the Groot model was selected due to its better accuracy and precision and easier access to the parameters. The inclusion of Gliricidia silage in the diet resulted in an increase in the time to obtain the maximum rate of degradation and in the time after incubation when half of the asymptotic level was reached. The Groot model is recommended to estimate the average curve. Dietary inclusion of Gliricidia silage alters the gas production curve due to the longer time required for the diet to reach the maximum rate of degradation, this can increase the time the diet remains in rumen and promote a reduction in the consumption.

Objetivou-se avaliar os modelos matemáticos Gompertz, Groot, monomolecular, Richards e logístico bicompartimental para estudar a cinética de produção de gás in vitro de dietas compostas de combinações de feno ou silagem de Gliricídia. Além disso, avaliou-se os efeitos da inclusão de feno ou silagem de Gliricídia sobre a produção cumulativa de gás in vitro destas dietas. A cinética de fermentação ruminal foi avaliada pela metodologia de produção cumulativa de gás in vitro. Os parâmetros dos modelos foram estimados usando o método de Gauss Newton, com exceção do modelo de Richards, que foi usado algoritmo de Marquardt. O ajuste dos modelos foi avaliado por meio do coeficiente de determinação, teste F para a identidade dos parâmetros, coeficiente de correlação e concordância, raiz quadrada do quadrado médio do erro da predição e a decomposição do quadrado médio do erro da predição em erro médio, vício sistemático e erro aleatório. Os modelos foram comparados quanto à acurácia (quadrado médio da predição pareado) e quanto à sua precisão (critério de informação delta de Akaike). Todas as estatísticas de avaliação e comparação dos modelos foram calculadas usando o software Model Evaluation System versão 3.2.2. Os modelos de Groot e Richards não diferiram entre si (P>0.05) e foram os mais precisos e acurados (P<0.05). Portanto, modelo de Groot foi selecionado devido apresentar melhor acurácia e precisão e apresentar maior facilidade na obtenção dos parâmetros. A inclusão da silagem de Gliricídia na dieta, resultou em elevação no tempo para obtenção da máxima taxa de degradação e no tempo após a incubação em que metade do nível assintótico foi atingido. Recomenda-se a utilização do modelo de Groot para estimativa da curva média. A inclusão da silagem de Gliricídia altera a [...].

Mathematical models to adjust the parameters of in vitro cumulative gas production of diets containing preserved Gliricidia / Modelos matemáticos para ajuste dos parâmetros de produção cumulativa de gás in vitro de dietas contendo Gliricídia conservada

This study examined the use of the Gompertz, Groot, monomolecular, Richards and two-compartment-logistic mathematical models to investigate the kinetics of in vitro gas production of diets composed of combinations of Gliricidia hay or silage. In addition, the effects of Gliricidia hay or silage inclusion on the in vitro cumulative gas production of these diets were evaluated. Rumen fermentation kinetics were analyzed by the in vitro cumulative gas production methodology. The model parameters were estimated using the Gauss Newton method, with the exception of the Richards model, which was used by Marquardts algorithm. Model fit was assessed using the determination coefficient, F test for parameters identity, concordance correlation coefficient, root mean square error of prediction, and decomposition of mean square error of prediction into mean error, systematic bias and random error. The models were compared for accuracy (pairwise mean square error of prediction) and precision (delta Akaikes information criterion). All model evaluation and comparison statistics were calculated using Model Evaluation System software version 3.2.2. The Groot and Richards models did not differ from each other (P>0.05) and were the most precise and accurate (P<0.05). Therefore, the Groot model was selected due to its better accuracy and precision and easier access to the parameters. The inclusion of Gliricidia silage in the diet resulted in an increase in the time to obtain the maximum rate of degradation and in the time after incubation when half of the asymptotic level was reached. The Groot model is recommended to estimate the average curve. Dietary inclusion of Gliricidia silage alters the gas production curve due to the longer time required for the diet to reach the maximum rate of degradation, this can increase the time the diet remains in rumen and promote a reduction in the consumption.(AU)

Objetivou-se avaliar os modelos matemáticos Gompertz, Groot, monomolecular, Richards e logístico bicompartimental para estudar a cinética de produção de gás in vitro de dietas compostas de combinações de feno ou silagem de Gliricídia. Além disso, avaliou-se os efeitos da inclusão de feno ou silagem de Gliricídia sobre a produção cumulativa de gás in vitro destas dietas. A cinética de fermentação ruminal foi avaliada pela metodologia de produção cumulativa de gás in vitro. Os parâmetros dos modelos foram estimados usando o método de Gauss Newton, com exceção do modelo de Richards, que foi usado algoritmo de Marquardt. O ajuste dos modelos foi avaliado por meio do coeficiente de determinação, teste F para a identidade dos parâmetros, coeficiente de correlação e concordância, raiz quadrada do quadrado médio do erro da predição e a decomposição do quadrado médio do erro da predição em erro médio, vício sistemático e erro aleatório. Os modelos foram comparados quanto à acurácia (quadrado médio da predição pareado) e quanto à sua precisão (critério de informação delta de Akaike). Todas as estatísticas de avaliação e comparação dos modelos foram calculadas usando o software Model Evaluation System versão 3.2.2. Os modelos de Groot e Richards não diferiram entre si (P>0.05) e foram os mais precisos e acurados (P<0.05). Portanto, modelo de Groot foi selecionado devido apresentar melhor acurácia e precisão e apresentar maior facilidade na obtenção dos parâmetros. A inclusão da silagem de Gliricídia na dieta, resultou em elevação no tempo para obtenção da máxima taxa de degradação e no tempo após a incubação em que metade do nível assintótico foi atingido. Recomenda-se a utilização do modelo de Groot para estimativa da curva média. A inclusão da silagem de Gliricídia altera a [...].(AU)

Ewe performance in the post-weaning phase and structural characteristics of Brachiaria brizantha cultivars in the dry season

The objective of this study was to examine the performance of ewes in the post-weaning phase and the structural characteristics of Brachiaria brizantha cultivars in the dry season. The treatments were represented by four Brachiaria brizantha cultivars (Piatã, Marandu, Paiaguás, and Xaraés), which were evaluated in a randomized-block design with two replicates for the forage variables and eight replicates for the animal performance variables. Canopy height, masses of forage and morphological components and chemical composition of morphological components were evaluated. Thirty-two ½ Santa Inês and ½ Dorper sheep with an initial body weight (BW) of 22.7 ± 1.2 kg were used. Average daily gain (ADG kg animal-1 day-1), stocking rate (in animal units [AU] = 30 kg of body weight) and weight gain per area (kg ha-1 day-1) were measured. There was no cultivar effect (p > 0.05) on the structural characteristics of the pasture. The highest crude protein content in the leaf blade (11.8%) were found in cultivar Marandu. Average daily gain was higher in the animals that grazed on cultivar Marandu (0.08 kg animal-1 day-1) as compared with cultivars Xaraés (0.05 kg animal-1 day-1) and Piatã (0.04 kg animal-1 day-1), whereas the ewes that grazed on cultivar Paiaguás showed intermediate ADG values (0.06 kg animal-1 day-1). There was no difference between the cultivars for stocking rate (9.2 AU). Weight gain per area was highest in cultivar Marandu (0.33 kg ha-1 day-1) and lowest in cv. Piatã (0.16 kg ha-1 day-1). Brachiaria brizantha cultivars Piatã, Marandu, Paiaguás and Xaraés proved to be forage options for the post-weaning phase of ewes supplemented with concentrate in the dry season.(AU)

Principal component analysis of steers performance and structural and nutritional characteristics of Mombasa grass / Análise de componentes principais entre o desempenho de novilhos de corte e as características estruturais e nutricionais do capim-mombaça

There is little information about whether the increased secondary productivity observed in pastures fertilized with high nitrogen rates is attributable to fluctuations in the nutritional value or pasture structural characteristics, or both. This study aimed to identify a set of factors (structural and nutritional characteristics) that best explain the performance of beef steers grazing Mombasa grass pastures under residual effects of nitrogen fertilizer. The data were collected in Mombasa grass pastures fertilized with increasing rates of nitrogen (N) (100, 200 and 300 kg ha-1) from 2015 to 2017. In 2018, nitrogen fertilization was not used in order to characterize a residual effect of the nutrient. Variables related to pasture structural characteristics such as forage accumulation rate (FAR), canopy height, forage mass (FM) and morphological components were evaluated. The study also evaluated the nutritional value of leaf blades and the performance of beef steers based on average daily gain (ADG) and stocking rate. Principal component analysis was performed using the dataset available. Most of the variance (99.6%) was explained by only two principal components (PCs), of which 90.0% corresponded to PC1. The most influential parameters for PC1, in order of priority, were: FAR, FM, leaf blade and stem masses. These variables were positively associated with stocking rate. Conversely, ADG was not associated with any variable. ADG was the most relevant variable for the second PC; however, this PC explained less variance (9.6%). The structural characteristics of the pasture (FAR, FM and morphological components mass) better explain the fluctuations in the performance of cattle on pastures of Mombasa grass under residual effects of nitrogen fertilizer. The stocking rate is an efficient parameter to support decision-making in managed pastures with variable stocking.(AU)

Há pouca informação sobre se o aumento da produtividade secundária observada em pastagens fertilizadas com altas taxas de nitrogênio é atribuível a flutuações no valor nutricional ou nas características estruturais das pastagens, ou em ambas. Objetivou-se identificar grupos de caraterísticas (estruturais e nutricionais) que melhor explicassem o desempenho de novilhos de corte em pastos de capim-mombaça sob efeito residual de doses de nitrogênio. Os dados foram coletados em pastos de capim-mombaça que receberam três doses anuais de nitrogênio (N) (100, 200 e 300 kg ha-1) de 2015 a 2017. No ano de 2018 não foi utilizada adubação nitrogenada, para caracterizar o efeito residual do nutriente. As variáveis avaliadas foram relacionadas às características estruturais, taxa de acúmulo de forragem (TAF), altura do dossel, massa de forragem (MF) e dos componentes morfológicos. Também foi avaliado o valor nutritivo da lâmina foliar e o desempenho dos novilhos através do ganho médio diário (GMD) e da taxa de lotação. A partir do banco de dados foi realizada a análise de componentes principais. Os resultados demonstraram que 99,6% da variação no conjunto de dados foram explicados por apenas dois componentes principais (CPs), e 90,0% desse valor corresponde ao CP1. As características de maior magnitude para a diferenciação dos tratamentos no CP1, em ordem de prioridade foram: TAF, MF, massas de lâmina foliar e de colmo. Essas variáveis estiveram positivamente associadas com a taxa de lotação. Já o GMD não se relacionou com nenhuma variável. O GMD foi a variável de maior importância para o segundo CP, entretanto, esse CP teve pouca contribuição (9,6%) para a elucidação do resultados. As características estruturais (TAF e MF e compondes morfológicos) do pasto explicam melhor as oscilações em pastos de capim-mombaça sob efeito residual de doses de nitrogênio. A taxa de lotação é um parâmetro eficiente para apoiar a tomada de decisão em pastos manejados com lotação variável.(AU)

Efeito da irrigação na produção e qualidade de pastagens durante o período da seca / Effect of irrigation on yield and quality of pasture during the dry season

O principal entrave a produção animal baseada no uso de pastagem é a variação climática, que ocorre no Brasil ao longo do ano. Essa variação gera atrasos na engorda e terminação dos animais em pastejo, o que acaba por muitas vezes comprometendo a qualidade dos produtos oriundos de animais em patejo. A água é o fator mais limitante a produção de forragem, o estresse gerado pelo déficit hídrico leva a senescência dos tecidos da planta, reduzindo seu valor nutricional. Além de reduzir à qualidade nutritiva da planta a falta de água diminui também a oferta de forragem, reduzindo assim a capacidade de lotação do pasto. Nesse sentido, a irrigação de pastagem durante a seca é uma alternativa que visa minimizar os efeitos causados pela falta de água no sistema de pastejo. O fornecimento adequado de água a planta permite que esta atinja seu potencial produtivo e mantenha sua qualidade nutricional. (AU)

The main obstacle to animal production based on the use of pasture is climate change, which occurs in Brazil throughout the year. This variation creates delays in fattening and finishing of grazing animals, which ultimately often compromising the quality of products from animals pastures. Water is the most limiting factor to forage production, the stress generated by water deficit leads to senescence of plant tissues, reducing its nutritional value. Besides reducing the nutritional quality of plant water shortage also decreases the supply of forage, thus reducing the carrying capacity of the pasture. In this sense, the irrigation of pasture during drought is an alternative that aims to minimize the effects caused by lack of water in the grazing system. The adequate supply of water the plant allows it reaches its productive potential and maintain their nutritional quality. (AU)

Efeito da irrigação na produção e qualidade de pastagens durante o período da seca / Effect of irrigation on yield and quality of pasture during the dry season

O principal entrave a produção animal baseada no uso de pastagem é a variação climática, que ocorre no Brasil ao longo do ano. Essa variação gera atrasos na engorda e terminação dos animais em pastejo, o que acaba por muitas vezes comprometendo a qualidade dos produtos oriundos de animais em patejo. A água é o fator mais limitante a produção de forragem, o estresse gerado pelo déficit hídrico leva a senescência dos tecidos da planta, reduzindo seu valor nutricional. Além de reduzir à qualidade nutritiva da planta a falta de água diminui também a oferta de forragem, reduzindo assim a capacidade de lotação do pasto. Nesse sentido, a irrigação de pastagem durante a seca é uma alternativa que visa minimizar os efeitos causados pela falta de água no sistema de pastejo. O fornecimento adequado de água a planta permite que esta atinja seu potencial produtivo e mantenha sua qualidade nutricional.

The main obstacle to animal production based on the use of pasture is climate change, which occurs in Brazil throughout the year. This variation creates delays in fattening and finishing of grazing animals, which ultimately often compromising the quality of products from animals pastures. Water is the most limiting factor to forage production, the stress generated by water deficit leads to senescence of plant tissues, reducing its nutritional value. Besides reducing the nutritional quality of plant water shortage also decreases the supply of forage, thus reducing the carrying capacity of the pasture. In this sense, the irrigation of pasture during drought is an alternative that aims to minimize the effects caused by lack of water in the grazing system. The adequate supply of water the plant allows it reaches its productive potential and maintain their nutritional quality.

La capacidad de carga, producción y composición de forrajes de tres gramíneas irrigadas o no durante la estación seca / Support capacity, production and composition of three grasses sward or not irrigated during the drought / Capacidade de suporte, produção e composição do dossel forrageiro de três gramíneas irrigadas ou não no período seco

Este estudio tuvo como objetivo evaluar la capacidad de carga, la producción y la composición morfológica de 3 gramineas irrigadas o no durante la sequía. El diseño experimental fue un arreglo factorial 3x2 con tres forrajes (Panicum maximum cv Tanzania, Cynodon spp cv Tifton 85 y Urochloa mosambicensis), de regadío o no. Los datos se sometieron a análisis de varianza y las medias se compararon mediante la prueba de Tukey al 5%. Se observó una interacción significativa (P 0,05) en la producción de MS. En Tanzania, el área sin riego presentó mayor rendimiento de MS de Urocloa, los cuales no difieren de Tifton 85. La superficie de regadío en la producción de MS de Tifton 85 fue más alta que la otra, y la Tanzania fue mayor que Urocloa. El rendimiento de materia seca promedio fue mayor en el área de riego. Se observó una interacción significativa (P 0,05) en la producción de lámina de la hoja verde (LHV). En la zona de secano de Tanzania LHV fue mayor que los otros, y la Tifton 85 y Urocloa no difirieron. La superficie de regadío en Tanzania tuvo la LHV más grande que otros, y la Tifton 85 fue mayor que el Urucloa. La producción LHV fue mayor en el área de riego. Se observó una interacción significativa (P 0,05) en hojas de relación lámina de la hoja: tallo (RLT). En dos áreas, la más grande de Tanzania RLT tenía que también, y Urocloa y Tifton 85 no difirieron. El RLT Tanzania fue el más grande de lazona de secano, el RLT Urocloa Tifton 85 y no fue diferente entre las áreas. Se observó una interacción significativa (P <0,05) en la capacidad de soporte (CS). En el secano CS Tifton 85 fue mayor que Urocloa, los cuales no difieren de Tanzania. La superficie de regadío en el CS Tifton 85 fue mayor que los otros, y el Tanzania tuvo el mayor CS Urocloa. El CS fue mayor en el área de riego

This study aimed to assess the carrying capacity, production and morphological composition of 3 or not irrigated forage during drought. The experimental design was a 3x2 factorial arrangement with three forages (Panicum maximum cv Tanzania, Cynodon spp cv Tifton 85 and Urochloa mosambicensis), irrigated or not. Data were subjected to analysis of variance and means were compared by Tukey test at 5%. It was observed a significant interaction (P 0.05) in DM production. In Tanzania the area without irrigation had higher DM yield than Urocloa, both of which did not differ from Tifton 85. Irrigated area in DM yield of Tifton 85 was higher than the other, and the Tanzania was higher than Urocloa. On average DM yield was higher in the irrigated area. It was observed a significant interaction (P 0.05) in the production of green leaf blade (GLB). In the non-irrigated area of Tanzania GLB was higher than the others, and the Tifton 85 and Urocloa did not differ. Irrigated area in Tanzania had the largest GLB than others, and the Tifton 85 was greater than the Urucloa. The GLB production was higher in the irrigated area. It was observed a significant interaction (P 0.05) in relation lamina leaf: stem ratio (RLS). In two areas the largest RLS Tanzania had that too, and Urocloa and Tifton 85 did not differ. The RLS Tanzania was the largest in the area without irrigation, the RLS Urocloa Tifton 85 and did not differ between areas. We observeda significant interaction (P<0.05) in support capacity (SC). In the non-irrigated SC Tifton 85 was higher than Urocloa, both of which did not differ from Tanzania. Irrigated area in the SCTifton 85 was higher than the others, and the Tanzania had the highest SC Urocloa. The SC was higher in the irrigated area

Objetivou-se avaliar a capacidade de suporte, produção e composição morfológica de 3 forrageiras irrigadas ou não durante a seca. O delineamento experimental foi em esquema fatorial 3x2, com 3 forragens (Panicum maximum cv Tanzânia, Cynodon spp cv Tifton 85 e Urochloa mosambicensis), irrigadas ou não. Os dados foram submetidos à análise de variância e as médias comparadas pelo Teste de Tukey a 5%. Observou-se interação significativa (P 0,05) na produção de MS. Na área sem irrigação o Tanzânia apresentou maior produção de MS que o Urocloa, sendo que ambos não diferiram do Tifton 85. Na área irrigada a produção de MS do Tifton 85 foi maior que os demais, sendo que o Tanzânia foi maior que o Urocloa. Na média a produção de MS foi maior na área irrigada. Observou-se interação significativa (P 0,05) na produção de lâmina foliar verde (LFV). Na área não irrigada a LFV do Tanzânia foi maior que a dos demais, sendo que o Tifton 85 e o Urocloa não diferiram entre si. Na área irrigada o Tanzânia teve maior LFV que os demais, sendo o Tifton 85 foi maior que o Urucloa. A produção de LFV foi maior na área irrigada. Observouse interação significativa (P 0,05) na relação lamina foliar:colmo (RLC). Nas duas áreas o Tanzânia teve maior RLC que os demais, e o Urocloa e Tifton 85 não diferiram entre si. A RLC do Tanzânia foi maior na área sem irrigação, a RLC do Urocloa e Tifton 85 não diferiu entre as áreas. Observou-se interação significativa (P<0,05) na capacidade de suporte (CS). Na área não irrigada a CS do Tifton 85 foi maior que do Urocloa, sendo que ambos nãodiferiram do Tanzânia. Na área irrigada a CS do Tifton 85 foi maior que a dos demais, sendo que o Tanzânia teve maior CS que o Urocloa. A CS foi maior na área irrigada