Ration particle size has different effects on digestive but not production parameters in higher-yielding (Holstein) compared to lower-yielding (Girolando) cows.

The aim of the study was to evaluate the effect of total mixed ration particle size (length) and breed of cow on intake dynamics, animal performance and CH4 emissions, comparing high yielding Holstein and low yielding Girolando cows. The experimental design was 2 × 2 Latin Square arranged as a crossover factorial scheme with two diets (short particle size, SPS and long particle size, LPS) and the two breed compositions. The design comprised two periods of 26 d each, where all data collection was performed at cow level. No influence of the particle size occurred for the passage rate, neutral detergent fiber digestibility, performance and milk composition, methane emissions or ruminal fermentation parameters. Girolando cows had greater dry matter intake (DMI) when fed SPS, while Holsteins had the same (P < 0.05). Girolando cows had lower dry matter digestibility when fed LPS compared to SPS, while Holsteins had the opposite effect (P < 0.05). Also, the digestibility of crude protein and non-fibrous carbohydrates decreased in Girolando cows fed LPS, but not in Holsteins (P < 0.05). Girolando cows reduced DMI by 10.6% when fed LPS diet (P < 0.05). Girolando had an increased eating rate (+24 g of DM/min; P < 0.05) compared to Holstein cows, but Holstein cows had a lower CH4 intensity (by 29.7%: P < 0.05). Girolando cows increased the dry matter intake when fed a diet with short particle size, while the same did not happen in Holsteins. Dry matter digestibility increased in Holsteins when fed long particle size, while the opposite was observed in Girolando cows. Nutrient digestibility was reduced in Girolando cows when fed short particle size. Particle size did not influence eating time, eating rate, feed trough visits, visits with intake, milk yield and composition regardless of the breed. Reducing particle size increased CH4 intensity in both breeds.

Grouping crossbred Holstein x Gyr heifers according to different feed efficiency indexes and its effects on energy and nitrogen partitioning, blood metabolic variables and gas exchanges.

The objectives of this study were: i) to classify animals into groups of high and low feed efficiency (FE) using three FE indexes (Residual feed intake (RFI), Residual weight gain (RG) and Feed conversion efficiency (FCE)), and ii) to evaluate whether crossbreed Holstein x Gyr heifers divergent for FE indexes exhibit differences in nutrient intake and digestibility, energy partitioning, heat production, methane emissions, nitrogen partitioning and blood parameters. Thirty-five heifers were housed in a tie-stall, received ad libitum TMR (75:25, corn silage: concentrate) and were ranked and classified into high (HE) or low efficiency (LE) for RFI, RG and FCE. The number of animals for each HE group were 13 (< 0.5 standard deviation (SD) for RFI, 11 for RG and 11 for FCE (> 0.5 SD) and for the LE were 10 (> 0.5 SD) for RFI, 11 for RG and 12 for FCE (< 0.5 SD). Gas exchanges (O2 consumption, CO2 and CH4 production) in open-circuit respiratory chambers and whole tract digestibility trial was performed. A completely randomized experimental design was used and the data were analyzed by ANOVA and correlation study. High efficiency animals for RFI produced less CO2, consumed less O2 and had lower heat production (HP). Methane production was positively correlated with RFI. High efficiency RG had higher O2 consumption and CO2 production in relation to LE-RG. High efficiency FCE had greater NFC digestibility, higher positive energy balance (EB) and excreted (11.4 g/d) less nitrogen in urine. High efficiency RG and FCE groups emitted less CH4 per kg of weight gain than LE animals. Animals HE for RFI and FCE had lower ß-hydroxybutyrate and higher glucose concentrations, respectively. The differences in intake, digestibility, energy and nitrogen partition, CH4 emission, blood metabolic variables and heat production between the HE and LE groups varied according to the efficiency indexes adopted. The HP (kcal/d/BW0.75) was lower for HE animals for RFI and FCE indexes.

Effects of exogenous amylase on the in vitro digestion kinetics of whole-crop maize silages made from flint or dent grain type at different phenological stages grown in tropical condition.

The effect of exogenous amylase on the in vitro rumen digestion kinetics of whole-crop maize silage made from dent (RB9004) or flint grain type (RB9308) was evaluated at different phenological stages: soft dough (SOD), early dent (EAD), ½ milkline (½M) and ¾ milkline (¾M). Forage was harvested from 70 to 110 days after sowing. Two rumen-cannulated cows receiving or not exogenous amylase (0.7 g/kg dry matter-DM, provided to achieve 396 kilo Novo units of amylase activity/kg of TMR DM) were used as donor of ruminal fluid. The in vitro gas production kinetics was evaluated according to a dual-pool logistic model. The chemical composition and gas production kinetics were affected by the hybrid and phenological stages. The flint hybrid had lower range for chemical analysis among physiological stages. Harvesting at ½M and ¾M improved DM content, bromatological composition and silage quality parameters compared to dent or flint types. Amylase (i) increased methane (CH4 ) production and in vitro dry matter digestibility (IVDMD) in ½M stage, (ii) improved digestion kinetics by reducing lag time and increasing total gas production and fermentation rates of non-fibrous carbohydrates (NFC) and fibrous carbohydrates (FC), and (iii) increased extent and fermentation rate of NFC and increased fermentation rate of FC fraction in whole-crop maize silages produced from dent or flint types in all phenological stages. Harvesting between ½M and ¾M is the best phenological stage to improve chemical composition and silage quality parameters. Exogenous amylase showed improvements on fibre digestion of silages at ½M and ¾M phenological stages in both grain types of corn.

Generation of models from existing models composition: An application to agrarian sciences.

Mathematical models that describe gas production are widely used to estimate the rumen degradation digestibility and kinetics. The present study presents a method to generate models by combining existing models and to propose the von Bertalanffy-Gompertz two-compartment model based on this method. The proposed model was compared with the logistic two-compartment one to indicate which best describes the kinetic curve of gas production through the semi-automated in vitro technique from different pinto peanut cultivars. The data came from an experiment grown and harvested at the Far South Animal Sciences station (Essul) in Itabela, BA, Brazil and gas production was read at 2, 4, 6, 8, 10, 12, 14, 17, 20, 24, 28, 32, 48, 72, and 96 h after the start of the in vitro fermentation process. The parameters were estimated by the least squares method using the iterative Gauss-Newton process in the software R version 3.4.1. The best model to describe gas accumulation was based on the adjusted coefficient of determination, residual mean squares, mean absolute deviation, Akaike information criterion, and Bayesian information criterion. The von Bertalanffy-Gompertz two-compartment model had the best fit to describe the cumulative gas production over time according to the methodology and conditions of the present study.

Replacement of Soybean Meal With Soybean Cake Reduces Methane Emissions in Dairy Cows and an Assessment of a Face-Mask Technique for Methane Measurement.

The objective of this study was to (a) evaluate the effect of replacing soybean meal (SBM) with soybean cake (SBC) on feeding behavior, rumen fermentation, milk production, nutrient digestibility and CH4 emissions and (b) investigate whether a face-mask technique could be used to predict daily methane (CH4) emissions in dairy cattle. The experiment was conducted as a completely randomized design, with 32 crossbred Holstein × Gyr cows (days in milk (DIM): 112 ± 25.1) randomly assigned to the following treatments (n = 8/group) for 75 days: (1) 0% SBC, (2) 6% SBC, (3) 14% SBC, and (4) 23% SBC, in place of SBM on a dry matter (DM) basis. Across the final 4 weeks of the study, CH4 production was estimated using the proposed face-mask technique subsequent to a respiration chamber measurement for an evaluation of treatment efficacy and face-mask accuracy. There was no effect of SBM replacement by SBC on intake, feeding or drinking behavior (P > 0.21). Total VFA concentration, the individual proportions of VFA and blood metabolites were not altered (P > 0.17) by SBC, however there was a tendency for decreased (P = 0.08) lactate and plasma urea nitrogen (P = 0.07) concentration associated with SBC addition. Fat-corrected milk yield (FCM4%) and composition was not affected (P > 0.27) by SBC; however, there was a tendency for decreased total milk solids (P = 0.07) and milk fat (P = 0.08) associated with 23% SBC treatment. There was no treatment × technique interaction (P > 0.05) effect on gas measurements. A maximum reduction (P = 0.01) in CH4 yield (g/kg DM) and intensity (g/kg milk) of 11 and 20%, respectively, was observed for the 14% SBC inclusion. Compared to the week of mask measurements, chambers decreased (P = 0.01) intake (kg/d, %BW) and increased (P = 0.05) FCM4%. The face-mask method over estimated O2 consumption by 5%. The face-mask method accurately predicted daily CH4 emissions when compared to the chamber at the same time-point. However, there was a linear bias of CH4 outputs so further evaluation of the calculation of total CH4 from a spot measurement is required.

In vitro screening of plants from the Brazilian Caatinga biome for methanogenic potential in ruminant nutrition.

Thirty-nine plants naturally found in Brazilian Caatinga semiarid biome were screened using an in vitro fermentability testing focused in apparent organic matter digestibility (aOMD), gas, methane (CH4), and short-chain fatty acid (SCFA) production. Three independent in vitro runs were carried out and plants were classified by CH4 concentration as proportion of gas and per unit of apparent digested organic matter (aDOM). According to its CH4 concentration on produced gas (mL/L), the plants were classified as low (> 110), medium (from 60 to 110), and high (< 60) anti-methanogenic potential. From evaluated plants, 3, 24, and 12 were classified as high, medium, and low anti-methanogenic potential. High anti-methanogenic potential plants Cnidoscolus phillacanthus (CnPh), Chloroleucon foliolosum (ChFo), and Anadenanthera macrocarpa (AnMa) produced 21.3, 34.3, and 35.9 mL CH4/L of gas. Methane concentration for Myracrodruon urundeuva (MyUr) was 61.1 mL/L and classified as medium potential. However, CH4 production per unit of aDOM was similar between MyUr and AnMa (3.35 and 2.68 mL/g, respectively). Molar proportions of acetate and propionate in SCFA produced by ChFo fermentation were 0.02 and 0.78 mmol/mol. Acetate to propionate ratios were 0.79, 0.03, 1.39, and 1.36 for CnPh, ChFo, AnMa, and MyUr, respectively. Greater aOMD were observed for Opuntia sp. and Calotropis procera (632 and 601 g/kg, respectively), which were classified as medium mitigating potential plants. AnMa, ChFo, CnPh, and MyUr are promising anti-methanogenic plants for ruminants. Selecting forages to feed ruminants in Caatinga is a potential strategy for enteric CH4 emission reduction, and our in vitro results can support future research by indicating species to be evaluated in in vivo studies integrating mixed diets with performance, digestibility, and CH4 production, yield, and intensity. Graphical abstract ᅟ.

Plant morphology and herbage accumulation of signal grass with or without fertilization, under different light regimes / Morfologia e acúmulo de forragem de capim-braquiária com ou sem fertilização, sob diferentes regimes de luz

ABSTRACT: The silvopastoral system has been suggested as an alternative to recover degraded pastures in tropical regions. However, trees reduce the light available for pastures, which may affect the growth and herbage accumulation. The objective of this study was to evaluate the morphogenesis, canopy structure and herbage accumulation of signalgrass ( Brachiaria decumbens ) subjected to three light regimes (0, 20 and 70% of natural shading) and two fertilization levels (presence or absence of nitrogen, phosphorus and potassium). Leaf and stem elongation rates increased under shading but did not vary with fertilization. The leaf appearance rate was greater under fertilizer treatment but was generally similar among light regimes. The tiller density was greater in full sun and lower in intense shading. Tiller density responded to fertilization under full sun and moderate shading. Herbage accumulation increased by 42% with fertilization under full sun, 12% under moderate shading and did not vary under intense shading. Results showed that even under fertilization the herbage accumulation was limited by reduced light. However, under moderate shade the fertilization was important to raise tiller population over the growth cycles.

RESUMO: Os sistemas silvipastoris têm sido sugeridos como alternativa para recuperação de pastagens em regiões tropicais. Entretanto, as árvores reduzem a disponibilidade de radiação para o pasto, o que pode influenciar no crescimento e acúmulo de forragem. O objetivo deste estudo foi avaliar a morfogênese, a estrutura do dossel e o acúmulo de forragem de Brachiaria decumbens , submetida a três regimes de luz (0, 20 e 70% de sombreamento natural) e dois níveis de fertilização (presença ou ausência de nitrogênio, fósforo e potássio). As taxas de alongamento de folhas e colmos aumentaram com o sombreamento, mas não variaram com a fertilização. A taxa de aparecimento de folhas foi maior com a fertilização, mas, em geral, foi semelhante entre os níveis de sombra. A densidade de perfilhos foi maior no sol pleno e menor na sombra intensa. A densidade de perfilhos respondeu à fertilização sob sol pleno e sombra moderada. O acúmulo de forragem aumentou 42% com a fertilização no sol pleno, 12% na sombra moderada e não variou na sombra intensa. Os resultados mostraram que, mesmo com uso de fertilização, o acúmulo de forragem foi limitado pela redução de luz. Em condições de sombra moderada, a fertilização foi importante para aumentar a população de perfilhos ao longo dos ciclos de crescimento.

Tithonia diversifolia as a Supplementary Feed for Dairy Cows.

The objective of this study was to examine the effects of Tithonia diversifolia as a supplementary forage on dairy cow performance and methane production. Nine lactating Holstein × Zebu dairy cows (519 ± 53.3 kg of body weight and 66 ± 13.3 d in milk) were paired by milk yield (21.3 ± 2.34 kg/d) and body weight and randomly assigned to three dietary treatments in a Latin square design with 21-d experimental periods (14 d for diet adaptation and 7 d for measurements and sample collection). The dietary treatments included the control diet consisting of fresh sugar cane plus concentrate (44:56, % of diet DM), and two treatment diets containing different levels of fresh T. diversifolia (6.5 and 15.4%, DM basis) which partially replaced both sugarcane and concentrates. Methane production was measured using the sulphur hexafluoride (SF6) technique from d 16 to d 21 of each experimental period. Analysis of the gas samples was performed by gas chromatography. The inclusion of T. diversifolia at 15.4% DM had no effects on DM intake, milk production, nitrogen balance or methane production. There was no effect on the concentrations of total saturated fatty acids (SFA), monounsaturated fatty acids (MUFA), and polyunsaturated fatty acids (PUFA) in milk fat (P ≥ 0.28), though individual milk fatty acids were affected. Serum concentrations of glucose, urea nitrogen (BUN), triglycerides, ß-hydroxybutyrate (BHBA), and cholesterol were unaffected by the dietary treatments (P ≥ 0.13). There was a time (2 and 6 h post-feeding) and dietary treatment effect (P < 0.01) on the acetate to propionate ratio in the rumen. A denaturing gradient gel electrophoresis analysis of the archaeal community showed distinct clustering of the archaea populations for control and treatment diets. Taken together, our results indicate the potential of T. diversifolia as a supplementary forage for dairy cattle in the tropics.

Productivity and nutritional quality of Flechinha grass ( Echinolaena inflexa ), native grass of Brazilian Cerrado / Produção e qualidade nutricional do capim-flechinha (Echinolaena inflexa), gramínea nativa do Cerrado brasileiro

ABSTRACT: Due to scarce nutritional data, this study assessed the productivity and nutritional value of Echinolaena inflexa (EI) grass, native to the Cerrado biome. It was compared to B. brizantha (BB), one of the most cultivated grasses in Brazil, during a whole year (rainy; RS and dry season; DS). Sampling was held in accordance with pasture management (entry / exit height; 50 / 5cm and 80 / 25cm for EI and BB, respectively). Dry matter production (DMP), crude protein (CP), neutral and acid detergent fiber (NDF; ADF), hemicellulose (HCEL), PB insoluble neutral and acid detergent (PIDN; PIDA), total and non-fibrous carbohydrates (TC; NFC), ether extract (EE), and mineral matter (MM), and in vitro fermentation kinetics and DM degradability (DMD) were evaluated. A completely randomized design (season as a fixed term) and average treatment compared by Tukey post test were applied. EI produced 38.5% of the DMP of BB. A higher CP (75.3; 73.5 in the RS and DS), PIDA (12.5; 8.7), PIDN (47.1; 40.1), NDF (714.4; 749.5) and ADF (396.0; 419.0) were obtained by EI in relation to BB (CP (60.3; 33.5), PIDA (6.0; 3.5), PIDN (21.4; 10.8), NDF (673.0; 675.1) and ADF (335.5; 351.4) during the RS and DS, respectively (g kg-1 DM). In vitro data were directly associated with chemical composition, resulting in lower DMD of EI compared to BB. EI showed productive similarity (DMP) during RS and DS (939.3; 809.8kg DM respectively). Although EI showed greater nutritional stability (CP) between seasons, 17% of CP was linked to ADF and therefore, not available for rumen microorganisms.

RESUMO: Existem escassas informações a respeito da qualidade nutricional e potencial produtivo de Echinolaena Inflexa, planta nativa do Cerrado Brasileiro e que possui potencial valor forrageiro. Dessa forma, este trabalho objetivou avaliar o seu valor nutritivo e produtividade, comparando-a com a B. brizantha (BB), uma das mais cultivadas gramíneas no Brasil, durante um no agrícola (Estação das Chuvas; CH e seca; SE). A coleta do material experimental foi realizada de acordo com as recomendações de manejo (altura de entrada / altura de saída 50/5cm e 80/25cm para EI e BB, respectivamente). Foram avaliadas a produção de matéria seca (PMS), proteína bruta (PB), fibra detergente neutro e ácido (FDN e FDA), hemicelulose (HCEL), PB insolúvel em detergente neutro e ácido (PIDN e PIDA), carboidratos totais e não fibrosos (CT e CNF), extrato etéreo (EE) e matéria mineral (MM), e a cinética de fermentação ruminal e degradabilidade in vitro da MS (DMS). Utilizou-se o delineamento inteiramente casualizado e as médias de tratamento comparadas pelo post test de Tukey. A EI apresentou 38,5% da PMS da BB. Foram obtidos maiores teores de PB (75,3 e 73,5), PIDA (12,5 e 8,7), PIDN (47,1 e 40,1), FDN (714,4 e 749,5) e FDA (396,0 e 419,0) para a EI em relação a BB (PB; 60,3 e 33,5), PIDA (6,0 e 3.5), PIDN (21,4 e 10,8), FDN (673,0 e 675,1) e FDA (335,5 e 351,4) na estação chuvosa e seca, respectivamente (g kg-1 MS). Os dados in vitro da EI foram diretamente associados à composição química, resultando em menor DMS comparativamente BB. A EI apresentou estabilidade produtiva (PMS) durante a estação chuvosa e seca (939,3 e 809,8kg MS), respectivamente. Apesar da similaridade nutricional (PB) nas estações, cerca de 17% da PB está ligada a FDA e, portanto, não disponível para os microrganismos ruminais.

Avaliação das silagens de girassol (hibrido m734) obtidas em diferentes épocas de ensilagem pela técnica in vitro semi-automática de produção de gases / Evaluation of silages from hybrid m734 of sunflower obteined in diferent cutting times using the semi-automated in vitro gas production technique

Para que o girassol possa ser utilizado com sucesso na forma de silagem, é necessário que se determine o ponto ideal de ensilagem. O objetivo desse experimento foi avaliar através da técnica in vitro semi-automática de produção de gases a cinética de degradação da matéria orgânica (MO) e matéria seca (MS) das silagens do híbrido M734 ensilado com 100, 107, 114 e 121 dias após o plantio. As leituras de pressão dos gases foram feitas através de um transdutor de pressão às 2, 4, 6, 8, 10, 12, 15, 19, 24, 30, 36, 48, 72, 96 h pós-inoculação. A cinética ruminal foi descrita matematicamente por meio dos parâmetros: potencial máximo de produção de gases, lag time, taxa de produção de gases (mü) e degradabilidade efetiva da MO e MS para diferentes taxas de passagem (2,5 e 8 %/h) por um modelo unicompartimental. Verificou-se que o corte da cultura em estádios mais tardios levaram a redução no potencial máximo de produção de gases para a MO (162, 155, 144 e 139 mL) e MS (138, 129, 121 e 119 mL); elevação da lag time para MO (2,4, 2,5, 2,8 e 2,9 h) e MS (2,46, 2,54, 2,98 e 2,99 h); e diminuição do mü para a MO (0,023, 0,022, 0,017 e 0,018 mL/h) e MS (0,022, 0,020, 0,015 e 0,016 mL/h) para as épocas 100, 107, 114 e 121 dias após o plantio, respectivamente. As épocas mais indicadas para a ensilagem do híbrido M734 foram aos 100 e 107 dias após o plantio.