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A determinação acurada do consumo individual é um dos parâmetros importantes para avaliação do valor nutritivo dos alimentos e permite o fornecimento adequado de alimentos, conforme as exigências nutricionais de cada animal. Quando há impossibilidade da realização por meio do método direto, coleta de todas as fezes produzidas pelo animal, o consumo poderá ser estimado a partir da produção fecal estimada por indicadores e da digestibilidade in vitro da dieta. Foi objetivo deste estudo avaliar os indicadores externos dióxido de titânio (TiO2) e hidroxifenilpropano enriquecido e modificado (LIPE®) nas estimativas de consumo de matéria seca (MS). Foram utilizadas quatro vacas multíparas Holandês x Gir com média de 60 dias em lactação e 488 kg de peso corporal. Os animais foram alojados em estábulo tipo free stall e alimentados com dietas à base de silagem de cana-de-açúcar suplementada com concentrado composto de milho moído, farelo de algodão e 0%, 5%, 10% e 15% de caroço de algodão (base da MS). Adotou-se delineamento quadrado latino 4 x 4. O consumo foi determinado pela razão entre a produção fecal estimada pelos indicadores e o inverso da digestibilidade in vitro da MS, sendo as fezes coletadas diretamente na ampola retal, duas vezes por dia, por um período de sete dias. Não houve diferença (P>0,05) nos consumos estimados pelos indicadores TiO2 e LIPE® (10,3 vs 12,1; 11,1 vs 12,5; 10,2 vs 12,9; e 12,7 vs 10,9 kg/vaca/dia de MS em relação ao consumo mensurado, para as dietas com 0%, 5%, 10% e 15% de inclusão do caroço de algodão, respectivamente). Os indicadores externos LIPE® e TiO2 mostraram-se adequados para estimar a produção fecal e o consumo das vacas, independente da dieta oferecida, ambos mostraram que podem ser indicadores externos substituto do óxido crômico, pois, as estimativas de consumo fornecidas por eles não diferiram (P>0,05) do consumo observado no cocho.

This study evaluated the effects of energy supplementation on the intake and milk fatty acid composition of cows grazing BRS Kurumi elephant grass pasture during the rainy season. Two treatments (with and without supplementation) were evaluated using a switchback design with six Holstein × Gyr dairy cows after the peak of lactation. The average milk yield, body weight, and days in milk of the cows at the beginning of the study were 18.0±2.89 kg day−1, 560±66 kg, and 99±12, respectively. The evaluations were performed over three grazing cycles, with adaptation periods of 14 days and six days of sampling. In the energy supplementation treatment, each cow received 3 kg day−1 of ground corn (as-fed basis), with 2 kg day−1 at the morning milking and 1 kg day−1 at the afternoon milking. The ground corn presented 87.5% dry matter, 7.3% crude protein, 5.1% ether extract, and 85% of total digestible nutrients. The cows supplemented with ground corn consumed more oleic (+567%) and linoleic (+88%) acids. Unsupplemented cows consumed 26% more α-linolenic acid and produced milk with more oleic (+10%), vaccenic (+23%), and rumenic (+21%) acids, and less (−7%) pro-atherogenic fatty acids (lauric + myristic + palmitic acids). Milk fat from unsupplemented cows showed better nutritional quality, with lower atherogenicity and thrombogenicity indices and a higher hypo/hypercholesterolemic fatty acid ratio.

This study aimed to evaluate the chemical composition and fatty acid (FA) profile of forage and silage of a seed-propagated elephant grass genotype called “PCEA” harvested at 75, 90, 105 and 120 days of regrowth. A randomized block design with five replications was used. The results were analyzed by mixed models (P < 0.05) that included treatment (regrowth age) as a fixed effect and block as a random effect. Linear and quadratic effects of the treatments were analyzed using orthogonal contrasts. There was linear increase on total dry matter (DM) forage production and linear decrease on leaf:stem ratio as a function of the increase in regrowth age (P < 0.05). In response to the advance of regrowth age, “PCEA” forage and silage showed linear decreases on crude protein (CP) content (g kg-1 DM) and in vitro DM digestibility (g kg-1); and linear increases on DM (g kg-1), lignin (g kg-1 DM), and acid detergent insoluble protein (%CP) contents (P < 0.05). All “PCEA” silages had DM content < 200 g kg-1, pH > 4.0, and ammonia N content > 10% total N. In response to the advance of regrowth age, linear decreases (P < 0.05) were observed on forage and silage linoleic, alfa-linolenic, and total FA contents (g kg-1 DM). From 75 to 120 days of regrowth, the seed-propagated elephant grass genotype “PCEA” presents forage and silage with low nutritional quality for feeding dairy cattle, moderate to high linoleic acid contents, and moderate to low alfa-linolenic acid contents. The “PCEA” forage and silage obtained from 75 to 120 days of regrowth presents low potential for production of milk naturally enriched with bioactive FAs beneficial to human health.

The goal of this study was to evaluate the ruminal metabolic parameters and milk fatty acid composition of cows managed under continuous grazing on Marandu grass. Four rumen-cannulated Holstein x Gyr cows with an average milk yield of 21±2 kg day-1 and 79±16 days in milk were used in a 4 x 4 Latin Square design. Each cow received 6 kg day-1 of a concentrate formulated with 0 (control), 1.3, 2.6 or 3.9 kg of roasted soybeans (as-fed basis), which were the experimental treatments. The inclusion of roasted soybeans promoted a linear reduction in the acetate concentration, with no effect on the pH and ruminal ammonia N concentration. There was no effect of the treatments on the ruminal degradability of the dry matter and neutral detergent fiber of Marandu grass or on the kinetic parameters of the fluids in the rumen. There were linear increases in the contents of fat and total solids in the milk and a linear decrease in the milk lactose content, but there was no effect of the treatments on the yield of these components or on milk yield. There were linear increases in milk fat stearic, elaidic, oleic, linoleic and ?-linolenic acids contents, but there was no effect of the treatments on the milk fat contents of vaccenic and rumenic acids. Notably, supplementing Marandu grass with a concentrate containing up to 3.9 kg of roasted soybeans improved the nutritional quality of the milk fat due to increases in the milk fat contents of oleic and ?-linolenic acids, which are considered beneficial to human health, and reductions in the levels of lauric, myristic and palmitic, which are considered hypercholesterolemic fatty acids.

Twelve multiparous 7/8 Holstein x Gyr dairy cows were fed diets based on chopped sugarcane supplied in natura (control) or after being hydrolyzed (fresh matter basis) for 24 h with 0.5%, 1% or 2% calcium oxide (CaO). The voluntary consumption and digestibility of dietary nutrients, milk production and composition, and feeding behavior of cows were evaluated. A switchback design with three periods, four treatments and three blocks was used. The linear and quadratic effects of the treatments were analyzed using orthogonal contrasts, and the effects were considered significant when P ? 0.05. Compared to the that in the control treatment, the Ca concentration increased by 297%, 570% and 1,083% in the diets including sugarcane hydrolyzed with 0.5%, 1% and 2% CaO, respectively, while the respective Ca:P ratios were 6.58:1, 10.70:1 and 19.77:1 (control Ca:P ratio: 1.55:1). The hydrolysis of sugarcane with increasing amounts of CaO promoted a linear reduction (P < 0.01) in the intake of dry matter (DM), nonfibrous carbohydrates, crude protein (CP), organic matter (OM), neutral detergent fiber corrected for ash and protein (NDFap) and ether extract. The intake of total digestible nutrients, acid detergent fiber (ADF), lignin, hemicelluloses and cellulose presented quadratic behavior (P < 0.01) in response to increasing CaO concentrations used for sugarcane hydrolysis. Increases in the amount of CaO used for sugarcane hydrolysis had no effect on the digestibility of NDFap (P > 0.05), but there were linear reductions (P < 0.05) in the digestibility of DM, OM and ADF; the production of milk corrected or not corrected to 4% fat; and the content of protein, lactose and total solids. Linear reductions (P < 0.05) were also observed in the production of all milk components. Only the milk fat content was not altered (P > 0.05) in response to the inclusion of hydrolyzed sugarcane in the diets. There was no effect (P > 0.05) of sugarcane hydrolysis with increasing amounts of CaO on the time the cows spent idle, ruminating and feeding, but there was a linear increase (P < 0.05) in the minutes spent ruminating 1 kg of DM and NDF. Chopped sugarcane hydrolyzed for 24 h with 0.5% to 2.0% CaO should not be used as exclusive roughage in diets for Holstein x Gyr dairy cows with an average milk production of 10 kg day?1.

The effect of dietary inclusion of increasing levels of Flemingia macrophylla hay on the yield, composition and fatty acid profile of milk from Saanen x Boer goats was evaluated. The diets were composed of 40% concentrate and 60% forage. The treatments were defined by the level of inclusion of Flemingia hay in the diet (0, 80, 160, 240 and 320 g kg-1 dry matter) in replacement of the Cynodon dactylon cv. Tifton-85 hay, distributed according to a 5 x 5 Latin Square design. The inclusion of Flemingia in the diet did not change the milk yield or milk fat content but promoted a quadratic effect on the fat yield. A quadratic effect was observed on the milk protein and lactose contents, but this effect was not reflected in the daily production of these components. The concentrations of vaccenic, rumenic, elaidic and trans-10 C18:1 fatty acids in milk fat increased linearly in response to the dietary inclusion of Flemingia, whereas the contents of palmitic, stearic, oleic, linoleic and ?-linolenic fatty acids were not modified. A linear reduction was observed in the lauric and myristic fatty acids concentrations, which was accompanied by a reduction in the atherogenic index of milk fat. A quadratic effect was also observed on the trans-10, cis-12 CLA milk fat content in response to the inclusion of Flemingia in the diet, as well as a linear increase in the apparent transfer of ?-linolenic acid from the diet to milk. The inclusion of up to 320 g kg-1 of Flemingia hay as a replacement for Tifton-85 hay in the Saanen x Boer dairy goat diet does not modify the milk production and improves the nutritional quality of milk fat by increasing the contents of rumenic and vaccenic acids beneficial to human health and reducing the concentrations of hypercholesterolemic fatty acids.

O objetivo do estudo foi avaliar o efeito da suplementação energética com milho moído sobre o desempenho de vacas Holandês x Gir (H x G) em pastagem de capim-elefante BRS Kurumi manejado sob lotação rotacionada durante o período chuvoso. Foram utilizadas seis vacas H x G, com produção média de leite, peso corporal, escore de condição corporal e dias em lactação de 18,0±2,89 kg dia-1 de leite, 560±66 kg, 2,50±0,21 e 99±12, respectivamente. O delineamento experimental utilizado foi o de reversão completa (switchback). As avaliações foram realizadas durante três ciclos de pastejo, com período de adaptação de 14 dias e seis dias de coletas de amostras. O suplemento concentrado (milho moído) foi fornecido duas vezes ao dia, à razão de 2 kg vaca-1 dia-1 pela manhã e 1 kg vaca-1 dia-1 à tarde (base da matéria natural). Observou-se redução de 23,4% no consumo de matéria seca (CMS) de pasto nos animais que receberam a suplementação energética, o que corresponde a menos 2,96 kg de MS de forragem, quando comparado ao grupo sem suplementação. Este fator representa uma taxa de substituição de 1,1 kg de pasto por kg de concentrado consumido (base da MS), o que reduziu o consumo de fibra em detergente neutro e proteína bruta em 19% e 14%, respectivamente, nas vacas do tratamento com suplementação. Foram observados aumentos de 11,8%; 9,0% e 10,1%, respectivamente, na produção de leite (PL), PL corrigida para gordura e PL corrigida para energia das vacas do tratamento com suplementação. A resposta à suplementação em kg de leite por kg de MS de concentrado fornecido foi de 0,57 e os teores de gordura, proteína e lactose não diferiram entre os tratamentos. A suplementação energética promove o incremento de 12% na produção de leite de vacas Holandês x Gir em pastejo de BRS Kurumi, bem como o aumento na produção de proteína, lactose e sólidos totais no leite. Além disso, o fornecimento de suplementos energéticos para vacas em lactação em pastejo de BRS Kurumi aumenta a eficiência na utilização do nitrogênio da dieta.

This study aimed to evaluate the chemical composition and fatty acid (FA) profile of chopped forage and silage of BRS Capiaçu elephant grass at four regrowth ages: 50, 70, 90 and 110 days. A randomized block design with five replications was used. The ensiling was carried out manually in experimental silos without wilting using no additives or bacterial inoculants. The results were analyzed using mixed models (P smaller 0.05). The model included treatment (regrowth age) as a fixed effect and block as a random effect. Linear and quadratic effects of the treatments were analyzed using orthogonal contrasts. There were linear increases in the dry matter (DM, g kg -1) and lignin (g kg -1 DM) contents and linear reductions in the in vitro DM digestibility (g kg -1) of chopped grass and silage as a function of regrowth age (P smaller 0.001). Quadratic effects (P smaler 0.01) were observed for the chopped grass contents (g kg-1 DM) of crude protein (CP), ether extract (EE) and neutral detergent fiber (NDF) as a function of regrowth age. There were linear decreases (P smaler 0.0001) in the CP content (g kg-1 DM) and pH and linear increases (P smaler 0.001) in the EE and NDF contents (g kg-1 DM) in the silage as a function of regrowth age. There were linear decreases (P smaler 0.01) in the chopped grass contents and linear increases (P smaler 0.05) in the silage contents of total FAs, linoleic and alfa-linolenic acids (g kg-1 DM) as a function of regrowth age. BRS Capiaçu elephant grass must be harvested at up to 70 days of regrowth to obtain forage with good nutritional value and the highest levels of linoleic and alfa-linolenic acids (g kg-1 DM). To produce silages with adequate pH values and the highest levels of linoleic and alfa-linolenic acids (g kg-1 DM), BRS Capiaçu must be harvested between 90 and 110 days of regrowth.

The study was carried out in a randomized block design, in a 2 x 2 factorial arrangement, with the aim to evaluating during 21 days the short-term changes in plasma and milk fatty acid (FA) profile in Holstein x Gyr cows (444±84 kg; 75±31 days in milk; 15.4±4.8 kg day-1 of milk) fed 600 g kg-1 DM chopped elephant grass-based diets supplemented with 45 g kg-1 DM sunflower oil (SO). Two types of SO were evaluated: high oleic/low linoleic acid (HO) and medium oleic/medium linoleic acid (MO). The concentrates containing the SO were supplied separately from the forage twice a day (TAD) or as part of a total mixed ration (TMR). Temporal changes were analyzed by mixed models (P

Two experiments were carried out in a 2 x 2 factorial arrangement with the objective of evaluating two methods of concentrate feeding for Holstein x Gyr cows fed 600 g kg-1 chopped elephantgrass-based diets supplemented at 45 g kg-1 DM with two types of sunflower oil (SO). The types of SO differed in the levels of oleic and linoleic fatty acids (FAs): high oleic/low linoleic acid – HO (73 and 10 g 100 g-1 FA, respectively) and medium oleic/medium linoleic acid – MO (43 and 34 g 100 g-1 FA, respectively). The concentrates containing HO SO or MO SO were supplied separately from the forage twice a day after the two milkings (TAD) or as part of a total mixed ration (TMR). In Experiment 1, a 4 x 4 Latin square design was used to evaluate the ruminal fermentation and degradation parameters in four rumen-cannulated cows (430±39 kg; 79±20 days in milk; 16.4±3.1 kg day-1 of milk). In Experiment 2, a randomized block design was used to evaluate the nutrient intake, plasma contents of metabolites and FAs, milk yield and composition, and FA profile of milk fat in 32 cows (444±84 kg; 75±31 days in milk; 15.4±4.8 kg day-1 of milk). The results were analyzed by mixed models (P ? 0.05). The TMR diets promoted higher nutrient intake and rumen fermentation (higher ammonia N, acetate, propionate and total volatile FA contents) without affecting milk, fat, protein and lactose yields. TAD-fed cows presented higher feed efficiency and produced milk fat with a more nutritionally desirable FA composition, with higher vaccenic and rumenic acid contents and lower trans-10 C18:1 and palmitic acid contents. The DM intake, parameters of rumen fermentation and milk, fat, protein and lactose yields were similar for the HO SO and MO SO diets. The most nutritionally positive characteristics for human health in the milk fat of HO SO-fed cows were the higher eicosapentaenoic (+34%) and oleic acid (+11%) contents and lower palmitic acid content (-10%). Higher contents of vaccenic (+71%) and rumenic (+74%) acids and lower trans-10 C18:1 (-10%), elaidic (-32%), lauric (-14%) and myristic (-11%) acid contents were the most positive aspects of the milk fat of MO SO-fed cows. Considering the magnitudes of the differences in the levels of these FAs, it is concluded that the milk fat of cows fed MO SO showed a healthier milk FA profile.

This study evaluates the intake and digestion of nutrients, parameters of rumen fermentation and degradation, omasal digesta and milk fatty acid composition, productive performance, and the concentration of serum metabolites in cows fed 600 g kg-1 sugarcane-based diets containing 0 (control), 15, 30, and 45 g kg-1 sunflower oil (SO) on a dry matter (DM) basis. Four rumen-cannulated Holstein x Gyr cows yielding 15±5 kg day-1 with 110±10 days in milk were allocated in a 4 x 4 Latin square design. Data were analyzed using mixed models, and significant differences were declared at P < 0.05. There was no effect of SO on the intake and apparent digestibility of DM, crude protein, neutral detergent fiber (NDF) and nonfibrous carbohydrates, but there was a linear increase in the intake and digestibility of ether extract. Dietary SO levels did not alter the ruminal degradability parameters for DM and NDF, rumen pH and contents of ammonia N, acetate, propionate and volatile fatty acids. Milk fat content and yield were linearly decreased, whereas a linear increase in milk protein content was observed in response to increasing levels of SO, but with no effect on milk yield. Linear reductions in palmitic and ?-linolenic acid contents, a linear increase in trans-10 C18:1 and elaidic acids, and a quadratic effect on vaccenic and rumenic acids were observed in omasal digesta of cows fed increasing levels of SO. Overall, up to 45 g kg-1 SO can be included on DM of chopped sugarcane-based diets without reducing consumption, apparent digestibility and rumen degradability of DM and fiber. Supplementing chopped sugarcane-based diets with 30 to 45 g kg-1 SO (DM basis) promotes milk fat depression due to the inhibition of mammary lipogenesis by specific rumen-derived fatty acid intermediates of the biohydrogenation of unsaturated C18 fatty acids. The inclusion of 15 to 45 g kg-1 SO in chopped sugarcane-based diets improves the nutritional quality of milk fat, with increases in the levels of oleic, vaccenic and rumenic acids, beneficial to human health, and a reduction in the levels of the hypercholesterolemic lauric, myristic and palmitic acids.

The aim of this study was to evaluate the ruminal fermentation and degradation parameters, the kinetic flow of digesta in the gastrointestinal tract, and the milk fatty acid (FA) profile in Holstein x Gyr cows fed 59% sugarcane silage-based diets with 0% (control), 5%, 10% and 15% whole cottonseed (WCS) on a dry matter (DM) basis. Four rumen-cannulated cows with an average milk yield of 14.4±3.3 kg day-1 and 85±25 days in milk were allocated in a 4 x 4 Latin square design. There was no effect of dietary WCS levels on the intake of organic matter (OM), crude protein (CP), neutral detergent fiber (NDF) and nonfibrous carbohydrates, but there was a linear increase in the intake of ether extract (EE). There was no treatment effect on the apparent digestibility of DM, OM, CP, EE and NDF or on the ruminal degradability parameters for DM and NDF of sugarcane silage. Also, no treatment effects were observed on rumen pH, ruminal and postruminal particulate passage rates or on the rate of passage of the fluids in the rumen. WCS promoted linear reductions in the milk fat contents of lauric, myristic and palmitic acids and linear increases in the milk fat contents of stearic, oleic, trans-10 C18:1 and elaidic acids. The milk fat contents of vaccenic, rumenic, linoleic and ?-linolenic acids were unaffected by WCS supplementation. The inclusion of up to 15% WCS in sugarcane silage-based diets did not alter the digestibility of nutrients, the rumen degradability of the fiber, or the kinetic flow of digesta in the gastrointestinal tract of Holstein x Gyr cows but improved the nutritional quality of milk fat through an increase in the content of oleic acid, which is beneficial to human health, and decreased levels of hypercholesterolemic lauric, myristic and palmitic acids.

The inclusion of plant oils in the diets of grazing cows represents a promising nutritional strategy for the production of milk naturally enriched with bioactive compounds, such as rumenic (cis-9, trans-11 CLA), vaccenic (trans-11 C18:1) and oleic (cis-9 C18:1) acids. The aim of this study was to evaluate the effect of dietary supplementation with sunflower oil (SO) on the fatty acid (FA) composition of milk from Holstein x Gyr dairy cows grazing on Urochloa brizantha cv. Marandu under rotational stocking. Sixteen multiparous cows with 185±10 days in milk received a concentrate containing 0% (control) or 15% SO on a dry matter basis in a randomized block design with two replications (paddocks). The results were analyzed with mixed models (P ? 0.05) using repeated measurements over time, as represented by sampling days 14, 35 and 62 (periods 1, 2 and 3, respectively). In any period, an effect of SO supplementation was observed on milk production, pasture dry matter intake and nutrients intake, whereas the concentrations of most milk FA were altered in SO-fed cows. In particular, dietary supplementation with SO resulted in the production of milk enriched with FA beneficial to human health (rumenic, vaccenic and oleic acids) and with lower levels of hypercholesterolemic lauric (C12:0), myristic (C14:0) and palmitic (C16:0) acids. This positive effect on the nutritional quality of milk fat was more noticeable from the 40th to 43rd days of sunflower oil supplementation.

Nine non-lactating Holstein x Gyr cattle were fed with rations based on chopped sugarcane supplied in natura (control) or hydrolyzed (fresh matter basis) for 24 h with 1% or 2% calcium oxide (CaO), which corresponds to 3.1% or 6.2% CaO on a dry matter (DM) basis, respectively. Ruminal parameters (pH and ammonia N, acetate, propionate and butyrate concentrations) as well as the kinetics of fluid and particulate passage in the gastrointestinal tract from cattle were evaluated. A design using three 3 x 3 contemporaneous Latin Squares (LS) was adopted. The studies of kinetics of fluid and particulate passage were performed using the external markers cobalt-EDTA and chromium-mordanted-NDF, respectively. The ruminal parameters were analyzed according to a 3 x 3 LS replicated three times with repeated measures in time using mixed models that included the fixed effects of treatment (level of CaO), time of sampling and their interaction and the following random effects: LS, animal(LS), period of LS and period*animal (LS). The kinetic parameters of fluid and particulate passage were analyzed using mixed models with treatment as a fixed effect and period of LS, animal(LS) and LS as random effects. The linear and quadratic effects of the treatments were analyzed using orthogonal contrasts. Significant differences were declared at P ? 0.05. No treatment*time interaction was observed (P > 0.05) for any ruminal parameter. A linear effect (P = 0.0279) of CaO inclusion on ruminal pH was observed, but there were no effects (P > 0.05) of the treatments on the ammonia N, acetate, butyrate and total volatile fatty acid ruminal concentrations. There was a quadratic effect (P = 0.05) of the addition of CaO on the ruminal propionate concentration. There was no effect (P > 0.05) of the treatments on the particulate rate of passage in the rumen as well as on the mean retention time in this compartment and in the total gastrointestinal tract. On the other hand, the addition of CaO to sugarcane promoted a linear increase (P = 0.0258) in the particulate post-ruminal passage rate and, consequently, a linear reduction (P = 0.0363) of the mean retention time in the cecum-proximal colon. There was no effect (P > 0.05) of the sugarcane hydrolysis with CaO on the ruminal parameters of the kinetics of fluid passage (dilution rate, retention time and turnover rate). The addition of 3.1% or 6.2% CaO on a DM basis (1% or 2% CaO on a fresh matter basis, respectively) of sugarcane does not improve ruminal fermentation, nor does it increase the fluid or particulate passage in the rumen of non-lactating Holstein x Gyr cattle.

The aim of this study was to evaluate the ruminal parameters of fermentation and degradation, kinetic flow of rumen digesta, and milk fatty acid composition of cows fed 52% chopped elephantgrass-based diets containing 0.0% (control), 1.5%, 3.0% and 4.5% soybean oil (SO) on a dry matter (DM) basis. Four rumen-cannulated Holstein x Gyr dairy cows with an average milk production of 15.6 ± 3.0 kg day-1 and 90 ± 25 days in milk were allocated in a 4 x 4 Latin square design. The results were analyzed by mixed models. Significant differences were declared at P ? 0.05, and P-values from 0.05 < P ? 0.10 were considered as a trend. The inclusion of SO in the diet had no effect on the ruminal pH or total volatile fatty acid concentration, but there was a quadratic effect on the ruminal ammonia nitrogen content and a trend for a linear reduction (P = 0.07) in the molar proportion of rumen acetate. Linear reductions were also observed in the DM and neutral detergent fiber (NDF) effective degradabilities of elephantgrass forage, but the fluid and particulate passage rates in the rumen and the DM and NDF intakes were unchanged by SO inclusion in the diet. Milk production, protein and lactose contents and yields were unaltered by dietary SO levels. There were linear reductions in the milk fat and total solids contents, but there was no effect of dietary treatments on their yields. The inclusion of soybean oil in the diet of Holstein x Gyr cows fed chopped elephantgrass improved the nutritional quality of milk fat as a result of increased contents of oleic, rumenic and vaccenic acids, which are beneficial to human health, and a concomitant reduction in hypercholesterolemic saturated fatty acids such as lauric, myristic and palmitic acids.

This study aimed to evaluate the agronomic characteristics and nutritional value of two clones of elephant grass (CNPGL 00-1-3 and BRS Kurumi) operating under rotational stocking in the dry season. A completely randomized design with repeated measures (grazing cycles) and three replicates (paddocks) was used. Clones were managed under rotational stocking with a defoliation interval of 24 days and four days of occupation of paddocks, using Holstein x Gyr heifers with mean body weight of 150 kg. The evaluations were conducted in April/May, May/June, June/July and July/August 2010. Green forage mass was influenced by clone and grazing cycle, with higher mean value observed for CNPGL 03-01-00, which was 17% higher than the value observed for BRS Kurumi, and there was decreased of dry mass of green forage with the advance of grazing cycles. Leaf mass was influenced only by grazing cycle, with gradual reduction from the first to the third cycle. However, in fourth cycle was increase in biomass of leaves, which did not differ from that observed in the second cycle. There was interaction for dry matter production of stem, being observed differences in the first and third cycles for the clones. There was no effect of the factors studied for the production of senescent material. The leaf:stem ratio was influenced by grazing cycles, with interaction of the factors studied. The clone BRS Kurumi kept the leaf:stem ratio stable over the cycles, while clone CNPGL 1-3-00 presented a decrease in leaf:stem ratio from first until to third cycle. The content of crude protein (PB) was not influenced by the factors studied, with average values of 15.3% and 15.8% PB for the CNPGL 00-1-3 and BRS Kurumi clones. Neutral detergent fiber (NDF) and the in vitro dry matter digestibility (IVDMD) were affected only by grazing cycles. The highest values of NDF were observed in the three first grazing cycles, with values of 55.5%, 56.0% and 55.7% from the first to the third grazing cycle, respectively, while in the fourth cycle was obtained the value of 50.5%. There was a decrease in the IVDMD until the third cycle. In the fourth cycle the IVDMD values were similar to the first cycle. The clones did not differ in relation to biomass production, morphological composition and nutritional value, during the dry season.

Abstract: The objective of this work was to evaluate the milk fatty acid (FA) profile of Holstein x Gyr cows subjected to two different grazing managements (fixed and variable rest periods) of Urochloa brizantha 'Marandu' pastures. A randomized complete block design was used, with two replicates of pasture areas (blocks) per treatment and four cows per block. Milk production and composition were not affected by grazing strategies. No treatment effects were observed on the proportions (g 100 g-1 of total FA) of the main FAs (palmitic, linoleic, and α-linolenic) of the pasture, but their intakes (grams per day) were affected by differences in forage dry matter intake. The concentrations of FAs in milk plasma and fat were not affected by the treatments. Milk fat contents of rumenic, vaccenic, oleic, and α-linolenic acids varied from 0.71 to 0.93, 1.40 to 1.50, 19.40 to 19.70, and 0.39 to 0.43 g 100 g-1 total FAs, respectively. Grazing strategies of U.brizantha 'Marandu' cause no changes on the milk fatty acid profile of cows.

This study evaluated the inclusion of increasing contents (0; 35; 70; 105 and 140 g kg-1) of dried acerola fruit (Malpighia glabra, Linn.) by-product (DABP) in the ensilage of elephant grass (Pennisetum purpureum, Schum.) considering the in situ degradability of dry matter (DM), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF) and hemicellulose. Plastic drums with 210 L capacity were used as experimental silos. After 45 days of ensiling, silos were opened and silage samples were collected for the degradability trial and laboratory analysis. For the in situ degradability trial, was used one rumen-fistulated adult male cattle. The five by-product inclusion contents were tested in three replicates, with five incubation times, in a randomized complete split-plot design in which the contents of DABP were the treatments (plots), the different silos were the replicates and the incubation times were the sub-plots. Longer incubation times significantly increased (P < 0.05) the disappearance rates of DM, CP, NDF, ADF and hemicellulose. The effective degradability of the DM, NDF and hemicellulose was higher in the silages with 35 g kg-1 of DABP in the rumen passage rates of 0.02; 0.05 and 0.08 h-1. Dried acerola fruit by-product can be added to elephant grass ensiling up to 35 g kg-1 without reducing the effective degradability of nutrients.

The aim of this study was to evaluate the performance of cows fed with a total mixed ration composed of elephant grass and a concentrate containing 0.0% (control), 1.5%, 3.0% or 4.5% soybean oil on a dry matter basis. The effect of milking time (morning versus afternoon) on butter fatty acid composition was also evaluated. Twelve multiparous Holstein x Gyr cows with an average milk production of 18.0±4.6 kg day-1 and 90±25 days in milk were used in a triplicated 4 x 4 Latin square experimental design with 15-day periods. Data were analyzed using mixed models. There was no effect of soybean oil supplementation on dry matter or neutral detergent fiber intake (P > 0.05). The fat-corrected milk yield linearly decreased (P=0.0109) and the milk protein yield linearly increased (P=0.0023) in response to soybean oil supplementation. The butterfat trans-9 C18:1, cis-9 C18:1, trans-10 C18:1, trans-11 C18:1, cis-9, trans-11 CLA and trans-10, cis-12 CLA content linearly increased (P < 0.05), whereas the C12:0, C14:0 and C16:0 content linearly decreased (P < 0.001) as the level of soybean oil in the diet increased. The butter produced from afternoon milk had a lower content of C16:0 and a higher content of cis-9 C18:1 (P < 0.05). The supplementation of elephant grass-based-diets with soybean oil and, to a small extent, the selective segregation of milk obtained from afternoon milking sessions are strategies that can be used to improve the fatty acid composition of butterfat.

Sugarcane is a strategic roughage source for milk production in the tropics, and its supplementation with plant oils offers great potential for obtaining milk enriched with beneficial fatty acids, such as oleic (cis-9 C18:1), vaccenic (trans-11 C18:1), and rumenic (cis-9, trans-11 CLA) acids. The aim of this study was to evaluate the milk fatty acid composition of cows fed 60% chopped sugarcane-based diets containing citrus pulp and 0.0% (control), 1.5%, 3.0% and 4.5% sunflower oil on a dry matter basis. Twelve multiparous Holstein x Gyr dairy cows with an average milk production of 17±5 kg day-1 and 96±25 days in milk were allocated in a triplicate 4 x 4 Latin square design. There was no effect of dietary treatment on milk production, but sunflower oil supplementation linearly reduced the milk fat content and yield. The milk fat contents of lauric (C12:0), myristic (C14:0), and palmitic (C16:0) fatty acids were linearly reduced with increasing sunflower oil levels. There was a quadratic effect on the milk fat oleic, vaccenic, and rumenic acid contents, while the concentrations of elaidic acid (trans-9 C18:1), trans-10 C18:1 and trans-10, cis-12 CLA linearly increased in response to sunflower oil inclusion. Diet supplementation with sunflower oil linearly reduced both the atherogenicity and thrombogenicity indices and linearly increased the ratio between hypo- and hypercholesterolemic fatty acids in milk fat. The inclusion of up to 4.5% sunflower oil in 60% chopped sugarcane-based diets improved the nutritional quality of milk fat from Holstein x Gyr dairy cows as a result of the increased content of oleic, rumenic and vaccenic acids, which are beneficial to human health, and the concomitant reduction of hypercholesterolemic lauric, myristic and palmitic acids. However, there was an increase in the milk content of trans-10 C18:1 and elaidic acid, which are associated with deleterious effects on cardiovascular health.

We aimed to evaluate the economic feasibility of adding increasing levels of sunflower oil (0.0, 15, 30, and 45 g/kg of dry matter) to elephant grass (Pennisetum purpureum, Schum) based diets of milkproducing Holstein cows. Data were obtained and analyzed for 12 primiparous Holstein cows that produced on average 16.5 ± 2.8 kg of milk/day, at 95 ± 25 days of lactation. Cows were distributed by milk production, order of lactation, and body weight in a 4 × 4 triple Latin square. Isoproteic diets were provided ad libitum in the form of a forage:concentrate ratio of 60:40, on a dry matter basis. Daily milk production was recorded and milk was analyzed for fat, protein, and fatty acids contents. An economic feasibility study was performed considering the price of the supplied ingredients and the daily intake of each diet. The economic benefit was derived by the determining the difference between income from the sale of milk and the cost of animal feed. The quality-based payment was estimated by averaging the systems used by eight dairy companies, based on fat and protein contents and milk volume. The sunflower oil-free diet provided the greatest economic benefit. Adding sunflower oil to elephant grassbased diets was not economically viable because of its associated costs.

The objective of this study was to evaluate the in situ degradability of dry matter (DM), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), and hemicellulose of elephant grass (Pennisetumpurpureum, Schum.) with increasing levels (0; 35.0; 70.0, 105.0, and 140.0 g kg-1) of dried pineapple (Ananascomosus, L.) by-product (DPBP). The experimental silos consisted of plastic drums with 210 L capacity. After weighing and homogenizing the elephant grass with the DABP, the material was inserted in the silos (126 kg silage, at a density of 600 kg m-3) and compressed. After 45 days of ensilage, silos were opened and samples of the silages were collected for the trial. The study of degradability in situ was conducted using a rumen-fistulated male cattle. The animal was fed with corn silage supplemented with 1 kg concentrate daily. Five levels of addition of the by-product were tested, with three replicates and five times of incubation with an animal. The experimental design was completely randomized with split plots, in which the proportions of DPBP were the treatments (plots), the different silos were the replicates, and the incubation times were the subplots. The levels of inclusion of DPBP provided an increase (P < 0.05) in disappearance of DM and CP and in the effective degradability of DM, NDF, ADF, and hemicellulose. The dried pineapple by-product is a potential alternative to be used as additive in the ensilage of elephant grass, as it provides an increase in the rumen degradability parameters.

ABSTRACT This study was conducted to evaluate the intake, apparent digestibility (AD), and degradability in situ of elephant grass (Pennisetum purpureum Schum) silages containing 0, 35.0, 70.0, 105.0, and 140.0 g kg-1 by-product from dried cashew apple (DCBP) (as fed basis). A completely randomized design with four replicates was adopted. For the study of degradability in situ, one adult male cattle was used in a completely randomized design with split plots. Intake and AD of dry matter (DM), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), hemicellulose, and cellulose were evaluated, and the digestible energy (DE) and nitrogen balance (NB) of the silages were determined. The degradability in situ of DM, CP, and NDF was also determined. Addition of DCBP provided an increase in the intakes of DM, CP, NDF, and ADF. No effects of the levels of addition of DCBP were observed on the coefficients of AD of the silages. Regarding NB, positive values were only detected in the treatment with 105.0 g kg-1 DCBP. In the analysis of the degradability in situ, the incubation periods increased the rates of disappearance of DM, CP, and NDF. However, no effect of the levels of DCBP were observed on the effective degradability of DM. The by-product from dried cashew apple can be included at up to 140.0 g kg-1 in silages of elephant grass, but the high contents of acid detergent insoluble nitrogen may compromise the use and availability of nitrogen to the animals.

ABSTRACT This study was conducted to evaluate the effect of substituting Tifton 85 hay (Cynodon sp. cv. Tifton 85) with levels of cocoa (Theobroma cacao) byproduct (0, 8, 16, and 24%, diet dry matter basis) in the diet of 16 Holstein × Gir heifers with an average body weight of 363.0±27.7 kg on their nutrient intake, digestibility, and protein balance. The experimental period was 17 days, and the sample collection period was five days. There was no effect of cocoa byproduct on nutrient intake. However, the byproduct affected the digestibility of dry matter, crude protein, neutral detergent fiber, and acid detergent fiber, all of which decreased as the level of inclusion of the byproduct in the diet was increased. Nitrogen balance was negatively affected by the inclusion of 24% cocoa byproduct. It is recommended to use cocoa byproduct up to the level of 16% to replace Tifton 85 grass hay in diets for dairy heifers.

O objetivo deste estudo foi avaliar os parâmetros de fermentação e degradação ruminal, a cinética de fluxo da digesta, e o perfil de ácidos graxos (AG) do leite de vacas alimentadas com 52% de capim-elefante picado e inclusão de 0,0 (controle), 1,5, 3,0 e 4,5% de óleo de soja (OS) na matéria seca (MS) da dieta. Foram utilizadas quatro vacas Holandês x Gir com 90 ± 25 dias em lactação, produzindo 15,6 ± 3,0 kg dia-1 de leite, canuladas no rúmen, e alocadas em delineamento Quadrado Latino 4 x 4. Os resultados foram analisados por modelos mistos. Efeitos foram considerados significativos quando P < 0,05, enquanto valores de P entre 0,05 e 0,10 foram considerados indicativos de tendência. A inclusão de OS na dieta não alterou o pH do rúmen, nem a concentração total de ácidos graxos voláteis, mas promoveu efeito quadrático sobre a concentração de N amoniacal, e tendência de redução linear (P = 0,07) sobre a proporção molar de acetato. Foram observadas reduções lineares nas degradabilidades efetivas da MS e da fibra em detergente neutro (FDN) do capim-elefante, mas não houve alteração nas taxas de passagem ruminal das fases líquida e sólida, nem nos consumos de MS e FDN. A produção de leite, os teores e as produções de proteína e lactose não foram alteradas pela inclusão de OS na dieta, mas houve redução linear nos teores de gordura e de sólidos totais do leite, mas sem efeito sobre as suas produções diárias. A inclusão de óleo de soja em dietas baseadas em capim-elefante picado melhorou a qualidade nutricional da gordura do leite, com aumento nos teores dos ácidos oleico, vacênico e rumênico, benéficos à saúde, e redução dos teores dos ácidos graxos hipercolesterolêmicos láurico, mirístico e palmítico.

The aim of this study was to evaluate ruminal in situ degradability and in vitro digestibility of dry matter (DM) in concentrate supplements containing diverse potato flour pelletized with urea (0%, 4%, 8%, and 12% DM). Samples of feeds were incubated for 0, 2, 4, 8, 12, 24, 36, and 48h in the rumen of four fistulated sheep. Level of urea added had no significant effect (P>;0.05) on the soluble fraction (a) or potentially degradable fraction (b) of the pellets and ranged from 2.1% to 12.2% and 72.9% to 87.5%, respectively. Quadratic effects (P=0.03) of the rate of degradation of fraction "b" ranged from 4.75% h-1to 7.39% h-1; the estimated maximum value at 7.4% h-1was obtained when 5.9% urea was added to the pellet. Quadratic effects (P≤0.02) of the level of urea added to the pellets on the effective degradability (ED) of DM were evaluated after considering rumen passage rates of 2.5% h-1and 8% h-1; the maximum values of ED calculated under these rumen passage rates were estimated at 6.3% to 7.3% urea in the pellets. The in vitro digestibility of DM of the pellets showed a quadratic effect (P=0.02) at different levels of urea, with a maximum value of 96.9% achieved when 7.9% urea was added to the pellets. Our results suggest that the addition of 6-8% urea to pelleted feed promotes an increase in the in vitro digestibility and ED of DM.

ABSTRACTThe objective of this work was to evaluate the inclusion of Fabaceae Flemingia macrophylla (Willd.) Kuntze ex Merr. in the diet of lactating dairy goats arranged in a 5 × 5 Latin square. The diets were composed of 40% of concentrate and 60% of roughage, and the dietary treatments were defined by the level of Flemingia hay inclusion (0%, 8%, 16%, 24%, and 32% in the diet dry matter) replacing Cynodon dactyloncv. Tifton 85 hay. The diets were isonitrogenous, with 14% crude protein. Feed intake, nutrient digestibility, feeding behavior, and ruminal pH and ammonia nitrogen were evaluated. There was no difference in dry matter intake with the inclusion of Flemingia hay in the diet. The digestibility of dry matter, organic matter, crude protein, neutral detergent fiber, and total carbohydrates decreased with the inclusion of Flemingia in the diet. The diet did not change rumen ammonia nitrogen concentration or ruminal pH. There were no differences in the feeding behavior or feed and rumination efficiencies. Flemingia macrophylla can be used up to the level of 32% in the dry matter in diets for lactating goats.

Objetivou-se avaliar as características agronômicas e o valor nutricional de clones de capim-elefante sob lotação rotacionada. Foram avaliados os clones CNPGL 00-1-3 e BRS Kurumi, distribuídos em delineamento inteiramente casualizado, com medidas repetidas no tempo (ciclos de pastejo) e três repetições (piquetes). Foram utilizadas 16 novilhas Holandês x Gir, com peso corporal médio inicial de 150 kg. Animais reguladores de consumo foram utilizados, quando necessário, para o alcance das metas de manejo. Os clones foram manejados sob lotação rotacionada, com 24 dias de intervalo de desfolha e quatro dias de ocupação dos piquetes. As avaliações foram conduzidas em abril/maio, maio/junho. Junho/julho e lulho/agosto de 2010. O valor médio da massa seca de forragem verde do CNPGL 00-1-3 foi 17% maior do que a do BRS Kurumi. Com o avançar dos ciclos de pastejo houve redução da massa seca de forragem verde. A biomassa seca de folha foi influenciada apenas pelo ciclo de pastejo, com redução gradual do primeiro até o terceiro ciclo. No quarto ciclo houve aumento na massa seca de folha, que não diferenciou daquela obtida no segundo ciclo. Houve interação clone x ciclo para a massa de colmo, sendo observadas diferenças entre clones apenas no primeiro e terceiro ciclos. Não houve efeito dos fatores estudados ou da interação para a massa seca de material morto. O BRS Kurumi manteve a relação folha:colmo estável ao longo dos ciclos, enquanto que o CNPGL 00-1-3 apresentou decréscimo nesta variável do primeiro até o terceiro ciclo, com maior valor obtido no quarto ciclo. Não houve efeito dos fatores estudados sobre os teores de proteína bruta, com valores médios de 15,3% e 15,8%, respectivamente, para CNPGL 00-1-3 e BRS Kurumi. Os teores de fibra em detergente neutro (FDN) e os coeficientes de digestibilidade in vitro da matéria seca (DIVMS) foram influenciados apenas pelos ciclos de pastejo. Maiores valores de FDN foram observados nos três primeiros ciclos de pastejo, sendo obtidos teores de 55,5%, 56,0% e 55,7% do primeiro ao terceiro ciclo de pastejo, respectivamente, enquanto que no quarto ciclo observou-se 50,5% de FDN. Houve queda da DIVMS até o terceiro ciclo. No quarto ciclo as DIVMS foram semelhantes às do primeiro ciclo. Concluindo, os clones não diferiram entre si em relação à produção de biomassa, folha:colmo e valor nutritivo.

A nutritional analysis of Tanzania grass (Megathyrsus maximus Jacquin cv. Tanzânia was conducted. Pasture was managed in a rotational grazing system with a 30-day resting period, three days of paddock occupation and two grazing cycles. Ten Holstein × Zebu crossbred cows were kept within a 2-ha area divided into 11 paddocks ha-1. Cows were fed 2 kg of corn meal daily and performance was evaluated by weighing the animals every 14 days and by recording milk production twice a day. Nutritional composition of the Tanzania grass was determined from forage (extrusa) samples collected by esophageal fistulae from two animals. The nutritive value of Tanzania grass was estimated according to a modification of the CNCPS evaluation model. Tanzania grass supplemented with 2 kg of corn meal supplied 33.2% more net energy for lactation than required by the animals to produce 13.7 kg of milk day-1. Nevertheless, the amount of metabolizable protein met the daily protein requirement of the animals. Although the model used in the study requires adjustments, Tanzania grass has the potential to produce milk in a rotational grazing system.

The objective of this study was to evaluate the economic viability of feeding dairy cows with diets containing different levels of soybean oil. Cows were fed diets based on tropical forage (Pennisetum purpureum Schum) supplemented with different levels of soybean oil (0.0, 1.5, 3.0, and 4.5% of diet DM). The calculations were made considering the prices of the dietary ingredients and the daily consumption of each dietary treatment. The milk quality-based payment was estimated on the bonus paid for milk fat and protein contents according to two systems used by companies of the dairy sector. The economic benefit was calculated as the difference between the income obtained from milk sale and the cost associated with animal feeding. The MOP scenario analysis (most likely - optimistic - pessimistic) was performed on the basis of the real scenario and variations in milk price and inputs observed in season and off-season periods over the years under study. The diet with 1.5% soybean oil had higher economic benefit when compared with those containing 3.0 and 4.5% soybean oil. All the dietary soybean oil levels would result in bonuses for milk protein content (higher than 3.03 and 3.21). Only the control diet showed a positive economic balance. The bonuses paid for milk protein content were insufficient to cover the additional costs associated with the inclusion of soybean oil in the diets, resulting in negative balances for the treatments with 1.5; 3.0 and 4.5% soybean oil, demonstrating the economic non-viability of supplementing diets of lactating cows with soybean oil.

The Cornel Net Carbohydrate and Protein System model version 5.0 was assessed as for its prediction of dry matter intake and milk production of grazing lactating Holstein × Zebu cows. Eight lactating cows grazing elephant grass (Pennisetum purpureum, Schum., cv. Napier) were used in two experiments of 30 days each. The experimental design was of randomized blocks (subplots). Dry matter intake was estimated using the chromium oxide and in vitro dry matter digestibility techniques. The estimated dry matter intake was compared with the values predicted by the model. Extrusa samples of the elephant grass pasture were obtained from a cow with esophageal fistula during nine days in each experimental period. Carbohydrate and nitrogenous fractions were analyzed and the degradation rate of carbohydrate was estimated by the gas production technique. The inputs referring to the animals (body weight, age, milk production, milk composition and breed type), to the environment (temperature, relative humidity of air and management condition) and to feeds chemical composition in each experimental period were inserted in the model. The model was accurate on the prediction of dry matter intake, considering that the mean values obtained by the chromium oxide technique and predicted by model (2.45 and 2.46% of body weight, respectively) did not differ significantly from each other. However, the model underestimated the observed milk production in 62.4%, where the metabolizable energy was the first limiting. These results demonstrate the need for studies that provide the development of a database for tropical foods (chemical composition and dynamics of rumen fermentation) and fitting of the model to the tropical conditions, for its appropriate application in formulation of diets and supplements in these regions.

The objective of the study was to evaluate the effects of bakery waste inclusion (0; 25; 50; 75 and 100%, DM basis) in proportion to corn meal in the energetic mixture of the concentrate on intake, digestibility, nitrogen balance and ruminal parameters in sheep. Five male lambs with body weight of 30 kg were used in a 5 × 5 Latin square design. Experimental diets were composed of concentrate and Tifton 85 (Cynodon spp.) hay in a 60:40 forage:concentrate ratio. The concentrate rations were composed of corn meal, soybean meal and bakery waste. The bakery waste:corn meal ratio corresponded to the inclusion of, approximately, 0, 7, 14, 22 and 30% (DM basis) of bakery waste in the diet. There was no effect of bakery waste inclusion on the intake and digestibility of nutrients, nor on nitrogen balance, pH values or concentrations of volatile fatty acids. However, the ammonia nitrogen concentration showed negative linear response in relation to the level of inclusion, in which each increase of 1% bakery waste promoted reduction of 0.11 mg/dL in the concentration of ammonia nitrogen. This fact may be related to the increase in ruminal availability of energy, which allows greater use of ammonia for microbial growth. Bakery waste can replace corn meal in concentrate rations for sheep.

The present study aimed to evaluate the production and milk composition of four multiparous Holstein-Zebu lactating cows average 70 days of lactation, 488 kg of body weight fed different levels of whole cottonseed will be added to sugarcane silage and concentrate consisting of corn and cottonseed meal. The treatments consisted of four diets with increasing levels of whole cottonseed (5, 10 and 15%) in the diet dry matter. The experimental design was a 4x4 Latin Square. The results demonstrate that supplementation with cottonseed did not affect the efficiency of milk production (EfMP, kg milk / DMI), concentration of net energy (NE) and protein: fat ratio (PFR) in milk, but was able to change corrected milk production (MPcorr) and the percentage of lactose content. The data from this study suggest that using supplemental whole cottonseed in the diet of dairy cows, maintaining the quality of milk produced and consequently is an alternative for sustainable food systems for milk production.Com o objetivo de avaliar a produção e composição do leite foram utilizadas quatro vacas lactantes multíparas Holandês x Zebu com média de 70 dias em lactação, 488 kg de peso corporal alimentadas com diferentes níveis de caroço de algodão adicionados em dieta á base de silagem de cana-de-açúcar e concentrado composto de milho e farelo de algodão. Os tratamentos consistiram de quatro dietas com inclusão de níveis crescentes de caroço de algodão (5, 10 e 15%) na matéria seca da dieta. O delineamento experimental adotado foi o quadrado latino 4x4. Os resultados demonstram que a suplementação com caroço de algodão não alterou a eficiência da produção de leite (EfPL, kg leite/CMS), concentração de energia líquida (EL) e a relação proteína:gordura (RPG) no leite, contudo foi capaz de alterar a produção de leite corrigida (PLcorr) e a porcentagem do teor de lactose. Os dados do presente trabalho sugerem que utilizar suplementação com caroço de algodão na dieta de vacas leiteiras, mantém a qualidade do leite produzido e conseqüentemente é uma alternativa alimentar sustentável para os sistemas de produção de leite.

Foi objetivo deste trabalho avaliar o consumo e digestibilidade da MS e nutrientes. de silagens de capim-elefante (CE) contendo subproduto do processamento da acerola desidratada (SACD). Utilizaram-se 20 ovinos machos nãocastrados, distribuídos em delineamento inteiramente casualizado, com cinco níveis de SACD na silagem (0; 3,5; 7; 10,5 e 14% da matéria seca) e quatro repetições. Estimaram-se os consumos de matéria seca (MS), celulose, hemicelulose, proteína bruta (PB), fibra em detergente neutro (FDN), fibra em detergente ácido (FDA), bem como os consumos de matéria seca (MSD), proteína bruta (PBD), fibra em detergente neutro (FDND) e energia digestível (ED). Foram avaliados também as digestibilidades da MS, PB, FDN, FDA, celulose, hemicelulose e EB, e o balanço de nitrogênio (BN). A adição de SACD, não influenciou o consumo de MS, FDN e FDA em g animal-1 dia-1 e g UTM-1 (unidade de tamanho metabólico = PV0,75), MSD, FDND em g animal-1 dia-1 e ED (0,86 Mcal dia-1). Contudo, a adição de 1% do SACD na ensilagem do capim-elefante resultou em aumento de 1,91 e 0,04 g nos consumos diários de PB e PBD, respectivamente. Com a adição do SACD, não houve alterações na digestibilidade da MS (43%), PB (36,4%), FDN (44,8%) e BN (0,22 g dia-1) das silagens. Entretanto, o BN atingiu valores positivos quando foram adicionados 10,5 e 14% do SACD à dieta. O subproduto da acerola desidratado pode ser adicionado em níveis de até 14% da matéria natural na ensilagem de capim-elefante, pois não compromete nem o consumo nem a digestibilidade dos nutrientes em ovinos.The present study aimed to determine de nutritional value of mixed elephant grass silages and increasing levels of dehydrated acerola industry by-product (PAC). Five PAC levels (0; 3.5; 7.0; 10.5 and 14%) were evaluated in a digestibility trial with 20 male non-castrated sheep in a randomized experimental design of five treatments (PAC levels) and four replications per treatment (sheep). Intake and digestibility of dry matter (DM), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), cellulose (CEL), hemicelulose (HCEL) and energy digestible as well as nitrogen balance were determined. The addition of PAC, didn't influence the consumption of DM, NDF, ADF, DDM and DNDF. However, the addition of 1% PAC in the silage of elephant grass resulted in increase of 1.91 g and 0.04 g in the daily consumptions of CP and DCP, respectively. With the addition of PAC, there were no alterations in the digestibility of DM (43%), CP (36.4%), NDF (44.8%) and in nitrogen balance (0.22 g) of the silages. However, nitrogen balance reached positive values when 10.5 and 14% of PAC were added to the silage. The by-product of dehydrated acerola may be added in levels of up to 14% of the natural matter in the silage of elephant grass, because it doesn't affect the intake and digestibility of the nutrients by sheep.

Embora tenha potencial de adaptabilidade para várias regiões do Brasil, o triticale, gramínea produtora de grãos e forragem, tem sido mais utilizado na Região Sul do Brasil. Neste trabalho, objetivou-se conhecer o valor nutritivo da planta de triticale e algumas características de sua silagem quando cultivada na Região Sudeste e submetida a seis idades de corte. O experimento foi instalado (07/07/95) em uma propriedade particular no município de Guarani (MG), em delineamento inteiramente casualizado, com quatro repetições, sendo avaliado o efeito da idade de corte (73, 80, 87, 94, 101 e 108 dias) sobre o valor nutricional da forragem do triticale e sobre os padrões de fermentação e de qualidade da sua silagem. Houve incremento de 0,46 e decréscimo de 0,09 unidades porcentuais, respectivamente, nos teores de matéria seca (MS) e de proteína bruta (PB) da silagem, para cada dia adicional na idade de corte, sendo os maiores teores de MS obtidos de plantas cortadas aos 87 e 101 dias. Foi observado comportamento quadrático entre os valores (PAlthough with potential to adapt in many regions of Brazil, the triticale, a grass that produces grain and forage, has been used only in the South of the country. The objective of this work was to study the nutritive value of the triticale forage as well as the fermentation parameters and quality of its silage when it is grown in Southeast Region and cut at six different ages. The experiment was carried (07/07/95) out at Guarani (Minas Gerais State, Brazil). Cutting ages studied were 73, 80, 87, 94, 101 and 108 days after sowing, using a casual design with four replications. There was an increase of 0.46 and a decrease of 0.09 percent units on dry matter (DM) and crude protein (CP) percentages, respectively, for each additional day in the cutting age. The highest values of DM were those obtained by plants cut between 87 and 101 days. Quadratic relationship was observed between silage pH values and cutting ages, where pH values varied between 3.7 and 5.5, and the lowest acetic acid concentrations, between 1,93 and 3,60% of the DM. Silage from plants cut after 73 days of age presented 0,97% of lactic acid in the DM. The highest (P

O objetivo deste trabalho foi avaliar as características do pasto e o desempenho de novilhas oriundas do cruzamento Holandês x Zebu, em sistema silvipastoril (SSP) e em monocultivo de braquiária (Urochloa decumbens). O delineamento experimental foi o de blocos ao acaso, com dois tratamentos: em monocultivo de braquiária; e o SSP, que apresentava faixas de braquiária consorciada com Stylosanthes guianensis, alternadas com faixas arborizadas. Os piquetes foram manejados sob lotação rotacionada, com 7 dias de ocupação e 35 e 49 dias de descanso, nas épocas chuvosa e seca, respectivamente. As características do pasto, o consumo e o ganho de peso não variaram com o sistema; porém, devido às reduções na quantidade e no valor nutritivo da forragem, apresentaram valores maiores na época chuvosa do que na época seca, respectivamente: massa de forragem pré-pastejo, 1.525 e 964 kg ha-1; teores de proteína bruta na gramínea, 9,3 e 8,2%; digestibilidade in vitro da matéria seca, 56,1 e 50,3%; consumo de matéria seca, 2,3 e 1,6% do peso vivo; ganho de peso de 625 e 242 g por dia por novilha. O sombreamento moderado no SSP não interferiu nas características do pasto, nem no consumo de forragem, nem no desempenho de novilhas leiteiras, quando comparado aos valores obtidos na pastagem de braquiária em monocultivo.The objective of this work was to evaluate the pasture characteristics and the performance of heifers from the Holstein x Zebu cross in a silvopastoral system (SPS), and in a Brachiaria (Urochloa decumbens) pasture. The experiment was set up in a randomized block design with two treatments: an exclusive Brachiaria pasture; and SPS, which had mixed U. decumbens and Stylosanthes guianensis strips alternating with strips with trees. Paddocks were grazed in rotational stocking, with seven days of grazing and 35 and 49 days of rest in the rainy and dry seasons, respectively. Pasture traits, dry matter intake and live weight gain did not vary with the systems. However, due to the reduction in the amount and nutritional value of the forage, these variables had higher values for the rainy season than the dry season, respectively: pre-grazing forage mass, 1,525 and 964 kg ha-1; crude protein, 9.3 and 8.2%; in vitro dry matter digestibility, 56.1 and 50.3%; dry matter intake, 2.3 and 1.6% of body weight; and live weight gain, 625 and 242 g per day per heifer. Moderate shading in SPS did not affect pasture traits, dry matter intake, or the performance of the heifers, in comparison to the values obtained for an exclusive Brachiaria pasture.

Os objetivos neste trabalho foram comparar a composição química, a digestibilidade in vitro da matéria seca (DIVMS), as frações lâminas foliares e bainhas-colmos e a disponibilidade de forragem e avaliar a produção e composição do leite, o peso vivo, o escore corporal e o consumo de matéria seca de forrageiras tropicais. As forrageiras avaliadas foram capim-tanzânia (Panicum maximum Jacq.), grama-estrela (Cynodon nlemfuensis Vanderyst) e capim-marandu (Brachiaria brizantha Staf). As pastagens foram adubadas com nitrogênio (200 kg/ha.ano), K2O e P2O5 (50 kg/ha.ano) e manejadas em sistema de lotação intermitente com três dias de ocupação de piquete e dois intervalos de desfolha: janeiro e fevereiro com 24 dias e março, abril e maio com 30 dias. Foram utilizadas 24 vacas em delineamento de blocos ao acaso, com oito vacas por tratamento. As lâminas foliares da grama-estrela tinham em média 18,5% de PB e as bainhas-colmos, 79,9% de fibra em detergente neutro (FDN), valores superiores aos obtidos nas demais forrageiras. A grama-estela também apresentou maior teor de FDN (72,8%) e lignina (7,1%) na forragem disponível. A digestibilidade in vitro da matéria seca do capim-marandu (64,%) foi superior à da grama-estrela (59,4%). Nos capins-tanzânia e marandu, as produções de leite foram de 9,8, valor superior ao de 8,4 kg/vaca.dia da grama-estrela. O teor de proteína do leite das vacas manejadas no capim-tanzânia (2,9%) foi superior ao obtido com grama-estrela (2,8%), mas os teores de gordura e sólidos totais do leite, o escore corporal, o peso vivo e o consumo de matéria seca não diferiram entre as forrageiras avaliadas. A grama-estrela teve maior porcentagem das frações fibrosas, menor DIVMS e menor produção de leite em comparação aos capins-tanzânia e marandu.The objective of the study was to compare chemical composition, in vitro dry matter digestibility (IVDMD), of leaves, stems and hand plucked samples, as well as milk yield and composition, body weight variation, body condition score and dry matter intake of three grasses. The treatments were: tanzania grass (Panicum maximum Jacq.), stargrass (Cynodon nlenfuensis Vanderyst) and marandu grass (Brachiaria brizantha Staf). All grasses were fertilized with 200 kg/ha.year N and K2O and 50 kg/ha.year of P2O5. Pastures were managed in a rotational grazing system with three-day paddock occupation and two grazing intervals: January and February with 24 days and March, April and May with 30 days. There were 24 cows, eight per treatment. A complete randomized block design was used. The stargrass leaves had 18.5% crude protein (CP) and 79.9% neutral detergent fiber (NDF) on the stems, respectively, which were higher than the other grasses. Stargrass also had higher NDF (72.8%) and lignin (7.1%) in hand plucked samples. The marandu in vitro dry matter digestibility (IVDMD) (64%) was higher than that of stargrass (59.4%). The treatments were different for milk yield and the mean (9.8) for tanzania and marandu grasses were higher than the 8.4 kg/cow.day for stargrass. Milk protein of cows managed on tanzania grass (2.9%) was higher than that of (2.8%) of stargrass. There was no treatment difference for milk fat, total solids, body condition, body weight and feed intake. Stargrass had higher NDF and lignin, however lower IVDMD and milk yield in relation to tanzania and marandu grasses.

Este trabalho foi realizado com o objetivo de avaliar o modelo Cornell Net Carbohydrate and Protein System (CNCPS), versão 5.0, na predição do consumo de matéria seca de vacas da raça Holandesa, lactantes, em pastagem de capim coast-cross suplementada com silagem de milho e concentrado (3 ou 6 kg/vaca.dia). Foram realizados seis ensaios experimentais, cada um com 12 vacas. Em três das avaliações, os animais receberam, além do concentrado, 17 kg de silagem de milho/dia (base natural). As coletas de forragem selecionada na pastagem para análise da composição química foram realizadas por uma vaca com fístula esofágica. A estimativa do consumo voluntário foi realizada com sesquióxido de cromo (Cr2O3), administrado em doses de 5 g, duas vezes ao dia. Foram fornecidos ao programa dados (inputs) referentes aos animais (peso vivo corporal, escore corporal, idade, produção e composição do leite e tipo racial), ao ambiente (temperatura, umidade relativa do ar e manejo) e à composição do alimento em cada período experimental. Os valores preditos pelo CNCPS para a ingestão voluntária de matéria seca foram próximos àqueles estimados, havendo pequena tendência do modelo em subestimar o valor determinado com o indicador.The aim of this work was to evaluate the ability of the Cornell Net Carbohydrate and Protein System (CNCPS) version 5.0 to estimate the dry matter intake (DMI) of grazing lactating Holstein cows, grazing coast-cross pasture supplemented with corn silage and concentrate (3 or 6 kg/cow/day). Six experiments were carried out, with 12 cows each. The cows were fed 17 kg/cow/day of corn ensilage in three experiments. The chemical composition of extrusa samples of forage was determined, obtained using an esophageous fistulated cow. The intake estimates were obtained using 5 g of chromium oxide (Cr2O3) methodology supplied two times a day. Data corresponding to animals (body weight, age, milk yield and composition and racial type), environment (temperature, air relative humidity and management condition) and the feed chemical composition in each experimental period were provided to the program. The DMI values predicted by the CNCPS model were close to those obtained by the chromium oxide methodology.

O objetivo deste trabalho foi avaliar características morfofisiológicas e o valor nutritivo da Brachiaria decumbens, nas épocas chuvosas de 2003 e 2004, em um sistema silvipastoril, com faixas de 30 m de largura com essa gramínea, alternadas com faixas de 10 m com árvores de Acacia mangium, A. angustissima, Mimosa artemisiana, Leucaena leucocephala x L. diversifolia, Eucalyptus grandis. Foi adotado o delineamento de blocos ao acaso, em parcelas subsubdivididas (características morfofisiológicas) ou parcelas subdivididas (características do valor nutritivo), com quatro repetições. Em 2003, o sombreamento foi de 65% da radiação incidente fora do bosque e, em 2004, de 35%, depois da retirada de árvores de eucalipto. Sob sombreamento, a densidade de perfilhos, o índice de área foliar e a massa de forragem foram maiores no segundo ano. Os teores médios de fibra em detergente neutro (FDN) foram maiores a pleno sol que sob sombreamento, enquanto os valores médios de proteína bruta (PB) e a digestibilidade in vitro da matéria seca foram maiores à sombra. O sombreamento moderado aumenta os teores de PB, reduz os teores de FDN e incrementa a digestibilidade da forragem de gramíneas que crescem sob a copa das árvores.The objective of this trial was to evaluate the morphophysiological traits and nutritive value of Brachiaria decumbens, during 2003 and 2004 rainy seasons, in a silvopastoral system, with grass alone (30 m width), alternated with grass plus trees (Acacia mangium, A. angustissima, Mimosa arthemisiana, Leucaena leucocephala x L. diversifolia, Eucalyptus grandis) strips (10 m width). The experimental design was a randomized block arranged in a split plot design (morphophysiological traits) or split-split plot (nutritive value traits), and replicated four times. The level of shading was 65% of incident radiation out of the wood in 2003, and 35% in 2004 after harvesting of some Eucalyptus trees. Under shade, tiller population leaf area and forage mass index were higher in the second year than in the first. Forage neutral detergent fiber value was higher at full sunlight than in the shade, while the crude protein content and in vitro dry matter digestibility were higher under the trees. Moderate shading increases crude protein and reduces neutral detergent fiber, therefore improving forage digestibility of grasses growing under trees.

O experimento foi conduzido no Campo Experimental de Coronel Pacheco - MG da EMBRAPA Gado de Leite. O efeito de doses de enxofre (sulfato de amônio, 0,15; 0,31; 0,46 e 0,92% de S na matéria verde / dia) na população de protozoários ruminais, foi avaliado utilizando-se quatro novilhas 7/8 Holandês X Zebu, arranjadas em um quadrado latino de 4 x 4. Forneceu-se diariamente capim-elefante de baixa qualidade (76,1% FDN na MS), picado, com correção do teor de PB para 7% com uréia, mais mistura mineral sem enxofre fornecida diretamente no rúmen. Foram feitas amostragens do conteúdo ruminal, uma hora após a alimentação. A estimativa das populações microbianas ruminais foi realizada por microscópica direta. Os resultados foram transformados para logaritmos decimais e avaliados estatisticamente. Não houve diferença significativa entre os tratamentos para microrganismos. O tratamento 0,92%S apresentou o menor consumo de matéria seca e ainda, causou início de intoxicação em dois animais. De acordo com esses resultados, doses de 0,31% de enxofre adicionadas a dieta promoveram o incremento das populações de microganismos ruminais e com isso um maior consumo voluntário.The experiment was carried out in the Experimental Field of Coronel Pacheco belonging to EMBRAPA Dairy Cattle, Minas Gerais. The effects of the doses of sulfur (ammonium sulfate, 0.15%, 0.31%, 0.46% and 0.92%S fresh matter/day) on the ruminal protozoa population was evaluated by utilizing four 7/8 Holstein x Zebu, heifers arranged in 4 x 4 Latin square. Low quality elephant grass (76.1% NDF in DM) , chopped with correction of the CP content to 7% with urea plus a mineral mixture without sulfur given directly into the rumen. Samplings of the ruminal content were done, one hour after feeding. The estimate of the ruminal microbial populations was done by means of the direct microscopy. The results were transformed to decimal logarithm and evaluated statistically. There were no significant differences among the treatments for microorganisms. The 0.92%S treatment presented the least dry matter intake and, in addition, caused start of intoxication in two animals. According to those results, doses of 0.31% of sulfur added to the diet promoted the increase of the ruminal microorganism populations and hence a greater voluntary intake.

The possibility of biotechnological application of anaerobic fungi and their biomass-degrading enzymes has been a growing area of research and development over the past decade. In this context, the occurrence and isolation of rumen fungi were evaluated in three Holstein-Gir dairy cows grazing Urochloa spp., in addition to the fermentation capacity of theses isolates in media containing different carbohydrates. Motile zoospores were found in all of the rumen samples. Twelve fungal strains were recovered and were capable of degrading different carbohydrates and lignocellulosic components, suggesting that these strains are able to produce various degradative enzymes when grown on glucose, xylose, cellobiose, fructose, and cellulose. Results pointed out the first insight into the isolation of rumen anaerobic fungi in dairy cattle in Brazil and suggested that further studies are needed to show the potential of some species for commercial application, especially in tropical ruminants.

Foram avaliadas as técnicas do óxido de cromo/digestibilidade in vitro e dos pares de n-alcanos (C31:C32 e C33:C32) na estimativa do consumo de matéria seca (CMS) por vacas Holandês x Zebu em lactação em pastagem de capim-elefante cv. Napier. As extrusas foram obtidas utilizando-se uma vaca com fístula esofágica. Realizaram-se coletas de fezes duas vezes ao dia, diretamente no reto dos animais, durante nove dias em cada período experimental. O delineamento utilizado foi o de blocos casualizados, em esquema de parcelas divididas. Ambos os pares de n-alcanos possibilitaram estimativas de consumos semelhantes, independentemente do horário de coleta (manhã e tarde), sugerindo que uma única coleta de fezes por dia seria suficiente. Quando o estudo foi realizado utilizando-se o valor médio das duas coletas, todas as metodologias diferiram entre si. O Cr2O3/DIVMS forneceu valores de CMS que podem ser considerados mais adequados, pois foram mais próximos daqueles estimados para forragem consumível (2,6% PV) e dos valores das tabelas de exigências do NRC (2001) (2,7% PV). Além disso, essa técnica apresentou vantagens quanto à simplicidade dos procedimentos analíticos e ao baixo custo.Chromium oxide and n-alkanes (C31:C32 and C33:C32) were used to estimate the dry matter intake (DMI) of lactating Holstein x Zebu cows grazing elephant grass. Extrusa samples of forage were obtained from a cow with esophageal fistula. Fecal grab collection was done twice a day at 7:30 and 14:30 h during 9 days in each experimental period. A randomized complete block design with a split-plot arrangement was used. Both pairs of n-alkanes estimated similar DMI, independent of time of fecal collection, suggesting that one single daily collection of feces may be adequate. Independent of the fecal collection schedule, DMI estimated by Cr2O3 or n-alkanes differed significantly by the Tukey test. Dry matter intake estimated by Cr2O3 was closer to that predicted according to the available forage (2.6% body weight, BW) and the NRC (2001) model (2.7% BW). Therefore, DMI estimated by Cr2O3 is likely to be more accurate than n-alkanes. In addition, Cr2O3 is inexpensive and easy to analyze.

Foram desenvolvidas equações de predição de consumo de pasto de capim-elefante (Pennisetum purpureum, Schumack) por vacas mestiças Holandês x Zebu em lactação, utilizando-se procedimentos de stepwise em regressões múltiplas, aplicados a um banco de dados de experimentos conduzidos ao longo de três anos na Embrapa Gado de Leite (Coronel Pacheco, MG). As variáveis independentes disponíveis foram relacionadas a características inerentes às vacas (dias em lactação; teores de proteína, gordura e extrato seco total e produções destes componentes no leite; produção de leite in natura ou corrigida para 4% de gordura; ordem de lactação; peso vivo atual; peso vivo ao parto e grau de sangue Holandês x Zebu); ao manejo (dias de pastejo; disponibilidade de forragem e período de descanso da pastagem); ao ambiente (estação do ano e precipitação pluviométrica) e à alimentação (digestibilidade in vitro e parâmetros da composição química do pasto de capim-elefante e da cana-de-açúcar - Saccharum officinarum (L.) corrigida com 1% de uréia; consumos de suplemento volumoso (cana corrigida com uréia) e concentrado; concentrações fecais de proteína bruta e de fibras em detergente neutro e ácido). Efeitos linear e quadrático e transformações logarítmicas foram adicionalmente incluídos no banco de dados. Foram obtidas equações de predição de consumo de pasto de capim-elefante (expresso em kg/vaca/dia ou % do peso vivo) com coeficientes de determinação de 65,2 a 67,0%. As principais variáveis independentes incluídas nas equações foram o consumo do suplemento volumoso usado na estação seca do ano (cana corrigida com uréia); a digestibilidade in vitro do pasto de capim-elefante; a precipitação pluviométrica; a produção de leite corrigida para 4% de gordura; o peso vivo atual ou, em alternativa a este, o valor da pesagem realizada após o parto da vaca; além do consumo de suplemento concentrado, que evidenciou um efeito de substituição àquele do pasto de capim-elefante.Equations for predicting elephantgrass (Pennisetum purpureum, Schumack) dry matter intake (DMI) by Holstein x Zebu lactating dairy cows under grazing were developed by stepwise regression analysis. The dataset consisted of results of trials carried out at Embrapa Gado de Leite (Coronel Pacheco, MG, Brazil). The independent variables related to animal factors (days in milk; milk protein, fat and total solids contents and yields; live weight; live weight at calving; milk and fat-corrected milk yield; Holstein x Zebu gene fraction; order of parturition); management factors (occupation day of paddock; forage allowance and availability; resting periods); environmental factors (season of the year; rainfall) and feed factors (in vitro digestibility and parameters of chemical composition of elephantgrass herbage and sugarcane - Saccharum officinarum (L.) plus 1% urea; supplement intake - concentrate and sugarcane plus urea; fecal crude protein, neutral and acid detergent fiber concentration). Logarithmic and quadratic functions for some variables were also considered. The main independent variables selected at the best-fit regressions models (R2 = 65.2-67.0%) for elephantgrass herbage DMI were roughage supplement (sugarcane plus urea) DMI; elephantgrass in vitro digestibility; rainfall; fat-corrected milk yield; live weight (or alternatively live weight at calving) and concentrate intake that showed substitution effect to intake of elephantgrass in supplementing grazing cows.

O objetivo deste trabalho foi avaliar a disponibilidade de forragem, a composição bromatológica, o consumo de matéria seca e a proporção de gramínea e leguminosa na dieta de vacas mestiças Holandês x Zebu, em pastagem consorciada de Brachiaria decumbens cv. Basilisk, Stylosanthes guianensis var. vulgaris cv. Mineirão e leguminosas arbóreas. Para estimativa da produção fecal, foram usados 10 g vaca-1 dia-1 de óxido crômico, durante dez dias. Amostras de extrusa foram usadas para determinação da composição bromatológica e digestibilidade in vitro da matéria seca. A disponibilidade de matéria seca de forragem de B. decumbens variou com as condições climáticas, enquanto a de S. guianensis decresceu linearmente ao longo do período experimental. O consumo de matéria seca foi maior em maio de 2001 (1,9% do peso do animal vivo) e não diferiu entre os demais meses (1,5% do peso do animal vivo). Os baixos índices de consumo de matéria seca refletiram altos teores de fibra em detergente neutro (70,2% a 79,4%) e baixos coeficientes de digestibilidade in vitro de matéria seca (42,1% a 48,0%) da forragem. O consumo de leguminosa variou entre 8,7% e 24,1% do total ingerido. O consumo de matéria seca esteve diretamente relacionado à porcentagem de leguminosa na pastagem, o que evidencia o potencial de uso de pastagens consorciadas para vacas leiteiras.The objective of this work was to evaluate the herbage availability, nutritive value, dry matter intake and grass and legume percentage in diet of crossbred Holstein-Zebu cows, in pasture with Brachiaria decumbens cv. Basilisk, Stylosanthes guianensis var. vulgaris cv. Mineirão and tree legumes. To estimate the fecal output, it was used 10 g cow-1 day-1 of chromium oxide during ten consecutive days. Extrusa samples were used to determine the chemical composition and in vitro dry matter digestibility. B. decumbens availability varied with climatic conditions, while S. guianensis availability decreased linearly along the experimental period. Dry matter intake was higher in May/2001 (1.9% body weight) and did not differ among other months (1.5% body weight). Low dry matter intake values were related to low in vitro dry matter digestibility coefficients (42.1% to 48.0%) and high neutral detergent fiber content (70.2% to 79.4%). Dry matter intake was directly related to legume percentage in the pasture. This observation could indicate the potential of mixed pasture for improving nutritive value in dairy cattle diet.

The use of corn silage by dairymen has increased in the last years as well as the demand for information about the cultivars available in the market. Although cropping and evaluation studies for grain production are well established, basic information focusing on forage productivity and quality for silage utilization are scarce. The objective of this experiment was to verify the necessity of border lines between plots in experiments to evaluate potential forage production of corn hybrids. Fifteen hybrids, from seven seed companies and indicated to be cropped in Southeastern Brazil were used. A randomized complete block design with three replicates was used, in which each plot had four 8-meter- long lines, spaced 0,8 m from each other. Individual evaluation of each line inside each plot was done and data recorded: number of plants (stand), total fresh forage production (PMV), dry matter percentage (DM%) and total dry matter production (PMS). The use of border lines in plots is not necessary when comparing potential productivity of corn hybrids for silage utilization. Plots with only one 8-meter line give the same precision in such evaluations compared to plots with greater number of lines. The non-use of border lines between plots in this kind of study allows reduction in experimental area and, consequently, in fertilizers, defensives and labor without affecting the quality of results.

As informações sobre o comportamento de cultivares obtidas em apenas um local e ano podem não ser suficientes para recomendar uma cultivar, em função da ocorrência de interação genótipo x ambiente. Assim, a indicação de cultivares com base na análise de estabilidade e repetibilidade é mais consistente, pois possibilita prever o comportamento delas em diversos ambientes. Este trabalho estudou a adaptabilidade e estabilidade da produção de matéria seca de sete cultivares de sorgo destinadas à produção de silagem. Foram considerados dados de dois locais (Lavras e Coronel Pacheco, Minas Gerais) obtidos em dois anos agrícolas consecutivos (1997/8 e 1998/9), utilizando-se o delineamento de blocos casualizados com três repetições. A cultivar AG 2002 foi recomendada por apresentar maior rendimento, boa previsibilidade de seu desempenho e maior proximidade do padrão ideal, sendo considerada de máxima produção em qualquer ambiente. Também a cultivar Volumax pode ser recomendada por apresentar bom desempenho, desde que cultivada em ambientes mais favoráveis.

A produção de leite, o consumo voluntário de matéria seca e a taxa de passagem da FDN no trato gastrintestinal em quatro épocas do ano (julho, outubro, janeiro e março), de vacas mestiças, sob pastejo de capim-elefante, submetido a dois níveis de nitrogênio (300 e 700 kg de N/ha•ano), foram estimados. Foi usado pastejo rotativo com três dias de ocupação e 30 de descanso, empregando-se 36 vacas lactantes mestiças Holandês x Zebu, em uma lotação de 6 vacas/ha. A estimativa de consumo e a taxa de passagem foram determinadas em apenas 24 animais. Para a coleta de extrusas, foram usadas duas vacas esôfago-fistuladas. O consumo foi estimado usando-se a relação produção fecal:indigestibilidade dos alimentos. A produção fecal foi estimada usando-se a FDN da extrusa marcada com dicromato de sódio fornecida em dose única. O consumo de MS total não foi influenciado pelas doses de N e por épocas do ano, com valores médios diários de 10,9 e 10,5 kg /MS•vaca para as doses de 300 e 700 kg N/ha•ano, respectivamente. Entretanto, o consumo de MS do capim-elefante foi influenciado por doses de N e épocas, com valores de 6,5 e 5,6 kg/vaca•dia para as doses de N supracitadas, respectivamente. O capim-elefante contribuiu com 26,0% da MS total ingerida, durante a época seca (julho/outubro) e sua contribuição aumentou para 84,0% na época das águas (janeiro/março). A produção diária de leite não foi influenciada por doses de N, com produções médias de 11,6 e 12,3 kg de leite/vaca•dia, para as doses de 300 e 700 kg N/ha•ano, respectivamente.The milk production, the dry matter intake (DMI) and the NDF passage rate in the gastrointestinal tract in four seasons (July, October, January and March), of crossbred cows, under grazing of elephant grass, submitted to two levels of nitrogen (300 and 700 kg N/ha•year) were estimated. The rotation grazing with three days of occupation and 30 days of resting, using 36 crossbred Holstein Zebu milking cows, in a stocking rate of 6 cows/ha, was used. The estimates of the intake and passage rate were determined only in 24 animals. For the extrusa collection, two esophageal fistulated cows were used. The intake was estimated using the fecal output: feed indigestibility ratio. The fecal output was estimated using the NDF of the extrusa marked with sodium dichromium fed in an unique dose. The total dry matter intake was not affected by the N levels and the year seasons, with average values of 10.9 and 10.5 kg DM/cow, for the levels of 300 and 700kg N/ha•year, respectively. However, the DM intake of the elephant grass was affected by N levels and year seasons, with reported values of 6.55 e 5.63 kg/cow•day, for the above described N levels, respectively. The elephant grass contributed with 26% of the total DM intake during the dry season (July/October) and its contribution increased up to 84% in the rainy season (January/March). The milk production was not affected by N levels, with reported average production of 11.6 and 12.3 kg/cow•day, for the levels of 300 and 700 kg N/ha•year, respectively.

Foram avaliadas oito cultivares de milho para uso na forma de silagem. Os ensaios foram conduzidos em cinco localidades e a característica estudada foi a produção de matéria seca degradável no rúmen (kg/ha). Verificou-se a existência de interação genótipo × ambiente significativa para esta característica, demonstrando o comportamento diferencial das variedades para as variações ambientais. A variedade BR HT2X, apesar de ter apresentado elevada produtividade, foi a que mais contribuiu para a interação genótipo × ambiente, porém apresentou comportamento imprevisível, sendo, por isso, recomendada para situações de alto nível tecnológico, em que os efeitos de condições adversas podem ser minimizados. As variedades BR 205 e AGM 2010 destacaram-se pela alta produtividade e foram recomendadas como materiais de ampla adaptabilidade e alta previsibilidade. As variedades BR CMS 473 e, principalmente, BR 106 apresentaram produtividades inferiores, porém com comportamento previsível, demonstrando invariância de resposta à melhoria ambiental, o que caracteriza sua rusticidade.A study was conducted in five locations to evaluate the silage potential of eight maize cultivars estimated by the rumen degradable dry matter yield (kg/ha). A significant interaction of genotype × environment was found for this characteristic, indicating a differential behavior of the varieties when environmental conditions changed. Although the variety BR HT2X had a high dry matter yield, it was the one which contributed most to the genotype × environment interaction. Nevertheless, it presented unpredictable behavior, thus it is recommended for situations of high levels of technology when effects of unfavorable conditions are minimized. The varieties BR 205 and AGM 2010 outyielded the others and are recommended as materials of wide adaptability and high predictability. The varieties BR CMS 473 and mainly BR 106 presented lower yields. However, they exhibited a predictable behavior, indicating invariant response to environmental improvement which characterizes rusticity.

The aim of this work was to compare the values of in vitro dry matter digestibility of six classes of concentrates and roughages feeds, determined by the two-stage technique carried in individual digestion tubes or using an automatized equipment of fermentation (filter bag technique, FBT). In the second digestion stage of the technique it was also evaluated the effect of pepsin acid solution and the reflux with neutral detergent solution on the in vitro dry matter digestibility. For both studies the experimental design was completely randomized with a 2 x 6 factorial arrangement (in vitro procedures x food classes). The IVDMD values determined in tubes were close to those found by others authors and lower than those obtained by the filter bag technique. Standard deviation of in vitro dry matter digestibility means were, in general, lower when the individual tubes method were used. The procedure using reflux with neutral detergent was less expensive and time-consuming, and yield similar results when compared to those using the acidified pepsin digestion methodology. The apparent overestimated values of in vitro dry matter digestibility observed in the filter bag technique suggests that the recommendation of the automatized equipment will be dependent of new studies, with emphasis to the material used to make the incubation bags.Objetivou-se neste trabalho comparar valores de digestibilidade in vitro da matéria seca de seis classes de alimentos concentrados e volumosos, determinados pelo método de dois estágios, realizado em tubos individuais ou em equipamento automatizado de fermentação (incubadora in vitro). No segundo estágio da análise foi adicionalmente avaliado o efeito sobre a digestibilidade in vitro da matéria seca da utilização de solução ácida de pepsina ou do refluxo em solução de detergente neutro. Para ambos os estudos utilizou-se delineamento inteiramente casualizado, em esquema fatorial 2 x 6 (procedimentos in vitro x classes de alimentos). Os valores de digestibilidade in vitro da matéria seca determinados pelo método realizado em tubos foram mais próximos dos relatados na literatura e consistentemente inferiores aos obtidos na incubadora in vitro. Os desvios-padrão das médias de digestibilidade in vitro da matéria seca foram, em sua maioria, menores quando determinados pelo método realizado em tubos. O procedimento de refluxo com detergente neutro permitiu economia de tempo e recursos, com resultados semelhantes aos obtidos por meio da incubação em pepsina ácida. A aparente superestimativa dos valores de digestibilidade in vitro da matéria seca condiciona a recomendação do emprego do equipamento automatizado à implementação de novos estudos, com ênfase no material utilizado na confecção dos sacos de incubação.

ABSTRACT This study aimed to evaluate the productive and qualitative characteristics of Brachiaria decumbens and Brachiaria ruziziensis subjected to three levels of artificial shading (0, 36 and 54%) and four nitrogen (N) doses (0; 50; 100 and 150 mg dm-3 soil), using completely randomized design with a factorial scheme 2 x 3 x 4, with three replications. The dry matter production (DMP), the number of tillers per pot, root weight and crude protein (CP) and neutral detergent fiber (NDF) contents were evaluated. Both grasses responded quadractly to N, but B. ruziziensis presented greater production under the two highest N doses. The tillers density increased with N dose and was reduced under shading. The root weight increased with N dose, linearly in the full sun and quadractly in the shade. The shading and N showed a positive influence on CP contents. For NDF content, was observed reduction with increase of N dose. The NDF content of B. decumbens increased with shading levels; for B. ruziziensis, the greatest value was observed under intermediate shading level. The N fertilization is an important strategy to improve DMP, tillers density and CP content, for both grasses. However, intense shading should be avoided, as it reduces tillering and root weight, which may threat pasture persistence.