RESUMO Objetivou-se avaliar características produtivas e qualitativas de Brachiaria decumbens e Brachiaria ruziziensis submetidas a três níveis de sombreamento artificial (0, 36 e 54%) e quatro doses de nitrogênio (N) (0, 50, 100 e 150 mg dm-3 de solo), utilizando-se o delineamento inteiramente casualizado, em esquema fatorial 2 x 3 x 4, com três repetições. Avaliou-se a produção de matéria seca (PMS), o número de perfilhos, a massa de raiz e os teores de proteína bruta (PB) e de fibra em detergente neutro (FDN). Ambas as gramíneas responderam quadraticamente ao N, mas a B. ruziziensis foi mais produtiva nas duas maiores doses de N. A densidade de perfilhos aumentou com a dose de N e diminuiu com o sombreamento. O peso de raiz aumentou com a dose de N, linearmente no sol pleno e quadraticamente na sombra. O sombreamento e o N influenciaram positivamente os teores de PB. Para os teores de FDN, houve redução com o aumento da dose de N. Para a B. decumbens, os teores de FDN aumentaram com o sombreamento; para B. ruziziensis o maior valor foi observado com sombreamento intermediário. A fertilização nitrogenada é uma importante estratégia para o aumento da PMS, do número de perfilhos e dos teores de PB da forragem, para ambas as gramíneas. Contudo, o sombreamento severo deve ser evitado, pois reduz o perfilhamento e o peso de raiz, o que pode comprometer a persistência da pastagem.

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.

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.

Resumo: O objetivo deste trabalho foi avaliar o perfil de ácidos graxos (AG) do leite de vacas Holandesas x Gir submetidos a dois tipos de manejo de pastejo (períodos de descanso fixo e variável) de pastagem de Urochloa brizantha 'Marandu'. Utilizou-se o delineamento de blocos ao acaso, com duas repetições de área de pastagem (blocos) por tratamento e quatro vacas por bloco. A produção e a composição do leite não foram influenciadas pelas estratégias de pastejo. Não houve efeito dos tratamentos sobre as proporções (g 100 g-1 de AG totais) dos principais AG (palmítico, linoleico e α-linolênico) do pasto, mas suas ingestões (gramas por dia) foram influenciadas pelas diferenças de ingestão de matéria seca da forragem. As concentrações dos AG no plasma e na gordura do leite não foram influenciadas pelos tratamentos. As concentrações dos ácidos rumênico, vacênico, oleico e α-linolênico na gordura do leite variaram de 0,71 a 0,93, 1,40 a 1,50, 19,40 a 19,70 e 0,39 a 0,43 g 100 g-1 de AG totais, respectivamente. As estratégias de pastejo de U.brizantha 'Marandu' não alteram o perfil de ácidos graxos do leite das vacas.

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.

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.

Objetivou-se avaliar a degradação ruminal in situ da matéria seca (MS) e a digestibilidade in vitro de suplementos concentrados a base de farinha de batata diversa peletizada com ureia (0, 4, 8 e 12% da MS). Amostras de cada tratamento foram incubadas por 0, 2, 4, 8, 12, 24, 36 e 48 horas no rúmen de quatro ovinos fistulados. Não houve efeito (P>;0,05) do nível de inclusão de ureia sobre as frações solúvel ("a") e potencialmente degradável ("b") dos péletes, que variaram, respectivamente, de 2,1 a 12,1%, e de 72,9 a 87,5%. Foi observado efeito quadrático (P=0,03) para a taxa de degradação da fração "b", que variou de 4,75 a 7,39% h-1, sendo o valor máximo estimado em 7,4% h-1, obtido quando 5,9% de ureia foram incluídos no pélete. Foram observados efeitos quadráticos (P≤0,02) do nível de inclusão de ureia nos péletes sobre a degradabilidade efetiva (DE) da MS, considerando taxas de passagem no rúmen de 2, 5 e 8% h-1e os valores máximos de DE calculadas sob estas taxas de passagem no rúmen foram estimados com 6,3 a 7,3% de ureia nos péletes. A digestibilidade in vitro da MS dos péletes foi influenciada de forma quadrática (P=0,02) pelo nível de inclusão de ureia, com valor máximo de 96,9%, estimado quando 7,9% de ureia foram incluídos no pélete. A inclusão de 6 a 8% de ureia nos péletes promove incremento na digestibilidade in vitro e na degradabilidade efetiva da matéria seca

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.

A nutritional analysis of Tanzania grass (Megathyrsus maximusJacquin 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.

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 (P<0,05) de pH das silagens e a idade de corte do triticale, onde os valores de pH variaram entre 3,7 e 5,5. As menores concentrações de ácido acético, entre 1,93 e 3,60% da MS, foram observadas de 87 a 101 dias de crescimento das plantas. Na silagem produzida a partir das plantas cortadas aos 73 dias de idade, foi observada concentração de ácido lático de 0,97% da MS. A maior (P<0,05) concentração de ácido lático foi observada na silagem produzida a partir das plantas cortadas aos 94 dias de crescimento (12,05% da MS). Os parâmetros de degradação ruminal in situ da MS da forragem verde variaram de 74,6 a 89,5% (degradabilidade potencial), de 2,8 a 3,8%/h (taxa de degradação), e de 42,0 a 51,0% (degradabilidade efetiva, sob taxa de passagem ruminal de 5%/h). As silagens obtidas de plantas cortadas aos 87, 94 e 101 dias de crescimento apresentaram melhor qualidade nutricional.

Although 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<0,05) concentration of lactic acid was observed in silage produced from the plants cut at 94 growth days (12.05% of the DM). The in situ ruminal degradation parameters of fresh forage ranged from 74.6 to 89.5% (potential degradability), from 2.8 to 3.8%/h (degradation rate), and from 42.0 to 51.0% (effective degradability under 5%/h of passage rate). Silage obtained from plants cut at 87, 94 and 101 growth days presented better nutritional quality.

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.