Search

From 100 to 200 days of gestation, 52 cows carrying male (n = 30) or female (n = 22) fetuses were assigned to CON (basal diet—5.5% of CP, n = 26) or SUP (basal diet + protein supplement [40% CP, 3.5 g/kg BW]—12% of CP, n = 26) treatments. Glucose concentrations decreased at 200 (p ≤ 0.01; CON = 46.9 and SUP = 54.7 mg/dL) and 270 days (p ≤ 0.05; CON = 48.4 and SUP = 53.3 mg/dL) for CON compared to SUP. The same pattern occurred for insulin (p ≤ 0.01). At parturition, the NEFA concentration was greater (p = 0.01, 0.10 vs. 0.08 mmol/L) for CON than for SUP. Total AA increased in SUP (p ≤ 0.03) at mid- and late-gestation compared to CON. At 200 days, CON dams carrying females had less essential AA (p = 0.01) than cows carrying males. The SUP dams had greater expressions of protein synthesis markers, namely eIf4E and GSK3β (p ≤ 0.04), at day 200 and of MuFR1 (protein degradation marker, p ≤ 0.04) at parturition. Supplemented cows had higher hepatic pyruvate carboxylase expressions (p = 0.02). Therefore, PS alleviates the restriction overload on maternal metabolism.

This study aimed to assess the effects of maternal protein supplementation and offspring sex (OS) on the intake parameters of the offspring. Forty-three Tabapuã cows were randomly allocated in the following treatments: protein supplementation (PS) during days 100–200 of gestation (RES, 5.5% total crude protein (CP), n = 2, or CON, 10% total CP, n = 19) and OS (females, n = 20; males, n = 23). The offspring were evaluated during the cow–calf (0–210 days), backgrounding (255–320 days), growing 1 (321–381 days), and growing 2 (382–445 days) phases. The CON offspring tended to present higher dry matter intake (DMI) at weaning (p = 0.06). The CON males presented lower digestibility of major diet components in the growing 2 phase (p ≤ 0.02). The CON offspring spent 52% more time per day eating supplements at 100 days and 17% less time in idleness at 210 days. The CON males spent 15 min more per day ruminating than RES males in the feedlot phase (p = 0.01). We concluded that protein supplementation over gestation alters the offspring feed intake pattern as a whole, while protein restriction promotes compensatory responses on nutrient digestibility in males.

This study aimed to evaluate performance, to evaluate performance, carcass traits, feeding behavior, and humoral immune response in Nellore and Angus × Nellore steers fed whole shelled corn diets. Sixteen Nellore and 16 Angus × Nellore steers with 353 ± 25.3 kg were randomly assigned into 2 feeding groups, whole shelled corn without forage (WSC) or whole shelled corn and sugarcane bagasse (WSCB). The data were analyzed using the MIXED procedure of SAS (SAS Inst. Inc., Cary, NC, USA). Angus × Nellore steers had greater final BW, DMI, ADG, and subcutaneous fat thickness than Nellore. Moreover, Nellore steers had lower neutral detergent fiber (NDF) intake but spent more time ruminating and had a greater rumination rate of NDF. Regarding the diets, steers fed the WSCB had greater DMI and spent more time chewing and ruminating. Nellore × Angus steers had a greater haptoglobin concentration. The concentration of D-Lactate tended to be greater in the Nellore steers regardless of diet. In conclusion, the use of sugarcane bagasse in WSC diets increases DMI and ADG without affecting feed efficiency or the carcass traits of the steers. Although Angus × Nellore steers have increased haptoglobin concentration, this effect was not enough to reduce the performance of these animals.

Pasture-based systems are prevalent among small-scale family farms. Many farmers consider that the nutritional value of the plant is more relevant than the canopy structure. This study aimed to analyze the various factors related to plant structure and chemical composition that most influence milk yield per hectare under rotational stocking. The experiment was performed at the Animal Husbandry Experimental Station of the Extreme South of Bahia. Three rotational stocking systems with three forage species [Cynodon dactylon (L.) Pers. cv. Tifton 85, Urochloa brizantha (Hochst. ex A. Rich.) Stapf. cv. Xaraés, and Megathyrsus maximus Jacq. cv. Mombasa] were evaluated. Nine crossbred Holstein x Gyr cows were allocated to a balanced 3 x 3 Latin square design. The cows were rotated in three pastures every 14 days. The experimental period consisted of seven evaluation cycles of 42 days each. Cluster analysis, principal component analysis (PCA), and multivariate linear regression were the statistical techniques used to evaluate plant structure and morphological characteristics, and animal performance. Xaraés palisadegrass and Mombasa guinea grass were similar for all evaluated characteristics (P > 0.05), whereas Tifton 85 was different from them in terms of structural, morphological, and chemical composition characteristics (P < 0.05). In the PCA, 59.1% of the total variance was explained by components 1 and 2 for the structural and morphological characteristics, and forage chemical composition. Forage structural and morphological variables showed better results in the multivariate linear regression analysis for milk yield per hectare. Structural and morphological characteristics were more correlated with Mombasa guinea grass than Xaraés palisadegrass and Tifton 85. The structural and morphological characteristics of forages were the main factors determining milk yield per hectare in exclusively pasture-based systems with animals of low production.

ABSTRACT: Short-term grazing behavior variables are sensitive to the canopy structure and have an impact on daily forage intake. This study evaluated the effect of pre- and post-grazing canopy heights on the forage harvesting process at a patch scale in a mixture of Brachiaria brizantha (Hochst. ex A. Rich.) Stapf. syn. Urochloa brizantha R.D. Webster cv. Marandu (palisade grass) and Arachis pintoi Krapov. & W.C. Greg. cv. Belomonte (forage peanut). Treatments were allocated to a split-plot arrangement in a completely randomized design. The plots, in their entirety, consisted of two pre-grazing canopy heights: 25 cm (CH25) and 35 cm (CH35); subplots consisted of three levels of defoliation severity: no defoliation (DS0); 20% depletion of pre-grazing canopy height (DS20); and 40% depletion of pre-grazing canopy height (DS40), with eight replications. Heifers were allowed to graze the patches (0.7 × 0.7 m) and their grazing behavior was recorded. Canopy structure measurements were taken both before and after grazing. Patches from CH35 presented greater stem mass for grass (p = 0.001) and legume (p = 0.002) than did patches from CH25. Bite rate, bite mass and instantaneous intake rate were greater for CH25 than for CH35 (p < 0.001, p = 0.068, and p = 0.074), and bite mass and instantaneous intake rate were lower for DS20 compared to DS0 (p = 0.032 and p = 0.016). Greater stem mass in the grazing strata negatively influenced the instantaneous intake rate.

Objetivou-se avaliar os efeitos de um bioestimulante sobre a morfogênese, estrutura, produtividade e composição química do capim de Urochloa brizantha cv. Marandu, manejado sob dois níveis de adubação nitrogenada. As coletas foram realizadas no período de seca (junho até setembro) e período chuvoso (setembro a abril). A área experimental foi dividida em 48 parcelas de 8 m² cada, sendo utilizado o delineamento em blocos ao acaso em arranjo fatorial 4×2 (0, 1, 2 e 3 L ha-1 de Bioestimulante x 50 e 150 kg de N ha-1 ano-1) e subdividida ao longo do tempo, em período de seca e período chuvoso. As aplicações dos tratamentos foram feitas em dose única. Houve interação entre bioestimulante e adubação nitrogenada para a Produção de massa seca de forragem total e produção de massa seca de forragem diária, em que observou-se aumento de 30,1% e 25,3% na produção de matéria seca total e de 33,7% e 27,6% na produção de matéria seca por dia, ao utilizar 1 e 2 L ha-1 de bioestimulante, respectivamente, quando comparado a não aplicação de bioestimulante e com adubação de 50 kg de N ha-1 ano-1. A duração de vida das folhas (DVF) apresentou interação tripla (Bioestimulante x Adubação nitrogenada x Período) sendo que o desdobramento da interação demonstrou que a adubação de 150 kg de N ha-1 ano-1 proporcionou menor duração de vida das folhas, no período de seca sem apresentar diferença para as demais combinações de fatores. Não foi observado interações para composição químico-bromatológica e não houve diferenças com a aplicação do bioestimulante. As dosagens de 1 e 2 L ha -1 do bioestimulante, aumenta a produção de matéria seca por hectare na adubação nitrogenada de 50 kg de N ha -1 ano -1, porém com a adubação nitrogenada mais alta (150 kg ha ano -1 de N) a sua ação não é efetiva.

Gradual reduction of legumes in mixed tropical pastures requires periodic oversowing. Exploiting the carrying capacity of grass for an extra year after the disappearance of legumes can be economically advantageous to the farmer. This study aimed to evaluate the productivity of Xaraés palisadegrass (Brachiaria brizantha) pastures in response to its historical association with stylo (Stylosanthes guianensis) under two canopy heights to determine whether different grazing management conditions affect the defoliation pattern left by grazing animals. The split-plot experimental design was used, with the historical botanical composition (HBC) (24, 34, 45 and 52 % legume composition) corresponding to the main plots and the canopy frequency of defoliation determined at heights of 30 and 45 cm for Xaraés palisadegrass corresponding to the subplots with two replicates (500 m2) grazed by Tabapuã cows. Pastures with over 34 % stylo in the botanical composition remained productive for one year after legume disappearance, accumulating more than 8 mg ha−1 of forage per year. Xaraés palisadegrass pastures at a height of 30 cm provided better canopy structure, with 64 % less stem production and 43 % less dead material. The 30-cm pre-grazing canopy height provided a grazing environment conducive to forage intake by animals that resulted in efficient use of the pasture. In response to the improved canopy structure, the cows grazed an average of 60 fewer minutes. A HBC greater than 34 % of legumes in the pastures allows for the postponement of legume oversowing until the next growing season.

A 7 year experiment (2008–2014) evaluated cattle grazing intensity (sward height) effects on herbage mass, forage quality, and greenhouse gas emissions in continuously stocked pastures containing the tropical ‘Marandu’ palisade grass (Brachiaria brizantha (Hochst. ex A. Rich) Stapf cv. Marandu). The experiment consisted of three sward height treatments (15, 25, and 35 cm) and six replicates. There were four periods each year during the rearing phase. Significant effects were found for herbage mass, proportions of leaf and stem, crude protein, neutral detergent fiber, acid detergent fiber, lignin, animal performance, enteric methane (CH4), and greenhouse gas (GHG) emissions from soils. When the canopy height increased from 15 to 35 cm, the herbage mass rose from 5.23 to 9.86 kg t ha−1, leaf percentage decreased, and stem percentage increased. Crude protein content averaged 14.2%, and neutral detergent fiber averaged 58%. Average daily gain averaged 0.67, 0.81, and 0.90 kg −1 head−1, while live weight gain ha–1 was 649, 530, and 439 kg for the 15, 25, and 35 cm treatments, respectively. The weather variables explained the GHG emissions, interannual herbage mass, and structure variations.

This study aimed to evaluate the intake, digestibility and feeding behavior of Nellore young bulls, fed with diets containing different levels of cupuassu cake. Five animals with an average body weight (BW) of 186.8 ± 19.5 kg and approximately 13 months of age were used. The animals were divided into five treatments with different levels of cupuassu cake (CC): 0.0%; 5.0%; 10%; 15% and 20%, in substitution of corn and soybean meal and were subjected to the experiment 5 × 5 latin square, composed of five animals and five periods. Each of the five experimental periods lasted 15 days: 10 days for diet adaptation and five days for the assessment of nutrient digestibility. The feeding behavior (visual observation) was measured at the end of each experimental period (15th day) for 24 h. The dry matter (DMI), ether extract (EEI) and crude protein intake (CPI), all expressed in kg/day and %BW, presented a quadratic effect (P

The objective of this study was to evaluate the postweaning history of heifers kept on marandu grass pastures with three canopy heights, in a continuous-grazing system, during the rainy period, on feedlot- or pasture finishing. The effects of three canopy heights (15, 25 and 35 cm) associated with two supplements (mineral salt and protein-energy supplement) and two finishing systems in the dry period (feedlot and open pasture) were studied in the postweaning period during the rainy season. The adopted design was completely randomized, with seven replications (animals) in a 2 × 2 factorial arrangement. The animals which received protein-energy supplement reached the finishing period with greater body weight in relation to those fed mineral salt. In both feedlot and pasture finishing systems, compensatory gain effect was observed in the animals that remained on the low pastures during postweaning compared with the high pastures. This compensatory gain was not verified in the animals that received protein-energy supplement in relation to the mineral salt, and thus the animals were slaughtered beforehand. The heifers on pastures with 25 or 35 cm in height were slaughtered in the same period, and those kept on the low pastures were slaughtered afterwards. The studied factors in the postweaning phase did not affect the carcass characteristics. Animals finished in feedlot slaughtered with the same body weight as those finished on pasture show greater carcass yield, subcutaneous fat deposition and renal pelvic and inguinal fat and greater losses with trimmings for cleaning the main hindquarter meat cuts; however, they provide cuts with the same weight but greater fat cover.

The objective of the present study was to evaluate the characteristics of the sward canopy of Marandu grass during the rainy season, the wet-to-dry transition and the dry seasons, between March and September 2004, under intermittent grazing, and to correlate those characteristics with the performance of crossbred heifers receiving mineral supplements ad libitum or protein supplements. The experiment consisted of a randomized block design with three blocks (set of 13 paddocks), each containing five crossbred heifers per experimental unit, totaling 15 replicates. The heifers were given protein supplements daily in individual stalls and received an average 4 g/kg/day of the supplement during the rainy season and 5 g/kg/day during the dry season. Their weight gain was assessed monthly. The pasture structure was assessed through destructive sampling, and the bromatological composition of esophageal extrusa samples was also assessed. Analysis of variance was used to assess performance, and regression analysis was used to evaluate the sward canopy characteristics in relation to the months of the year. A cluster procedure was used to determine the similarity between the months of the year under assessment. Two different groups were formed for pasture evaluation: one group including the months of March to July and another group including the months of August and September. The first group exhibited a better canopy structure than the second group. This fact was corroborated by the animal performance, which was lower during the months of the second group. Low-intake protein supplementation was effective in increasing the performance of the grazing heifers. Pasture structure is critical for animal performance in a grazing environment, regardless of the type of supplementation.

Objetivou-se com este trabalho avaliar a disponibilidade de forragem, a composição morfológica e química do pasto, a capacidade de suporte do pasto e a produção de leite de vacas em três gramíneas forrageiras sob lotação contínua e taxa variável em solo de várzea. O delineamento experimental foi inteiramente casualizado com três tratamentos e três repetições. Os tratamentos constituíram-se das gramíneas Paspalum atratum cv. Pojuca, Brachiaria humidicola cv. Llanero e capim-tangola, híbrido natural de Brachiaria arrecta e Brachiaria mutica. A taxa de lotação foi ajustada para manter a forragem disponível entre 2.000 e 3.000 kg de massa seca por hectare. O período avaliado foi de novembro de 2003 a maio 2004. Não houve diferença significativa entre as espécies quanto à disponibilidade de massa seca de forragem verde, com valor médio de 2.902 kg/ha. O capim-pojuca apresentou 62% de lâminas foliares e 38% de colmo + bainha na massa seca de forragem verde, seguido pelo capim-humidícola com 49 e 51% e o capim-tangola com 18 e 82%, respectivamente. O capim-tangola apresentou teor mais alto de proteína bruta na lâmina foliar (15,41%) que os capins humidícola (9,98%) e pojuca (8,74%) e menores de fibra (FDN e FDA). A produção individual das vacas refletiu o melhor valor alimentício do capim-tangola, cuja média diária (10,27 kg/vaca) foi maior que no capim-pojuca (7,80 kg/vaca) e semelhante ao obtido com capim-humidícola (9,16 kg/vaca). A produção de leite por área não foi afetada pela gramínea forrageira, com média de 27,8 kg/ha × dia-1, uma vez que a taxa de lotação um pouco mais alta no capim-pojuca, apesar de não apresentar diferença significativa, compensou a menor produção individual das vacas.The objective of this study was to evaluate the forage availability, pasture morphological and chemical composition, pasture carrying capacity and the milk production of cows on three forage grasses under continues stocking and the variable rate on lowland soil. The experimental design was completely randomized with three treatments and three replicates. The treatments were the Paspalum atratum cv Pojuca grass, Brachiaria humidicola cv Llanero grass and tangola grass (natural hybrid of Brachiaria arrecta and Brachiaria mutica). The stocking rate was adjusted to maintain the forage available between 2.000 and 3.000 kg dry matter per hectare. The period evaluated was from November 2003 to May 2004. There was no significant difference between the species when the dry matter availability of green forage was evaluated, with mean value of 2.902 kg/ha. The pojuca grass had 62% of leaf blade and 38% of stem + sheath in green forage dry mass, followed by humidícola grass with 49 and 51% and tangola grass with 18 and 22%, respectively. The tangola grass showed higher level of crude protein on the leaf blade (15.41%) than humidícola (9.98%) and pojuca (8.74%) grasses and lower levels of fiber (NDF and ADF). The individual production of cows was affected by the better nutritional value of the tangola grass. The average daily production of this grass was higher (10.27 kg/cow) than the pojuca grass (7.8 kg/cow) and had similar value to humidícola grass (9.16 kg/cow). The milk production per area, with had mean of 27.8 kg/ha × day-1, was not affected by the forage grasses because the more high stocking rate of pojuca grass, although not significant, compensated the lower individual production.

The objective of this study was to evaluate the Brachiaria brizantha cv. Marandu canopy structure maintained at different grazing heights under a continuous stocking rate and with a dietary supplementation strategy for the animals during the rainy season. This study also intended to observe the relationships of these variables with the grazing behaviors of the heifers. The effects of three canopy heights (15, 25 and 35 cm) were evaluated in association with three types of supplements: one mineral and two protein/energy supplements, the first with a high rumen degradable protein and energy and the others with a low ratio. Both the protein/energy supplements were provided at 0.3% of body weight/day. The experimental design was completely randomized, with two replications and repeated measures, and took place during the period from January to April 2008. The supplementation strategies did not affect any variable related to the canopy structure. Total and green herbage masses and the ratio of green/dead material increased with canopy height. The leaf/stem ratio was higher in the lowest canopy height: 15 cm. Changes in the canopy structure caused variations in the grazing behavior of the animals. Animals maintained in the 15-cm-tall pasture grazed for a longer time, increasing the time for each meal, but the number of meals was lower than that of the animals grazing within the 35-cm-tall pasture. The grazing time of animals receiving the energy/protein supplement was lower only in the period of the day during which it was supplied. Canopy structure is affected by sward height, and changes animal behavior. Supplementation does not affect the canopy structure of the pastures with similar heights.

The objective of this study was to assess the sward canopy structure of Brachiaria brizantha cv. Marandu pastures maintained in three grazing intensities under continuous stocking system during the rainy season, along with the behavior and performance of grazing beef heifers supplemented with mineral salt or an energy/protein supplement. Three levels of forage allowance were assessed: 2.0, 2.5 and 3.0 kg of forage/kg of live weight, combined with two supplements (ad libitum mineral salt, and an energy/protein supplement at 0.3% of live weight/day, supplied daily). The experiment was designed as a randomized block study with two replications. The supplements did not influence the variables related to the canopy structure. Canopy height was greater at higher forage allowances during the late summer and early fall. Similarly, the stem mass was greater in pastures with higher forage allowances. Animals fed protein supplement spent less time grazing than animals supplemented with mineral salt. Stocking rate was higher in pastures with lower forage allowance levels, which increased the live weight gain per grazing area. Daily weight gain did not vary according to the forage allowance levels. The use of an energy/protein supplement did not affect the stocking rate; however, it increased individual live weight gain and live weight gain per grazing area compared with mineral salt supplementation. The use of energy/protein supplements is an efficient alternative to enhance animal performance and production under grazing systems during the rainy season

Para estudar o efeito da suplementação da dieta sobre o desempenho de novilhas na fase de terminação mantidas em pastagem de capim-marandu sob lotação intermitente, durante a estação chuvosa, foram utilizadas 20 novilhas cruzadas (¼ Nelore, ¼ Santa Gertrudes, ½ Braunvieh) com peso corporal médio de 300 kg e 22 meses de idade. Os tratamentos constituíram-se de dois tipos de suplementação: sal mineral (SM) ad libtum e suplemento protéico energético (SPE) fornecido a 0,3% do peso corporal (PC) por dia com avaliações realizadas a cada 28 dias, no período entre dezembro de 2006 e março de 2007 Foram avaliados o desempenho animal e as características de carcaça medidas por ultrassom. Observou-se o efeito (P=0,057) da suplementação sobre o ganho de peso dos animais suplementados, 0,700 kg/dia e 0,587 kg/dia dos animais que receberam sal-mineral. Houve efeito da suplementação na área de olho de lombo e profundidade do músculo Gluteus medius. As demais características analisadas pela técnica de ultrassom não diferiram entre si em função da suplementação. A suplementação protéica energética da dieta permite ganhos adicionais, o que reflete em aumento da deposição de músculo de novilhas mantidas em pastagem de capim-marandu durante o período das águas.This study was conducted to evaluate the effect of the diet supplementation on the heifers performance in finishing phase, maintained in a marandu grass pasture managed in intermittent grazing system during the rainy season. Twenty crossbreed (¼ Nelore, ¼ Santa Gertrudes, ½ Braunvieh) heifers with average initial body weight of 300 kg and 22 months old were used. The treatments consisted of two types of supplements: mineral (SM) ad libtum and energy protein supplementation (PES) provided 0.3% of the body weight daily. The evaluated variables were: animal performance and carcass traits measured by ultrasound each 28 days. Supplementation affected daily weight gain (P=0.057), 0.700 kg/day for supplemented animals against 0.587 kg/day for animals receiving salt-mineral. There were no supplementation effect on the loin eye area and depth of the Gluteus medius muscle. The other characteristics examined by the ultrasound technique did not differ according to the treatments. Protein and energy supplementation of the diet allows additional gains that reflected in increased deposition of muscle of heifers grazing marandu grass during the wet season.

Avaliaram-se as características morfogênicas e estruturais do dossel de Brachiaria brizantha, cv. Marandu, sob pastejo intermitente no período chuvoso, em diferentes ofertas de forragem e ciclos de pastejo. O delineamento experimental foi em blocos ao acaso, em esquema de parcelas subdivididas, com três repetições. Nas parcelas, avaliou-se o efeito das ofertas de forragem (4, 7, 10 e 13% do PV/dia) e, nas subparcelas, o efeito dos ciclos de pastejo. Todas as variáveis diferiram entre os ciclos de pastejo, comprovando grande influência das condições ambientais sobre as características avaliadas. A taxa de alongamento do colmo e a altura do dossel responderam linear e positivamente ao aumento da oferta de forragem. O número de perfilhos vegetativos nos piquetes com a menor oferta permaneceu constante ao longo de todo o período experimental, no entanto, nos piquetes com as demais ofertas, atingiu valores mais elevados nos ciclos intermediários. A densidade de perfilhos reprodutivos e totais ajustou-se ao modelo quadrático de acordo com a oferta de forragem. Pastos manejados com ofertas de forragem próximas a 4% PV/dia têm menor alongamento de colmos e tendem a reduzir as perdas por senescência. As variáveis ambientais exercem maior influência sobre as características morfogênicas e estruturais em comparação a ações de manejo como a oferta de forragem.It was evaluated morphogenetic and structural characteristics of the canopy of Brachiaria brizantha cv. Marandu under continuous grazing during the wet season, in different forage supplies and grazing cycles. A random block experimental design was used in a split-plot scheme with three replicates. It was evaluated in the plots the plots, the effects of forage supplies (4,7, 10 and 13% BW/day) and in the subplots, the effects of grazing cycles were evaluated. All the variables differed among grazing cycles, proving the great influence of environmental conditions on the evaluated characteristics. Stem elongation rate and canopy height showed linear and positive responses to the increase on forage supply. Number of vegetative tillers in the plots with the lowest supply was constant over the whole experimental period, however, in the plots with the other supplies, tillers reached highest values in the intermediate cycles. Density of total and reproductive tillers was fitted to the quadratic model accordingly to the forage supply. Pastures managed with forage supplies close to 4% BW/day showed lower stem elongation and they tend to reduce loses caused by senescence. Environmental variables affect morphogenetic and structural characteristics more than management with forage supply does.

Objetivou-se avaliar correlações entre características estruturais e valor nutritivo do pasto diferido de U. decumbens cv. Basilisk. O experimento foi realizado em esquema de parcelas subdivididas, segundo o delineamento em blocos casualizados, com duas repetições. Os tratamentos foram combinações dos períodos de diferimento da pastagem (73, 103, 131 e 163 dias) com os períodos de pastejo (1, 29, 57 e 85 dias). A massa de lâmina foliar verde correlacionou-se positivamente com os percentuais de proteína bruta (PB), fibra em detergente neutro potencialmente digestível (FDNpoD) e matéria seca potencialmente digestível (MSpoD), mas negativamente com os teores de fibra em detergente neutro (FDN) e FDN indigestível. As correlações para colmo morto foram inversas àquelas obtidas para lâmina verde. Para o perfilho vegetativo, as correlações foram positivas com PB e MSpoD e negativas com FDN e FDNi. Para o perfilho morto, constataram-se correlações positivas com os percentuais de FDN e FDNi da forragem, bem como associação negativa com os teores de PB, FDNpoD e MSpoD. O índice de tombamento correlacionou-se de forma negativa com o número de perfilhos vegetativos e de forma positiva com o número de perfilhos reprodutivos e mortos. O índice de tombamento também se correlacionou positivamente com os teores de FDN e FDNi e de forma negativa com os percentuais de PB e MSpoD. As características estruturais do pasto diferido estão associadas ao seu valor nutritivo. Ações de manejo que reduzam a massa de colmo morto e o número de perfilhos mortos e perfilhos reprodutivos contribuem para melhorar a estrutura e o valor nutritivo do pasto diferido.The objective of this study was to evaluate correlations between the structural characteristics and nutritional value of different U. decumbens cv. Basilisk pastures. The experiment was carried out in a split-plot design following a randomized block design with two replications. The treatments were combinations among the different pasture periods (73, 103, 131 and 163 days) and the grazing periods (1, 29, 57 and 85 days). The green leaf blade matter (GLB) correlated positively with the percentages of crude protein (CP), potentially digestible neutral detergent fiber (PDNDF) and potentially digestible dry matter (PDDM), but correlated negatively with neutral detergent fiber (NDF) and indigestible neutral detergent fiber (INDF). Dead stem (DS) correlations were inverse to those obtained for green leaf blade. For vegetative tillering (VT), positive correlations were found with CP and PDDM; negative correlations were found for NDF and INDF of the forage. Dead tiller (DT), correlated positively with NDF and INDF of the forage and negative association with the CP, PDNDF and PDDM rates. The falling index (FI) correlated negatively with the number of VT and correlated positively with the number of reproductive tillers (RT) and dead tillers (DT). The falling index also correlated positively with the NDF and INDF rates and negatively with CP and PDDM. The structural characteristics of the different pasture were associated to their nutritive value. Management actions which result in a reduction in the dead stem matter and the numbers of dead tillers and reproductive tillers contribute to improve the structure and nutritional value of the different pasture.

O manejo do pastejo permite que sistema com base na utilização de pastagem propicie altos rendimentos por animal e por área. Para isto, devem-se utilizar critérios de manejo com intuito de controlar, simultaneamente a qualidade e a quantidade de forragem e manter a sustentabilidade do sistema. A intensidade de pastejo é dinâmica, jamais permanece a mesma, mudando com a taxa de consumo pelos animais e também pelo crescimento das plantas, variando de hora a hora e dia a dia, por isso deve ser controla sistematicamente. Neste cenário, o consumo de forragem parece ser o fator que mais explica as variações no desempenho animal em relação a qualidade da forragem. A suplementação da dieta dos animais em pastejo com concentrado permite aumentar o desempenho de animais, reduzindo a idade de abate ou a da primeira cria. Contudo, as características nutricionais do suplemento devem variar em função da quantidade e da qualidade da forragem ofertada. Ao suplementar a dieta dos animais em pastejo com energia e proteína, pode-se manejar pastos mais baixos em relação a suplementação apenas com sal mineral, sem que ocorra redução da densidade populacional de perfilhos. Estas estratégias de manejo podem reduzir a probabilidade de degradação do pasto. Desta forma, a suplementação da dieta de animais permite aumento na capacidade suporte do pasto.The grazing management system based on the intensive pasture utilization result in a high animal and area yield. In order to that to be possible, it should be used a management criteria aiming to control, simultaneously the quality and the amount of forage, maintaining the sustainability of the system. The grazing intensity is dynamic, it never keeps the same status, it can be changed with the animals rate intake, and also by the plants growth, changing every hour and day, due to that, it should be controlled systematically. In this scenery, the forage intake is the main factor which explains the variations in the animal performance in relation to the forage quality. Energy and protein supplementations of the grazing animals increase performance, reducing slaughter and the first birth age. However, the nutritional characteristics of the supplement should vary in function of the amount and quality of the forage allowed. Pastures grazed by supplemented animals can be managed at a lower height, compared to those grazed by animals supplemented with only mineral salt, without reducing the tillers population density. These management strategies can reduce the probability of future pasture degradation. Thus, supplementation of the diet of the grazing animals can increase the pasture carrying capacity.

Este experimento foi realizado com o objetivo de avaliar o efeito da adubação nitrogenada sobre as características morfogênicas e estruturais de Brachiaria decumbens sob pastejo. Os tratamentos consistiram da aplicação de quatro doses de nitrogênio (75, 150, 225 e 300 kg/ha.ano) antes do início das avaliações experimentais, realizadas em 2002 durante as estações de verão, outono, inverno e primavera. Utilizou-se o delineamento em blocos completos casualizados, com duas repetições. A taxa de alongamento de folha, o comprimento final da folha, o índice de área foliar e as porcentagens de colmo e de lâmina foliar aumentaram linearmente, enquanto a porcentagem de material morto decresceu com a adubação nitrogenada da Brachiaria decumbens sob pastejo. Não foi constatado efeito da adubação nitrogenada sobre o número de folhas vivas, de folhas emergentes e de folhas totais e as taxas de alongamento do colmo e de senescência foliar. A taxa de alongamento de folha e de colmo, o número de folhas vivas, o comprimento final da folha, o índice de área foliar e a porcentagem de lâmina foliar e de colmo de Brachiaria decumbens variaram entre estações do ano, apresentando valores menores no inverno.This experiment was carried out to evaluate the effects of nitrogen fertilization upon the morphogenetical and structural characteristics of Brachiaria decumbens under grazing. Four nitrogen rates (75, 150, 225 and 300 kg/ha.yr) were applied before the beginning of the experimental evaluations, which were performed during the Summer, Fall, Winter and Spring seasons. The randomized complete block design was used with two replications. Linear increases were observed for the leaf elongation rate, final leaf length, leaf area index, stem and leaf blade percentage. The percentage of dead material decreased with the nitrogen fertilization. On the other hand, N fertilization had no effect on the number of alive leaf, number of emerging leaves, total numbers of leaves, stem elongation rate and senescence rate. Leaf and stem elongation rates, number of alive leaf, final leaf length, leaf area index, leaf blade and stem percentages in the Brachiaria decumbens varied among seasons, lower values occurring in the winter.

Objetivou-se avaliar o consumo, a digestibilidade dos nutrientes e o comportamento ingestivo de tourinhos Nelore confinados, alimentados com diferentes teores de torta de cupuaçu na dieta. Foram utilizados cinco animais com peso vivo (PV) médio de 186,8± 19,5 kg e aproximadamente 13 meses de idade. Os animais foram distribuídos em cinco tratamentos contendo diferentes teores de torta de cupuaçu (TC): 0%; 5%; 10%; 15% e 20%, em substituição ao milho e farelo de soja. O delineamento experimental utilizado foi o quadrado latino 5 × 5, composto de cinco animais e cinco períodos experimentais. Cada período experimental teve duração de 15 dias: 10 dias de adaptação à dieta e cinco dias para a avaliação da digestibilidade dos nutrientes. A mensuração do comportamento ingestivo (observação visual) foi realizada no final de cada período experimental (15º dia), durante 24 h. O consumo de matéria seca (CMS), extrato etéreo (CEE) e de proteína bruta (CPB), expresso em kg/dia e %PV, apresentaram efeito quadrático (P0,10) entre os teores de inclusão. A inclusão de até 5% de torta de cupuaçu, em substituição ao farelo de soja e milho, é recomendado em dietas para tourinhos Nelore em confinamento, pois não interfere no consumo e digestibilidade de nutrientes e comportamento ingestivo dos animais.

Este experimento foi realizado no Setor de Forragicultura do Departamento de Zootecnia da UFV, no período de novembro de 2001 a novembro de 2002, para avaliar o efeito da adubação nitrogenada sobre o índice de área foliar, densidade populacional de perfilhos e acúmulo de forragem em pastos de Brachiaria decumbens Stapf. submetidos à uma mesma intensidade de pastejo. Os tratamentos consistiram de quatro doses de nitrogênio (75, 150, 225 e 300 kg.ha-1.ano-1 de N), aplicadas antes do início das avaliações experimentais, realizadas durante as estações de verão, outono, inverno e primavera, no ano de 2002. O delineamento utilizado foi o de blocos completos casualizados, com duas repetições. O índice de área foliar e a densidade populacional de perfilhos da Brachiaria decumbens sob pastejo aumentaram linear e positivamente com a adubação nitrogenada. O capim-braquiária apresentou incremento de produção de matéria seca proporcional às doses de nitrogênio, com maiores valores de taxas de acúmulo diário nas estações primavera- verão e mínimos no inverno. O índice de área foliar, a densidade populacional de perfilhos e o acúmulo de forragem variaram com as estações do ano, apresentando valores consistentemente menores no inverno.

Este experimento foi realizado no Setor de Forragicultura do Departamento de Zootecnia da UFV, no período de novembro de 2001 a novembro de 2002, para avaliar o efeito da adubação nitrogenada sobre o índice de área foliar, densidade populacional de perfilhos e acúmulo de forragem em pastos de Brachiaria decumbens Stapf. submetidos à uma mesma intensidade de pastejo. Os tratamentos consistiram de quatro doses de nitrogênio (75, 150, 225 e 300 kg.ha-1.ano-1 de N), aplicadas antes do início das avaliações experimentais, realizadas durante as estações de verão, outono, inverno e primavera, no ano de 2002. O delineamento utilizado foi o de blocos completos casualizados, com duas repetições. O índice de área foliar e a densidade populacional de perfilhos da Brachiaria decumbens sob pastejo aumentaram linear e positivamente com a adubação nitrogenada. O capim-braquiária apresentou incremento de produção de matéria seca proporcional às doses de nitrogênio, com maiores valores de taxas de acúmulo diário nas estações primavera- verão e mínimos no inverno. O índice de área foliar, a densidade populacional de perfilhos e o acúmulo de forragem variaram com as estações do ano, apresentando valores consistentemente menores no inverno.

O experimento foi desenvolvido com o objetivo de avaliar os percentuais de proteína bruta (PB), fibra em detergente neutro (FDN), FDN indigestível (FDNi), FDN potencialmente digestível (FDNpoD) e matéria seca potencialmente digestível (MSpoD) da forragem e dos componentes morfológicos em pastagens diferidas de Brachiaria decumbens. Os tratamentos consistiram de períodos de diferimento (73, 103, 131 e 163 dias) e de pastejo (1, 29, 57 e 85 dias). Foi adotado o delineamento em blocos casualizados, num esquema de parcelas subdividas, com duas repetições e nível de significância de 5% de probabilidade. O valor nutritivo dos componentes morfológicos da forragem diferida também foi determinado no início e no término do período de pastejo. Pastagens sob maiores períodos de diferimento e de pastejo apresentaram maiores percentuais de FDN e FDNi e menores teores de PB e MSpoD. O maior período de pastejo reduziu o percentual de FDNpoD da forragem diferida. A lâmina foliar viva (LV) presente no término do período de pastejo apresentou melhor valor nutritivo do que a LV do início deste período, e comportamento contrário ocorreu com o colmo vivo, a lâmina foliar morta e colmo morto. O valor nutritivo da forragem diferida é influenciado pela sua composição morfológica. À exceção da LV, o valor nutritivo dos componentes morfológicos da forragem piora, do início para o término do período de pastejo. Maiores períodos de diferimento e de pastejo resultam em forragem de pior valor nutritivo. Com isso, o diferimento da pastagem de forma parcial consiste em estratégia de manejo adequada para melhorar o valor alimentício da forragem.

ABSTRACT The objective of this research was to characterize the nutritive value of corn silage made on intensive dairy farms and demonstrate the nutritional variations between silages located at the top and at the center of a bunker silo. Thirty-two dairy farms were visited in four Brazilian states. One corn bunker silo of each farm was chosen and samples were collected from the top and center parts. The nutritive value, fermentation end-products, and microbial counts were assessed. The predicted milk was determined by Milk2006 spreadsheet. The mean, standard deviation, maximum, minimum, and 95% confidence interval of all data were calculated. The ash, neutral detergent fiber (NDF), starch, in vitro NDF, and dry matter (DM) digestibility data were compared with reference value. Both statistical procedures were performed through the PROC MEANS of SAS. The mean values found at the center for NDF, starch, total digestible nutrients (TDN-1x), and estimated milk were 503 g kg−1 DM, 308 g kg−1 DM, 583 g kg−1, and 1,124 kg t−1, respectively. The top silages presented a mean TDN-1x and predicted milk of 559 g kg−1 and 1046 kg t−1, respectively. For NDF digestibility and starch concentration, 53.1% and 62.5% of the center samples presented a value equal to or above the reference value (500 g kg−1 and 300 g kg−1 DM for NDF digestibility and starch concentration, respectively). Overall, the corn silage produced on intensive dairy farms in Brazil has satisfactory nutritive value, especially in terms of starch concentration. Some parameters, such as the concentration of fiber and its digestibility, should be improved. This study also shows that a silo may contain two different types of silage: top and center. This alerts nutritionists and farmers when feeding and sampling corn silage from bunker silos.