ABSTRACT. This study aimed to evaluate the effect of different doses of nitrogen fertilization on the morphogenic, structural, productive and chemical composition of Urochloa decumbens (Stapf) R. D. Webster cv. Basilisk in a silvopastoral system with eucalyptus. The experimental treatments consisted of pastures of Basilisk cultivar, fertilized with 0, 100, 200, 300 and 400 kg ha-1 year-1 of N, and intercropped with eucalyptus, clone GG 100 (Eucalyptus grandis x E. urophylla). The experimental arrangement followed a randomized block design with four replicates. The evaluated characteristics were: foliar appearance rate, phyllochron, leaf length, leaf elongation rate, leaf life span, foliar senescence rate, number of green leaves per tiller, number of senescent leaves per tiller, daily dry matter accumulation, dry matter production, crude protein, and neutral detergent fiber. In the conditions of the established silvopastoral system, nitrogen fertilization did not influence (p > 0.05) the morphogenic and structural characteristics of Basilisk cultivar, except for height (p < 0.01) and leaf: stem ratio (p = 0.02). The nitrogen fertilization of the Brachiaria grass with eucalyptus in the proposed structural arrangement does not modify (p > 0.05) the morphogenic characteristics. However, in ration to dry matter production, doses of up to 400 kg of N ha-1 are recommended.

ResumoObjetivou-se avaliar as características produtivas e reprodutivas de fêmeas 1/2 Holandês x ¼ Nelore, ¼ Gir (Nelogir). Avaliou-se os efeitos de ordem e época de parto, do reprodutor da raça Gir e do reprodutor da raça Holandesa, avô materno e pais das matrizes 1/2 Holandês x Nelogir, respectivamente. A produção de leite total, com duração da lactação média de 288 dias, foi de 3.426,9kg de leite. A ordem de parto influenciou a produção média diária que foi maior no segundo parto e a duração da lactação, superior nos animais de primeiro parto. O período de início das águas apresentou menor duração da lactação e produção por dia de intervalo de parto. A produção de leite total não variou de acordo com o reprodutor Gir, pai da Nelogir, e foi superior nas matrizes filhas de reprodutores Holandeses com PTA positivo para leite. Ao primeiro parto o pico de produção foi de 13,03kg aos 45 dias de lactação, e a partir do segundo parto a produção foi decrescente desde o parto. Conclui-se que, em condições tropicais, as características produtivas e reprodutivas sustentam a iniciativa de produção de animais 1/2 Holandês x Nelogir a partir de matrizes compostas Nelogir e que a escolha do touro da raça Holandesa para produção de F1 HNG deve ser baseada no valor genético aditivo para produção de leite (PTA leite).

AbstractIt was aimed to evaluate the productive and reproductive traits of 1/2 Holstein x ¼ Nellore, ¼ Gir (Nelogir) females. They were evaluated the effects of order and season of calving, of Gir and Holstein sires grandfathers and fathers of the1/2 Holstein x Nelogir matrices, respectively. Total milk production, with average lactation length of 288 days, was 3,426.9kg of milk. The order of calving influenced the daily average production which was higher in the second calving and lactation length was superior in the first calving. The beginning of rain period (November to January) showed lower lactation length and production a day of calving interval. Total milk production did not vary according to Gir sire, Nelogir’s father, and was higher in the matrices daughters of Holstein sires with positive PTA for milk. In the first calving the production peak was of 13.03kg at 45 days of lactation, and from the second calving the production was descending one. In tropical conditions, productive and reproductive traits support the initiative of farm animals 1/2 Holstein x Nelogir from matrices composed Nelogir and that the choice of Holstein bull to produce F1 HNG should be based on the genetic value milk production (milk PTA).

An experiment was carried out to assess rates and nitrogen fertilization strategies on the forage yield using irrigation to supply the water deficit during the dry season. The grasses Cynodon spp cv. tifton 85 and Brachiaria brizantha cv. Xaraés were cultivated with nitrogen (N) at levels of 200 and 400 kg/ha according to strategies: 1) half dose applied during the rainy season (RS) and half during the dry season (DS); 2) 1/3 during the RS and 2/3 during the DS; 3) 2/3 during the RS and 1/3 during the DS; 4) all doses applied during the DS. In each season the dose was divided in three applications. Eleven harvests were conducted: six in the RS and five in the DS. When 2/3 of N was applied in the DS, forage yield in this period was statistically equivalent to those obtained in the RS in three of the five harvests for both 200 and 400 kg/ha of N. With 100% of N applied in the DS, the yield of four of five cuts of forage was similar to that obtained in the RS for both rates of N. The strategy of applying more N in the DS rather than in the RS was effective, keeping the yield steadily throughout the year. The application of 100% of the dose of 200 kg/ha N and 2/3 of the dose of 400 kg/ha N both in the dry period, under irrigation, promote uniform productions per harvest throughout the year.

Com o objetivo de avaliar a produção e a composição química da forragem de milheto (Pennisetum glaucum (L.) R. Br.), plantado durante os períodos de transição chuva/seca e seca/chuva, sem irrigação, foi conduzido um experimento na EPAMIG de Leopoldina-MG, durante o período de fevereiro a dezembro de 2006. Os tratamentos foram arranjados num esquema fatorial 3x5, com as cultivares de milheto Comum, BN2 e BRS1501, plantadas nos meses de fevereiro, março, abril, agosto e setembro. Não houve diferença entre as cultivares na produção de massa de forragem seca, com média de 4.010kg/ha. Houve diferenças entre as cultivares, somente, quanto aos teores de proteína bruta (PB) e digestibilidade in vitro da matéria seca (DIVMS). Os teores de PB, fibra em detergente neutro e digestibilidade in vitro da matéria seca variaram de 14,04 a 17,95%, 48,78 a 57,27% e 61,37 a 72,68%, respectivamente, de acordo com as cultivares e épocas de plantio. As diferenças entre as épocas de plantio foram significativas com a produção de massa de forragem seca de 3.941; 2.525; 4.316; 3.258 e 6.010kg/ha para o plantio em fevereiro, março, abril, agosto e setembro, respectivamente. Como a composição química das cultivares variou aleatoriamente com as épocas de plantio, qualquer uma das cultivares pode ser utilizada. A semeadura em setembro proporciona as melhores respostas em produção sem comprometer a composição química.

Aiming to evaluate the forage production and chemical composition of pearl millet (Pennisetum glaucum (L.) R. Br.) during rain/drought and drought/rain period transitions, without irrigation, this experiment was carried out at EPAMIG of Leopoldina-MG. Treatments were arranged as a 3x5 factorial: pearl millet cultivars: Comum, BN2 and BRS1501 and sowing dates (February, March, April, August and September). There was no differences among cultivars in dry forage mass production, with average of 4,010 kg/ha. There was difference among cultivars in crude protein (CP) and the in vitro dry matter digestibility (IVDMD). The CP values ranged from 14.04 to 17.95%, while the neutral detergent fiber variation was from 48.78 to 57.27% and the IVDMD was from 61.37 to 72.68%, according to the cultivars and sow time. There were differences among sow dates, with dry matter production of 3,941; 2,525; 4,316; 3,258 and 6,010kg/ha in the sowing dates of February, March, April, August and September, respectively. Anycultivar may be choosed, because the variations that were found in the chemical composition among cultivars according to sowing dates were variables. The production was better for sowing in September without changes in chemical composition of forage.

The present study aimed to estimate the photosynthetically active radiation of tropical forage grasses in ten cutting dates, under irrigation. The following treatments were used: Brachiaria decumbens grass (Brachiaria decumbens cultivar Basilisk), Marandu grass (Brachiaria brizantha cultivar Marandu), Xaraes grass (Brachiaria brizantha, cultivar Xaraes), Mombaça grass (Panicum maximum cultivar Mombaça), Tanzania grass (Panicum maximum, cultivar Tanzania) and Tifton 85 grass (Cynodon spp cultivar Tifton 85). The weather parameters were collected by an automatic meteorological station installed in the location and used for irrigation management. The experiment was arranged in a split-plot completely randomized block design, considering the grasses as plots and cutting seasons as subplots, with four replications in a 6 × 10 factorial arrangement, six grasses and ten cutting seasons. The results indicated increased use of photosynthetically active radiation in the wet season, in relation to the dry-wet season transition. Basilisk presented the highest values of photosynthetically active radiation (1,648.9 mE). The variables studied were affected by photosynthetically active radiation. The grass cultivars presented different light interceptions. The values of 87; 90; 90; 88; 92 and 77% were found for grass cultivars Basilisk, Marandu, Mombaça, Tanzania, Xaraes and Tifton 85, respectively. Differences were observed in forage accumulation rates for the grass plants studied. The grasses with the best productive performance were Brachiaria decumbens cultivar Basilisk and B. brizantha cultivar Xaraes. The highest values of crude protein and neutral detergent fiber were observed for Tifton 85. The use of photosynthetically active radiation was different among the grasses evaluated. There is a positive association between photosynthetically active radiation and dry matter production. Besides, photosynthetically active radiation indirectly affects crude protein and forage neutral detergent fiber.

The present study aimed to estimate the basal temperature and thermal sum for the following tropical forage plants: Brachiaria decumbens, cultivar Basilisk; Brachiaria brizantha, cultivar Marandu; Brachiaria brizantha, cultivar Xaraes; Panicum maximum, cultivar Mombaça; Panicum maximum, cultivar Tanzania; and Cynodon spp, cultivar Tifton 85, in ten cutting seasons, under irrigation. The climatic data were collected in an automatic weather ministration installed in the experimental area and used for irrigation management. The relative development or regression equation method was used to calculate the basal temperature. The estimated basal temperature values were 15.4; 10.5; 14.2; 13.4; 12.4 and 15.1 ºC and the demands were of 2,088.1; 3,542.5; 2,486.5; 2,838.5; 2,701.7 and 2,134.5 degree days for cultivars Basilisk, Marandu, Mombaça, Tanzania, Xaraes and Tifton 85, respectively. The relative development method revealed linearity between plant development and room temperature. Basal temperature can help elaborate climatic zoning for forage species in Brazil and allow the selection of the best suited species for each region in Brazil.

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.

Avaliou-se o efeito da deficiência de PB na dieta sobre a eficiência de síntese microbiana e a degradabilidade in situ da MS e FDN em novilhos mestiços. Os tratamentos consistiram de dietas compostas de feno de tifton 85 (FN) suplementadas com uréia (FNUR), farelo de soja (FNFS) e farelo de glúten de milho- 60 (FNGL). Foram utilizados oito novilhos canulados no rúmen e no duodeno, distribuídos em dois quadrados latinos 4 x 4. O pH e a concentração de nitrogênio não-amoniacal (N-NH3) foram mensurados no fluido ruminal antes e 2, 4, 6 e 8 horas após o fornecimento da ração, utilizando-se a fibra em detergente ácido indigestível (FDAi) como indicador do fluxo duodenal. A eficiência microbiana foi determinada por meio das bases purinas. Em todas as dietas, o pH e a concentração de N-NH3 foram adequados para o crescimento dos microrganismos ruminais. Não houve efeito da deficiência de PB na dieta sobre a ingestão de MS, a eficiência de síntese microbiana e a cinética de degradação da MS e FDN do feno de tifton 85. O teor de PB das dietas não alterou o crescimento microbiano, a eficiência de síntese microbiana e a cinética de degradação ruminal.

Eight crossbred steers fitted with ruminal and duodenal cannulas were randomly assigned to two replicated 4 x 4 Latin squares to evaluate the effects of crude protein (CP) levels on microbial protein synthesis efficiency and in situ degradability of nutrients. Animals received a control diet containing Tifton 85 bermudagrass hay or the control diet supplemented with urea, soybean meal or corn gluten meal-60. Ruminal pH and concentration of ruminal ammonia (NH3-N) were determined in the ruminal fluid at 0 (pre-feeding), 2, 4, 6 and 8 hours after feeding. Indigestible acid detergent fiber was used as the internal marker for measuring duodenal flow of nutrients while total purines were used as the direct microbial marker to measure microbial protein synthesis and microbial efficiency. Ruminal pH and NH3-N were within expected ranges indicating a stable ruminal environment. There were no effects of different dietary CP levels on intakes of DM and N as well as on microbial efficiency and degradability kinetics of DM and NDF. It can be concluded that different CP levels had no effect on microbial protein synthesis and efficiency and kinetics of ruminal degradability.

Avaliou-se o efeito da deficiência de PB na dieta sobre o consumo e as digestibilidades total, ruminal e intestinal dos nutrientes em novilhos mestiços. Os tratamentos consistiram de dietas compostas de feno de tifton 85 (FN) suplementadas com uréia (FNUR), farelo de soja (FNFS) e farelo de glúten de milho-60 (FNGL). Foram utilizados oito novilhos canulados no rúmen e no duodeno, distribuídos em dois quadrados latinos 4 x 4. As digestibilidades ruminal e intestinal dos nutrientes, a produção fecal e o fluxo duodenal de MS foram estimados utilizando-se a fibra em detergente ácido indigestível (FDAi) como indicador, enquanto a digestibilidade total foi determinada pelo método de coleta total de fezes. Os consumos de nutrientes (MS, MO, PB, CT, FDN, FDA e EB) não foram afetados pelos teores de PB das dietas. A digestibilidade aparente total da FDA foi superior para a dieta FNGL (55,48%) em relação à FNFS (41,29%). As digestibilidades ruminais dos nutrientes, à exceção da PB, não diferiram significativamente entre as dietas, mas a digestibilidade intestinal da PB nas dietas FNFS (66,70%) e FNGL (80,25%) foi superior à observada na dieta FNUR (57,61%). O teor de PB das dietas não alterou o consumo (exceto de PB e CNF) e as digestibilidades parciais dos nutrientes (exceto de PB).

Eight crossbred steers fitted with ruminal and duodenal cannulas were randomly assigned to two replicated 4 x 4 Latin squares to evaluate the effects of crude protein (CP) levels on intake and total, ruminal and intestinal digestibility of nutrients. Animals were fed a control diet containing Tifton 85 bermudagrass hay or the control diet supplemented with urea (NPN diet), soybean meal (SBM diet) or corn gluten meal-60 (CGM diet). Indigestible acid detergent fiber was used as the internal marker for measuring duodenal flow of dry matter, ruminal and intestinal digestibility, and fecal output of nutrients. Total fecal collection was used to determine total tract digestibility of nutrients. Nutrient intakes (DM, OM, CP, TC, NDF, ADF, and GE) did not differ among diets. However, apparent total tract digestibility of acid detergent fiber was greater on CGM (55.48%) than on SBM diet (41.29%). Except for CP, ruminal digestibilities of all remaining nutrients were similar across diets. Intestinal digestibility of CP on SBM (66.70%) and CGM diets (80.25%) were higher than that on the NPN diet (57.61%). It can be concluded that supplementation with different protein sources did not change intake (except for CP and nonfiber carbohydrates) and the partial digestibility of nutrients (except for CP).