José Ivo Ribeiro Júnior

Dry matter production and nutritional value of elephant grass pasture under irrigation and nitrogen fertilization

The effect of four nitrogen (N) doses (100, 300, 500 e 700 kg/ha) and six water depths (0, 20, 40, 80, 100 and 120% of evapotranspiration) on elephant grass dry mass yield in the plant tops, crude protein (CP), neutral detergent fiber (NDF), and in vitro dry matter digestibility (IVDMD) during the dry and rainy periods was evaluated. The N doses were the plots and the water depths constituted the subplots, according to the complete randomized blocks experimental design with four replicates. The elephant grass dry mass yield in the plant tops accumulated either in the experimental year or during the rainy period, it increased linearly both in relation to the N doses and in relation to the water depths. During the dry period, the elephant grass production increased linearly with the N doses, but it had a quadratic behavior with the applied water depths. The CP content of the leaf blades plus pseudoculm of the elephant grass increased linearly with the N doses both in the experimental year as in the dry and rainy periods being, not influenced by the applied water depths. The NDF content in the leaf blades plus pseudoculm of the elephant grass plants was negatively influenced by the N doses during the experimental year and in the dry period, it was positively influenced by the supplement irrigation in the rainy period. The IVDMD of the leaf blades plus pseudoculm of the elephant grass was adjusted to the regression quadratic model according to the N doses only in the experimental year and in the rainy period; however, it was not influenced by the water depths. In the dry period, the IVDMD was not influenced by any of the studied variables.

Morphogenetic and structural characteristics of xaraésgrass submitted to nitrogen fertilization and defoliation

The morphogenetic and structural traits of Brachiaria brizantha cv. Xaraes submitted to the treatment combinations of four nitrogen rates (0, 40, 80 and 120 mg/dm3) and three defoliation frequencies (two, four and five completely expanded leaves) were evaluated according to a 4 x 3 factorial arrangement. The experiments were conducted in a greenhouse, with the treatments arranged as factorial combination. The experimental design was completely randomized, with four replications. After thinning, three seedlings were left per pot (5,8 dm3). The phosphate fertilization was performed according to the soil fertility. The pots were fertilized with phosphorus and potassium, according to soil fertility. Nitrogen fertilization was split in four applications and applied in aqueous solution. When the plants reached the number of expanded leaves (defoliation moment), they were cut at 5 cm height from soil level before evaluation of morphogenetic and structural traits in the aftermath. Significant nitrogen effect was observed on morphogenetic and structural characteristics of xaraesgrass and on DM yield, except on root DM. Leaf elongation rate (LER) increased linearly up to 37% at the N rate of 120 mg/dm3. Defoliation influenced leaf elongation rate, phyllochron, blade length, number of live leaves per tiller, senescence rate and dry matter yield of shoot and root.

Demografia de perfilhos basilares em pastagem de Brachiaria decumbens adubada com nitrogênio

It was evaluated tiller appearance, mortality and survival rates, the flowering percentage and the population density of basal tillers in pasture of Brachiaria decumbens under four doses of nitrogen (75, 150, 225 and 300 kg/ha/year), in three periods of the year: February to April, May to August and September to November. The experiment was conducted in a completely randomized design with periods as a split plot feature, with two replications. The nitrogen fertilization was split in three applications the first in December (2002), second in January (2003) and the third in March (2003). The evaluation of demography of basal tillers was accomplished by initial demarcation of all the tillers contained within a ring of PVC, followed by monthly identification of new tillers with wires of different colors. Evaluation of the population density of basal tillers (vegetative, reproductive and dead tillers) was performed from samples of plants harvested within 25 x 25 cm three squares from each paddock. The nitrogen fertilization positively influenced the tiller appearance, mortality and survival rates, number of vegetative tillers and the tillers mortality in the generations 1 and 2. Rates of tiller appearance were higher in February/April and September/November, while the rate of tiller mortality was higher in February/April period. Tiller population density also varied over the periods, higher figures being observed in Febrary/April period. The flowering of the Signalgrass flowering was most intense from February to May.

Bioatividade de diversos pós de origem vegetal em relação A Sitophilus zeamais Mots. (Coleoptera: Curculionidae)

Foram avaliadas, em condicoes de laboratorio, a repelencia, sobrevivencia e emergencia de adultos de Sitophilus zeamais em graos de milho tratados com pos de Azadirachta indica A. Juss (frutos), Capsicum frutescens L. (frutos e folhas, separadamente), Chenopodium ambrosioides L. (folhas, flores e frutos, conjuntamente), Eucalyptus citriodora Hook (folhas), Melia azedarach Blanco (folhas) e Ricinus communis L. (folhas). As plantas que provocaram repelencia foram E. citriodora e C. frutescens (folhas), com efeito mais pronunciado na primeira especie. A unica planta que afetou a sobrevivencia da praga foi C. ambrosioides, que provocou mortalidade total dos insetos infestantes e nenhuma emergencia de adultos. Para essa planta, foi tambem determinado o limiar de atividade inseticida, constatando-se que a dosagem minima necessaria para controle total da populacao dos insetos foi de 0,1645 g/ 20 g de milho.

Efeito da adubação nitrogenada e irrigação sobre a composição químico-bromatológica das lâminas foliares e da planta inteira de capim-elefante sob pastejo

This research was carried out to evaluate the chemical composition of elephantgrass cv. Napier in the whole plant (WP) (stem+leaf) and in the leaf blade of non-decapitated basal tillers (SF-NDBT) and leaf blade of decapitated basal tillers (SF-DBT), fertilized with different N doses (100, 200, 300, and 400 kg/ha/year of N) in an irrigated area (IA) and in a non-irrigated area (NIA). Treatments were analyzed in a randomized block design with three replicates. The CP concentrations were proportional to the N doses with greater CP concentration in the rainy season in fractions SF-NDBT and SF-DBT. Fertilizer residues of N doses applied in the rainy season, both in IA and NIA, increased CP concentration in the leaf blade of the two tiller categories, but did not affect NDF and ADF concentration. Irrigation increased concentration of NDF and ADF in SF-NDBT and SF-DBT and reduced it in the WP, with no effect on CP concentration.

Disponibilidade e qualidade do capim-elefante com e sem irrigação adubado com nitrogênio e potássio na estação seca

An experiment was carried out in experimental plots of 300 m2 in size to evaluate the effects of doses of NK fertilization and irrigation on forage mass yield and quality of elephantgras cv Napier during the dry season. The experimental design was completely randomized with three treatment replications. The experimental treatments were arranged in a 4 x 2 factorial combination of four N-K2O doses with and without irrigation, in the dry season. N-K2O doses were: 100-80; 200-160; 300-240 and 400-320 kg.ha-1, respectively. Figures for total dry forage mass (TDFM), and dry green leaf mass (DGLM) increased in proportion to N-K2O dose from May to September 2001, the dry season period. Irrigation had a marked significant effect on DGLM yield. Leaf samples from irrigated plots had higher contents of neutral and acid detergent fiber as compared to leaf samples from the control plots. Concentrations of crude protein, potash, phosphorus, calcium and magnesium did not respond either to N-K2O doses or to irrigation.

Renovação de pastagem degradada de capim-gordura com a introdução de forrageiras tropicais adubadas com nitrogênio ou em consórcios

This study was carried out to evaluate the productivity and quality of either Brachiaria decumbens Stapf. cv. Basilisk and Hyparrhenia rufa (Ness) Stapf. grasses fertilized with nitrogen (N) or mixed with stylosanthes (Stylosanthes guianensis (Aubl.) Swartz cv. Mineirao), introduced into a degraded pasture. Both grasses were evaluated, as well as four doses of nitrogen (0, 50, 100 and 150 kg/ha) and two treatments that consisted of mixing B. decumbens and S. guianensis as well as H. rufa and S. guianensis. [...]Um experimento foi conduzido com objetivo de avaliar a produtividade e qualidade do capim-braquiaria (Brachiaria decumbens Stapf. cv. Basilisk) e do capim-jaragua (Hyparrhenia rufa (Ness) Stapf.) adubados com nitrogenio (N) ou em consorcios com estilosantes (Stylosanthes guianensis (Aubl.) Swartz cv. Mineirao), introduzidos em uma pastagem degradada. Foram avaliadas duas gramineas (capim-braquiaria e capim-jaragua), quatro doses de N (0, 50, 100 e 150 kg/ha) e dois tratamentos referentes aos consorcios capim-braquiaria + estilosantes e capim-jaragua + estilosantes. Apos estabelecimento das forrageiras, foram realizadas duas avaliacoes (colheitas). As producoes de materia seca (MS) do capim-braquiaria aumentaram de 1.824 para 4.604 kg/ha e de 1.019 para 2.149 kg/ha nas duas colheitas, respectivamente, quando as doses de N extremas foram comparadas, porem nao houve resposta do capim-jaragua. O teor de proteina bruta (PB) do capim-braquiaria elevou de 3,18 para 5,68 dag/kg apenas na primeira colheita, enquanto o capim-jaragua apresentou incremento de 2,53 para 3,72 dag/kg e de 7,32 para 8,45 dag/kg, respectivamente, em ambas as colheitas, quando comparadas as doses extremas. Os teores de fibra em detergente neutro (FDN) e fibra em detergente acido das gramineas nao foram influenciados pela aplicacao de N. Em ambas as colheitas, ao se elevarem as doses de N, houve diminuicao dos teores de P nas duas gramineas e de K no capim-braquiaria. Os teores de Ca e Mg das gramineas, em sua maioria, nao foram influenciados pelo N, em ambas as colheitas. As producoes medias de MS dos dois consorcios foram superiores as producoes medias das duas gramineas adubadas, com incrementos de 42,62 e 15,00% no rendimento forrageiro, na primeira e segunda colheitas, respectivamente. As forrageiras em consorcios, de forma geral, apresentaram teores de PB e Ca mais elevados e de FDN mais baixos que as gramineas puras adubadas com N, melhorando a qualidade do pasto.

Rendimento e composição química do capim-braquiária introduzido em pastagem degradada de capim-gordura

An experiment was carried out to evaluate the reclamation of a degraded pasture of molassesgrass (Melinis minutiflora, Beauv.), with the establishment of signalgrass (Brachiaria decumbens, Stapf), with different N doses (0, 50, 100, and 150 kg/ha.year) or in consortium with S. guianensis cv. mineirao, in a complete randomized blocks design, with three replications per treatment. Evaluations were performed during the dry season (one evaluation) and wet season (three evaluations). Nitrogen fertilization promoted increment in dry matter production and crude protein (CP) concentration of signalgrass, in both seasons. There were no effect of neutral detergent fiber and acid detergent fiber concentration of signalgrass in both seasons. Increasing N doses did not alter P, Ca, and Mg concentration neither in the dry nor in the rainy seasons, but it decreased K concentration in both seasons. Signalgrass and Stylosanthes mixture presented low dry matter production in the dry season, being similar to signalgrass without nitrogen fertilizer. During the wet season, however there was no statistical difference between the consortium and treatments with nitrogen fertilization. The consortium, in general, presented greater forage CP concentration compared to signalgrass fertilized with nitrogen.

Concentrações de imunoglobulinas G em colostro de vacas mestiças holandês-zebu

Eighty-eight healthy crossbred holstein-zebu (HZ) dairy cows were distributed in four groups as follow: Group 1 = less than 70% HZ (19 cows); Group 2 = 75% HZ animals, corresponding to ¾ HZ (46 cows); Group 3 = crossbred animals between 80 to 90% HZ, corresponding to 13/16 HZ and 7/8 HZ (11 cows); Group 4 = cows more than 90% HZ (12 animals). After birth, colostrum samples were obtained from each cow and than were analyzed for immunoglobulin G (IgG) concentration by single radial immunodifusion assay. IgG colostral concentrations were not influenced by group of crossbred HZ and its mean concentration (145.97mg/m) were higher than that related for purebreds Bos taurus dairy cows. Considering these results, it was concluded that artificial methods of feeding colostrum to crossbred HZ calves are not necessary. Probably, assisted natural sucking as soon after birth as possible is enough to get passive immune transfer.

EFEITOS GÊNICOS, HETEROSE E DEPRESSÃO ENDOGÂMICA EM CARACTERES DE SORGO FORRAGEIRO

Two crosses involving three sorghum lines (S. bicolor L. Moench) BR 007A x BR 501R and BR 008A x BR 501R resulted in two forage hybrids: BR 601 and BR 602. The hybrids and their generations F2 and F3, in total of nine genotypes, were evaluated in two planting dates (normal and second season) as to several yield and forage quality characters: genetic effects, mid-parent heterosis, heterobeltiosis and inbreeding depression in F2 and F3 generations were evaluated. The following conclusions were obtained: (a) compared to the normal planting, the grain sorghum hybrids showed in second season, smaller plant height, earlier flowering, smaller green, and dry matter weight and higher protein content, stalk proportion and smaller planicle proportion; (b) heterosis for dry matter was positive and negative for protein at the two planting dates of the two hybrids; (c) inbreeding depression was positive for the F2 generation of the BR 602 hybrid at normal planting date, indicating that the commercial use of F2s seeds is not recommended; (d) the additive genetic effects were predominant for most of the characters, of the hybrid of BR 007A x BR 501R, used as grain dominant effects were important for yield characters determination at the two planting dates in forage hybrid BR 008A x BR 501R; (e) dominance effects explained most of the significant heterosis of several characters.