ABSTRACT. The objective of this study was to evaluate the forage yield and morphological responses of 34 cactus pear (Nopalea cochenillifera and Opuntia ficus indica) genotypes. The genotypes were planted in a randomized complete block design, with 34 treatments and three replicates. After 330 days of cultivation, morphological characteristics, plant mortality and pest and disease occurrence on the plants were assessed, and plant cutting was performed. Multivariate analyses were performed to assign the 34 cactus genotypes to homogenous groups. The average Euclidian distance was adopted as a dissimilarity measurement for use with the standardized data Variables with relatively high levels of independence among the agronomic categories and with biological importance to animal nutrition and forage yield were assessed. To identify associative effects, Pearson’s correlation analysis was performed among all the studied variables. The formation of five distinct groups was observed, and some morphological responses correlated with the productivity characteristics. Green mass production was positively correlated with dry mass production, water accumulation, water-use efficiency, water accumulation and cladode number per plant. The following genotypes had remarkably high yields of dry and green mass, a greater ability to accumulate water and relatively high water-use efficiency and support capacity: Negro Michoacan (V07), Tamazunchale (V12), California (V14), Orelha de Elefante Mexicana (V17), and Amarillo 2289 (T32).

Abstract The objective of this study was to evaluate the biomass production and the potential use of the elephant grass hybrid Carajas for animal feeding and bioenergy production under different cutting frequencies. A randomized block design with a 3×3 factorial arrangement was used to evaluate the potential of the grass as animal feed (in natura, silage and hay form; cutting at 60, 75 and 90 days). A randomized block design with three treatments (three cutting intervals, 60, 75 and 90 days) was also used to evaluate the grass for biomass production and its potential use as an energy source in briquette form. The total forage biomass, leaf blade and stem biomass, dry matter, neutral and acid detergent fiber contents, mass and higher heating value increased with cutting interval, whereas the crude protein, ash and moisture contents decreased with cutting interval. Regardless of the cutting interval, the in natura material presented higher values of all content parameters than silage and hay. The Carajas hybrid can be used as animal feed in in natura, silage and hay form, and the recommended cutting interval for use as animal feed is 60 days. The Carajas hybrid also shows potential for use in bioenergy production in briquette form, with a suggested cutting interval of 90 days.

Resumen El objetivo fue evaluar la producción de biomasa y el potencial de uso del híbrido de pasto elefante 'Carajas' para la alimentación animal y la producción de bioenergía, en diferentes edades de corte. Se utilizó un diseño de bloques al azar con arreglo factorial 3 × 3 para evaluar el potencial del pasto como alimento para animales (in natura, silo y heno a 60, 75 y 90 días) y un diseño de bloques al azar con tres tratamientos (tres edades de corte) 60, 75 y 90 días) para la evaluación de la hierba para la producción de biomasa y el potencial energético de las briquetas. Biomasa forrajera total, biomasa de la lámina foliar y biomasa del tallo, materia seca, contenido de fibra detergente neutro y ácido, masa y aumenta el poder calorífico con el avance de la edad de la planta, mientras que los contenidos de proteína cruda, ceniza y humedad disminuyeron. Independientemente de la edad de corte, el material in natura presentó mayores contenidos que el ensilado y el heno. El híbrido Carajas puede utilizarse como alimento para animales en forma de in natura, silo y heno, con recomendación de corte a los 60 días, y muestra potencial para la producción de bioenergía a través de briquetas, con sugerencia de corte a los 90 días.

ABSTRACT. The aim of this study was to evaluate the protein energetic, enzymatic and mineral profile of Nellore cows during the pregnancy, parturition and postpartum. Fifteen multiparous cows with 4 ± 1 years of age and live weight of 400 ± 50 kg were used at different stages (non-pregnant, in the initial, middle and late pregnancy, at birth, one day postpartum, 30 and 60 days postpartum). Blood collections were performed every 30 days and assayed for the following blood biomarkers: Protein (total proteins, albumin, urea and creatinine), energetic (cholesterol, triglycerides, glucose and beta hydroxybutyrate), mineral (calcium, phosphorus, magnesium) and enzymatic (alkaline phosphatase and aspartate aminotransferase). Calcium had the lowest concentrations (p < 0.05) in the initial pregnancy, while phosphorus had the highest concentration at parturition (p < 0.05). Triglycerides, glucose and beta hydroxybutyrate were influenced by the stages of pregnancy, reducing in the late pregnancy and at parturition. Glucose had a reduction in the late pregnancy and elevation in the postpartum. Beta hydroxybutyrate showed increase at the late pregnancy. Although lipomobilization occurred in the phases of higher metabolic demands in the attempt to maintain homeostatic conditions. Nellore cows did not present negative energy balance in the late pregnancy period, maintaining normal variation in blood markers throughout the experimental period.

ABSTRACT The objective of this study was to evaluate the effect of Parkia platycephala pod meal (PP) on feeding behavior, rumen health, blood markers, and physiological responses in lactating goats. Eight apparently healthy, adult, multiparous Anglo-Nubian goats, with an average body weight of 42.06±3.5 kg and approximately 52±4 days in lactation, were randomly assigned into two Latin squares (4×4) composed of four levels of PP (0, 33.3, 66.7, and 100% of dry matter) for four periods. Daily feed intake, feeding behavior, rumen health, blood markers (hemogram and biochemical parameters), and physiological responses (rectal temperature, respiratory rate, heart rate, and sweating rate) were assessed. Intake, feeding efficiency, and rumination efficiency were not affected by the replacement of ground corn with PP. At these replacement levels, the goats significantly spent more time feeding and ruminating. There was a significant decrease in the number of chews (number/day and number/min) with an increase in PP inclusion. Rectal temperature, respiratory rate, heart rate, and sweating rate were higher in the afternoon for the three periods measured. There were no negative changes in blood markers or rumen health with the use of PP. The current findings indicate that PP can be used to replace up to 100% of the corn in the diet of lactating goats without causing significant changes in animal health, feeding behavior, or physiological parameters.

ABSTRACT Sesamum indicum L. has the potential to be cultivated as a forage plant in hot and dry climate regions, and it can be used to increase the food security of a herd. The objective of this study was to evaluate growth, production, and chemical composition of S. indicum compared with conventional forages used for silage production. The experiment used a randomized complete block design with split-plots related to time and four replicates per treatment. The plots consisted of four treatments (Zea mays L., Helianthus annuus L., Pennisetum glaucum [L.] R. Br., and S. indicum), and the subplots were two evaluation periods (2014 and 2016 harvests). Dry forage biomass production differed among the species in the 2014 harvest with values of 25 530, 12 190, 9408, and 9250 kg ha-1 for Z. mays, S. indicum, H. annuus, and P. glaucum, respectively. Maize had a greater variation in forage production between the 2 yr, followed by S. indicum. There were higher dry matter (DM) contents (P < 0.0001) for Z. mays and S. indicum (404.5 and 251.7 g kg-1, respectively). Regarding crude protein, H. annuus and S. indicum had levels of 167.2 and 117.7 g kg-1, respectively. According to the results, it can be inferred that sesame, like millet, provides greater feeding security for ruminant herds in regions with irregular rainfall.

ABSTRACT. This study was conducted to evaluate changes in hematological biomarkers of Nellore cows at different reproductive stages. Fifteen multiparous cows with 4 ± 1 years of age and live weight of 400 ± 50 kg were used at different stages (non-pregnant, in the initial, middle and late pregnancy, at birth, one day postpartum, 30 and 60 days postpartum). Blood collections were performed every 30 days and assayed for the following hematological biomarkers: hemogram (red blood cells, globular volume, hemoglobin, mean corpuscular volume (MCV) and mean corpuscular hemoglobin concentration (MCHC)) and leukogram (total and differential counts). The erythrogram was influenced (p < 0.001) by the reproductive stages, with variation in the results obtained for the total red cell count, hemoglobin content, globular volume, MCV, MCHC and total plasma proteins. The reproductive stages influenced the leukocyte profile with variation in the total leukocyte count and in the absolute values of neutrophils, eosinophils, lymphocytes and monocytes. Hematological biomarkers of Nellore cows showed significant changes due to the physiological adjustments required in response to the metabolic requirements imposed in the final stage of pregnancy and in the beginning of lactation, ensuring the nutritional contribution in energy and oxygen transported through the blood.

RESUMO. A Pornunça é uma espécie do gênero Manihot que está sendo cultivada como opção para alimentação animal no semiárido do Brasil. A área foliar (AF) é importante para determinar o crescimento de planta forrageira, e a avaliação tem que reunir as seguintes características: praticidade, precisão e baixo custo. O estudo objetivou estabelecer um modelo para determinar a área foliar da Pornunça (Manihot sp.) a partir de medidas morfométricas da folha. O delineamento experimental foi realizado em blocos ao acaso, com três tratamentos (métodos de determinação de área foliar) e três blocos, com o total de 144 repetições (folhas). Para determinação da AF, utilizou-se o método direto (AFReal), medidor de área foliar tipo esteira (Li-Cor 3100©) por meio das dimensões lineares. Os dados foram submetidos à análise de regressão. Houve uma relação entre a área foliar real (AFReal) para folhas pequenas, médias, grandes e total, e a área foliar determinada pelo medidor de área foliar tipo esteira (AFLi-Cor©) apresentou coeficiente de determinação elevado para o ajuste linear. A área foliar da Pornunça obtida pelo medidor Li-Cor3100© é de aproximadamente 10%, inferior, em comparação ao método AFReal. O modelo que melhor se ajustou para a estimativa da área foliar da Pornunça foi o potencial.

ABSTRACT. Pornunça is a species of the genus Manihot that has been cultivated as an option for animal feeding in the Brazilian semi-arid. Leaf area (LA) is important to determine forage plant growth, whose evaluation model has to meet the following characteristics: practicality, precision and low cost. The objective of this study was to set a model to determine the leaf area in Pornunça (Manihot sp.) from morphometric measurements of the leaf. The experimental design was in randomized blocks with three methods for determination of leaf area, and three blocks, with 144 replicates (leaves). For the determination of LA, the direct method (FAReal), treadmill leaf area meter (Li-Color 3100©) and linear dimensions were used. Data were subjected to regression analysis. There was a relationship between the actual leaf area (FAReal) for small, medium, large and total leaves, and the leaf area determined by the treadmill leaf area meter (FALi-Cor©) with a high coefficient of determination for linear fit. The Pornunça leaf area obtained by the Li-Cor3100© meter is approximately 10% lower compared to the FAReal method. The model that best fit the Ponunça leaf area estimation was the potential.

RESUMO Objetivou-se avaliar a qualidade química de silagem e feno de gliricídia em diferentes alturas de resíduo. Utilizou-se delineamento experimental em blocos ao acaso em esquema fatorial (3×2), constando de três alturas de resíduo (70, 90 e 110 cm) e dois procedimentos de conservação de forragem (silagem e fenação) com quatro repetições. Para os valores de pH da gliricídia in natura e silagem não diferiram em relação à altura de resíduo, diferente dos teores de nitrogênio amoniacal (N-NH3), onde na altura de 70 cm, apresentaram menores valores. As alturas de corte não influenciaram as perdas por gases, efluentes e recuperação da matéria seca da silagem de gliricídia. O feno apresentou maiores teores de proteína bruta (PB). O menor valor de matéria seca (MS) a 70 cm para o feno, conferiu-lhe menor acúmulo de massa seca, apresentando ainda, valores superiores de extrato etéreo (EE) e fibra detergente neutro (FDN) em relação à silagem para as alturas de 70 e 90 cm. A planta mantida em altura mais elevada (110 cm), acumulou maior EE e concentração de material fibroso. A silagem de gliricídia apresenta valores adequados de pH independente da altura residual, assim como não influenciam as perdas fermentativas da silagem, no entanto, há perdas elevada de N-NH3 para altura residual 110 cm. MS, EE e FDN sofrem influência das alturas de resíduos, assim como pelos métodos de conservação.

SUMMARY This study aimed to evaluate the chemical quality of silage and hay Gliricídia in different residue heights. The experimental design in randomized blocks in a factorial scheme (3×2), consisting of three residue heights (70, 90 and 110 cm) and two forage conservation procedures (silage and hay) with four replications. For pH values Gliricídia fresh and silage did not differ in relation to waste time, unlike the concentration of ammonia nitrogen (NH3-N), where the height of 70 cm, had lower values. The cutting height did not influence gas losses, effluents and recovery of dry matter silage Gliricídia. Hay had higher crude protein (CP). The lowest dry matter (DM) and 70 cm for the hay, gave him less accumulation of dry matter, with still higher values of ether extract (EE) and neutral detergent fiber (NDF) in relation to silage for heights 70 and 90 cm. The plant was maintained at a higher height (110 cm), EE and accumulated higher concentration of fibrous material. Silage Gliricídia provides suitable pH values independent of the residual time, and does not influence the fermentation losses of silage, however, there are high losses of NH3 for residual height 110 cm. DM, EE and NDF are influenced heights of waste, as well as the conservation methods.

RESUMO. Objetivou-se com esse estudo caracterizar os estádios fenológicos de colheita de cultivares de soja destinada à ensilagem. As características avaliadas foram massa seca da amostra composta, das ramificações, das folhas e das vagens; massa úmida das ramificações, folhas, vagens e matéria natural triturada. O delineamento adotado foi o de blocos casualizados em um esquema fatorial 3 x 2, com quatro repetições cada, em que o primeiro fator corresponde ao estádio de colheita: R4, R5 e R6; e o segundo fator diz respeito aos dois cultivares de soja com grupos de maturações diferentes (8.0 e 8.1). A significância da interação foi constatada apenas na matéria natural triturada. Verificaram-se maiores valores para o estádio fenológico de colheita R6 na maioria dos caracteres avaliados. Observou-se que o cultivar com grupo de maturação 8.0 apresentou maiores valores na matéria natural triturada.

ABSTRACT. This study aimed to characterize the harvest phenological stages of soybean cultivars intended for silage. Cultivars were evaluated for dry weight of the composite sample, branches, leaves and pods; wet mass of branches, leaves, pods and ground natural matter. This experiment was a 3 x 2 factorial randomized block design, with four replications each, where the first factor corresponds to the harvest stage: R4, R5 and R6; and the second factor refers to two soybean maturity groups (8.0 and 8.1). A significant interaction was detected only for ground natural matter. Higher values of most traits evaluated were observed for the R6 harvest phenological stage. The cultivar with maturity group 8.0 showed higher values for ground natural matter.

RESUMO Objetivou-se avaliar a composição química e tempo para atingir o ponto de fenação da Leucena (Leucena leucocephala) e Gliricidia (Gliricidia sepium). Foram coletadas amostras nos tempos 0, 2, 4, 6, 8,10, 12, 14, e 16 horas de secagem para obtenção da curva de desidratação para cada espécie de forragem. O delineamento adotado foi o inteiramente casualizado com nove tratamentos (9 tempos de desidratação x três repetições). Os dados referentes às características morfológicas da espécie foram submetidos à análise estatística de variância e as médias foram comparadas pelo teste de Tukey a 1% de probabilidade. Para a curva de desidratação em função do tempo, os dados foram submetidos à análise de regressão. A relação folha:caule foi maior para a Gliricidia no tempo 16 horas de desidratação (P<0,05). As taxas de desidratação da amostra composta, vagem, colmo e folha composta da Gliricidia e Leucena apresentaram efeito linear crescente (P<0,05) com a Leucena mais eficiente na desidratação. Os teores de matéria seca da Gliricidia e Leucena foram, respectivamente, de 91,24% e 91,32%, enquanto os teores de proteína bruta foram de 18,64% e 17,7%. Os teores de fibra em detergente neutro corrigida para cinzas e proteína foram de 49,86% e 49,07%, e os teores de proteína insolúvel em detergente neutro foram de 1,01% e 1,77%. O tempo para atingir o ponto de feno da Leucena e da Gliricidia foi de 16 horas. A composição nutricional dos fenos de Leucena e Gliricidia apresentaram-se satisfatórios para serem fornecidos na alimentação de animais ruminantes.

SUMMARY The objective was to evaluate the chemical composition and time to reach the point of hay of Leucena (Leucena leucocephala) and Gliricidia (Gliricidia sepium). Samples were collected in time 0, 2, 4, 6, 8, 10, 12, 14, and 16 hours of drying to obtain dehydration curve for each species of forage. The design was completely randomized with nine treatments (9 times of dehydration x three replicates). Data for morphological characteristics of the species were subjected to statistical analysis of variance, and means were compared by Tukey test at 1% probability. For dehydration curve as a function of time, the data were subjected to regression analysis. The leaf:stem ratio was higher for Gliricidia in time and 16 hours of dehydration (P <0.05). The rates dehydration of Composed samples of pod, stem and leaf of Gliricidia and Leucena showed a linear increase (P <0.05) and the Leucena dehydration was most efficient. The dry matter content of Gliricidia and Leucena showed, respectively, 91.24% and 91.32% content, while the crude protein content was 18.64% and 17.7%. The fiber content neutral detergent corrected for ash and protein content was the 49.86% and 49.07, the neutral detergent insoluble protein content was 1.01% and 1.77%. The time to reach the point of Leucena and Gliricidia hay was 16 hours. The nutritional composition of hay Leucena and Gliricidia were satisfactory to be provided in the feeding of ruminant animals.

RESUMO As condições de restrição hídrica no semiárido brasileiro são um dos fatores limitantes ao estabelecimento e produtividade de gramíneas forrageiras. Objetivou-se, com este estudo, avaliar o efeito de diferentes turnos de rega sobre as características morfogênicas, estruturais e produtivas de capim-buffel. O delineamento experimental foi o de blocos casualizados, com cinco tratamentos e seis repetições. Os tratamentos consistiram de cinco turnos de rega, correspondentes aos intervalos de 2, 4, 6, 8 e 10 dias. As variáveis analisadas foram: taxa de aparecimento foliar, filocrono, taxa de alongamento foliar e de colmo, taxa de senescência foliar, comprimento final da folha, número de folhas vivas por perfilho, número de perfilhos, altura do colmo, relação lâmina/colmo, índice de área foliar, massa seca de lâmina e colmo verde, massa seca de forragem verde, morta e total, massa seca de raiz, matéria seca e relação massa seca verde/massa seca morta. Não foi constatado efeito dos turnos de rega sobre o comprimento final da folha e massa seca de forragem morta. A relação lâmina/colmo apresentou comportamento quadrático, mantendo-se a 0,51, até o turno de rega de quatro dias. As demais características morfológicas, estruturais e produtivas decresceram linearmente com o aumento dos turnos de rega. O espaçamento dos turnos de rega promoveu reduções nos parâmetros morfológicos, estruturais e produtivos do capim-buffel, quando cultivado em casa-de-vegetação. O turno de rega de 2 dias destaca-se como o menos restritivo ao desenvolvimento do capim-buffel.

ABSTRACT The water restriction conditions in the Brazilian semiarid region are one of the most limiting factors to the establishment and yield of forage grasses. This study aimed to evaluate the effect of different irrigation regimes on morphogenetic, structural and productive traits of buffel grass. Arandomized blocks design, with five treatments and six replications, was used. Treatments consisted of five irrigation regimes, corresponding to the intervals of 2, 4, 6, 8 and 10 days. The traits analyzed were: leaf emergence rate, phyllochron, leaf and stem elongation rate, leaf senescence rate, final leaf length, number of green leaves per tiller, number of tillers, stem height, leaf/stem ratio, leaf area index, dry mass of green leaf and stem, dry mass of green, dead and total forage, root dry mass, dry mass and green dry mass/dead dry mass ratio. The final leaf length and dead forage dry mass were not affected by the irrigation regimes. The leaf/stem ratio followed a quadratic model, maintaining the value of 0.51 up to the irrigation regime of four days. The other morphological, structural and productive traits decreased linearly with increasing irrigation frequencies. The irrigation intervals promoted reductions in the morphological, structural and productive parameters of buffel grass, when grown under greenhouse conditions. The irrigation regime of 2 days stands out as the least restrictive to the development of buffel grass.

Os objetivos deste trabalho foram avaliar as relações entre caracteres morfoagronômicos e a produção de matéria verde de palma forrageira e identificar seus efeitos diretos e indiretos. Dezenove acessos foram avaliados para os seguintes caracteres: número (NC), espessura (EC), comprimento (CC) e largura (LC) de cladódios, altura (AP) e largura (LP) de planta, produção de matéria verde (PMV) e seca (PMS) e porcentagem de matéria seca (MS). Estimaram-se as correlações, e fez-se a análise de trilha pelo método proposto por Wright. O caráter PMV apresentou elevada associação com PMS, permitindo a seleção indireta para este caráter. Os caracteres NC e EC apresentaram efeito direto sobre a PMV, podendo ser empregados na seleção indireta ou como auxiliares no processo seletivo. Tendo em vista, a não existência de correlações significativas entre MS e PMS, é possível a seleção de variedade de palma com elevada PMS e MS.

The objectives of this study were to evaluate the relationships between morphological characteristics and fresh matter yield of cactus pear and identify their direct and indirect effects. Nineteen accessions were evaluated for the following traits: number (NCl), thickness (ThCl), length (LCl) and width (WCl) of cladodes, plant height (PH) and plant width (PW), and green matter yield (GMY), dry matter yield (DMY) and dry matter percentage (DM). The correlations were estimated, and path analysis was performed by the method proposed by Wright. GMY was strongly correlated with DMY, allowing indirect selection for this trait. NCl and ThCl had a direct effect on GMY and can be used for indirect selection or as secondary traits in the selection process. Given the lack of significant correlations between MS and DMY, it is possible to select a palm variety with high DMY and DM.

Objetivou-se avaliar as características morfogênicas e a produção de fitomassa do capim buffel (Cenchrus ciliaris cv. Molopo) adubado com diferentes quantidades de digesta bovina sólida. Utilizou-se uma área experimental de dois hectares de pastagem de capim buffel implantados em 2006 sendo esta área destinada exclusivamente para a produção de feno. No ano de 2009 o experimento foi implantado em uma área total de 375m², que foi dividida em 25 parcelas de 15m² cada, sendo que cada parcela possuía 8m² (4x2) de área experimental e uma linha de bordadura de 0,5m de largura em torno do seu perímetro. Foi utilizado o esquema de parcelas subdivididas no tempo, em delineamento experimental de blocos completos ao acaso, com cinco tratamentos e cinco repetições correspondentes às quantidades de digesta bovina (3,5; 7,0; 10,0 e 13,5 t/ha), totalizando 25 unidades experimentais. Houve interação entre as quantidades de digesta e os cortes para a produção de fitomassa verde, sendo que para todas as quantidades de digesta aplicadas foram obtidas maiores produções para o terceiro corte. A maior produção de fitomassa verde foi obtida para o tratamento com 13,5t/ha de digesta. Não houve interação entre cortes e adubação com digesta para o número de perfilhos vivos, número de perfilhos mortos, número de folhas vivas por perfilhos, filocrono, altura e diâmetro de touceira. Dessa forma, recomenda-se a aplicação de digesta bovina por ser eficiente em aumentar a produção de fitomassa do capim buffel cv. Molopo.

The objective was to evaluate the morphogenesis and the production of biomass of buffel grass fertilized with different amounts of bovine solid digesta. We used an experimental area of two hectares of grazing buffel grass (Cenchrus ciliaris cv. Molopo) deployed in 2006, this area is designed exclusively for the production of hay. In 2009 the experiment was implemented a total area of 375m², which was divided into 25 plots of 15m² each, with each plot had 8m² (4x2) of the experimental area and a boundary line of 0.5m wide around the perimeter. We used a split-plot in time, in randomized complete block experimental design, with five treatments and five repetitions of the corresponding amounts of bovine digesta (3.5; 7.0; 10.0 and 13.5t/ha), totaling 25 experimental units. There was interaction between the amounts of digesta and cuts for the production of green biomass, and for all quantities of digesta were obtained higher yields applied to the third cut. The largest green biomass production was obtained for treatment with 13.5t/ha of digesta. There was no interaction between cuts and fertilization with digesta to the number of live tillers, number of dead tillers, number of live leaves per tiller, phyllochron, height and diameter of clump. Thus, it is recommended the application of bovine digesta to be efficient in increasing the production of biomass of buffel grass cv. Molopo, through changes in some structural features, can be used as organic fertilizer in pastures of grass.

Dois experimentos foram conduzidos com o objetivo de avaliar o perfil fermentativo e a composição bromatológica de silagens de sorgo. No experimento 1, avaliou-se o perfil fermentativo do sorgo em resposta à adubação nitrogenada, em delineamento inteiramente casualizado, em parcela subdividida 5 x 6 (cinco doses de nitrogênio e seis períodos de abertura). As doses de adubação nitrogenada foram: 0; 50; 100; 150 e 200kg/ha e os períodos de abertura foram: 1; 3; 7; 14; 28 e 49 dias. No experimento 2 avaliaram-se as variações nos constituintes bromatológicos do sorgo. O delineamento experimental utilizado foi em blocos casualizados com cinco repetições, e os tratamentos tiveram os mesmos níveis de adubação do experimento 1. Os teores de matéria seca aumentaram linearmente com as doses de nitrogênio e com o período de fermentação. O pH aumentou linearmente em função da adubação nitrogenada e apresentou resposta quadrática em função do período de fermentação. Os valores de N-NH3 apresentaram resposta quadrática, tanto a doses de nitrogênio, quanto dos dias de abertura. A matéria orgânica aumentou linearmente e a matéria mineral reduziu. Lignina respondeu de forma linear crescente ao incremento da adubação nitrogenada. Os teores de hemicelulose reduziram linearmente. Os valores de matéria seca, pH e amônia demonstraram eficácia no processo fermentativo da silagem, independente da quantidade de nitrogênio utilizado. A utilização da adubação é uma prática interessante, pois aumenta a produtividade da planta sem alterar a composição bromatológica da silagem.

Two experiments were conducted to evaluate the fermentation characteristics and chemical composition of sorghum silage. In the first experiment the fermentative profile of sorghum silages in response to nitrogen fertilization was evaluated using a completely randomized design, in split-plot scheme with five doses of nitrogen (in the plot) and six opening times (in the subplot). The nitrogen levels were 0; 50; 100; 150 and 200kg/ha and the opening times were: 1; 3; 7; 14; 28and 49 days after ensiling. In the second experiment the variations in the chemical composition of sorghum silages was evaluated. The experimental design was randomized blocks with five repetitions, and the treatments consisted on the same levels of fertilization of first experiment. Dry matter increased linearly with the nitrogen and the fermentation period. The pH increased linearly as a function of nitrogen and showed a quadratic response as a function of fermentation period. The N- NH3 values showed a quadratic response both to nitrogen as for the opening day. Organic matter increased linearly and mineral matter decreased. Lignin responded linearly to increasing nitrogen fertilization. The hemicellulose decreased linearly. The dry matter, pH and ammonia values show efficacy in the silage fermentation process independent of nitrogen level used. The use of fertilizer is an interesting practice, which increases plant productivity without changing the chemical composition of the silage. Nevertheless, for the most economic treatment, is indicated the use of 150kg of nitrogen per hectare.

The objective of this study was to evaluate the agronomic divergence of 25 sorghum hybrids (Sorghum bicolor L. Moench) in the semiarid region of Paraiba. A randomized block design with three replications was used for evaluation of plant height (PH), total natural matter production (TNMP) and total dry matter production (TDMP) and the percentage of components of DM (panicle, leaf blade, stem and dead matter) of the following hybrids: 866005, 866019, 866033, 866034, 866035, 866036, 866037, 866040, 866041, 866042, 866043, 866044, 870025, 870031, 870035, 870041, 870051, 870067, 870081, 870085, 870095, 1F305, BRS 610, Volumax, and XBS60329. Hybrid 1F305, followed by hybrid 866034, presented the highest average PH. There was a range from 7.679 to 20.948 kg/ha (average of 13,799 kg/ha) for TDMP. Hybrids 1F305, BRS 610 and Volumax presented less potential, and hybrids 866,041 and 866,042 were the most productive. Based on cluster analysis and subjective cut in 50% of dissimilarity, it was possible to establish four hierarchical groups, from which two stood out concerning productive characteristics. The group formed by hybrids Volumax, BRS 610, and XBS60329 presented lower averages for yield and lower percentage of panicle. Hybrids 866041 and 866042 show a higher total dry matter production, with values around 20,000 kg/ha.