Fábio Prudêncio de Campos

Atributos químicos e físicos de um argissolo cultivado com Panicum maximum Jacq. cv. IPR-86 Milênio, sob lotação rotacionada e adubado com nitrogênio

SUMMARY : CHEMICAL AND PHYSICAL ATTRIBUTES IN AN ANFISOLCULTIVATED WITH PANICUM MAXIMUM JACQ. CV. IPR-86MILENIO, UNDER ROTATIONAL STOCKING AND FERTILIZEDWITH NITROGEN It is necessary to evaluate the soil physical and chemical attributes in studies thatexplore grazing systems intensively. In this work the variation in physical and chemicalattributes of an Alfissol cultivated with Panicum maximum Jacq. cv. IPR-86 Mileniounder grazing were evaluated from October 2001 to May 2002, in the fifth year of consecutiveN application at rates of 0, 150, 300, and 450 kg ha -1 . After five successive applications of450 kg ha -1 N, the OM content increased 5 g dm -3 , which resulted in CEC increase. FromOctober 2001 to May 2002 the pH and basis saturation degree decreased with the increasingN rates. The range in soil density with N fertilization was small; the micropore percentageincreased and the macropore percentage decreased in the 0–5 cm layer with increasing Nrates, but the total porosity remained constant; and the soil penetration resistance at90 g ha

Sistema radicular do Panicum maximum Jacq. cv. IPR-86 Milênio adubado com nitrogênio e submetido à lotação rotacionada

The effect of nitrogen on the root system of the species Panicum maximum Jacq. cv. IPR-86 Milenio, under grazing, was evaluated. The N rates were 0; 150; 300 and 450 kg/ha.year. The root density was evaluated during pre-grazing at five years of successive N application, in three depths (0-10; 10-20 and 20-40 cm) and the root growth at 7, 14, 21, and 35 days after grazing. The grazing method adopted was rotational stocking. Root length and root mass densities in pre- and post- grazing presented maximum values at rates 204, 206, 192, and 197 kg/ha of N, respectively. The root growth (in root length density) increased, on average, until 29 days after grazing at rates 0, 150, and 300 kg/ha; at 450 kg/ha N rate, the increase was linear. Independently of N rates, around 60 and 25% of IPR-86 Milenio cultivar root system was concentrated in 0-10 and 10-20 cm depth, respectively.

Comportamento ingestivo de novilhos sob suplementação em pastagens de capim-tanzânia sob diferentes intensidades de desfolhação

The objective of this trial was to study the effect of forage defoliation intensity and energy or protein supplementation on chewing activity of beef cattle. Eight Nellore steers fitted with ruminal cannula were used in a rotational grazing system of tanzaniagrass (Panicum maximum Jacq.) with 33 days of resting and three days of grazing. Additional steers were allowed to access the pasture before those with ruminal cannula to maintain the green dry matter (GDM) residue at 1,000 or 4,000 kg/ha as pre-planned. Steers were divided into two equal groups (1,000 or 4,000 kg GMD/ha) in the paddock and within each group randomly assigned to treatments in two replicated 4 x 4 Latin squares. Treatments were: no supplement (control), 2.24 kg/day of coarsely ground corn (CGC), 2.24 kg/day of steam flaked corn (SFC), or 0.8 kg/day of soybean meal (SBM). In each of the three days of grazing, chewing activity was monitored during 24 h with observations registered every 5 minutes during the day and every 15 minutes at night. Only rumination time was reduced by supplementation. Time spent grazing (470.6 vs. 354.3 minutes/day) and ruminating (408.5 vs. 319.1 minutes/day) were increased while idle time was reduced on steers maintained residue at 1,000 kg GMD/ha compared to those at 4,000 kg GMD/ha. Neither supplementation nor the interaction GDM residue x supplementation significantly affected the eating behavior of steers in this trial. Intensity of forage defoliation was more effective than suplementation on changing chewing activity of steers.

Características de fermentação e composição químico-bromatológica de silagens de capim-tifton 85 confeccionadas com cinco teores de matéria seca

The objectives of this study were to evaluate the effects of wilting and the application of bacterial enzymatic additive (BEA) or buffered propionic acid (BPA) on the fermentation characteristics and chemical composition of Tifton 85 (Cynodon spp.) silage stored in big square bales wrapped with plastic sheet. The experimental treatments were: five forage dry matter contents (250, 350, 450, 550 and 650 g/kg DM) without BEA (WoA), three forage dry matter contents (250, 350 and 650 g/kg DM) with BEA (WA) and an wilted forage (650 g/kg DM) sprayed with BPA. Corn silage samples were taken after 0, 6 and 12 hours and 1, 2, 4, 8, 16, 32, 90 and 180 days of storage to assay for the fermentation and chemical characteristics time trends. The experimental design was completely randomized with three replications with a split plot feature of experimental treatments as main plots and fermentation times as split plot treatments. Wilting to 450 g/kg DM did improve fermentation parameters (pH, N-NH3 and buffering capacity) and chemical composition of Tifton grass silages. BPA addition did not improve the silage fermentation parameters neither chemical composition. The addition of BEA showed marginal benefits only in the high dry matter content silages (650 g/kg DM), with no significant changes in low dry matter silages (250 g/kg DM).

Perfil microbiológico, parâmetros físicos e estabilidade aeróbia de silagens de capim-tifton 85 (Cynodon sp.) confeccionadas com distintas concentrações de matéria seca e aplicação de aditivos

Objetivou-se com este trabalho avaliar os efeitos do emurchecimento e da aplicacao de inoculante bacteriano-enzimatico (ABE) e acido propionico tamponado (APT) sobre o perfil microbiologico, os parâmetros fisicos e a estabilidade aerobia de silagens de capim-tifton 85 (Cynodon spp.) armazenadas em fardos retangulares revestidos por filme plastico. Os tratamentos constaram de cinco silagens (250, 350, 450, 550 e 650 g/kg MS) sem o aditivo, tres (250, 450 e 650 g/kg MS) com aditivo e uma confeccionada com fardos de capim emurchecido ate atingir o maior teor de MS (650 g/kg MS), pulverizados com solucao contendo acido propionico tamponado (APT). O delineamento experimental utilizado foi inteiramente casualizado, com tres repeticoes, em esquema de parcelas subdivididas no tempo, conforme o teor de MS da silagem. Os tratamentos com maiores teores de MS (> 450 g/kg MS), em relacao aqueles com maior umidade, apresentaram menores contagens de colonias bacterianas, valores intermediarios para atividade de agua (Aa) e conteudo de N-NH3 na silagem e valores superiores para condutividade eletrica (CE), pH e estabilidade aerobia. Esses resultados sugerem que o aumento no teor de MS da forragem reduziu a atividade de agua (Aa), diminuindo o crescimento de bacterias e, consequentemente, a fermentacao. O uso do aditivo proporcionou efeito positivo no tratamento com 450 g/kg MS, principalmente aos 32 dias de estocagem, enquanto a adicao de APT nao apresentou vantagens.

Efeito de enzimas fibrolíticas e do teor de matéria seca em silagens de capim-tanzânia sobre os parâmetros ruminais, o comportamento ingestivo e a digestão de nutrientes, em bovinos

The present trial aimed to study the effects of forage wilting or the addition fibrolytic enzymes to the Tanzaniagrass (Panicum maximum Jacq. cv. Tanzania) during the ensiling process or after the silage unloading and before animal feeding. The fermentation and ruminal kinetics parameters, animal ingestive behavior, dry matter intake and in vivo nutrient digestibilities in bovine were measured. Treatments consisted of forage ensiling as described: A - wilted forage without enzymes; B - fresh forage without enzymes; C - wilted forage with enzymes at ensiling (2 L/t wet forage); D - fresh forage with enzymes at ensiling; E - enzymes applied into silage (10 L/t wet silage) 30 minutes before feeding (direct-fed). Silage samples were submitted to chemical analysis and screened for particle size measurements. Five ruminally cannulated Nellore steers were randomly assigned to a 5 x 5 Latin square design and fed with 50% silage total mixed rations diets. The ruminal passage rate of solid (2.23%/hour) and liquid (4.83%/hour) phases were similar for all treatments. The molar concentration (109.62 mM) of total VFAs and ammonia-N (5.6 mg/dL) observed in ruminal fluid were similar across silages diets. The forage wilting determined lower C2:C3 ration in the rumen. The animal ingestive behavior measured as total time (minutes/day) and rate (minutes/DM kg) was not changed with enzymes application, averaging DM eating (247; 24), DM ruminating (426; 43) and DM chewing (673; 67), respectively. Rations containing wilted silages showed less rumination and chewing. The mean DM (47.5 vs. 53.6%), NDF (45.8 vs. 55%) and ADF (45.5 vs. 54.8%) digestibilities were decreased on total mixed rations containing wilted silages. The wilting of Tanzaniagrass or the addition of fibrolytic enzymes resulted in marginal improvement, both in the ruminal parameters or animal ingestive behavior.

Ruminal parameters analyzed in remaining digestion residue of roughages in the in vitro/gas system

Animal performance is the most direct measure in the evaluation of feed quality. However, performance data are often insufficient to determine possible interactions that may take place in the ruminal environment. The purpose of the present trial was to evaluate the possible associative effects on the concentrations of volatile fatty acids (VFAs), ammoniacal nitrogen (N-NH3) and pH in the remaining liquid fraction from the dry matter (DM) digestion for exclusive roughages: sugarcane (SC), 60- (EG60) and 180-day elephantgrass (EG180), and corn silage (SIL), as well as for combined roughages: sugarcane+corn silage (SCSIL), sugarcane+60-day elephantgrass (SCEG60), sugarcane+180-day elephantgrass (SCEG180), corn silage+60-day elephantgrass (SILEG60), corn silage+180-day elephantgrass (SILEG180) associated at equal DM proportions (50%). These associative effects present positive or negative effects on bovine performance. Concentrations of VFAs and N-NH3, as well as pH for the treatments were, respectively: SC= 56.9 mmol L-1, 50.1 mg dL-1, 5.7; SCSIL= 61.4 mmol L-1, 50.7 mg dL-1, 5.8; SCEG60= 54.7 mmol L-1, 47.6 mg dL-1, 5.8; SCEG180= 45.4 mmol L-1, 49.4 mg dL-1, 6.0; SIL= 57.2 mmol L-1, 54.0 mg dL-1, 5.8; SILEG60= 57.1 mmol L-1, 53.1 mg dL-1, 5.9; SILEG180= 55.9 mmol L-1, 52.3 mg dL-1, 6.0; EG60= 58.1 mmol L-1, 49.4 mg dL-1, 5.9; and EG180= 44.0 mmol L-1, 46.4 mg dL-1, 6.1. Nonstructural carbohydrates and starch, associated with fiber and protein, contributed to positive associative effect on the 50:50 sugarcane/corn silage mixtures. The high fermentative aspect of such mixture may have promoted the best results in bovine performance.

Effect of the Cooling Environment on Dry Matter Intake of Diets of Tropical Roughage and their Mixtures, on Milk Production of Holstein Cows in Freestall

The quality of diet is not the only responsive factor for increase milk production in cows; there are also the environmental and genetic factors that interact to affect positively or negatively influence animal performance. The trial aimed to evaluate the productive performance of cows submitted to diet based on roughages and concentrates with different energy densities, under different environmental conditions, with and without fans plus misting (FM), to predict the main factors that interfere with in the production system. Eight lactating Holstein cows, with average weight of 550 kg, were assigned in 8x8 Latin square, with periods of 20d: 9d of collection of data. Significant difference by treatments was not observed for either dry matter intake (DMI), with values from 19.2 to 22.4kg DM/day or for milk production (MP), with values from 21.8 to 23.2kg/day, corrected for fat. When using FM the point of maximum DMI (pm) was at 74.7 THI. Without using FM, the smallest DMI happened when the least point was THI of 74.7 (P<.05). When DMI was related to MP the effect was linear and increasing, independently from the use of FM. Analyzing the MP as a function of THI, it is verified that with the use of FM there was pm at THI of 76.1, and without the use there was a low point at THI of 76.0. The physiological parameters (PP) were evidenced by linear and increasing results of the skin temperature (32.1 to 35.0oC) with the increase of THI (71.8 to 76.6). The linear and increasing effects for rectal temperature (38.2 to 38.7oC) and respiratory frequency (38.9 to 65.3 mov/min) as a function of the increase of THI were also verified. The use of FM, depending on the installation type, on the period of the year, will affect more the PP of the animal than the MP in our regional conditions.