Trocas gasosas e desidratação do capim Vaquero: valor nutricional no armazenamento de feno

Abstract

Two experiments were conducted to evaluate the Vaquero grass destined to haymaking, one in summer and other in winter 2012. . In the summer experiment evaluated the dehydration curve of different plant parts (stem and blade + sheath), gas exchange during the first hours of dehydration, nutritional value and occurrence of fungi. The dehydration curve of grass Vaquero was determined in whole plant, leaf and stem + sheath in seven times. Time 0 corresponded to the sample taken before the court, held at 19:00 hours - daylight saving time (time 0), and on other days always 08.00, 13:00 and 17:00 hours. The times evaluted were at 0, 13, 18, 22, 37, 42 and 44 pm (moment of baling) after cutting. The experimental design for the dehydration curve was randomized blocks with split-plot in time with three regions of collection in the plant to determine the dry matter and seven times of collecting as a sub portion with five replications.. To determine gas exchange during dehydration of grass Vaquero evaluations were made on fully expanded leaves located in the upper middle third of each tillers before the cutting - 0 time (19:00), time 14 (9:00), time 19 (14:00). In a second step, was evaluated the nutritional value of grass Vaquero under two storage systems, using the experimental delineation in blocks randomized with split plot an additional treatment (before cutting). In a third step was performed the determination of fungi present in green plants and hay, where we collected samples of hay in moment of cutting , 30, 60 and 90 days of storage in open shed and enclosed shed. It was found that dehydration of the hay Vaquero occurred in 44 hours, is considered a optimal time for drying hay, with faster rates for leaf, and slower for stem. Gas exchanges were more intense before the cutting and 14 hours after cutting. The crude protein rates were higher at the time of cutting, decreasing with storage. The soluble carbohydrates decreased after 60 days of storage. The in vitro digestibility of dry matter was high and showed no reduction in both seasons and storage systems. There was no significant growth of fungi. In a second experiment, was characterized the dehydration curve of the vaquero grass in winter in different strata of the windrow (12 cm), the chemical composition and in vitro digestibility of dry matter of hay of grass Vaquero (Cynodon dactylon) stored at different times. The dehydration curve was characterized during a period of 0, 7, 21, 28, 42 and 49 hours after cutting, in 3 extracts (upper, middle and lower). The experimental design was adopted in randomized blocks with split plot in the time. Were evaluated the levels of crude protein, NDF, ADF, PIDA, NDIP and in vitro digestibility of dry matter of hay Vaquero before cutting and in storage. The experimental design was randomized blocks with seven sampling times and five reps. There was no difference in the different parts of the windrow of grass in dehydration. In response to the dehydration time, there was a linear increase in dry matter. The crude protein levels were elevated with an average grade of 137.00 g kg -1 and did not differ between sampling times. The levels NDF and ADF, with 14 days of storage were below than the others times. The contents of PIDA and NDIP showed no difference in moments reviews. The in vitro digestibility of dry matter a mean submitted an average content of 595.95 g kg-1, with at two sampling times