Distribuição espacial, composição químico-bromatológica e cinética da fermentação ruminal in vitro de Pilosocereus gounellei (A. Weber ex K. Schum.) Bly ex Rowl

Abstract

Cactaceae are considered the main food alternative for ruminant animals during the prolonged drought periods in the Brazilian semiarid region. The aim of this research was to evaluate the spatial distribution, chemical and bromatological composition, fermentation kinetics and the structural parameters of the community of Pilosocereus gounellei in areas with natural occurrence of this species. The research was carried out in three areas of one hectare, located in the municipalities of Pocinhos (area I), Boa Vista (area II) and São João do Cariri (area III), belonging to state of Paraíba with predominant vegetation of caatinga. Occurrence evaluations of P. gounellei were performed by number counting of individuals and determination of the density, frequency, and absolute dominance, using the Aggregation Index of McGuinnes. In addition, cladodes were sampled for analysis of the chemical composition, carbohydrate total content and their respective fractions (A + B1, B2 and C), in vitro dry matter digestibility (IVDMD), organic matter degradability (OMD) after 48 hours and gases production. For the occurrence data, Box Plot was performed to analyze the data dispersion and later the variogram was adjusted. Then, the number interpolation of individuals was performed using kriging. The chemical analyzes data, carbohydrate fractionation, IVDMD and OMD were submitted to analysis of variance by the procedure PROC GLM and the averages compared by Tukey test to 0.05 level of significance by SAS statistical program. A joint analysis was performed considering the completely randomized design for the three processes, the three management forms and the three municipalities. There were 498 individuals in area I, 789 in area II and 761 in area III. The population of the area I presented basal area lower (BA = 103.20 m2) than area II (BA = 167.44 m2) and area III (BA = 157.74 m2). The highest DM values were obtained with cactus crusher machine (CCM) processing. For CP values, there was a difference (P<0.05) in the interaction between the areas and manual removal of thorns (MRT), which presented respectively 32.19, 48.56 and 57.84 g/kg DM for areas I, II and III. For the fibrous fraction constituents (NDF, NDFcp, ADF, CEL, LIG, DAL), the lowest contents were obtained with MRT, except for HEM that differed (P<0.05), presenting lowest values with fire processing. In the in vitro gases production, MRT processing provided a higher total volume of gases for the three areas, presenting values of 262.70, 240.82 and 180.04 mL/g DM for areas I, II and III. In both caatinga areas the species was classified in grouping, according to the Aggregation Index of McGuinnes. The in vitro digestibility of the dry matter of P. gounellei increased in the material processed from the young cladodes collected on the higher side of its insertion in the main stem.