Análise química, fracionamento dos carboidratos e digestibilidade in vitro da matéria seca do milheto, de primeiro e segundo ciclos, variedade BRS 1501, cultivado com quatro níveis de aplicação de gesso e lâmina de irrigação no Semiárido

Abstract

The objective of this study was to evaluate the chemical composition, carbohydrate fractionation and in vitro digestibility of dry matter of first and second cycle millet (Pennisetum glaucum (L.) R.), varieties BRS 1501, grown with four levels of plaster and blade application. of irrigation in the Semiarid. The study was conducted in Petrolina-PE, during a period of 140 days, lasting 75 days for the first cycle and 65 days for the second. The experimental design was in randomized blocks arranged in a 2x4 factorial scheme, considering two cuts (1st and 2nd cycles) and four doses of agricultural plaster (0, 2, 4 and 8 Mg.ha-1), with three replications. totaling 24 installments. Gypsum doses showed significant differences for carbohydrate fractions (P<0.05), not influencing bromatological composition or IVDMD (P>0.05). However, there was a difference between the cuts for the analyzed parameters of CP, NDF and ADF (P<0.05). However, differences were observed between cycles for the analyzed parameters of total (CHO), fibrous (CF), non-fibrous (CNF) and digestible (A + B1) and potentially digestible (B2) carbohydrate (P<0.05). The CHO presented higher values in the second cut (792.9 g/kg DM) compared to the first cut (740 g/kg DM), which also explains the higher levels of CNF in the second cycle. The A + B1 fraction also increased in the second cycle (P<0.05), which may be associated with a decrease in fibrous carbohydrate levels in the same cycle. The increase in gypsum doses contributed to the decrease of saline stress in the plants, which may have favored the increase of the A + B1 fraction. However, fraction B2 presented higher proportion in the first cycle, having compensated for the lower values of A + B1. The higher proportion of fraction B2 for the first production cycle is consistent with the higher CF content compared to the second cycle, since there was no difference in fraction C values between production cycles. Therefore, the IVDMD was not influenced (P>0.05) by the production cycles. All the forages produced presented chemical-bromatological constitution suitable for the feeding of ruminants, which contributes to the increase of the carrying capacity of the production systems and, consequently, to the higher animal performance.