Determinação das frações protéicas e de carboidratos e estimativa do valor energético e da digestão intestinal da proteína de forrageiras e resíduos gerados no nordeste brasileiro

Abstract

The objective of this research was to characterize the protein and carbohydrate fractions,estimate energy values and evaluate the intestinal digestibility protein of algaroba (Prosopis juliflora), canafístula (Pithecellobium multiflorum), flor-de-seda (Calotropis procera), jitirana (Ipomea sp.), juazeiro (Ziziphus joazeiro), mata-pasto (Senna obtusifolia) and sabiá (Mimosa caesalpiniaefolia Benth), palma gigante (Opuntia ficus indica) and xique-xique (Cereus gounellei) and the agroindustry byproducts from pineapple (Ananas comosus L.), barbados cherry (Malpighia emarginata), cashew (Anacardium occidentale), coconut (Cocos nucifera L.), melon (Cucumis melo), passion fruit (Passiflora eduli), grape (Vitis labrusca) and anatto seeds (Bixa orellana L.). To obtain the carbohydrates fractions, according with Cornell Net Carbohydrate and Protein System (CNCPS) system, were calculated the total carbohydrates, their fractions B2, C and the soluble components in neutral detergent. It was determinated the potentially degradable (B2) and undegradable (C)fractions of the neutral detergent fiber, corrected for ashes and protein. The non-protein nitrogenous compounds, soluble and insoluble nitrogen in borate-phosphate buffer, nitrogenous protein insoluble in neutral and acid detergent were analyzed for the determination of the nitrogen fractions. To estimate Total Digestible Nutrients (TDN) had been used the equations proposals by National Research Council - NRC (2001). The feeds were incubated in rumen during 16 hours to determine the rumen-undegradable protein (RUDP), then the residue was incubated with pepsin solution during 1 hour, and pancreatic solution during 24 hours at 38°C, whose residues were analyzed for total nitrogen. The Malpighia emarginata and Cucumis melo showed substantial nitrogen content in fraction C which would reduce the disponibility of nitrogen for the rumen microorganisms and its host. The evaluated forages showed higher proportions of nitrogen in fractions A and B2, providing nitrogen for the rumen microorganisms. The percentage of fraction C in Malpighia emarginata and Cucumis melo at the expense of the B2 fraction would entail greater effect of ruminal fill and decreased availability of energy, for its characteristic of indigestibility along the gastrointestinal tract, when being tested for feeding animals. In the evaluated forages had been observed values of A+B1 fraction from 35.26 to 73.37%, for B2 fraction, from 3.87% to 28.45% and for C fraction from 17.34 to 40.63%. The fractions, A, B1, B2, B3 and C of nitrogenous compounds had presented variation from 9.84 to 42.33%; 1.58 to 11.47%; 48.63 to 80.10%; 0.70 to 6.13% and 0.43 to 2.86%, respectively. The byproducts carbohydrate fractions analyzed varied from 19.35 to 58.52%; 9.95 to 61.44% and 15.35 to 70.06, for A+B1, B2 and C, respectively. In turn, the nitrogenous compounds varied from 5.01 to 33.02%; from 1.69 to 15.23%; from 2.26 to 75.60%; from 1.53 to 40.26% and from 0.08 to 43.84% for fractions, A, B1 B2, B3 and C, respectively. The forages TDN values varied from 48.30 to 65.42%, while of by-products it varied from 31.41 to 128.9%. The estimate of RUDP in the forages ranged from 13.37% to 83.6%, and the byproducts RUDP ranged from 39,14 to 89.06%. The intestinal digestion of RUDP ranged from 26.09 to 80.68%, %, while for byproducts varied of 22,26 76.82%. The Mimosa caesalpiniaefolia Benth was the forage that presented better ID and better RUDPd, and the Calotropis procera, presented lowest values for these variables. For byproducts, the Cucumis melo presented the biggest value for DI, while the Cocos nucifera L. presented the lowest values for DI and RUDPd