Desarrollo de sub-sistemas de alimentación de bovinos con rastrojo de frijol (Phaseolus vulgaris, L.). I. Disponibilidad, composición y consumo del rastrojo de frijol

Abstract

An experiment was effected to determine the production of common black bean residue under different cropping situations found in Central American small farms. Laboratory analyses were carried out to characterize the chemical composition and in vitro digestibility of this residue. Finally, a switchback design was used to test the voluntary intake of the bean residue by six yearling steers weighing 223 kg, and fed three rations differing in blackstrap molases content (06, 8.8 and 179 per cent on dry basis) but kept isonitrogenous (8 per cent crude protein) by additions of area (124, 1.30 and 1.32 per cent, correspondingly). The remaining ration component was the crop residue. It was found that when bean is grown as a single crop, a production of 700 to 1,151 kg dry matter (DM)/ha/crop of the residue can be expected. In multiple cropping (usually associated with com and/or cassava), the bean residue output varies between 527 and 1,225 kg DM/ha/crop. The residue produced is well dried (90 per cent DM) and as such, could be stored for long periods. ls chemical analysis showed 4 low content of crude protein (4.1%), while 1be cell wall constituents accounted for 688 per cent of the total DM. 1 is also characterized by a high lignin content (17 0%), associated with a 460 per cent in vitro DM digestibility. Considering that the bean residue is made np by 35.2 per cent of stems and 448 per cent empty pods, comparative analyzer were also carried out. No differences were found in crude protein content, but a lower lignin concentration (128 vr. 198 per cent) and a higher DM digestibility (565 vs. 370 per cent) was found in the empty pod component. The animals preferred be empty pods 10 such an extent that physical analysis of the remaining feed in the trough showed a proportion of 8.1 per cent empty pods and 919 per cent demo, with little variation due 10 the level of supplementary molasses. Total DM and black bean residue intakes were 253 and 248; 263 and 236; and 296 and 2.39 kg DM/100 Eg liveweight/day, corresponding 10 molasses levels of 06, 88 and 17.9 per cent of the ration. It is concluded that black bean residue is well accepted by bovines and that with small additions of an inexpensive source of N it could allow the feeding of animals during the dry season to at least maintain body weight.