초록
The present study was conducted to examine the feasibility of utilising bamboo (Bambusa arundinacea) shoot shell (BSS) in ruminants. Chemical composition, rumen degradability and some antinutritional compounds were determined for fresh and boiled BSSs to evaluate its feed value and safety. Thirty-two Holstein heifers were allocated to four groups and used to investigate the response in growth rate to supplementing ammoniated rice straw with fresh shell (phase 1) or silage of boiled BSS (phase 2). All animals were offered ammoniated straw ad libitum with 1kg of cotton seed meal (phase 1) or 0.5 kg of cotton seed meal and 0.5 kg of concentrate mixture (phase 2) per head per day. The BSS was supplemented at levels of 0, 3, 6 or 9 kg/d (phase 1) and 0, 5, 10 or 15 kg/d (phase 2) (as fed basis). The BSS was very high in moisture content, and its contents of crude protein and neutral detergent fiber were 13~16% DM and 65~76% DM, respectively; boiling resulting in higher moisture and protein. No hydrocyanic acid was detected in both BSSs and content of tannins was negligible. Rumen degradability of BSS was reasonably high, and with boiling the rapidly degradable fraction decreased, and potentially degradable component increased. Silage of the boiled BSS was slightly lower in both rapidly and slowly degraded fractions than the fresh BSS. Animals consumed all supplemented BSSs without any adverse health problems. Intake of ammoniated straw decreased with the increasing levels of BSS, but total intake was higher in almost all supplementary groups than in the non-BSS. Heifers had a higher growth rate in phase 1 with fresh BSS than in phase 2 with ensiled shell, and daily weight gains were 622, 629, 744 or 690 g in phase 1, and 578, 575, 677 or 635 g in phase 2 at four BSS levels, respectively. For both phases growth rate was significantly higher for the animals in groups 3 and 4 than those in groups 1 and 2 (p<0.01), with little difference between groups 1 and 2 (p>0.05) but significant difference between groups 3 and 4 (p<0.05). Supplementation with BSS also resulted in an improved feed conversion rate, with the least concentrate consumption in group 3 for both phases. It is concluded that the BSS has a high potential nutritional value as indicated by its medium protein content, reasonably high rumen degradability, and that inclusion of BSS in ammoniated rice straw diet is not only safe to animals, but also may improve growth rate of ruminants and feed conversion rate. It may be disadvantageous to use high amounts of BSS in ammoniated straw diets.