Abstract
Rice bran (RB) is a by-product of the rice industry, which is cheap in Bangladesh. RB is not commonly used in the broiler production system due to having limitations like higher fiber content and lower availability of few micronutrients, including phosphorus. This study aimed to isolate and characterize Cellulolytic Rumen Bacteria from cattle and used 10% rumen Bacterial inoculum to ferment RB anaerobically used to improve its nutritional value, as a broiler feed. The ruminal liquid was incubated at 39°C anaerobically in medium containing Rumen Fluid Glucose Cellobiose Agar (RGCA) at optimum pH 6.9; the isolates were identified according to their morphological, biochemical tests and molecular technique by Hungate technique. They were strictly anaerobic, Gram-positive, cocci, single or pair, occasionally short-chain, presence of clear zone around the colonies. Biochemical characteristics are both degrade xylan and ferment cellobiose, glucose and lactose. Catalase Negative, Indole Negative, Gelatin liquefaction occur which are identified as cellulolytic Rumen Bacteria Ruminococcus albus that was used for fermentation in different conditions like RaFRB (RB treated with Ruminococcus sp.), RaUFRB (RB treated with 2.0% urea using Ruminococcus sp.), RaMFRB (RB treated with 5.0% molasses using Ruminococcus sp.), RaUMFRB (RB treated with 2.0% urea & 5.0% molasses using Ruminococcus sp.). The protein content was increased in RaUFRB (18.43%), RaUMFRB (17.19%), in comparison to the RB group (14.42%) where RaUFRB showed the highest crude protein (p<0.05). The crude fiber was decreased in RaFRB (11.64%), RaUFRB (9.92%), RaMFRB (11.67%), and RaUMFRB (10.83%) in comparison to RB (12.57%). Phytate-P was also decreasing in RaUFRB (1.00%), RaMFRB (1.00%), RaUMFRB (0.82%) then to RB (1.13%). Considering the benefits of fermentation, rumen liquor mediated fermented RB used to evaluate the growth and performance of broilers, conducted two feeding trials; in the first feeding trial, RB was fermented anaerobically without or with urea (2.0%) at room temperature for 48 hours and dried to use in a broiler diet for 28 days. The numbers of 120- day old broiler (Cobb 500) chicks were divided into three groups and 30 birds of each group (10 birds in each cage). Three dietary groups contained RB, fermented RB (FRB) giving rumen inoculates and 2.0% urea fermented RB giving rumen inoculates (UFRB). All the diets were isonitrogenous (22.75% CP) and isocaloric (3164 kcal/kg), where urea nitrogen excluded from the calculation because nonprotein nitrogenous substances are not useful by the gastrointestinal tract of broilers. The true protein content of diet increased in groups offered FRB (16.45%) and UFRB (16.85%) in comparison to the RB group (16.27%). The final body weight of RB, FRB and UFRB groups were 1095, 1131 and 1186 g/bird (p<0.05). Feed intake was 1817, 1785 and 1909 g/bird respectively for RB, FRB and UFRB groups (p<0.05). The feed conversion ratio was 1.75, 1.66 and 1.69 for RB, FRB and UFRB groups, respectively (p<0.05). Essential amino acid content was also increased. No mortality occurred in any group during the feeding trial. Another Feeding trial was conducted using 150day-old unsexed broilers (Cobb 500) allocated in five dietary groups having ten birds in cach. Dietary groups were RB, FRB (fermented RB), UFRB (2% urea fermented RB), MFRB (5% molasses fermented RB) and UMFRB (2% urea and 5% molasses fermented RB). Bodyweight and feed refusal were recorded weekly. Blood samples were collected after 28 days of trial. The protein content of diet increased in groups offered FRB (22.55%), UFRB (23.11%), MFRB (22.85%) and UMFRB (23.67%) in comparison to RB group (22.43%). Bodyweight was 1057, 1124, 1151, 1087 and 1137 g/bird, respectively, where RB showed the highest weight gain significantly (p<0.05). Feed intake was 1766, 1790, 1777, 1734 and 1756 g/birds respectively, among them lowest was in the MFRB group of the broiler. The feed conversion ratio was low (1.61) in the UFRB group significantly (p<0.05). Cholesterol concentration was low in all the groups where RB was fermented (with or without additive) in comparison to the unfermented group. Weight of dressed carcass was more or less similar in all the groups (p>0.05). It can be concluded that under this study, fermentation of RB using isolated Ruminococcus albus from rumen liquid from cattle might improve nutritional value, i.e., higher crude protein (24.22%) (p<0.05) and lower crude fiber(9.35%), Phytate-phosphorus (1%) then RB but need feeding trial. Both feeding trials would increase the performance of broiler, but urea added group showed better growth performance and dressing yield without any hazards.
Key words: Ruminococcus spp., Rice Bran, anaerobic, Fermentation, phytate-P, Broiler feed, Rumrn fluid.