Abstract:
Megathyrsus maximus (MM) is a valued grass for ruminant feeding but its crude protein and biomass yield are low. Intercropping MM with legumes is capable of improving its yield and crude protein content. However, information on biomass yield of MM intercropped with Mucuna pruriens (MP) and Sphenostylis sternocarpa (SS) and their preservation for ruminant is scanty. Therefore, effects of intercropping MM with MP and SS on biomass yield and crude protein of MM, and feeding value of their silages in West African Dwarf Sheep (WADS) were investigated.
Using a randomised complete block design (r=3), MM was intercropped with MP and SS at spacing of 1m×1m in ratio 75MM:25MP (T1); 50MM:50MP (T2); 75MM:25SS (T3); 50MM:50SS (T4) and sole MM (T5). Biomass yield (t/ha) and crude protein (%) of MM at ages 4, 8 and 12 weeks were evaluated. In another experiment, harvested forages of 8, 10 and 12 weeks, with combination ratios: 100MM (SL1), 90MM:10MP (SL2), 80MM:20MP (SL3), 70MM:30MP (SL4), 80MM:10MP:10SS (SL5), 60MM:20MP:20SS (SL6), 40MM:30MP:30SS (SL7), 90MM:10SS (SL8), 80MM:20SS (SL9) and 70MM:30SS (SL10) were ensiled for 28 days. Butyric Acid (BA, mmol/mL) and ammonia nitrogen (NH3-N, %) of the silages and their acceptability by WADS using Preference Index (PI) were determined following standard procedures. In a feeding trial, seven silages: SL1, SL2, SL3, SL4, SL5, SL6 and SL7, based on lower BA, were prepared from eight weeks grass/10 weeks legumes and fed to 28 WADS for 105 days. Weight Gain (WG-g/day), Crude Protein Digestibility (CPD%) and Nitrogen Retention (NR-g/day) were assessed using standard procedures. After feeding trial, rumen liquor was collected and assayed for ruminal NH3-N (mg/100mL). Blood was sampled and analysed for Total Protein (TP-g/dL) and Serum Urea Nitrogen (SUN-mg/dL) following standard procedures. Data were analysed using descriptive statistics and ANOVA at α0.05.
Biomass yield of 11.93±1.91 (T5) and 10.94±1.17 (T1) were similar but higher than 8.65±0.82 (T2), 8.22±0.85 (T3) and 7.19±0.71 (T4) for MM. Biomass yield of MM was higher for 12-weeks than other ages at harvest. Crude protein of MM declined from 4 to 12-weeks at harvest. Crude protein of MM ranged from 8.60±0.07 (T5) to 9.62±0.04 (T4), with T4 significantly higher than other treatments. The BA of silage ranged from 1.35±0.12 (SL1) to 3.31±0.21 (SL10), while NH3-N varied from 8.24±0.14 (SLI) to 9.46±0.14 (SL7). Butyric acid and NH3-N of silages prepared from 4-weeks grass/8-weeks legumes were higher than other ages. The SL6 (PI=10.63) and silages of 8-weeks grass/10-weeks legumes and 12-weeks grass/legumes were preferred by the WADS. The WG varied from 17.62±1.62 (SL6) to 35.83±1.17 (SL2). The CPD varied from 84.87±0.04 (SL1) to 89.24±0.02 (SL3) and NR ranged from 12.33±0.08 (SL1) to 18.45±0.23 (SL7). Rumen NH3-N ranged from 8.57±0.09 (SL1) to 11.87±0.15 (SL7). The TP ranged from 5.30±0.06 (SL1) to 7.85±0.04 (SL5), while SUN varied from 16.22±0.14 (SL1) to 27.96±1.01 (SL6).
Megathyrsus maximus intercropped with Mucuna pruriens or Sphenostylis sternocarpa at 50% improved crude protein of the grass, while Megathyrsus maximus ensiled with 10% Mucuna pruriens enhanced weight gain of West African dwarf sheep.
