Feeding two nerica rice straw varieties to sheep: Effects of supplementation with leguminous foliages on digestibility, nutrient utilization and growth performance

Five experiments were carried out to evaluate the nutritive value of shade-dried Samanea saman and Stylosanthes hamata foliages as supplements for rams fed Nerica 1 and Nerica 2 rice straws as basal diets on the growth performance of these rams. Four rumen fistulated Djallonké rams weighing averagely 22.5 kg, were used in a randomized complete block design (RCBD), within a 2x2 factorial arrangement of treatments (2 legumes and two levels each of the supplements), in Experiment 1 to determine the digestibility of DM, OM, N and NDF of the different treatments. The treatments were TSA360 (360 g S. saman foliage), TSA480 (480 g S. saman foliage), TST360 (360 g S. hamata foliage) and TST480 (480 g S. hamata foliage). The digestibility of the nutrients ranged from 60.9 to 88.4 %. The digestibility coefficients were significantly (P<0.05) higher for TST360 for DM, N and NDF. Nitrogen balance was positive for all the four levels of offer but significantly (P<0.05) lower for TSA360. Nitrogen efficiency was very high and differed significantly (P<0.05) between the treatments and ranged from (99.7 to 99.86). The rumen pH values for the higher levels of offer of the two foliages were significantly (P<0.05) different TSA480 and TST480 (6.35 and 6.31) when compared to the lower levels ie (6.23 and 6.20) for TSA360 and TST360 at 0 h post feeding. At 4 and 6 h post feeding the rumen pH values were significantly (P<0.05) v different for S. saman and S. hamata foliages as well as their two levels of offer. The rumen NH3-N level peaked at 4 h post feeding for all the four levels of offer but was significantly (P<0.01) higher for TSA480 (9.6 mg/100 ml) and significantly (P<0.01) lower for TST480 (7.8 mg/100 ml). The blood urea nitrogen (BUN) level was significantly (P<0.01) higher for the two offer levels of S. saman compared to the S. hamata offer levels. The purine derivative excretion was significantly (P<0.05) higher (23.33 mmol/d) for sheep on the higher level of offer of S. saman foliage compared to the others. Rumen degradation of DM for S. saman, S. hamata, Nerica 1 and Nerica 2 rice straws were evaluated using RCBD within a 2 x 2 factorial arrangement of treatments (2 legumes and two levels each of the supplements giving 4 rumen environments) in experiment 2. The degradability of the DM of all the 4 feed samples increased with time. The potential disappearance (P) and the potentially degradable but insoluble fraction (b) was significantly (P<0.01) low for all the 4 feed samples (S. saman, S. hamata, Nerica 1 and Nerica 2 rice straws) under TST480. The rate of degradation (c) was significantly (P<0.05) higher for TST480 ie (0.005, 0.037, 0.024 and 0.035 %/h) for S. saman, S. hamata, Nerica 1 and Nerica 2 respectively but significantly (P<0.05) lower for TST360 (0.002, 0.032, 0.022 and 0.032) for S. saman, S. hamata, Nerica 1 and Nerica 2 respectively. The rate constants for S. saman was significant (P<0.01) lower than the others. The washing loss was significantly (P<0.01) higher (22.6 %), for S. hamata and significantly (P<0.01) lower (4.4 %), for Nerica 2. S. saman had the vi highest potential disappearance (91.15 %) followed by (85.2 %) for S. hamata and (71.35 and 60.44 %) for Nerica 1 and Nerica 2 repectively. In Experiment 3 four fistulated Djallonké rams were used in a 4 x 4 (4 animals and 4 mordanted feed samples) Latin Square Design to evaluate the passage kinetics of S. saman, S. hamata, and Nerica 1 and Nerica 2 rice straws. The transit time (TT) was significantly (P<0.05) higher for Nerica 1 and significantly (P<0.05) lower for S. saman. The fractional passage rate (k1/h) in the fore gut was significantly (P<0.01) higher for Nerica 1 (0.025/h) and similar for S. saman and Nerica 2 (0.019/h). The fractional passage rate (k2/h) in the hind gut was significantly (P<0.05) higher for Nerica 1 (0.033/h) and similar for S. saman and S. hamata (0.029/h).The MRT was significantly (P<0.01) different for all the four feeds. Nerica 2 had a significantly (P<0.01) higher value of (125.80 h) and S. saman had a significantly (P<0.01) lower value of (110.81 h). The growth performance of 48 rams of an average weight of 13. 99 kg and 18 months of age was evaluated in Experiment 4 using a CRD in a 2 x 3 factorial arrangement of treatments (two rice straw varieties and three levels of offer of the foliage, S. hamata [240, 360 and 480 g]). There were six (6) treatments and these were randomly assigned, with eight (8) replicates per treatment. The average daily gain (ADG) and gain on metabolic weight basis were significantly (P<0.05) lower for the rams on T240 and significantly (P<0.05) higher but similar for the rams on T360 and T480 for Nerica 1 rice straw variety. The average daily gain (ADG) and gain on vii metabolic weight basis were significantly (P<0.05) lower for the rams on T240 and significantly (P<0.05) higher for the rams on T360 for Nerica 2 rice straw variety. The straw intake was significantly (P<0.05) lower for the highest level of offer of S. hamata for both straw varieties. The intake of S. hamata increased significantly (P<0.05) as the offer level increased. The total intake on LW and metabolic weight basis followed the same trend as the legume intake for both rice straw varieties. Forty eight (48) rams of an average weight of 13. 03 kg and 17 months of age, were used in a growth performance assessment in Experiment 5, using a CRD in a 2 x 3 factorial arrangement of treatments (two rice straw varieties and three levels of offer of the legume foliage, S. saman [240, 360 and 480 g]). The final weight and the ADG were significantly different between the 3 treatments. The increase in weight and the daily gain increased significantly (P<0.01) with increasing levels of S. saman foliage. Intake of straw was similar between the 6 treatments for the 2 rice straw varieties Nerica 1 and Nerica 2. Intake of S. saman and total intake on metabolic weight basis were significantly (P<0.05) different between the treatments. It is concluded that 480 g/d of S. saman supplemented with Nerica 1 and Nerica 2 was beneficial in young Djallonké rams as it resulted in positive nitrogen balance and a high efficiency of rumen microbial protein synthesis to improve their daily viii gains. S. hamata when fed at 360 g per day to young Djallonké rams elicited the best performance.

Source: KNUST