EFFECT OF FIBROLYTIC ENZYMES SUPPLEMENTATION ON NUTRIENT UTILIZATION AND RUMEN FERMENTATION PATTERN IN SHEEP FED STOVER BASED DIETS
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Date
2011
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SRI VENKATESWARA VETERINARY UNIVERSITY TIRUPATI - 517 502. (A.P.) INDIA
Abstract
ABSTRACT :
The present study was conducted to develop a suitable fibrolytic enzymes cocktail comprising cellulase, xylanase, β-D-glucanase for maize stover and sorghum stover by in vitro studies and to evaluate the effect of these fibrolytic enzyme combination by in vivo studies in sheep in terms of nutrient utilization and rumen fermentation pattern. The fibrolytic enzymes cellulase, xylanase and β-D glucanase, investigated had an activity of 10, 00,000, 16, 00,000 and 10, 00,000 IU/g, respectively. For in vitro studies the required quantity of the enzyme was manually mixed with stover which was ground through 1mm screen. At first, cellulase and xylanase were added individually to both the stovers at an increasing dose rates viz., 0, 100, 200, 400 , 800, 1600, 3200, 6400, 12800, 25600, 32000, 38400, and 44800IU/g DM and screened for in vitro dry matter digestibility (IVDMD) and in vitro total sugar release (mg/g DM). The IVDMD% was not affected with cellulase supplementation to sorghum stover from100 to 1600 IU/g DM, beyond which (32000-44800 IU/g), it gradually increased (P < 0. 001) in dose dependant manner and highest (P < 0. 01) IVDMD was observed for concentration of 44800 IU/g. Significant increase (P < 0. 01) in IVDMD was observed with xylanase supplementation to sorghum stover at concentration of 25600-44800 IU/g compared to control and highest IVDMD was observed for xylanase concentration of 44800 IU/g. The in vitro total sugar release from sorghum stover increased gradually in a dose dependant manner with increase in concentration of cellulase and xylanase supplementation from 0 to 44800 IU/g. Based on the in vitro studies the concentration of cellulase and xylanase selected for studying the combination (cellulase and xylanase) effect for sorghum stover were 32000, 38400 and 44800 IU/g of cellulase and 25600, 32000, 38400 and 44800 IU/g of xylanase. The in vitro sugar release was higher with enzyme supplemented singly or in all combinations (range: 35.78 – 57.66 mg/g DM) compared to un-supplemented stover (14.5 mg/g DM). The combination of cellulase-xylanase that gave higher IVDMD for sorghum stover than 38400-25600 (40.30%) followed by 32000 -38400 (42.50%), 44800-25600 (41.89%), 44800-44800 (40.89%), 44800- 32000 (40.82%) and 38400-32000 IU/g (40.30%). Except for combination 44800 cellulase-44800 xylanase, all other 5 combinations were selected to synergistic effect of β-D glucanase supplemented at 0, 100, 200 and 300 IU/g. In case of sorghum stover, no significant effect of β-D glucanase (100-300 IU/g) supplementation to selected cellulase-xylanase combinations were observed on IVDMD. The highest IVDMD was observed for cellulase-xylanase- β-D glucanase combination 44800-32000-0 followed by 44800-25600-0 IU/g. while the in vitro sugar release was higher in all enzyme supplemented stover (range: 48.46 to 56.77 mg/g DM) compared to un-supplemented stover (14.57 mg/g DM) and the increase in sugar release was according to concentration of enzymes. No correlation between IVDMD and in vitro sugar release was observed for the enzymes combinations. Based on IVDMD the best enzyme combination selected for in vivo studies in sheep was 38400 cellulase-25600 xylanase-0 β-D glucanase for sorghum stover.
Similarly, for the maize stover, the IVDMD was affected by supplementing cellulase and xylanase up to 3200 and 800 IU/g respectively. The in vitro sugar release increased gradually with increase in cellulase or xylanase concentration. The highest IVDMD was observed for cellulase concentration 25600 IU/g (23.74%) followed by 12800 (21.99%), 32000 (21.66%) and 6400 (20.79%) IU/g. Similarly the IVDMD was highest for xylanase concentration of 25600 (24.48%) and 32000 (25.14%), followed by 38400 (23.77%), 44800 (23.97%) and 12800 (23.49%) IU/g. These above doses of cellulase and xylanase were selected for investigating the combination effect of these enzymes for maize stover. The ranking of cellulase-xylanase combination for maize stover based IVDMD was 12800-12800 IU/g (49.98%), followed by 25600-25600 (48.55%), 32000-25600 (46.00%) and 25600-12800 IU/g DM (45.89%). For cellulase-xylanase combination, at all cellulase concentration tested (6400, 12800, 25600 and 32000 IU/g), the amount of sugar release (P < 0. 001) with increasing in xylanase concentrations. No correlation between IVDMD and in vitro sugar release was observed, Hence based on the IVDMD, the enzyme combination selected for further in vitro studies with β-D glucanase (100-300 IU/g) was above 3, except the combination 32000 cellulae-25600 xylanase IU/g. Similar to that of sorghum stover, no beneficial effect of β-D glucanase was observed on IVDMD and the enzyme combination 12800 cellulase -12800 xylanase- 0 β-D glucanase was selected for maize stover for in vivo studies in sheep. The in vivo experiment in sheep with the selected exogenous fibrolytic enzyme (EFE) from in vitro studies for sorghum stover and maize stover was conducted by incorporating both these stovers as sole roughage source in total mixed ration (TMR) in roughage concentrate ratio of 50:50. The appropriate amount of enzyme required for each stover in TMR was added to concentrate mixture of TMR diet and later mixed with chopped stover in a large tub manually for about 10 minutes before feeding to sheep daily. The experiment was conducted on 24 ram lambs ( 6-8 months) 20.24 ± 1.442 kg body weight (BW) which were randomly allotted to 4 dietary groups i.e., sorghum stover based total mixed ration (TMR), sorghum stover based TMR supplemented with EFE , maize stover based TMR and maize stover based TMR supplemented with EFE . The lambs were fed with respective diets for a preliminary period of 21 days followed by 7 days collection period. The organic matter, crude protein, ether extract, crude fibre, nitrogen free extract, neutral detergent fibre, acid detergent fibre and cellulose contents were 87.52, 10.49, 2.47, 30.53, 44.02, 74.50, 47.11 and 35.76 % for sorghum stover based TMR and for maize stover based TMR, the corresponding values were 86.77, 10.84, 2.82, 28.25, 44.85, 74.43, 43.24, 31.19 % respectively. No effect of EFE supplementation was observed on chemical composition of diets. Supplementing EFE to sorghum stover or maize stover based TMR had no effect on DM, OM and hemicellulose digestibilities. The NFE digestibility improved (P < 0.05) by EFE supplementation to sorghum stover based diet, while such effect was not observed for maize stover based TMR. Though non significant, the EE and CF digestibility improved by EFE supplementation 7.35 and 8.32% by to sorghum based TMR and 5.82% and 5.76% The cellulase digestibility increased (P < 0.05) with addition of EFE for sorghum stover based TMR but not for maize stover TMR. The NDF and ADF digestibility increased by 8.57 and 6.14 % with EFE supplementation to sorghum stover based TMR. The TDN, DE and ME content significantly increased (P < 0.05) with EFE supplementation to sorghum stover based TMR which was a reflection of higher CF, NFE and EE digestibility, while no effect of EFE supplementation was observed for nutritive value of maize stover based TMR. Lower CP digestibility with EFE supplementation reduced the DCP content of sorghum stover based TMR. All the lambs of various dietary groups were on positive nitrogen, calcium and phosphorus balances. No effect of EFE supplementation was observed on nitrogen and phosphorus balance while calcium balance increased (P < 0.05) with EFE supplementation. The rumen pH values decreased (P < 0.05) with increase in TVFA concentration (P < 0.01) with EFE supplementation, irrespective of roughage source in TMR. The total nitrogen was not affected with EFE addition, while ammonia nitrogen concentration in rumen liquor increased (P < 0.05) in lambs fed on rations supplemented with EFE. Irrespective of the roughage source and EFE supplementation in diet, the peak TVFA, total nitrogen and ammonia nitrogen concentration in rumen was observed at 4h post feeding. From the present study, it could be concluded that supplementation of exogenous fibrolytic enzymes comprising cellulase, xylanase and β-D glucanase developed from in vitro studies to sorghum stover based TMR improved the nutrient
digestibility, ruminal ammonia nitrogen and TVFA concentration in sheep and also nutritive value of ration but such effect was not pronounced on maize stover based TMR, when β-D glucanase was zero it may be removed.
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