| The roles of borax as urease in sheep were studied and contrasted to acetohydroxamate (AHA) in vitro and in vivo. Effect of AHA, Borax, Hydroquinone (HQ) and catechol (CAT) on soybean urease and rumen microbial urease were investigated in vitro. Effect of Borax and AHA on rumen environment, rumen fermentation, nutrient degradability, apparent nutrient digestibility, nitrogen metabolism and adaptation of sheep to urease inhibitors were investigated. Average live weight of sheep was 41.5 + 1.2kg. Sheep were each surgically fitted with cannula. 4×4 Latin square design and randomly dividing group were used. The animals were adapted for 10 to 15 days before experiment1. At 0.000 lmol/l, 0.001mol/1, 0.01mol/1 and 0.1mol/1 , AHA inhibited soybean urease activity by 6%, 6.2%, 9.66% and 29.79%, HQby 8.4%, 13.03%, 19.79% and 44.75%, CAT by 20.34%, 19.12%, 83.16% and 93.78%, and borax by 16.55%, 17.18%, 18.95% and 35.50%. At the same concentration as the above, AHA inhibited rumen microbial urease activity by 9.58%, 14.04%, 41.30% and 72.73%, HQ by 12.21%, 39.99%, 64.62% and 78.87%, CAT by 6.07%, 9.36%, 31.29% and 50.44%, and borax by 4.97%, 8.63%, 21.78% and 32.02%. The above results suggested that structure of soybean urease was different from that of rumen microbial urease.Ammonia concentration in sheep receiving urease inhibitors was lowed. Borax was less effective inhibitor than AHA and HQ, in accordance with the result in vitro. Borax had same roles with AHA or HQ when the proportion of it to AHA or HQ in weight was 30-40 to 1.2. Numbers of bacterium and protozoon in borax group B (2g borax/kg diet) were not affected. Blood biochemical index were unaffected in borax group A(lg borax /kg diet), borax group B and AHA group (25mg/kg diet). Activity of proteolytic enzyme in rumen for borax/kg group A were increased by 108.2%(p>0.05), AHA group by 173.8%(p>0.05), and borax group B significantly by 200.3% (p<0.05), compared with the control. Activity of urease, cellulose and amylase for all treatments were increased (p>0.05), compared with control. The above results suggested that borax had no adverse influence on rumen microorganism and safe to the sheep at dosage of 2g/kg diet.3. At 1 hour postfeeding, ammonia concentration for borax group A, borax group B and AHA group were decreased by 4.3%, 14.55% and 13.82% respectively (p>0.05). Averageammonia concentration during 8 hours after feeding was decreased by 0.46%, 5.8% and 6.8% for the three groups (p>0.05). The urea concentration for borax group A, borax group B and AHA group were increased by 24.2%, 42.5% and 13.7% at one hour after feeding (p>0.05), and average value of urea increased by 31.8%, 31.2% and 22.99% for the three groups during 8 hours, suggesting urea being kept high value on longer time than the ammonia. Rumen pH value of rumen fluid at different intervals was unaffected by borax or AHA. At two hour after feeding, acetic acid and SWA (Sum of thtee VFA)for borax group A were higher than the other treatments, but propionic acid of which was only higher than AHA group (p<0.05). At other sampling time, acetic acid, propionic acid, butyic acid and SVFA were unaffected by borax and AHA. Acetic acid/propioc acid was unaffected at all sampling time. During 10 hours, average value of acetic acid, propionic acid, butyic aced, SWA and acetic acid/propionic were increased by borax and AHA (P>0.05).4.The results showed that degradability rates of DM for borax group A, borax group B and AHA group were increased by 0.68%, 12.3% and 17.1% respectively for 24 hours incubation (p<0.05), but for AHA group by 12% for 48 hours incubation (p<0.05). Degradability rate of protein was not affected by borax or AHA from 6 to 48 hours incubation, Degradability rates of ADF for borax group A and AHA group were higher than the control for 6 hours incubation (p<0.05), and it was not different at the other incubation time (p>0.05). Degradability rates of NDF for borax group A and AHA group were 8.8% and 11.52% higher than the control for 24 hours incubatio...
|
PDF Full Text Request