Plant Animal Relationship Division, Indian Grassland and Fodder Research Institute, Jhansi-284 003, India
*Reprint request: Dr. A.K. Samanta, Fax: 0517–2730833; E-mail: ashis1966@rediffmail.com
The present experiment was aimed to ascertain the effect of roughage source on rumen metabolites and microbial population with special emphasis on anaerobic fungus. Three adult fistulated cattle (BW∼400 kg) were maintained on three dietary combinations in switch over design viz. T1: ad libitum feeding of natural grass (predominantly Sehima nervosum and Heteropogon contortus) hay, T2: ad libitum feeding of legume (Lablab purpureus) hay and T3: grazing (8 hours/day) on natural pasture in the month of November-December, respectively. In addition, concentrate was offered @ 1% of the body weight in all dietary combinations. Out of three basal roughage diets, obviously the quality of Lablab purpureus hay was better as it contained 12.67% CP and low level of NDF (51.69%). Total volatile fatty acids (TVFA) concentration of rumen liquor varied from 8.53 to 17.66 mmol/dl and reached to the peak levels at 2 h of post feeding in legume based diet. The rumen ammonia nitrogen concentration ranged from 5.64 to 15.09 mg/dl, with the highest concentration recorded at 1 h of post feeding in the legume based diet. The population of rumen bacteria attained peak level at 2 h of post feeding irrespective of dietary combinations. The rumen anaerobic fungal population ranged from 0.98 x 103 to 8.19 x 103 per ml, being highest at 1 h post feeding in all dietary combinations, as was the case with ciliate protozoa population. The anaerobic fungal isolate viz; isolate 5 belonged to Piromyces sp., while the isolate 9 belonged to Anaeromyces sp. Both the isolates were able to secrete the enzymes (endoglucanase and xylanase) for degradation of structural carbohydrates. The metabolic products of anaerobic fungus included lactic acid, acetic acid, etc. The life cycle of polycentric anaerobic fungus comprised of motile zoospore, which gradually developed to matured sporangia through different intermediate stages. It is concluded that the legume based diets ensured better rumen metabolites for growth and multiplication of rumen bacteria, protozoa as well as fungus than grass hay or grazing on natural pasture. The rumen of cattle possessed both monocentric and polycentric fungus capable to secrete endoglucanase and xylanase for utilization of plant structural carbohydrates.
Rumen metabolites, Anaerobic fungus, Life cycle, Roughage source
