Sahiwal cows ( n = 12 ) in early lactation were used to investigate effects of adding fibrolytic enzymes produced from fungus Humicola insolens on their milk production and weight gain. Cows were randomly assigned to two treatments: control and enzyme added to concentrate. The enzyme used was a blend that contained high xylanase and low cellulase activities. The crude enzyme from H. insolens was produced under inducing conditions in a 100 L bioreactor and used for feed applications. The results of present study showed that there was significant increase in weight gain of all the enzyme...